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Background: Plague is a bacterial zoonotic disease, caused by Yersinia pestis. Rodents are the natural hosts with fleas as the vehicle of disease transmission. Domestic and wild dogs and cats have also been identified as possible disease hosts. In Zambia, plague outbreaks have been reported in the Southern and Eastern regions in the last 20 years. Based on these observations, Y. pestis could possibly be endemically present in the area. Methods: To substantiate such possibility, sera samples were collected from rodents, shrews, dogs and cats for detection of antibodies against Fraction 1 gene (Fra1) of Y. pestis while organs from rodents and shrews, and fleas from both dogs and rodents were collected to investigate plasminogen activator gene (pla gene) of Y. pestis using ELISA and PCR respectively. Results: A total of 369 blood samples were collected from domestic carnivores, shrews and domestic and peridomestic rodents while 199 organs were collected from the rodents and shrews. Blood samples were tested for antibodies against Fra1 antigen using ELISA and 3% (5/165) (95% CI 0.99-6.93%) dogs were positive while all cats were negative. Of 199 sera from rodents and shrews, 12.6% (95% CI 8.30-17.98%) were positive for antibodies against Fra1 using anti-rat IgG secondary antibody while using anti-mouse IgG secondary antibody, 17.6% (95% CI 12.57-23.60%) were positive. PCR was run on the organs and 2.5% (95% CI 0.82-5.77%) were positive for plasminogen activator gene of Y. pestis and the amplicons were sequenced and showed 99% identity with Y. pestis reference sequences. All 82 fleas collected from animals subjected to PCR, were negative for pla gene. The specific rat-flea and dog-flea indices were 0.19 and 0.27 respectively, which were lower than the level required to enhance chances of the disease outbreak. Conclusions: We concluded that plague was still endemic in the area and the disease may infect human beings if contact is enhanced between reservoir hosts and flea vectors. The lower specific rodent-flea Indices and absence of Y. pestis in the potential vectors were considered to be partly responsible for the current absence of plague outbreaks despite its presence in the sylvatic cycle. [ABSTRACT FROM AUTHOR]

ABSTRACT. Field and commensal rodents were live-trapped at three villages in an active focus of plague (Yersinia pseudotuberculosis pestis) in Lushoto District, Western Usambara Mountains, Tanga Region, Tanzania, from December 1983 to November 1984. Their flea ectoparasites were collected, identified and counted. The rodent carcasses were serologically examined for specific plague antibodies and antigens, and bacteriologically examined for bipolar staining bacilli. A total of 1758 traps were set during the 12-month period and 924 animals were caught. From these, 1037 fleas were collected. Rattus rattus (L.), Praomys natalensis (Smith) and Lophuromys flavopunctatus Thomas comprised the largest proportions of the rodent population, while Dino-psyllus lypusus Jordan & Rothschild, Ctenophthalmus calceatus Waterston and Xenopsylla brasiliensis (Baker) were the dominant flea species. Rodents were most abundantly trapped during December and January. Flea indices were highest from December to May. Human plague was most active from November to March. Rodents contained plague antibodies every month except May and July, with a peak in September. Plague antigens and bipolar bacilli were detected in rodent organs during January-April. From the product of abundance and infection rate, the most prevalent rodent hosts of plague appeared to be R. rattus, Otomys ango-niensis Wroughton, P.natalensis and Pelomys fallax (Peters). Continuous integrated control of rodents and fleas was recommended, reinforced by quarantine and maintenance of a surveillance service for clinical detection, diagnosis and treatment of patients in the plague endemic area. [ABSTRACT FROM AUTHOR]

ABSTRACT. Laboratory-reared Ctenocephalides felis (Bouche) adults were tested with 0.5% malathion and 0.5% permethrin, using the standard WHO methods. After 24 h exposure to malathion (3.6 mg/cm2), 92% of the fleas died. The LT50 for malathion was approximately 8 h. Permethrin (0.45 mg/cm2) produced 100% mortality of exposed insects after 24 h while with a higher dose (0.9 mg/cm2) all fleas died after 8 h exposure. LT50 for the two doses of permethrin were 7.7 and 1.05 h, respectively. The failure of the diagnostic dose of malathion to kill 100% of the population was attributed to resistance. Permethrin is a suitable pesticide for controlling fleas of domestic animals in Tanzania. [ABSTRACT FROM AUTHOR]