Distribution and epidemiological significance of Salmonella serotypes of domestic animals in Lebanon.

DISTRIBUTION OF SALMONELLA SEROTYPES IN DOMESTIC ANIMALS IN LEBANON 171 Distribution and Epidemiological Significance of Salmonella Serotypes of Domestic Animals in Lebanon by NASSIM H. NABBUT 1 & HASSAN M. JAMAL 2 The morbid conditions that salmonellae produce in poultry and cattle have been recently the subject of particular interest and concern in Lebanon where they not only cause economic losses in these livestock but also constitute a potential hazard to human health. Results of isolations of salmonellae from post-mortem animal specimens sent to the Fanar Regional Poultry Laboratory from various regions of Lebanon during the period 1962-67 are reported here. Reports of similar isolations from beef-cattle imported from Middle Eastern countries or else- where, and slaughtered at 3 Lebanese abattoirs, are also included. Salmonellosis and other infectious diseases of Lebanon have been the subjects of a fairly recent review (Matossian, Garabedian & Hatem, 1965). Materials and methods The bacteriological examination for salmonellae of domestic poultry and other birds, cattle and other farm animals was carried out on necropsy material consisting of liver, heart, spleen, intestine and ovary. These organs were cultured directly on MacConkey agar plates which were subsequently examined after 24-48 hours of incubation at 37°C. Non-lactose- fermenting colonies suspected as being salmonellae were further identified by means of biochemical and serological tests according to standard methods (Edwards & Ewing, 1962). Intestines and ovaries, when available, were routinely examined by the selenite enrichment technique. Faecal specimens were obtained on rectal swabs of calcium alginate on metal rods from 900 beef cattle in 3 Lebanese abattoirs over a period of 1 year. The swabs, well coated with faecal material, were cultured in 1 5-ml, single-strength selenite-F broth. After overnight incubation at 37°C, all selenite cultures were subcultured on to desoxycholate citrate agar 1 Head of Bacteriology Department, Fanar Regional Poultry Laboratory, Fanar, Lebanon. Present address: Assistant Professor of Bacteriology and Virology, School of Medicine, American University of Beirut, Beirut, Lebanon. ' Senior Technician and Head of Enterobacteriaceae Section, Department of Bacteriology, Fanar Regional Poultry Laboratory, Lebanon. plates which were incubated at 37°C and examined after 24 and 48 hours. Colonies not fermenting lactose were identified as above. Results and discussion A total of 260 salmonellae representing 36 different serotypes were isolated for the first time in Lebanon from various animal species (Table 1). Out of a total of 214 chickens examined, Salmonella typhi- murium was present in 76 (35.5 %) and was the predominant serotype in chickens while S. bareilly, found in 54 chickens (25.2 %), was the second commonest serotype. S. pullorum was isolated on 12 occasions (5.1 %) from chickens in Lebanon during the period 1962-64. The frequency of Salmonella infections in the chickens examined varied from 2.5% to 3 %. This was the frequency in a select- ed group of diseased chickens that was brought to the diagnostic laboratory and by no means represents the frequency of infection in the general population of domestic poultry. S. dublin was the most frequent serotype isolated from cattle (14 of 19 cattle examined; 73.6 %). It has also been isolated on a few occasions from sheep and recently it has also been isolated from chickens. S. typhimurium was the second commonest serotype isolated from cattle (4 of 19 cattle examined; 21 %). These 2 serotypes, S. dublin and S. typhimurium, are of great public health importance. They are frequent- ly associated with gastroenteritis in both man and animals in Lebanon and elsewhere (Azar & Dowdes- well, 1953; Bowmer, 1964; Buxton, 1957; Merab et al., 1961; Taylor, 1967). S. typhimurium has established itself as the leading serotype not only in frequency but also in its distribution. It has been isolated from 10 species of animals in Lebanon (chicken, duck, pigeon, canary, parrot, partidge, cattle, pig, rabbit and horse). Of a total of 900 rectal swabs obtained from beef cattle aged 2-5 years, immediately after their slaugh- ter in 3 Lebanese abattoirs, 190 (21.1 %) were positive for salmonellae representing 33 different serotypes (Table 2). These observations prompted further investigations on the occurrence of salmonel- lae in the stools of 50 workers who were in close 2462D NOTES TABLE 1. SALMONELLA SEROTYPES ISOLATED FROM DOMESTIC ANIMALS IN LEBANON, 1962-67 Avian hosts Mammalian hosts I S. typhimurium S. bareilly S. dublin S. pullorum S. infantis S. oranienburg S. agama S. gloucester S. richmond S. bovismorbiflcans S. newport S. anfo var. S. concord Salmonella group C3 S. kentucky S. cerro S. lagos S. anatum S. virchow S. muenster S. anfo S. alamo S. bern S. bledgam S. choleraesuis S. enteritidis S. gallinarum S. haifa S. kaapstad S. lindenburg S. meleagridis S. nchanga S. poona S. thompson S. uno S. worthington Totals 76 54 2 12 9 9 6 5 5 4 4 3 3 2 2 2 2 1 1 1 214 3 0 a) 2 2 2 a %- 0 co 0 c a. a 3 4 1 4 .0. 1 1 3 6 0 0 aC 0 0 - I 85 55 2 12 9 9 6 7 5 4 4 4 3 3 2 2 2 2 2 1 1 1 1 I I I 1 233 4 14 C) 2 a CL u 19 2 1 a - 0 0- ._~~~~~~~~~~~~~~~~~d .a 0 -j cr C 1 1 1 1 2 2 0 7 17 II 1 27 0o I-4 92 55 19 12 9 9 6 8 5 4 4 4 3 3 2 2 2 2 2 1 2 I I I I 26 1 Serotype of Salmonella .o :C ._ 172 I 1 I I 1 I I DISTRIBUTION OF SALMONELLA SEROTYPES IN DOMESTIC ANIMALS IN LEBANON 173 TABLE 2 FREQUENCY OF SALMONELLAE IN BEEF CATTLE AT BEIRUT, FORN EL-SHOUBBAK AND BORJ-HAMMOUD ABATTOIRS Beirut abattoir Forn El-Shoubbak Borj-Hammoud Serotype of Salmonella abattoir abattoir Total No. % Total No. % Total No. % S. montevideo 23 4.6 _ _ 1 0.5 S. dublin 20 4.0 17 8.5 - - S. kentucky 16 3.0 - - 9 4.5 S. anatum 10 2.0 2 1.0 4 2.0 S. vejle 10 2.0 - - - - S. tennessee 7 1.4 _ _ _ S. kottbus 6 1.2 - - - - S. typhimurium 4 0.8 5 2.5 1 0.5 S. bovismorbificans 3 0.6 2 1.0 1 0.5 S.limete 3 0.6 - - - - S. muenster 3 0.6 - - - - S. newport 3 0.6 - - - - S.lomita 2 0.4 - - - - S. mondeor 2 0.4 - - - - S. anfo 2 0.4 - - - - S. frintrop 2 0.4 - - - - S. bern 1 0.2 - - - - S. carmel 1 0.2 - - - - S. falkensee 1 0.2 - - - - S. hofit 1 0.2 - - - - S. jedburgh 1 0.2 - - - - S. kokomlemle 1 0.2 - - - - S. london 1 0.2 - - - - S. shipley 1 0.2 - - - - S. uno 1 0.2 - - - - S. yaba 1 0.2 - - - - S. virchow -a - 3 1.5 4 2.0 S. anfo var. - - 1 0.5 1 0.5 S. infantis - - 1 0.5 - - S. kentucky var. - - 1 0.5 8 4.0 S. meleagridis - - 1 0.5 - - S. mocamedes - - 1 0.5 - - S. hindmarsh - - - - 1 0.5 Total 126 25.2 34 17.0 30 15.0 a Not isolated. 12 174 NOTES association with the cattle. S. dublin, S. anatum and S. bovismorbificans were recovered from 3 workers. This is of particular interest because it suggests that animals in abattoirs may be sources of salmonellae from which human infections can arise, directly or indirectly. REFERENCES Azar, J. E. & Dowdeswell, R. M. (1953) Lebanese med. J., 6, 337 Bowmer, E. J. (1964) Amer. J. med. Sci., 247, 467 Buxton, A. (1957) Salmonellosis in animals, Common- wealth Bureau of Animal Health, England (Review Series No. 5) Edwards, P. R. & Ewing, W. H. (1962) Identification of Enterobacteriaceae, Minneapolis, Burgess Matossian, R. M., Garabedian, G. A. & Hatem, J. (1965) Lebanese med. J., 18, 227 Merab, A., Taleb, N., Hatem, J. & Nasr, W. (1961) Presse med., 69, 2132 Taylor, J. (1967) Vet. Rec., 80, 147 Ovicides in Simulium Control * by R. C. MUIRHEAD-THOMSON & JUDITH MERRYWEATHER It has long been recognized that the control of Simulium, whether in its role as a biting pest or as a vector of human onchocerciasis, can best be achieved by regular applications of larvicidal chemi- cals to the streams and rivers in which the immature stages develop (McMahon, 1967). In the past, the larvicide of choice has been DDT, and it is envisaged that this chemical will continue to be the insecticide of choice for some time to come (WHO Expert Committee on Onchocerciasis, 1966). In the mean- time, screening programmes are being carried out to find a more suitable chemical to replace DDT, the ideal compound being one which would not only be more selective than DDT, but which would also be free of the undesirable residual properties which lead to is accumulation in aquatic habitats and aquatic organisms. When DDT is used as a larvicide, the average concentration used in control operations is 0.1 ppm, and the usual application period is 30 min (in the case of aerial application, the application period may be considerably reduced, to 5 min or less). * From the Department of Entomology, London School of Hygiene and Tropical Medicine, London, England. This research was carried out with the support of the Medical Research Council of Great Britain and the Ministry of Overseas Development of the Government of Great Britain and Northern Ireland. General experience has shown, both in the control of Simulium in Canada and in control operations against S. damnosum in Africa, that these larvicide dosages do not have any effect on Simulium eggs. In most cases this has been inferred from the speed of reinfestation of the habitat after larvicide applica- tion (Fredeen et al., 1953). The difficulty of finding Simulium eggs in large streams and rivers has made it difficult to confirm this conclusion by direct obser- vation, and has also limited the scope of controlled laboratory tests on ovicidal properties (Hocking, 1950). For those reasons, ovicides have never really received serious consideration in Simulium control, and the subject received no mention in the second report of the WHO Expert Committee Report on Onchocerciasis (1966). In the course of our present research programme on the laboratory evaluation of Simulium larvicides, the regular finding of egg masses of Simulium orna- tum in field breeding sites in streams made it possible to embark on a more systematic investigation on the effects of a wide range of candidate larvicides on eggs in the laboratory. Materials and methods Leaf blades of trailing vegetation with attached egg masses were brought in from the field and cut 2462E