Brucella in Tajikistan

Abstract: One of the most powerful megatrends of our time is urbanization. Urban and peri-urban (UPU) farming is a common practice in many low-income countries because it increases the incomes of families that are often restrained by limited economic resources. However, there is a concern that the growing number of people and livestock living close together in UPU areas will increase the transmission of different zoonotic pathogens such as Brucella. Brucellosis is one of the most common and economically important zoonoses globally and Central Asia represents an area with high incidence among humans and livestock. This thesis aims to assess the occurrence of Brucella among livestock in an UPU area and to elucidate how farmers understand and respond to this zoonosis. The results of this thesis might contribute to raising awareness of how livestock in urban areas can constitute a public health risk if they are infected with Brucella or other zoonoses. The four studies included in this thesis were conducted among small-scale livestock farmers in the UPU region of Dushanbe, the capital of Tajikistan. Blood samples were collected from 904 dairy cows and 667 sheep and goats and analysed with enzyme-linked immunosorbent assay (ELISA). The Brucella seroprevalence was 4.1% among the dairy cows at the herd level and ranged between 1.0% and 15.6% among sheep and goats at the individual level in the four included districts. Furthermore, 564 cow milk samples were analysed for Brucella DNA by IS711-based real-time PCR and 13.7% were found to be positive. All seropositive cows were positive by PCR, but 11.8% of the seronegative cows were also positive by PCR. Further characterization of the Brucella DNA suggests that there is a reservoir of B. abortus in the cattle population and a spillover of B. melitensis from small ruminants to cattle. A knowledge, attitudes and practice study targeting 441 households revealed poor knowledge of brucellosis and several high-risk behaviours, such as consumption of unpasteurized dairy products and not wearing protective clothing when handling potentially infectious materials like aborted foetuses and discharges. Brucella is widespread among the livestock in the UPU area of Dushanbe and this might constitute a serious risk to public health and cause significant economic losses. The discrepancy between serology and PCR results suggests that implementing complementary diagnostic strategies to detect false serological negative individuals might be warranted in Brucella control programmes. Poor knowledge, several high-risk behaviours and a willingness to learn more provide the rationale for developing campaigns to raise awareness of brucellosis and its associated risks among farmers.