zoonoses and communicable diseases common to ... - PAHO/WHO

DERMATOPHYTOSIS 337Diagnosis: Clinical diagnosis can be confirmed by the following methods: a)microscopic observation of hair and scales from lesions; this method can provide adiagnosis at the genus level, since the spores surround the hair shaft in an irregularmosaic when infection is due to Microsporum and are arranged in chains wheninfection is due to Trichophyton; b) the use of Wood’s light (filtered ultravioletlight), under which hair infected by many species of Microsporum exhibits a brightblue-green fluorescence; c) isolation in culture media, the only method that permitsidentification of the species.Control: Prevention of human dermatophytoses caused by zoophilic speciesshould be based on controlling the infection in animals, although this is difficult toaccomplish. Avoiding contact with animals that are obviously sick can prevent a certainpercentage of human cases. These animals should be isolated and treated withtopical antimycotics or griseofulvin administered orally. Remains of hair and scalesshould be burned and rooms, stables, and all utensils should be disinfected.Apparently healthy cats can be examined with Wood’s light. Controlling the rodentpopulation is a useful measure.In cold climates where animals are stabled over long periods of time, dermatophytosescan be a problem in cattle and horses. Man and animals respond to infectionwith a humoral and cellular immunity, as has been demonstrated by experimentsas well as by the observation that animals once infected are protected againstreinfection. Two vaccines were developed in the former Soviet Union: one for cattle,made from an attenuated strain of T. verrucosum, and another for horses, madefrom T. equinum. Both vaccines yielded satisfactory results in preventing dermatophytoses.The vaccine was used in Norway in 200,000 cattle with very good results(Aamodt et al., 1982). An eradication program was established in Gausdal, Norway;vaccination was required for all cattle for a period of six years, followed by voluntaryvaccination thereafter. The prevalence of infected herds was 70% and eradicationwas achieved in 1987. A live attenuated vaccine was used (two doses with aninterval of 14 days) along with disinfection of stables, isolation of infected animals,and other hygiene methods (Gudding et al., 1991).BibliographyAamodt, O., B. Naess, O. Sandvik. Vaccination of Norwegian cattle against ringworm. ZblVet Med B 29:451–456, 1982.Ainsworth, G.C., P.K.C. Austwick. Fungal Diseases of Animals. 2nd ed. Farnham Royal,Slough, United Kingdom: Commonwealth Agricultural Bureau; 1973.Allen, A.M., D. Taplin. Epidemiology of cutaneous mycoses in the tropics and subtropics:Newer concepts. In: Pan American Health Organization. Proceedings of the ThirdInternational Conference on the Mycoses. Washington, D.C.: PAHO; 1975. (ScientificPublication 304).Benenson, A.S., ed. Control of Communicable Diseases in Man. 15th ed. An official reportof the American Public Health Association. Washington, D.C.: American Public HealthAssociation; 1990.Canteros, C.E., G.O. Davel, W. Vivot, S. D’Amico. Incidencia de los distintos agentes etiológicosde micosis superficiales. Rev Argent Microbiol 25:129–135, 1993.