Infectious diseases of saiga antelopes and domestic livestock in Kazakhstan
This study combines an investigation of the ecology of the saiga antelope (Saiga tatarica) and the epidemiology of diseases shared by saigas and domestic livestock. Ecological data from 2 saiga populations were collected and analysed, including a comparison of 3 ageing techniques for saigas. A serological survey of 1,151 saigas and 958 domestic livestock (cattle, sheep and goats) was carried out. Official data and fann surveys provided information on policy and practice in disease control, showing that both veterinary provision and livestock numbers have collapsed since independence. Seroprevalence to brucellosis among saigas was 3.8% in the Betpak-dala population and zero in the Ustiurt population. No serological evidence of infection with foot-and-mouth disease (FMD), bluetongue, epizootic haemorrhagic disease (EHD), peste-des-petitesruminants (PPR) or rinderpest was found among saigas. A recently-developed enzymelinked immunosorbent assay (ELISA) was used to differentiate vaccine-induced antibodies to those caused by infection with FMD virus (FMDV). Serological evidence of infection with FMDV was found only in cattle (2.9%). Vaccine-induced antibodies to FMDV were found among 29.0% of cattle, 13.8% of sheep and 5.8% of goats, reflecting speciesdependent vaccination. Seroprevalence to brucellosis was 5.4% among cattle, 1.3% among sheep and 0.7% among goats. Of diseases not previously recorded in Kazakhstan, seroprevalence to bluetongue among livestock averaged 23.2%, EHD and PPR were found at low levels, and rinderpest was not found. Modelling of FMD and bluetongue sero-status found significant farm-level clustering. For FMD this may reflect the behaviour of individual owners, but as bluetongue is unrecognised, it may reflect small-scale differences in exposure to the vector. A model framework was developed for FMD dynamics in saigas, including a seasonally dependent transmission coefficient (P). This produced a pattern of FMD outbreaks similar to that seen in Kazakhstan in the 1950s and 1960s, with large epidemics in spring, dying out in the summer or autumn. The results suggest that FMD is not endemic in saiga, and that the saiga population is not a reservoir of infection for domestic livestock. However, saigas may constitute a reservoir of infection for brucellosis if full control of this disease in domestic livestock were attempted. Recommendations are made for disease control and saiga conservation in the light of these findings.