Potential roles of pigs, small ruminants, rodents, and their flea vectors in plague epidemiology in Sinda district, eastern Zambia

Journal of Medical Entomology, 2017, 1–7A cross-sectional study was conducted in the Eastern part of Zambia that previously reported a plague outbreak. The aim of the study was to evaluate the potential role of pigs, goats, and sheep as sero-surveillance hosts for monitoring plague, and to investigate the flea vectors and potential reservoir hosts to establish the current status of plague endemicity in the district. Serum samples were collected from 96 rodents, 10 shrews, 245 domestic pigs, 232 goats, and 31 sheep, whereas 106 organs were eviscerated from rodents and shrews. As for fleas, 1,064 Echidnophaga larina Jordan & Rothschild, 7 Xenopsylla cheopis (Rothschild), and 382 Echidnophaga gallinacea (Westwood) were collected from these animals in 34 villages. Enzyme-Linked Immunosorbent Assay (ELISA) and Polymerase Chain Reaction (PCR) tests were performed on serum, and organs and fleas to determine IgG antibodies against Fraction 1 antigen and pla gene of Yersinia pestis, respectively. ELISA results showed that 2.83% (95% CI¼0.59–8.05) rodents, 9.0% (95% CI¼5.71–13.28) domestic pigs, 4.7% (95% CI¼2.39–8.33) goats, and 3.2% (95% CI¼0.08–16.70) sheep were positive for IgG antibodies against Fra1 antigen of Y. pestis. On PCR, 8.4% (95% CI¼3.96–15.51) of the rodents were detected with Y. pestis pla gene, whereas all fleas were found negative. The common fleas identified were E. larina from pigs, whereas X. cheopis were the only fleas collected from rodents. The presence of sero-positive animals as well as the occurrence of X. cheopis on local rodents suggests that Y. pestis remains a risk in the district