Transmission of footrot in migratory sheep and goats of Nepal

Abstract

Combined sheep and goat flocks of Kaski and Lamjung Districts in the Western Development Region of Nepal, where footrot is endemic, were monitored throughout the period of migration to and from alpine pastures (3700–4500 m above sea level (a.s.l.)) for 2 consecutive years to study the epidemiological aspects of disease transmission. During 1991, two whole flocks of one village (Ghanpokhara) were observed; during 1992, a sample of 160 sheep and 40 goats from ten different flocks of three villages (Siklis, Tangting and Ghanpokhara) were observed. The period of upward migration through the forest (May–June) was found to be associated with footrot transmission (more than 60% of sheep and about 30% of goats became infected), so this was the critical period for sheep and goats to be protected. The alpine pastures, though wet, were not conducive to transmission of footrot, and a very low proportion of animals acquired the disease during descending migration through the forest (October–November). The period of maximum transmission was found to coincide with increasing rainfall and temperature. Both Baruwal sheep and Sinhal goats were found to be affected with footrot. The observation on the Ghanpokhara flocks in 1991 suggested that footrot was more prevalent in sheep than goats. However, when samples from different flocks were observed in 1992 the prevalence of footrot in goats and sheep was not significantly different. In contrast to sheep, footrot in goats was more likely to be confined to the interdigital skin. An improved understanding of the epidemiology of footrot in migratory goats and sheep was obtained from these observations. This is expected to result in improved management of the disease.