The Mazzoti test

r-4q:trF WORLD HEALTH ORGANIZATION ORGANISATION MONDIALE DE LA SANTE oNcrro/wP/ 7s. 9 ORIGINAL: ENGIISH EXPERT COMMITTEE ON EPIDB'IIOIOGY OF ONCHOCERCIASIS Geneva lO-18 November 1975 Draft agenda itenr 4,4 t'ON .l $J THE MAZZOTTI TEST B. 0. L. Duke Filarial Infections ion of Malaria and Other Parasltic Diseases World Health Organlzation, Geneva, Switzerland by o , (_- l! 1. IntroducEion l{azzottL (1948) first described rhe diagnostic test for lnfection with Onchocerca vo[!!!r which now bears his name. A patient suspected of infection with O. volvuIus, but in whoo no microfilariae or adult rrorms can be found, is given a small dose of diethylcarbpmazine citrate (DEC), usuaLly 25-50 mg for an adult. Ttle test is regarded as positive if itching of the skin, and eventually a pruritic papular erupti-on, develop over the ensulng 15 minutes to 24 hours. The reaction depends upon scanty and cryptic microfilariae becoming 'runmaskedrr in the skin. If no such reaction, or other evidence of microfilarial destruction develops, the test is negative, and the presumption is that the patienE is free from acEive microfilariae-producing infection. 2. Clinical characteristics of positive llazzottL reactions A positive YLazzottL tesE ls eesentlally a reaction in the skin wtrich has to be assessed cllnlcal1y, and whlch followe on the sudden onset of mtcrofllarlaL destruction. The time of onset varies. Itchlng and scratching may begln anythlng from 15 minutes to 24 hours after ingestion of the test dose. Wtrenever posslble, therefore, the tesE should be read once, 30 minutee - 3 hours after lngestion of the DEC, and again the followlng mornlng. Most c@only, if itching does not start withln 30 oinutes, it is delayed untlL 5-8 or more hours have passed. Posslbly thls is lndicatlve of two separate trraunological mechanlsus. In patients who have been treated wlth suramln to ktll the adult \rorms, but ln whom eone reeidual microfilarlae are still reachlng the skin, the Mazzotti test, repeated at, lntervale of 2-3 weeks after the Last doEe of euramln, produce a lees heavy and extenslve reactlon on each occaeion. Colncldent wtth thls lEs onset may becme more and more delayed, the latenE pertod extendlng gradually from about 8 hours up to nearer 24 hours. The reason for thls lE not knolvn. Typically the reaction starts with lntense itchlng, wtrlch is greatest in thoee parts of the body where most of the microfilariae are sltuated and may be accompanted by the appearance of eome urticarlal papules. The disEributlon of the reactlon is 1lke1y to be eimllar to that The iesue of this document does not constitute formal publication. lt should not be reviewed, abetracted or quoted without the agreement of the World Health Organization. Authors alono are reaponsible for views expressed in signed articlcs. Ce document ne constitue pas une publication. ll ne doit faire l'objet d'aucun compte rendu ou r6sumd ni d'aucune citation gans l'autorisation de I'Organisation Mondiale de la Sant6. Les opinions exprimdes dans les articles signds n'engagent que leurs auteurs. i ;! { # "!I -! . t, r.L ,T a a I oNcHo/wP/ 75 . 9 Page 2 of the original pruritic skin lesions (if any) which led to the suspicion Ehat Ehe patient was suffering frmr onchocerciasis. Ilowever, its extent is usually greater than that of the original lesions. Since lightly infected cases have very few adulE hrorms, the distribugion of the rash is likely to be uneven, often confined mainly Eo a single limb and related to theposition of the adult worms. Thus it may affect one buttock and leg, with scanty spread to the opposite buttock; or one arm and shoulder, with slight spread dor^rn the back and up the neck. Only an adult worm around the coccyx is likely to produce a synmetrical reaction across the buttocks and up the back. If there is a cryptic nodule on Ehe head'with microfilariae around the eye, then the face and anEerior segmenE of the eye may be involved, sometimes more on one side than the other. There may be hyperaemia of the conjunctiva, and photophobia and watering of the eye for 24-48 hours. In a matter of L2-24 hours after the test dose erythema may appear, along with a discreteitching, shotty, papular rash, which shows red on a light-coloured skin. The affected area of skin may become hot and indurated, and the skin fold is often thickened. Some enlargement and tenderness of the lynph glands draining the affected part usually develops within Z4-4ghours. Fever and malaise may accompany the reaction particularly during the first 24-72 hours.If no further DEC is given the reaction subsides in 3-5 days, during which time there areintermittent bouts of severe itchinB. Subsequently there may be some desqurmation as thedermatitis subsides. Microfilariae may also appear in the blood, the urine, or the sputum rilithin 2-5 hours of ingesEion of DEC, but such findings are unlikely in the lightly infected cases for whictr the Mazzotti tesE should be reserved. 3. Relief of the reaction Symptomatic relief from the effects of the ylazzotlL test may be achieved to some extent withantihistaminesror with aspirin or codeine. If very severe, or if Ehe Mazzotti Eestis to be followed imnediately by a therapeutic course of DEC, betamethazone may be given.If there are no contraindications to its use this drug will most effectively damp down the reaction (Duke & Anderson, L972, L97r. 4. Doses of DEC used in the Mazzotti test The dose of DEC normally given for the ylazzotti- test is 5o mg for an adult, and correspond-ingly less for a child (according to age and weight). In an adult a dose of 25 mg will oftenprove as effective as 50 mg, and in heavily infected persons doses as low as 5-10 ng mayproduce a reaction. However, these very smaIl doses may give rise Eo confusion in the type of lightly infected case for which the Mazzotti reaction is needed as a diagnostic procedure.In such Persons 50 mg ls a good standard dose. It is not excessive but it can be relied uponto produce a positive result in most of those who are harbouring microfilariae. If Ehe testis read as negative after 50 mg, but O. volvulus infect.ion is stil1 suspected on clinicalgrounds,adoseof2oom8mayu"t.i"iEpossib1ethatthismayproduceareaction where 50 mg has failed. 5. False negative reac tions False negative reactions Eo the MazzotEi test are probably uncoumon. It is difficultto assess their frequency for, if neither nodules nor microfilariae can be found, thediagnostician can then only resort towhatare, as yet, rather non-specific serologicalirrnunodiagnostic Lests for "filariasisrr. However, in some lightly infected butparasit,ologically Proven Patients, usually with symptomless infections of long standing, the usual itching papular eruption does not aPPear. rnsEead there may be only a slight induration of the skin withPractically no pruritus. similar types of reaction, occurring in persons found parasitologically negative, might well be read falsely as negaEive. Research into the prevalence of negative oNcHo/wP/ 75. 9 Page 3 ylazzotEi tests among very llghtly infected, but parasitologically proven microfilariae carriers(harbouring different strains of O. volvulus) would be h ighly desirable. Such a project should also be designed to determine whether, in parasitologically negative suspects, a provocative 50 mg dose of DEC would mobilize microfilariae sufficiently to render them detectable in skin snips, blood or urlne over the first hours or days after ingestion. Infections which are stil1 in the pre-patent phase (i.e. before microfil-arial production has begun) will also give a negative reaction, although this may be expected to change Eo positive if the test is repeaEed, weeks or months later, wtren microfilariae have begun Eo invade the skin. Usually pre-pa tent infections with O. volvulus are clinicall y silent, but in some persons vague itching may be felt at this sEage, some monEhs before true microfilarial rash develops. In such patients al(azzotti test may well be performed and correctly read as negative, only to be disputed when the patient attends another physician some months later and a positive resulE is recorded. A negative llazzottL test may also be found in paEients wiEh gross skin manifestatlons of the rtsowdatt typ". Such persons, for irmunological reasons which have yet to be elucidaEed, never become Eolerant of their microfllariae. Those nlcrofilariae which reach the skin aPPear to be destroyed almost inrmediately, with maxi-ma1 histological and clinical reaction, to such an extent that the patient nay be regarded as undergoing a permanent, sustained and chronic Mazzotti type of reaction throughout the duration of the infection. It is ofEen impossible to find microfilariae in skin snips from these persons, although they may be detected deep in the dermis if serial sections of the skin are examined. The ingestion of DEC ofcen produces little or no additional signs or slmpcoms of microfilarial destrucEion,for this is alreadyproceedingaE almost maximum level. TineliazzoEti test is therefore read as negative and the diagnosis has to be made on clinical grounds. 5. False positive reactions True false positive ylazzoEtL skin reactions are only likely to be encount,ered in infections with the other skin-dwelling microfilarial species, Dipetalonema streptocerca. Heavy infections with this parasite are uncomnon, and its distribution is localizea to certain parts of Africa(especially Ghana, Cameroon, and Zaire), where in many foci it coexists with the generally heavier and more prevalent infections with O. volrnrlus. There is little published evidence on the skin reacttons following sma11 do"""lFiEG-"ases of streptocerciasis, but in one European Patient havlng skin snips positive for microfilariae of D. streptocerca , no skin reaction was observed aft(glven therapeutically) rer 50 mg DEC, although a positive reaction did develop when dosageeached 200 mg thrice daily (Duke, lg57). ThereafEer the reaction was indistinguishable clinically from thaE of 0. vo1vu1us. but the papules produced were shownto contain microfilariae of D tocerca. In infections with this parasite, conEinuedtreatment with DEC at higher doses 2O0 mg thrice daily) nay lead to visible reactions aroundthe adult D. streptocerca worms in the skin (Mayers er aI. , L97Z). These may aid in thediagnosis, for such reactions are not usually seen in O. volvulus infection. After ingestion of 50 mg DEC, reactions to the presence of other filarial parasiEes, such as l{uchereria, Brugl9 or !g, are unLlkely to manlfest themselves as a parEiculate skin reaction, although it 1s posslble that urticarial wheale may appear. on the other hand the destructionof the clrculating microfllariae of these parasites may lead to febrile reacEions and a lrmph-angitls may develop in Brugia or l{uchereria lnfections from reaction round developing or adult\rorms. Finally, lt mtst be remembered that in onchocerciasis areas uninfected by hypochondriacal PaElents, who may have an unreasoni-ng fear ofrrthe filariar', as welt as some hearsay knowledgeof the effecEs of DEC, may claim that the ingestion of 50 mg DEC for the llazzottL tesr hasproduced itching trall over the body". In the absence of any visible skin eruption or scratch marks, and if there is no Eendency to localize the complaint to one particular quarter of thebody, these indlcations, coupled with the general attitude of the pat,ient, should serve toput the physician on his guard. oNcHo/wP/75. 9 Page 4 7. Histopathology In the affected skin there is hyperaemia and oedema around the microfilariae, and accumulations of eosinophils. The microfilariae gradually degenerate, usually surrounded by eosinophils, which themselves break down to granules. SomeEimes epithelioidcells and giant cells can be seen phagocytosing microfilariae. Microfilariae may also migrate to Ehe epidermis, there to provoke intra-epidermal oedema or abscesses, and they are eventually shed by desquamation. 8. Inrnunopathology IE is noE knorvn exactly how DEC acts upon microfilariae in the body. Neither the drug itself nor the serum from patienEs who are taking DEC, has any effect on live 0. volvulus microfilariae in vitro (Hawking et'a1., 1950). DEC produces its effect only on mlcrofLlariae within the body, where it is believed to have an opsonic action. The previousLy insusceptible microfilariae are suddenly recognized as foreign bodies by the cellular and humoral defence mechanisms of the host, and their destruction in the tissues is thus initiated. The first effect of DEC on microfilariae in connecEive tissue is Eo render thenr, for a short time, more motile. This action has been observed directly through the slit-1amp in the cornea of the eye (Anderson & Fuglsang, 1973). Within 30 minutes of the ingestion of DEC, microfilariae could be seen to move rapidly into the cornea from the limbus. This suggests that the microfilariae began to move in all directions in an attempt to escape fron the sudden activation of the bodyrs hitherto dormant defence system. A similar early increase in mobility may occur in the skin, to be followed later by death and destruction of the af fected microfi lariae. It is possible that DEC acts in some way on the surface of the microfilariae; perhaps dissolvingaprotective layer of host protein, and thus exposing Ehe true parasite antigens; perhaps by allorring antibodies Eo penetrate the hitherto resistant surface layers of the microfilariae; or perhaps by upsetting the static equilibrium of a protective layer of antibody coating their surface, thus activating complement, phagocytes aild killer cel-ls. Until more is known of the ways in which microfilariae manage to maintain themselves in the sub-epidermis and elsewhere, alive and unrecognized as foreign bodies, it is unlikely that the i-mrunological basis of the l{razzotti reaction will be elucidated. On the other hand the recrarkable unmasking action of DEC may itself provide a useful experimental tool for investigation of this very problem. Ihe rapid onset of the Ylazzotti reaction - in many cases it starts within 15-30 minut,es - suggests that IgE antibodies are sometimes involved. However, the facts that some reacti.ons do not start before 6-24 hours, and that most reactions continue for several days, imply that complex-mediated and cell-mediated (hypersensitivity) of Types IIT and IV must also be involved as the reacEion proceeds. 9. Indications for the l{azzoEti test The YLazzotti reaction is only necessary for diagnostic purposes in persons suspected of being lightly infected, but in whom microfilariae cannot be found after an acceptable number of skin snips have been examined. As such its main uses are as follows: (i) To confirm the diagnosis, already suspected on clinical grounds, in patients with recently acquired primary infectlons. This type of patient may suffer considerably from itching skin lesions but microfilariae are too scanty to be found readily in skin snips. { toNcHo/wP/ 75. 9 Page 5 (ii) To deEect lightly infected and often symptomless chronic carriers of microfilariaeliving in endemic areas. Such carriers may remain undetected ln surveys which rely soleIy on parasitologlcal dlagnosis, but, they may stl11 constltute a significant source of lnfection Eo the Slmullum vector. (iii) To assess the effects of treaEment. A change from a positive to a negative ltLazzolBL reaction after treatment may be taken to indicate that the patlent has become truly microfilariae-free; and in these circumstances it is one of the most stringent PracticaL tests of clinicoparasitological cure that rde possess. (iv) To detect light early infections in young children who do not readtly rolerate skin snips. Ln Ehis age-group it may also be of use, after vector control measures have been introduced, to give early warnlng of eontinuing transmlssion represented by occaslonal llght infectlone ln chlldren born after the onseE of control. (v) In areag under Slmullum control, the test may also be of uEe ln the flnal stagesto determlne when tntcilffiTf.l lnfectlone have flnally dled out in the untreated memberg of the human populatlon. If the test 18 uaed ln epldemlologlcal eurveys, lt shoutd be remembered that the manlfesta-tlone of a poeltlve reactlon mey well lcad the subJects to demendlng treatment for an lnfectlon of whlch hltherto they were happlly obllvl.oua. Where DEC te readily avelleble on the open market, lts use ln thlE teot may aleo lead to other more heavlly inflcted pereons experlmentlng wlth lte use ln aelf-treatmenE. Thla nay produce eome alarmlng resulte. 10. Contratndlcatlons to the uB e of the Mezzottl teBE It ls undeelrable and qulte unnecessary to use the Mazzottl te6t as a dtagnostic procedurein moderately or heavily lnfected patients in whorn mlcrofilariae are readily detectable, oftenln enormous numbers, ln normal skin snips. Indeed its careless use in heavily infected Patlents may exclte dangeroue reactlons of coIlapse, shortnese of breath, vertlgo, hlgh feveretc. whlch are often encounEered in the early stsges of treatment, when the dru! is usea ae a therapeutic mlcroftlarlclde (Rrglsang & Anderson, Lg74; Duke & Anderson, Lglir 1975). The therapeutlc uee of DEC always involvee the patlent undergolng a positlve Mazzotti reactton,the eeverlty of whlch ls usually directly proportlonal to the tntensity of hts lnfection.Anclllary drugs may well be requlred for lts conErol. The Mazzottl EeEE should only be used for dlagnosls when routlne parasltological methodehave falLed; and ln old or deblllteted peraons, or ln pregnant rdomen, even when they areparaeltologlcally negative, cllnlcal Judgernent ie necesEary before the tegt is employed. T'he test ehould never be ueed for whole-populaElon coverage ln epldemiological "r.r"y, withouEprevlous parasltologlcaL lnvestigation. Suumary The clinical features of the early and late manifestaEions of a positive liazzoftL reaction are described, and the dose of DEC used in the test is discussed. Some reasons for false negative and false positive tests are given. The histological and possible inrnunopathologicalbasis of the test are discussed. The uses of the test are described and some contraindicatlonsgiven.I t';'ir,* 'q IoNcHo/wP/ 75 . 9 Page 6 REFER.ENCES Anderson, J. Brit. J & Fuglsang, H. (1973) Living microfilariae of Onchocerca volvulus in the cornea, Ophthal. t 57, 7L2 Duke, B. O. L. (1957) A case of strePtocerciasis in a European, 5L,364-367 Ann. Erop. Med. Parasit., Duke, B. O. L. & Anderson, J to7 -Ll4 (L972) Onchocerciasis and its treatment, Tropical Doctor 'Z' Duke, B. O. L. L4L-L42 & Anderson, J. (1975) Onchocerciasis and its treatmentr Tropic al Doctor. :, Fuglsang, H. & Anderson, J. (1974) Collapse during treaEment of onchocerciasis wiEh diethylcarbamaz ine, Trans. roy. Soc. trop. Med. Hyg. , 68, 72-73 Hawking, F., Sewell, p., & IhursEon, J. P. (1950) The mode of action of hetrazan on filarial worms, BriE. J. Pharmacol. , !' 2L7 Mazzotti, L. (1948) PossibiLidad de utilizar como medio diagnostico en la oncocercosis, 1as reactj.ones alergicas consecutivas a la administracion de Hetrazan, Rev. Ins Salubr Enferm. trop. (t1ex) , 9, 235-237 \ Meyers, W. M., Connor, D. H., Harman, L. E., Fleshman, K', Moris, Human streptocerciasis. A clinico-pathologic study of 40 A identification of the adult filaria, Amer. J tr Med. R. & Neafic, R. C. (L972) fricans (zairans) including ., 21, 528-545 t + !' I