Browsing by Author "Nyirenda, S. S."

Now showing 1 - 4 of 4

Identification of risk factors associated with transmission of plague disease in eastern Zambia
(American society of tropical medicine and hygiene, 2017) Nyirenda, S. S.; Hang’ombe, B. M.; Machang’u, R.; Mwanza, J.; Kilonzo, B. S.
Plague is a fatal, primarily rodent-flea-borne zoonotic disease caused by Yersinia pestis. The identificatio of risk factors of plague was investigated through questionnaire interview and conducting focus group discussion (FGD) in Sinda and Nyimba districts of eastern Zambia. A total of 104 questionnaires were administered to individual respondents and 20 groups consisting of 181 discussants, which comprised FGD team in this study. The study revealed that trapping, transportation, and preparation of rodents for food exposed the community to rodent and their fleas suggesting that plague may have occurred primarily by either flea bites or contact with infected wild rodents. The study also revealed that most people in communities consumed rodents as part of their regular diet; therefore, contact with small wild mammals was a common practice. The mode of transportation of freshly trapped rodents, in particular, carcasses risked human to flea bites. Questionnaire respondents (75%) and FGD discussants (55%) indicated that trappers preferred to carry rodent carcasses in small bags, whereas 55.8% and 20% respectively, reported hunters carrying carcasses in their pockets. Carrying of carcass skewers on trappers’ shoulders was reported by 38.4% and 20% of individual respondents and FGD, respectively. All these activities were exposing humans to rodents and their fleas, the natural reservoirs and vectors of (.2 plague, respectively. This study also showed that there is a statistically significant = 4.6878, P < 0.05), between digging of rodents from their burrows and the presence of fleas on the hunter’s bodies or clothes, which exposes humans to potentially flea bites in an enzootic cycle.
Molecular, serological and epidemiological observations after a suspected outbreak of plague in Nyimba, eastern Zambia
(Sage, 2016) Nyirenda, S. S.; Hang’ombe, B. M.; Kilonzo, B. S.; Kabeta, M. N.; Cornellius, M.; Sinkala, Y.
Plague is a re-emerging zoonotic disease caused by the bacterium Yersinia pestis. The disease has caused periodic global devastation since the first outbreak in the 6th century.Twomonths after a suspected plague outbreak inNyimba district, sampleswere collected from94livestock(goats andpigs), 25 rodents, 6 shrews and33 fleas. Enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) techniques were used to investigate the presence of Y. pestis, which showed that 16.0% (4/25) of rodents, 16.7% (1/6) of shrews (Crocidura spp) and 6.0% (5/83) of goats were positive for IgG antibodies against Fraction 1 antigen of Y. pestis. Plasminogen activator (Pla) gene (DNA) of Y. pestis was detected in five pools containing 36.4% (12/33) fleas collected from pigs (n¼4), goats (n¼5) and rodents (n¼3). The detection of Pla gene in fleas and IgG antibodies against Fraction1 antigen in rodents, shrews and goats suggest that Y. pestis had been present in the study area in the recent past.
Potential roles of pigs, small ruminants, rodents, and their flea vectors in plague epidemiology in Sinda district, eastern Zambia
(Oxford University Press, 2017) Nyirenda, S. S.; Hang’ombe, B. M.; Kilonzo, B. S.; Kangwa, H. L.; Mulenga, E.; Moonga, L.
A 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.
Role of potential reservoir hosts and flea vectors in plague epidemiology in eastern Zambia
(Sokoine University of Agriculture, 2017) Nyirenda, S. S.
This thesis is prepared according to “Published manuscripts” format of the Sokoine University of Agriculture. This thesis discusses the role of potential plague reservoirs and their flea-vectors in the plague epidemiology in eastern Zambia. The goal was to identify and describe roles domestic pigs, goats and sheep, and rodents with their fleas play in maintaining and transmitting the plague pathogen, Yersinia pestis. Plasminogen activator gene (pla) of Y. pestis was successfully identified in fleas and rodents, and Immunoglobulin G (IgG) antibodies against Fraction 1 antigen (Fra1)of Y. pestis, were detected in serum samples from the domestic animals using conventional Polymerase Chain reaction (c-PCR) and indirect Enzyme-linked Immunosorbent Assay (i-ELISA), respectively. Quantitative and qualitative approaches were applied using open and close ended questionnaires by individual respondents and focus group discussion (FGD) to obtain data on human and animal activities in relation to plague disease. The findings indicate that hunting, transportation and preparation or handling of infected animals or their materials predispose humans to plague pathogens and risk of acquiring the disease. The dissertation comprised five publications. The first paper published in the Journal of Medical Entomology, presents the roles domestic pigs, small ruminants, rodents and their fleas, play in the epidemiology of plague in Sinda district in eastern Zambia. This presents the first published literature on plague in pigs and small ruminants and demonstrated the naturally occurring IgG antibodies against Fra1 antigen. The second paper, published in Tropical Doctor presents the findings in Nyimba district after a suspected plague outbreak, where pla gene and IgG antibodies were detected in fleas, and pigs, goats and rodents respectively. The third paper published in the Journal of Zoonotic diseases is a review paper which identified factors that precipitated the spread of plague between 1914 and 2014 in Zambia. The fourth paper published in the American Journal of Tropical Medicine and Hygiene and identified risk factors associated with plague epidemiology. The fifth paper has been submitted to BMC Microbiology Journal, revealed that pla gene of Y. pestis circulating among different hosts in the two districts were closely related to Antiqua (1.ANT) biovar.