Microfilaruria in onchocerciasis

Bull. Org. mond. Sanfl 1971, 45, 353-369Bull. Wid Hlth Org. Microfilaruria in Onchocerciasis A Clinical and Epidemiological Follow-up Study in the Republic of Chad* ALFRED A. BUCK,1 ROBERT I. ANDERSON,2 JOHN A. C. COLSTON, JR,3 CRAIG K. WALLACE,4 DANIEL H. CONNOR,5 LOUIS E. HARMAN, JR,6 MARTIN W. DONNER7 & JAMES P. GANLEY8 Microfilariae of 0. volvulus were recoveredfrom the urine of 11 % of the residents ofa village in the Republic ofChad where onchocerciasis was holoendemic. A follow-up study of the same population 3 years after the original investigation revealed that microfilaruria was still present and that living microfilariae of 0. volvulus could be recovered from small urine samples obtained by high catherization of the ureters. Radiological changes consistent with chronic pyelitis were found in 4 out of 14 persons with microfilaruria who were exa- mined by retrograde pyelography. The recovery of microfilariae in the urine was associated with the intensity of the infection, as determined by counts of microfilariae in skin snips and the number of onchocercomata. A systematic comparison for differences between onchocerciasis patients with and without microfilaruria revealed that the microfilaruria patients had a low weight: height ratio, deficient antibody responses in indirect haemagglu- tination tests with 0. volvulus antigen, elevated serum aminotransferase levels, and reduced systolic blood pressure. The presence of microfilariae of Onchocerca lvolvulus in urine samples of patients with onchocer- ciasis has been noted sporadically (Dyce Sharp, 1926; Liberia Research Unit, 1969; Oomen, 1969; Price, 1961). Buck et al. (1969) reported onchocercal * This study was supported by the Medical Research and Development Command of the US Army, Washington, DC, USA 1 Professor, Department of Epidemiology and Department of International Health, The Johns Hopkins University School of Hygiene and Public Health, Baltimore, Md., USA. 2Associate Professor, Department of Epidemiology and Department of International Health, The Johns Hopkins School of Hygiene and Public Health. 3 Instructor, Department of Surgery, Division of Urology, The Johns Hopkins Hospital, Baltimore, Md., USA. 4 Associate Professor, Department of Medicine and De- partment of Pathobiology, The Johns Hopkins Hospital. 6 Chief, Geographic Pathology Division, Armed Forces Institute of Pathology, Washington, DC, USA. 6 Chief, Department of Dermatology, Walter Reed Gene- ral Hospital, Washington, DC, USA. Present address: Asso- ciate Professor, Department of Dermatology, University of Virginia Medical Center, Charlottsville, Va., USA. 7Professor, Department of Radiology and Department of Radiological Science, The Johns Hopkins Hospital. 8 Research Fellow, Department of Epidemiology, The Johns Hopkins University School of Hygiene and Public Health, and Department of Ophthalmology, Wilmer Clinic, The Johns Hopkins Hospital. microfilaruria in 11 % of the population of a small village in the Republic of Chad where onchocerciasis was holoendemic. The findings were based on microscopic examinations of sediments obtained by triple concentration of large urine samples (Buck et al., 1969). The method was originally used as a rou- tine procedure in epidemiological studies to count the number of ova of Schistosoma haematobium in urine specimens of the residents of five contrasting communities in Chad (Buck et al., 1970). All examinations of the thiomersal-preserved urine sediments were made in Baltimore after the comple- tion of the entire study in Chad. This practice ruled out any possibility of conducting specific investiga- tions of this unusual manifestation of onchocerciasis while the team was still in the field. Analysis of the available data from the study revealed that the occurrence of microfilaruria was closely associated with the intensity of the skin infection with microfilariae of 0. volvulus, as determined by worm counts in routinely taken skin snips, and with the distance of the residences of the villagers from the Lim River, the only water body near the village that provided ideal conditions for continued breeding of Simulium damnosum, the 2733 - 353 - 354 A. A. BUCK AND OTHERS vector of onchocerciasis in the area. The analysis of the data provided no evidence that onchocercal microfilaruria was correlated with other endemic infections, notably schistosomiasis (S. mansoni and S. haematobium), malaria, loaiasis (Loa loa), and Wuchereriasis (W. bancrofti) (Buck et al., 1969). The clinical and epidemiological follow-up studies of microfilaruria were conducted in the same village between January and March 1970, exactly 3 years after the original investigations in Chad. The study had the 5 following principal aims: (1) to investigate whether onchocercal microfila- ruria had persisted as a relatively frequent clinical manifestation of onchocerciasis in the indigenous population; (2) to make taxonomic studies of the microfilariae recovered from urine samples for proper identifica- tion; (3) to determinate the portal of entry of the microfilariae into the urinary system; (4) to study specific clinical features of patients who had microfilaruria; and (5) to make systematic comparisons between persons with and without microfilaruria for clues to its pathogenesis. MATERIAL AND METHODS The investigations were carried out in a population sample in the village of Ouli Bangala, Republic of Chad (latitude 7°50' N., longitude 15° 52' E.). A detailed description of the environmental, cultural, and epidemiological features of this community of Laka tribesmen is given elsewhere (Buck et al., 1970). In the original study in 1967 the entire population of the village was examined so that reliable estimates of the prevalence of various endemic infections could be obtained (Buck et al., 1969, 1970). The population sample of the follow-up study included mainly families with residences in the immediate vicinity of the Lim River, where onchocerciasis was severe (Buck et al., 1969). This " purpose sampling " of households was preferred procedure for saving time and money because the denominator for the follow- up study should comprise only onchocerciasis patients with and without microfilaruria, who were similar with respect to other host and environmental characteristics. A total of 153 individuals, 79 males and 74 females, belonging to 34 households were selected from a map of the village on which all houses were listed. The routine examinations included (1) the listing of all family members by name, age, sex, degree of relationship to the head of household, and old (1967 study) and new house and family numbers; (2) mea- surement of body height and weight and of skinfold thickness at the midposterior midpoint of the upper arm over the m. trapezius and the epigastrium; (3) skin tests with PPD-S (Mycobacterium tuberculo- sis) and PPD-G (Myco. gause), S. mansoni antigen, and buffered saline; (4) a screening examination of the eyes by an ophthalmologist; (5) a screening examination of the skin for the presence of onchocer- coma (number and site), and other skin manifesta- tions of onchocerciasis, by a dermatologist; and (6) a standardized physical examination by a physi- cian. Urine and stool specimens were taken routinely and a 10-ml blood sample was drawn by vene- puncture. Skin snips for microfilarial counts were taken with a comeal-scleral biopsy instrument from the back, approximately 2 cm above the iliac crest as described previously (Buck et al., 1969). In addition to these routine procedures, a variety of special examinations were carried out on selected patients, including eye examinations by slit-lamp and funduscopy, conjunctival snips, punch biopsies from patients with specific skin lesions, liver needle- biopsies, and aspiration of bone marrow by sternal puncture. The findings of the study concerning ocular onchocerciasis and dermatological and pathological aspects of the disease will be published elsewhere. A number of families with known cases of micro- filaruria from the 1967 study were the first to be invited for examination. In addition to submitting the routine urine sample requested from all persons included in the study, these subjects were asked for a second urine specimen, which was examined imme- diately in the field for the presence or absence of microfilariae of 0. volvulus. The first 18 adults in whose urine microfilariae were found, and who, after explanation of the procedure, gave their informed consent, were selected for cystoscopy. Two persons with negative urine examinations were also examined as controls. After cystoscopic examination, 1 catheters were inserted into both ureters up to 20-24 cm and left in situ for 10-20 minutes for collection of urine samples from the left and right sides. These speci- 1 21F Brown Buerger cystoscopes, disposable ureteral catheters No. 6F, and pre-sterilized disposable catheter trays (supplied by C. R. Bard, Inc., Summit, N.J., USA) were used in the study. MICROFILARURIA IN ONCHOCERCIASIS 355 Table 1. Methods for laboratory procedures. Procedure Reference skin snip Buck et al., 1969 haemagglutination using 0. volvulus antigen Buck et al., 1 969 urine specimens Buck et al., 1 969 blood smears Buck et al., 1970 haematocrit Buck et al., 1970 haemaglobin Buck et al., 1970 stool specimens Buck et al., 1 970 serum chemistry SGOT " urea nitrogen a creatinine a total protein a cholesterol Zurkowski, 1 964 serum electrophoresis Grunbaum et al., 1963 immunoglobulins Cawley, 1969 routine field laboratory Buck et al., 1970 a See Instruction manual UM-IM-2; ultramicro analytical system, Beckman Instruments Inc., Fullerton, Calif., USA. mens were examined immediately for the presence of microfilariae. In addition to recording the number of larval worms, it was also noted whether they were living or dead. After collection of the urine samples, retrograde pyelography was performed by injecting 3-5 ml of contrast medium 1 into each catheter. The equip- ment used in the field consisted of a pulsed X-ray system 2 powered by a 3 000 W alternator and 14x 17 grid cassettes (75 lines, ratio 8 :1) 3 supplied with a high-speed X-ray screen, 4 and X-ray safety film 5 was used. The average exposure time was 5-7 seconds. Three films were taken for each I Retrografin, supplied by E. R. Squibb & Sons, Inc., New York, N.Y., USA. 2 Fexitron Medical X-Ray System, Supplied by Field Emission Corporation, McMinnville, Greg., USA. 3 Camplysholm Grid Cassette, supplied by Picker X-Ray Corporation, White Plains, N.Y., USA. I DuPont Patterson Hi-Speed Intensifying Screens, supplied by E. I. DuPont de Nemours & Co., Inc., Clifton, N.J., USA. 6 DuPont Cronex V X-Ray Film, supplied by E. I. DuPont de Nemours & Co., Inc., Clifton, N.J., USA. patient, a film of the abdomen before pyelography, a second film immediately after the injection of the contrast medium, and a third after the partial withdrawal of the catheters and reinjection of contrast medium. A variety of selected laboratory procedures used routinely in the study is shown in Table 1. RESULTS Frequency of microfilaruria Of the 136 individuals in the study from whom skin snips were taken, 72 (52.90%) had also partici- pated in the original investigations in 1967. Since the methods of taking skin snips and counting microfilariae were the same in both studies, it was possible to make comparisons for time-related differences in the intensity of the skin infection. Of the 72 individuals from whom paired data are available 26 (36.1 %) had similar counts; in 7 (9.7 %), the number of worms had decreased; but in 39 (54.2%) the infection had increased. Table 2 shows the percentage of persons who had microfilariae in single skin snips as well as the mean number of micro- filariae recovered from these snips. There appears to be a tendency for both the prevalence and the inten- sity of the infection to increase with progressing age. Nevertheless, the greatest rate of increase in the infection rates of the local population occurs within the first 4 years of life, as described previously (Buck et al., 1969). There were no significant Table 2. Prevalence of onchocerciasis and mean microfilarial counts in skin snips. Microfilariae in skin snip Age Number No. Percentage Mean positive positive counta 5-9 26 21 80.8 436 10-19 36 33 91.7 94.2 20-29 17 15 88.2 43.8 30-39 29 27 93.1 78.4 -40 28 28 100.0 110.0 total 136 124 91.2 79.7 a Positive snips only; males: 81.2, females 76.4. For difference t = 0.31. A. A. BUCK AND OTHERS Table 3. Prevalence of palpable nodules (onchocercoma) and of microfilaruria, by age. Age II 5-9 10-19 29-29 30-39 -40 total differences the prevak of subjects their urine ciation bel filaruria is ruria was when 20% the Lim I number 01 10.2 per 11 and a max As Buc distributio families in significant The questi of onchoc With nodules With microfilaruria or were of only temporary significance-i.e., the first aim of the study-can be answered: the micro- filaruria had indeed persisted. Number o No. Taxonomic studies - I - = -=- -- Urine sediments and the supernatant fluid of skin 13 52.0 8 32.0 snips macerated in saline were preserved in 1000 for- 25 1 3 52.0 8 32.0*°25 lmol and examined for microfilariae. The larvae were 36 26 72.2 14 38.9 isolated by centrifugation and stained overnight in 17 10 58.8 6 35.3 l-ml test-tubes with haematoxylin. Excess stain was 29 23 79.3 10 34.5 removed by centrifugation and the microfilarae were 28 20 71.4 8 28.6 transferred to slides for microscopic examination. __________________ |All microfilariae, regardless of their source, had the 135 1. 92 68.1 46 34.1 same general characteristics, i.e., they were sheath- less, had no terminal nuclei, had a slightly curved tail ending in a sharp point, and had dimensions that were consistent with those described for micro- filariae of 0. volvlilus (Belding, 1965). Fig. 1 (A) is between the two sexes. Table 3 presents a photomicrograph of a microfilaria recovered from once of onchocercoma and the proportion a urine sample, and Fig. I (B) is a view of the tail in the sample who had microfilariae in section of a larva found in a urine sample that was specimens. No clear-cut pattern of asso- obtained by ureter catheterization. Although the :ween age and onchocercoma and micro- microfilariae of both the skin and urine samples detectable. The frequency of microfila- had the same general morphological characteristics, 34.1 0' (about 14o% higher than in 1967, they had slight but statistically significant differences of the villagers who lived in the vicinity of in their length. The findings are summarized in Table River had this condition). The average 4 and show that the microfilariae from the urine f microfilariae excreted in the urine was samples were about 5 ,tm longer than those recovered 00 ml with a minimum of 1.5 per 100 ml from skin snips. The relative significance of this limum of 30.6 per 100 ml. difference is further amplified by the results shown :k et al. (1969) found previously, the at the bottom of the table, where a direct comparison n of microfilaruria within and between the of worm sizes from a urine sample and a skin snip .cluded in the study showed a statistically of the same patient is made. In contrast, only trivial familial aggregation of cases (P = 0.02). discrepancies were observed in the length of micro- ion of whether the urinary manifestations filariae obtained from the skin snips of persons with erciasis had persisted in the community and without microfilaruria. Table 4. Measurements of microfilariae by source of recovery. Source of microfilariae skin urine skin from patient with microfilaruria skin from patient without microfilaruria skin from case no. 096 urine from case no. 096 No. of worms measured 118 41 58 60 10 18 Length of microfilariae Mean SD SE ('m) (Mm) (>m) 311.1 316.3 310.8 311.4 309.5 318.9 9.7 8.7 9.3 10.1 5.5 9.2 0.89 1.35 1.26 1.31 1.74 2.16 t for difference 3.15 0.33 2.94 356 Fig. 1. Microfilariae from urine specimens, preserved in 10 % formol and stained with haematoxylin: (A) whole specimen (315 x 7 jim); (B) tail section. Fig. 2. Delayed film of a retrograde pyelogram (left) of a 40-year-old woman with microfilaruria to show calyceal distortion in the middle and lower system, and backflow of contrast medium from the lower calyces into the renal papillae on the left side. The radiographic changes are compatible with chronic infection and suggest focal papillary necrosis. The left upper calyceal system and the right kidney are normal. MICROFILARURIA IN ONCHOCERCIASIS Table 5. Mean length of microfilariae by source of recovery. Source of microfilariae a (1 ) frozen skin (2) skin preserved in 10 % formol (3) urine sediment preserved in 10 % formol (4) skin, placed in urine for 3 hours (5) skin, placed in urine, sediment preserved in 10 % formol overnight a Comparisons: 1-2, t=1.57; 1-3, t=3.84; 1-4, t=1.32; 1-5, t=5.0; 3-5, t=0.84. An experiment was conducted to investigate whe- ther the longer microfilariae in the urine might have resulted from their exposure to this biochemically unusual milieu. For this reason, living microfilariae recovered from deep-frozen skin snips (kept in the field and during transportation at - 1900C and in Baltimore at -80°C) were transferred to urinesam- ples, with and without preservation of the sediment in 10% formol. The length of the larvae was measured and compared for differences. The results are shown in Table 5. Statistically significant differences were observed only between microfilariae recovered from skin snips and those obtained from formol-preserved urine sediments. This finding indicates that the increased length of the larval worms has resulted from their extension in urine that contained formol; the width of the microfilariae was not measurably affected by the treatment. Portal of entry of microfilariae in the urinary system As already described, 20 subjects were selected for cystoscopy, ureter catherization, and retrograde pyelography after they had been screened for micro- filaruria; 18 had microfilaruria in the pre-examination and 2 with negative urine findings were selected as controls. The cystoscopic findings and the results of parasitological examinations of urine samples ob- tained by catheterization are summarized in Table 6. Of the 18 prescreened subjects with microfilaruria, 14 (78%) again had microfilariae in their bladder urine; 9 (50 %) yielded microfilariae in the small urine samples obtained by catheterization of the right ure- ter; and 5 (33 %) of the 15 specimens collected from the catheter in the left ureter were found to have larvae of 0. volvulus. Recovery of microfilariae from both sides was possible in 3 cases. In all, 11 (61 o/) of the 18 prescreened patients had microfilariae in ureter specimens. Of the two controls, one was positive for micro- filariae in the bladder urine. With the exception of one woman who had lesions of S. haematobium, con- firmed by biopsy, the bladder mucosa of all persons was normal. From the cystoscopic findings, there was no evidence to suggest that the microfilariae had entered the urinary tract in the bladder. This con- clusion is strongly supported by another finding made in the study. While 8 (44.4%) of the microfilaruria patients had living motile microfilariae in their urine samples collected from the ureters, all the larvae seen in the bladder urines were dead. The finding of schistosomiasis in only 1 (5 %o) of the 20 patients examined by cystoscopy is in good agreement with the overall prevalence of 6.50% of the infection in the general population. A more detailed discussion is given in the section dealing with differences be- tween onchocerciasis patients with and without microfilaruria. The third aim of the study was to find the portal of entry of the microfilariae into the urinary system. Although a final answer cannot be given, the results indicate that they enter the urinary tract somewhere in the kidney. Specific, clinical, and radiological findings associated with microfilaruria Of the 20 subjects selected for pyelography, 9 were males and 11 females. An unequivocal radiological diagnosis was possible in only 14 because 6 pyelo- S.D. S.E. Mean length (ginm) 309.7 311.9 316.4 312.0 318.0 L 1 0.4 _,_9.9 18.7 -.10.2 9.4 Number 100 100 40 50 50 :1.04 _L 1.00 -1. - 1.4 . 1..: 3 357 A. A. BUCK AND OTHERS Table 6. Cystoscopic diagnosis and parasitological findings in bladder and ureter urine specimens. Case Age Sex Cystoscopic diagnosis 1 26 M normal 2 13 F normal 3 40 F grade trabeculation 4 38 M normal 5 40 F 3 3x5-mm granulomas a 6 39 F normal 7 20 F normal 8 25 M normal 9 40 M normal 10 18 M normal 11 29 M normal 12 30 F normal 13 40 F normal 14 22 M normal 1 5 40 M grade trabeculation 16 33 F normal 17 31 F filmy yellow patch right base; no inflammation 18 35 F normal control 1 2 50 50 M F Igrade 1 normal trabeculation Cystoscopic bladder specimen Volume Micro- (ml) filariae 63 21 50 70 35 70 35 55 35 140 72 83 45 80 70 140 30 220 60 30 2 dead 0 1 1 dead 3 dead 2 dead 1 9 dead 0 1 dead 3 dead 9 dead 22 dead 9 dead 0 1 1 dead 0 14 dead Left catheter Depth Volume Micro- (cm) (ml) filariae . ..20 4 20 20 23 25 2 23 22 24 2 23 24 5 25 25 5 5 8 0 6 2 1 5 0 5 13 5 2 7 6 dead 24 6 dead 24 2 5 2 dead 22 2 0 23 4 __L_ 4 living 2 living 0 0 20 living 0 1 dead 0 0 2 living 0 0 0 0 0 0 Right catheter Depth Volume Micro- (cm) (ml) filariae 20 20 20 20 23 25 23 23 22 24 24 23 24 24 25 25 24 24 3 2 5 5 8 8 3 7 2 14 8 9 9 1 3 5 8 0 3 dead 7 living 4 living 1 living 16 living 0 4 dead 2 living 0 2 living 0 0 0 0 0 1 0 5 2 dead 22 1 0 23 4 0 "i Numerous ova of S. haematobium at biopsy. grams were non-diagnostic on account of poor quality related to long exposure times and technical limi- tations of the X-ray equipment that had to be used in the field. Of the 14 readable pyelograms, 4 showed definite and similar pathological changes, while 2 showed doubtful abnormalities. The radiological findings consist of calyceal dis- tortion without significant evidence of obstruction. The fine details of calyceal outline are lost, the for- nices blunted, and the mucosa appears irregular but without definite signs of ulceration. The radio- graphic changes are compatible with chronic infec- tion and are suggestive of focal papillary necrosis. As an example of the findings, the pyelogram of a 40-year-old woman is shown in Fig. 2. Urine examinations for protein and cellular com- ponents in the sediment revealed that most of the individuals with microfilariae in urine had mild albu- minuria not exceeding a concentration of 30 mg of protein per 100 ml. The findings are summarized in Table 7. The results of the microscopic examinations of the urine sediments of 25 patients with micro- filaruria, including all those who were examined by cystoscopy, are presented in Table 8. With one exception, all persons had leucocytes, and the majo- rity also red cells, in their urine specimens. Epithe- lial cells were present in all but 2 of the urines examined, including 7 samples with renal epithelium. The systolic and diastolic blood pressures of all sub- jects with microfilaruria were normal; none exceeded 358 MICROFILARURIA IN ONCHOCERCIASIS Table 7. Frequency of proteinuria in a non-random sample of residents with and without microfilaruria of 0. volvulus. Protein in No. urine 2 Residents examined x No. % with microfilaruria 24 16 66.7 6.7 without microfilaruria 29 9 31.0 135 mm Hg. The mean values were 105/70 for the microfilaruria group and 113/71 for the controls. A systematic comparison of the frequency distribu- tions of blood pressure values in all subjects with and without microfilaruria is shown in the following section, together with other findings made in the study. There was no evidence of impaired kidney function from the examination of serum urea nitro- gen and creatinine levels. The mean value of urea nitrogen was 9.5 mg/100 ml for subjects with micro- filariae in the urine and 8.9 mg/100 ml for those with- out. The corresponding mean levels for serum crea- tinine were 1.09 mg/100 ml in each group. The speci- fic gravity of the urine samples of subjects with micro- filaruria submitted for examination ranged from 1.001 to 1.022. The findings are consistent with chronic pyelitis and do not provide evidence that the worms produced nephritis. Table 8. Results of microscopic examinations of urine sediments of 25 patients (14 male and 11 female) with microfilaruria. No. of cells Leuco- Erythro- Epithel Castscytes cytes cells a Ca none 1 9 2 25 1 in 10 or more fields b 6 4 5 1 in 5-9 fields 8 6 3 1-4 per field 6 4 7 5-9 per field 0 1 1 >10 per field 2 1 c 1 clumps 2 0 6 a 7 patients had renal epithelial cells. b High-power field. c Patient with ova of S. haematobium. Comparisons between subjects with and without micro- filaruria The study of onchocerciasis in 1967 showed a statistically significant association between the fre- quency of microfilaruria and the number of micro- filariae in skin snips (Buck et al., 1969). A similar comparison was made in the present study. The re- sults are shown in Table 9. The mean counts were 98 microfilariae in skin snips for the microfilaruria group and 65.5 for the controls. The difference is on the borderline of statistical significance (P = 0.09). The proportion of subjects without microfilariae in their skin snips was similar in the two groups. Table 9. 0. volvulus skin counts and prevalence of microfilaruria. Microfilarial With microfilaruria count in No. in With_mcrofiaruri skin snip group No. 0 13 3 23.1 1-20 27 7 25.9 21-50 23 6 26.1 51-100 56 1 8 32.1 >200 1 7 9 52.9 total 136 43 31.6 The absence of palpable nodules (onchocercoma) in a considerable proportion of subjects with positive skin snips for onchocerciasis has been observed fre- quently (Augustine, 1957; Dyce Sharp, 1926; Nelson, 1966). The adults of 0. volvulus are not confined to the subcutaneous tissues but have been found in deeper tissues (Nnochiri, 1964; Steen & Price, 1964). One might speculate that the presence of micro- filariae in the urine could be related to their origin in parent worms living atypically in the deeper tis- sues. A comparison of the frequency by age of microfilaruria among subjects with and without pal- pable onchocercomata is shown in Table 10. Sex is disregarded in this and the following tables because an analysis revealed that differences were trivial. As can be seen, microfilaruria was equally frequent in subjects with and without nodules. If a relationship is assumed between the intensity of infection with 0. volvulus and the frequency of microfilariae in urine it might be speculated that the 359 A. A. BUCK AND OTHERS Number of palpable nodules )mo 1Go562 Fig. 3. Percentage distribution of the number of palpable nodules (onchocercoma). Solid line, subjects (91 ) without microfilaruria; broken line, subjects (45) with micro- filaruria. number of parent worms including those surrounded by fibrous tissue and recognizable as palpable nodules would be larger in the microfilaruria group than among persons without urinary onchocerciasis. A graphical presentation for comparison of the two groups is shown in Fig. 3. A more detailed analysis of the data revealed that about one-third of the sub- jects in either group had no palpable nodules (for Table 10. Frequency of microfilaruria among persons with and without palpable nodules (onchocercoma). Nodules absent Nodules present (years) No. in Microfilaruria No in Microfilaruria group No. % group No. % 0-9 12 4 33.3 13 4 30.8 10-19 10 2 20.0 26 12 46.2 20-29 7 2 28.6 10 4 40.0 30-39 6 2 33.3 23 8 34.8 > 40 6 3 50.0 22 5 22.7 total 41 13 31.7 94 33 35.1 differences between groups P = 0.4), but that the number of nodules among those with any evidence of onchocercoma was statistically significant with an average of 3.1 nodules per person in the microfilaruria group by comparison with 2.4 among the controls (P = 0.05). It should be emphasized that the clinical and laboratory data are based on the independent work of different specialists. Only at the time of the analysis of the data were the results of the various measurements revealed and used for cross-tabulation. It was interesting to compare the distribution of the onchocercomata by body site for differences be- tween the microfilaruria and the control groups. Table 11 shows the proportion of persons who had nodules in three major regions of the body. While all subjects in the microfilaruria group had palpable onchocercomata in the lower part of the body, only 77% of the controls had nodules at this site. A com- parison of the frequencies with which nodules were recognized at each of the three sites reveals a statisti- cally significant difference only for the pelvic regions and the legs; the dissimilarities in the proportion of nodules at the other two sites were trivial. The protocol of the physical examinations had special categories for recording the presence of en- larged lymph nodes by site. While there were only a o co w CL 360 MICROFILARURIA IN ONCHOCERCIASIS Table 11. Distribution of nodules (onchocercoma) in local residents with and without microfilaruria, by site; only individuals with palpable nodules are included. Without micro- With micro- filaruria filaruria Site of nodules (62 subjects) (33 subjects) x2 fordifference a No. in No. in group group % head and neck 4 6.5 3 9.1 0.22 thorax 32 51.6 19 57.8 0.31 pelvis and legs 49 77.1 33 100.0 8.02 a Disregarding combinations. scattered records of lymphadenopathies in the cervi- cal, submandibular, and axillary regions (too small in number for valid statistical analysis), enlargement of two categories of regional lymph node, inguinal and general, was noted with relatively great fre- quency. A comparison of the proportion of subjects with these two types of lymphadenopathy between the microfilaruria and control group is presented in Table 12. The results indicate that enlargement of inguinal lymph nodes was significantly more frequent among persons who had excreted microfilariae in their urine. Because the microfilaruria patients have quantita- tively heavier infections than subjects in the control group, as indicated by microfilarial counts and num- bers of nodules, it could be expected that they would also have higher antibody titres in serological tests using antigens prepared from 0. volvulus. The distri- bution curves of titres observed in indirect haemag- Table 12. Inguinal and general lymphadenopathy among local residents with and without microfilaruria. Microfilaruria Microfilaruria Type of 11absent present 2 lymphadenopathy (110 subjects) (46 subjects) x2 No. % No. % inguinal 28 25.5 20 43.5 4.9 general 51 46.4 20 43.5 0.1 both types 79 71.9 40 87.0 4.1 120w 4, 20 - Z a 10 -V 0. wHO 10363 <50 100 400 1600 Reciprocal haemagglutination titre to 0. volvulus Fig. 4. Percentage distribution of antibody titres in indirect haemagglutination tests with 0. volvulus antigen. Solid line, subjects (42) with microfilaruria; broken line, subjects (85) without microfilaruria. glutination tests with 0. volvulus antigen are shown in Fig. 4. The results are paradoxical because only 57% of the subjects with urinary onchocerciasis have significant titres of 1: 100 or more, whereas the comparable figure for the controls was 80% (P = 0.01). In the microfilaruria group there appears to be an immunological imbalance as reflected by the relative abundance of antigen and lack of anti- body. A similar finding was made in the previous study of the same population when Dirofilaria immi- tis instead of 0. volvulus was used as the antigen in the test. There were various co-endemic infections in the area that could have led to conditions in the host likely to promote onchocercal microfilaruria-notab- ly, filarial infections with Dipetalonema perstans, Loa loa, and Wuchereria bancrofti, schistosomiasis, and malaria. With the exception of W. bancrofti in- fections, adequate diagnostic information was pro- vided by the methods used routinely in the study. For estimates of the frequency of infections with W. bancrofti, which has nocturnal periodicity, a special night study was conducted. The results are included in Table 13, which compares the micro- filaruria and control groups for each type of infec- tion. Only two of the various categories had diffe- rences of a magnitude that was at the borderline of statistical significance, i.e., L. boa and malaria for persons who were 10 years of age or over. It is inte- resting to note that the proportion of microfilaruria patients who had plasmodia in blood smears showed no decrease with age, as is usually found in areas of 361 A. A. BUCK AND OTHERS Table 1 3. Frequency of schistosomiasis, filaraemia, and malarial parasitaemia in persons with and without onchocercal microfilaruria. With microfilaruria Infection S. haematobium ova S. mansoni ova D. perstans L. loa W. bancroftia P. falciparumIP. ma/ariae subjects under 10 years subjects over 1 0 years Without microfilaruria No. of Subjects No Subjects subjects with infection examined with infection examined (% exmne % Difference between groups 46 6.5 108 6.5 0 43 39.5 99 36.5 3.0 43 30.2 92 32.6 -2.4 43 18.6 92 7.6 11.0 43 7.0 92 5.4 2.4 5 40.0 1 6 62.5 -22.5 38 47.4 7 1 29.6 17.8 0 Night study results included. endemic malaria; the control subjects, however, showed the typical pattern. Subjects with onchocer- cal microfilaruria had twice as many proved infec- tions with L. loa as the control group. Whether these associations indicate a causal relationship of the sec- ond infections with onchocercal microfilaruria, or re- flect a general deficiency of host responses to infec- tions, or are merely spurious, cannot be decided at this time. A comparison of the ratios of age-adjusted body weight (in pounds) to height (in inches) for micro- filaruria patients and the control subjects revealed the following differences: among patients, the ratio was 1.31 for males and 1.41 for females; among con- trols, it was 1.43 for males and 1.44 for females. A systematic comparison of the data by age and sex for a statistical test of significance of the differences in the weight: height ratios revealed that for males P = 0.04 but for females P = 0.3 only. Another method of assessing the magnitude and possible dif- ferences of weight changes in onchocerciasis patients with and without urinary symptoms was possible because of the availability of comparable data from the 1967 study. The mean weight loss of all 10 micro- filaruria patients who were at least 20 years old in 1967 was 8.4 lb (3.8 kg) during the 3-year period, while that of 21 adults with proved infection of onchocerciasis without microfilaruria was 2.3 lb (I kg). The difference was not significant statisti- cally (t = 1.64), perhaps because of the small sample sizes. Another longitudinal study of weight changes was made by correlating the number of microfilariae in skin snips from the 1970 study to changes in the weight : height ratio that had occurred in all subjects who were at least 15 years old in 1967. The corre- lation coefficient r = -0.45 indicates that nega- tive changes of the weight: height ratio are associ- ated to some degree with increasing worm loads in the skin. Table 14 shows the mean differences in the weight: height ratio computed from the paired data of each adult who had participated in both stu- dies. The results suggest that weight loss is associ- Table 14. Changes of the weight: height ratio (W: H) between 1 967 and 1970 studies in relation to microfilarial counts in skin snips. Skin snip No. in Mean W: H Dif count group for 1970 W: I <50 50-1 00 >100 25 14 4 1.74 1.67 1.27 Fference in t forA 1967-70 difference +0.01 0.5 -0.05 1.1 -0.27 3.5 x2 p 0.13 0.08 3.59 0.13 0.80 3.41 0.5 _0.5 0.06 0.5 0.4 0.07 362- MICROFILARURIA IN ONCHOCERCIASIS 40 ,,, 30' ._ cn o 20 wa, CDa, 0 40 60 80 100 120 Blood pressure (mm Hg) 140 160 180 WHO 10364 Fig. 5. Frequency distributions of systolic subjects (41) with microfilaruria; broken ated with heavy worm loads. Observations of weight differences made in Liberia, comparing subjects with and without evidence of onchocerciasis, indicated that infected persons were relatively underweight (Libe- ria Research Unit, 1969). In our present study there were 6 persons (4 males and 2 females) with severe cachexia; all had skin counts of 200 or more micro- filariae per snip, and 5 of these 6 subjects had micro- filaruria. Pulmonary tuberculosis as a possible reason for wasting was ruled out by radiography. Other than an elevated L-aspartate: 2-oxoglutarate amino- transferase (2.6.1.1, SGOT) level in all 6 subjects there were no detectable differences in the spectrum and frequency of infections that were not also typi- cal of the entire population sample of the village. From the available information it is suggested that onchocerciasis may be a cause of wasting, and this may be aggravated further by malnutrition and simul- taneous chronic infections with other agents. As has already been mentioned, the blood pres- sures of persons with microfilaruria were lower than those of control subjects in groups with the same age composition. Fig. 5 shows the frequency distri- butions of the systolic and diastolic blood pressures for the two subgroups of onchocerciasis patients. The systolic means were 105 mm Hg in the microfila- ruria group and 113 mm Hg in the controls (t = 2.7); and diastolic blood pressures. Solid line, line, subjects (89) without microfilaruria. the diastolic values were similar with 69 and 71 mm Hg, respectively. The observed difference in systolic blood pressures fits the hypothesis that microfila- ruria is more often present in patients whose general physical condition is reduced by chronic infections and malnutrition. The prevalence of hepatomegaly was high in the population. A comparison of differences between the microfilaruria and control groups is shown in Table 15, separately for ages below and above 10 years. Hepatomegaly in adults was more frequent among subjects who had microfilariae in the urine than in Table 1 5. Frequency of hepatomegaly in residents with and without microfilaruria of 0. volvulus. Without microfilaruria With microfilaruria Age Hepato- Hepato- x2 forNo. in megaly No. in megaly difference group group No. 'I%No.< % 0-9 35 25 71.4 9 7 77.8 0.15 .10 73 I 21 28.8 36 17 47.2 3.62 total 108 46 42.6 45 24 53.3 1.48 7 363 A. A. BUCK AND OTHERS 40 30 20 I10 0 <20 20-39 40-59 60-79 80-99 > 100 Units of SGOT we: 10365 Fig. 6. Percentage distribution of SGOT levels. Solid line, subjects (43) with microfilaruria; broken line, subjects (95) without microfilaruria. the controls. Enlargement of the liver in an area where malaria is hyperendemic is frequently indi- cative of that disease. Since there was no difference between the two groups in the proportion of subjects who had ova of S. mansoni it is conceivable that the higher rates of hepatomegaly among subjects over the age of 10 years with microfilaruria may reflect the observed differences in the prevalence of malaria, as shown in Table 13. An interesting finding is shown in Fig. 6, which presents the percentage distribution of SGOT levels for subjects with and without microfilaruria. The differences between SGOT means and between the proportion of subjects in each group who had normal aminotransferase values are both statistically signifi- cant (P = 0.03; P = 0.05). Elevation of SGOT is frequently associated with parenchymal damage, pre- dominantly of the liver. It was, therefore, neces- sary to compare subgroups of persons with and with- out hepatomegaly in the microfilaruria and control groups for the degree of association with SGOT ele- vation. The results are summarized in Table 16 and are conclusive. There is no evidence that the presence of hepatomegaly has contributed to the high serum aminotransferase levels in either group of onchocerciasis patients. Moreover, the SGOT means are consistently higher in the microfilaruria group. This observation supports the assumption that the source of aminotransferase release into the blood stream may have been extrahepatic, possibly even parenchymal damage of kidney cells. There was no Table 16. Average SGOT levels in residents with and without microfilaruria and hepatomegaly. Hepatomegaly No Ttahepatomegaly ot l Microfilaruria Unitsof Unitsof Unitsof No. SGOT No. SGOT No. SGOT absent 34 37.5 55 36.5 89 36.9 present 21 53.0 20 51.0 41 52.0 difference 15.5 14.5 15.1 a a t for difference = 2.19. association between aminotransferase levels and the presence of plasmodia in blood smears. From the accumulated data it might have been speculated that serum cholesterol levels in patients with microfilaruria would be lower than in the con- trol group, because they are usually associated with the quality of nutrition, especially with foods contain- ing saturated fats. The opposite tendency was ob- served, as shown in Table 17. Relatively elevated cholesterol levels were not associated with hepato- megaly, nor was there any evidence of nephrosis, which is frequently associated with hypercholesterol- aemia. The difference in serum cholesterol means be- tween the two groups of residents is on the border- line of statistical significance (P = 0.07); it is much more pronounced in the youngest age group than in subjects above the age of 10 years, when the differ- ences become small. Whether this observation has any Table 17. Serum cholesterol levels (mg/100 ml) in local residents with and without microfilaruria. Age - 1 Without microfilaruria With microfilaruria (years) No. in Mean No. in Mean group level group Ilevel 0-9 16 139.8 5 187.0 10-19 21 149.8 14 157.7 20-29 11 169.3 6 169.6 30-39 19 165.2 10 177.2 >40 20 153.8 8 155.0 total 87 152.2 43 166.7 364 MICROFILARURIA IN ONCHOCERCIASIS Table 18. Levels of serum protein fractions (g/1 00 ml) determined by electrophoresis, and of haemoglobin in local residents with and without microfilaruria. Fraction total serum proteins albumin: males (70) females (61 ) a 1 a 2 haemoglobin: males (70) females (61 ) Micro- filaruria absent (mean for 88 subjects) 8.40 3.04 3.15 0.44 0.85 0.82 3.12 12.7 12.8 Micro- filaruria Dif- present ference (mean for 43 subjects) 8.30 2.81 3.09 0.45 0.79 0.86 3.25 12.3 12.7 -0.10 -0.23 -0.06 +0.01 -0.06 +0.04 +0.13 -0.4 -0.1 p 0.50 0.05 0.20 0.50 0.05 0.20 0.10 0.20 0.50 significance in attempts to explain the pathogenesis of onchocercal microfilaruria or is merely coinciden- tal must remain doubtful until it is possible to extend the studies to larger populations. The results of the examinations of serum proteins and of haemoglobin are summarized in Table 18. Generally, the total serum proteins were elevated, the concentration of albumin reduced, and that of y- globulin considerably increased; the albumin: globu- lin ratio was reversed in all cases. A comparison between patients with and without microfilaruria reveals statistically significant differences for only two protein fractions-namely, a reduction of the serum albumin in males and a reduction of the a-2 globulin fraction in both sexes of the microfilaru- ria group. The relative decrease in serum albumin is in line with other findings of the study, such as the reduced weight: height ratio, relative hypotension, increased microfilarial counts, lower antibody levels, increased SGOT levels, etc., which in combination could indicate the presence of wasting disease caused by chronic infection or malnutrition, or both. The slight decrease in a-2 globulin is difficult to explain. For a better appraisal of possible aberrations in the immune responses of the population sample, assays were made for immunoglobulins IgG, IgA, IgM, and IgD. The results are summarized in Table 19. The overall findings show that IgG was elevated by a factor of about 2.4 from the maximum of the nor- mal range, that the observed IgA and IgD levels were within the normal range, and that the macro- globulins (IgM) were raised by a factor of 2.3 above the maximum of the normal range. While IgG, IgA, and IgM levels were all higher in the patients with microfilaruria, the IgD level was significantly reduced in this group. Further detailed studies of various immunological aspects in this population are now being carried out. The results will be reported in another article. Although absolute counts of white blood cells were not made in the study, it was possible to make diffe- rential counts. The results are shown in Table 20 and indicate that the general response in this predomi- nantly adult population sample was characterized by eosinophilia and a relative lymphocytosis. An in- formative test for statistical significance for diffe- rences of the conditionally dependent relative per- centage of cell types between patients with and with- out microfilaruria shows a probability of 5% or less for the lymphocytes only. The frequency distribution of the percentages of large and small lymphocytes Table 19. Mean immunoglobulin levels (mg/100 ml) among local residents with and without microfilaruria. IgG IgA IgM IgD without microfilaruria (94 subjects) with microfilaruria (42 subjects) normal range (1 1 4 subjects) 2 850 2 980 600-1 200 171.1 a 332.9 21 2.8a 50-240 359.5 7.8 a 50-150 a Statistically significant at P=0.05. 10.3 a 0-30 365 A. A. BUCK AND OTHERS Table 20. Differential blood counts among local residents with and without microfilaruria. Subjects without microfilaruria with microfilaruria No. tested Neutrophils (%) Eosinophils (%) Monocytes (%) Lymphocytes (%) a 90 43 1 8 24 22 26 3 57 48 a t=5.2 for difference in the percentage of lymphocytes based on differential counts of 200 white cells per person. and of eosinophilic leucocytes is shown in Fig. 7. The results amplify the finding of a lower degree of lymphocytosis in the microfilaruria group. In support of a proposed hypothesis of the patho- genesis of onchocercal microfilaruria, a report of the results of histological studies of inguinal lymph nodes in onchocerciasis are given below. The lymph nodes were excised from a 40-year-old patient in the sample who had hanging groins. Much of the lymphoid tissue was replaced by fibrous tissue, which contained tortuous and dilated lymphatics. The few remaining islands of lymphoid tissue were circumscribed, widely separated, and 70 60- 50- 40 30 20- 10 0. 10 20 30 40 50 60 70 5 Percentage of small Pe Iymphocytes &ro l(.h66 contained only a few small germinal centres. In some areas, the fibrous tissue was hyalinized; in other areas it was oedematous and cellular, and contained clusters of plasma cells as well as scattered eosino- philic leucocytes, lymphocytes, fibroblasts, and giant cells. The fibrous tissue was permeated by many tor- tuous blood vessels; some of these were congested and some were surrounded by concentric layers of hyalinized collagen. Towards the periphery, the node contained nume- rous scattered microfilariae of 0. v,olvulus. This speci- fic identification was made because multiple sections of numerous microfilariae revealed that they were Fig. 7. Frequency distributions of the percentages of lymphocytes and eosinophilic leucocytes in differential counts. Solid line, subjects (41) with microfilaruria; broken line, subjects (88) without microfilaruria. 366 I 14 Fig. 8. Section of inguinal lymph node with onchocercal lymphadenitis. The remaining islands of lymphoid tissue are widely separated by broad bands of fibrous connective tissue. Section stained with haematoxylin and eosin; magnification x 6. This figure is reproduced by permission of the US Armed Forces Institute of Pathology, photograph No. 70-9317. MICROFILARURIA IN ONCHOCERCIASIS within the collagen (not in lymphatics or blood vessels), were sheathless, had a cephalic clear space of 7-11 ,tm, a nerve ring situated about 65 t,m from the anterior end, and a single row of 4-7 nuclei stopping short of the posterior end, which tapered to a fine point and formed a caudal clear space of about 10pm. Some microfilariae were degenerating and were surrounded by minute granulomas. Other findings included a thickened capsule and excessive perineu- ral mucin. Special stains revealed abundant reti- culum and a fibrinoid change in much of the colla- gen. These changes are characteristic of severe, ad- vanced, onchocercal lymphadenitis and are similar to those found by one of us in studies of lymph nodes in the Ubangui region of the Congo (Fig. 8), where hanging groin and elephantiasis were com- mon (Connor et al. 1970). DISCUSSION Microfilaruria is a well known complication in filariasis caused by W. bancrofti, but recovery of the microfilariae of 0. volvulus from urine has been observed only sporadically. Little significance was attributed to the few scattered reports of oncho- cercal microfilaruria because the origin of the larvae was thought to be the epithelium of the terminal ure- thra rather than the kidneys (Nelson, 1966). While there have been numerous studies and reviews on microfilaruria associated with chyluria (Abeshouse, 1934; Logan et al., 1948; Rusznyak et al., 1967; Wood, 1929), little is known as yet about the preva- lence of microfilaruria not accompanied by this dra- matic clinical sign. Although it has been noted that chyluria is a rare complication of filariasis among Africans as compared with its much more frequent occurrence in the Far East (Nelson, 1966), specu- lations about the regional discrepancy have been concerned mainly with racial differences in the ana- tomy of the perirenal lymphatics rather than with variations of the quality of nutrition (Nelson, 1966). It is well known that the amount of chyle in the urine is closely associated with the quantity of fat consumed (Abeshouse, 1934). In our previous studies in five villages of the Republic of Chad, microfilariae of W. bancrofti were recovered from the urine of two residents in an area where filariasis was endemic (Buck et al., 1970); neither urine contained chyle. The present studies have shown that living micro- filariae of 0. volvulus could be recovered from small urine samples that were collected from deeply in- serted ureteral catheters and that the larvae died soon after they reached the urine. This finding leaves little doubt that the microfilariae entered the urinary tract in the kidney, although the exact portal of their entry could not be determined. Retrograde pyelo- grams revealed radiological changes consistent with a diagnosis of chronic infection, the lesions resemb- ling those found in focal papillary necrosis; a back- flow of contrast material was noted in one of the patients examined. Based on experimental studies of the mechanisms of backflow, Abeshouse (1934) identified 4 different types: pyelovenous, pyelo- tubular, pyeloparenchymatous, and pyelolymphatic. While the findings and quality of the pyelogram from our patient did not permit an unequivocal diag- nosis of the type of backflow, the changes suggested either a pyelotubular or pyelolymphatic mechanism. Whether the similar radiological abnormalities seen in 4 of the 14 readable pyelograms truly reflect pathological changes associated with microfilaruria, especially lesions caused by microfilariae that pass from chronically inflamed perirenal lymphatics into the pelvis of the kidney, cannot be decided at this time. Rodhain & Gavrilov (1935) reported a case in which they found onchocercal microfilariae in the papillae of the kidney of an African who had died of leprosy and cachexia. Pathological changes of lymph nodes, similar to those described in this article, have frequently been observed in persons with onchocerciasis (Augustine, 1957). Rodhain (1952) believed that the lymphoid reaction might be anaphylactic in nature. Despite the fact that elephantiasis was not a feature of oncho- cerciasis in the population sample studied, it is never- theless conceivable that microfilariae of 0. volvulus may cause chronic inflammation of the pelvic lymph- atics in severe infections and that they may enter the pelvis of the kidney through a fistulous communi- cation. A comparison of onchocerciasis patients with and without microfilaruria who resided in the same gene- ral area of the village revealed that the microfilaruria group had heavier infections (higher skin-snip count and larger number of palpable nodules), that all had onchocercomata below the belt line, and that a signi- ficantly higher proportion had inguinal lymphadeno- pathy. Despite heavier worm loads, their antibody response was deficient, as indicated by the high pro- portion of persons who had antibody titres of only 1: 50 or less in indirect haemagglutination tests with 0. volvulus antigen. Various indices of the general 367 A. A. BUCK AND OTHERS health and nutritional state of the patients, such as weight: height ratio, serum albumin, systolic blood pressure, and SGOT levels showed that the micro- filaruria patients were inferior to the group of subjects who had onchocerciasis not complicated by micro- filaruria. Furthermore, the results of a longitudinal study are highly suggestive of a direct debilitating ef- fect on patients with severe onchocerciasis. This find- ing is supported by general observations made in Ethiopia (Oomen, 1969) and Liberia(Liberia Research Unit, 1969). The cycle of malnutrition combined with increased risks of reinfections and superinfections with larvae of 0. volvulus may lead to wasting disease. This is well demonstrated in our population sample. Because of their inferior socio-economic status and low position in the social structure of the community, these residents had to build their houses in the least desirable area of the village, i.e., in close proximity to the river where Simulium was breeding. The average interval between consumption of meat and fish as an indicator of the quality of their nutrition was significantly longer than that of persons living in other parts of the village (Buck et al., 1970). Two questions that have arisen as a result of the study will be investigated in the near future. The first is the way in which microfilariae of 0. volvulus enter the urinary tract in the kidney. Attempts will be made to obtain answers by studying known cases of onchocercal microfilaruria more thoroughly in a hospital where lymphangiography can be employed as a diagnostic technique. The second question is the geographic distribution of microfilaruria in oncho- cerciasis. For this purpose the epidemiological inves- tigations, including examinations of large urine sam- ples, will be extended to populations in other parts of Africa where onchocerciasis is also severe. ACKNOWLEDGEMENTS The authors thank Dr Tachon, Dr Nebout, and Dr Hoffman of the Service des Grandes Endemies for logistic support and professional advice and acknowledge with gratitude the continued co-operation and assistance of staff members of the Embassy of the United States of America, Fort Lamy, Republic of Chad. They also thank Dr I. G. Kagan, Center for Disease Control, US Public Health Service, Atlanta, Ga., USA, for supplying 0. volvulus antigen. RESUME LA MICROFILARURIE DANS L'ONCHOCERCOSE: tTUDE SUIVIE DE SES ASPECTS CLINIQUES ET EPIDEMIOLOGIQUES EN REPUBLIQUE DU TCHAD En 1967, des investigations menees dans un village du Tchad meridional avaient montre la presence de micro- filaires dans 11%Y des echantillons d'urine recueillis chez les habitants. Une fraction de cette population a fait l'objet en 1970 d'une nouvelle enquete. On a constate que la microfilarurie figurait toujours parmi les manifestations cliniques de l'onchocercose dans cette region. Sa frequence etait fonction de l'intensite de l'infection, evalu&e par numeration des microfilaires dans les prelevements cutanes, et du nombre de nodules pal- pables. Toutes les larves isolees a partir des echantillons d'urine etaient typiques d'Onchocerca volvulus. La cysto- scopie et le catheterisme des portions hautes des ureteres, pratiques chez 20 sujets presentant de la microfilarurie, ont montre la presence de microfilaires dans l'urine ureterale chez 11 d'entre eux; dans 8 cas, les larves etaient vivantes. La pyelographie ascendante a fait decouvrir des anomalies radiologiques chez 4 sujets sur 14 examines. Les lesions, rappelant celles de la py6lite chronique, consistaient en foyers de necrose papillaire. Une comparaison entre deux categories de malades - avec ou sans microfilarurie- a revele un certain nom- bre de differences. Chez ceux qui presentaient de la micro- filarurie, on decelait toujours, s'ils etaient porteurs de nodules, un nodule au moins situe au-dessous de la ceinture. On comptait parmi eux davantage de cas de lymphadenopathie inguinale et des taux moyens de transaminase glutamique-oxalacetique constamment plus eleves. Leur rapport poids/taille etait plus faible et leur pression sanguine systolique plus basse. Leur reponse immunitaire, en epreuve d'h6magglutination indirecte en presence de l'antigene 0. volvulus, etait paradoxalement deficiente en depit d'une charge parasitaire plus forte. Ils presentaient des taux superieurs d'immunoglobulines IgG, IgA et IgM, mais des taux moindres d'IgD. On notait chez eux de l'eosinophilie et de la lymphocytose, cette derniere etant cependant moins marquee que chez les sujets ne presentant pas de microfilarurie. 368 MICROFILARURIA IN ONCHOCERCIASIS 369 REFERENCES Abeshouse, B. S. (1934) Amer. J. Surg., 25, 427-450 Augustine, D. L. (1957) Bull. Wld Hlth Org., 16, 665-669 Belding, D. L. (1965) Textbook of parasitology, 3rd ed., New York, Appleton-Century, Crofts, pp. 499-506 Buck, A. A. et al. (1969) Amer. J. trop. Med. Hyg., 18, 217-230 Buck, A. A. et al. (1970) Health and disease in Chad, Epidemiology, culture and environment in five villages, Baltimore, Johns Hopkins Press. Cawley, L. P. (1969) Electrophoresis and immunoelectro- phoresis, 1st ed., Boston, Little, Brown & Co. Connor, D. H. et al. (1970) Human Path., 1 (in press) Dyce Sharp, N. A. (1926) Trans. roy. Soc. trop. Med. Hyg., 19, 373-388 Grunbaum, B. W. et al. (1963) J. Microchem., 7, 41-53 Liberia Research Unit (1969) Fourth Semi-Annual Report, Hamburg, Institute of Tropical Medicine, Hamburg Logan, A. H. Jr. et al. (1948) Amer. J. med. Sci., 216, 389-396 Nelson, G. S. (1966) Helminth. Abstr., 35, 311-336 Nnochiri, E. (1964) Ann. trop. Med. Parasit., 88, 89-93 Oomen, A. P. (1969) Studies on onchocerciasis and elephantiasis in Ethiopia, Haarlem, De Erven F. Bohn Price, D. L. (1961) J. Parasit., 47, 572 Rodhain, J. (1952) Mem. Inst. roy. colon. belge, 21, 1-56 Rodhain, J. & Gavrilov, W. (1935) Ann. Soc. belge Med. trop., 15, 552-559 Rusznyak, I. et al. (1967) Lymphatics and lymph circu- lation, New York, Pergamon Press Steen, F. G. & Price, D. L. (1964) Bull. Int. Path., 5, 27-34 Wood, A. H. (1929) J. Urol. (Baltimore). 21, 109-122 Zurkowski, P. (1964) Clin. Chem., 10, 451-543