Browsing by Author "Kilonzo, B. S."

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The effect of clay on the persistence of BTi toxicity against mosquito larvae in Morogoro, Tanzania IA
(2001) Kilonzo, B. S.; Madoffe, S. S.; Maliondo, S. M. S.; Msanya, B. M.; Mabagalla, R.; Kitojo, D. H.
Laboratory colonies of Anopheles gambiae and Culex quinquefasciatus were reared from parental larvae obtained from the Ifakara Health Research Centre and septic tanks ill Morogoro Municipality respectively. Water ponds (1M3 ) were constructed at selected sites and left open for mosquitoes to breed ill freely. Various concentrations of Bti crystals were-mixed with varying concentrations of clay and tested against third instar larvae of each species at various periods of time post-preparation. A total of 60 larvae (20 x 3) were exposed to each mixture in the laboratory, and each- experiment was replicated four times. Mortality rates were recorded after 241t. exposure. The observations revealed that for every concentration of Bti crystals used, the toxicity on both species of mosquitoes was less persistent in crystal/clay mixtures than in crystals alone. It was also shown that such persistence was much less in mixtures containing large concentrations of clay (5mg/ml) titan in those containing low concentrations (0.05 - 0.5 mg/ml) of clay. It wasfurther observed th at the toxicity against Culex and Anopheles larvae was more persistent in mixtures containing higher concentrations of Bti crystals (0.12 - 0.3 ug/ml) titan ill those containing low concentrations (0.03 - 0.06 ug/ml) of the toxin. Furthermore, it was observed that C. quinquefasciatus larvae succumbed to Bti crystal/clay mixtures for longer periods titan A. gambiae larvae. It was generally concluded that clays have 11 negative impact on the persistence of Bti toxicity against mosquito larvae and th at such impact is more significant in mixtures containing large concentrations clay. It was also concluded that despite the environmental friendliness of Bti, its applicability by communities is limited in view of its short persistence when it is adsorbed to tropical soils which are found in most natural mosquito breeding sites.
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.
Interaction between rodent species in agro-forestry habitats in the western Usambara Mountains, north-eastern Tanzania, and its potential for plague transmission to humans
(Australian Centre for International Agricultural Research, 2003) Makundi, R. S.; Kilonzo, B. S.; Massawe, A. W.
This study was carried out to determine rodent species composition and abundance, the interaction between them, and the possible implication in plague dissemination to humans. Over 2000 rodents were captured, identified and the relative species abundance determined. These animals belonged to six species, namely Mastomys natalensis, Arvicanthis nairobe, Lophuromys flavopunctatus, Grammomys dolichurus, Mus sp. and Praomys sp. They were distributed in two principal habitats, namely fallow land and forest. The distribution of the species overlapped, indicating interaction between them, but their abundance varied considerably between the habitats. Three species of fleas were collected from rodents. Of these, Dinopsylus lypusus was most abundant, followed by Leptopsylla aethiopica and Nosopsyllus fasciatus. Rodent population densities declined rapidly in August and September and were followed by outbreaks of human plague in October. The observations made in the current study suggest that declining rodent population abundance leads to more ‘free’ fleas which probably seek alternative hosts, including humans. This consequently facilitates an increase in the transfer of plague from rodents to humans. The study further indicated that M. natalensis and A. nairobe form a continuum between forest-inhabiting rodent species and peri-domestic premises which therefore creates an avenue for transferring the disease from a potential forest reservoir to the human population. The presence of specific anti-plague immunoglobulin (IgG and IgM) antibodies in blood sera of rodents was tested by enzyme-linked immunosorbent assay (ELISA). The presence of Yersinia pestis DNA was tested by polymerase chain reaction (PCR). Both tests revealed that M. natalensis, A. nairobe, Rattus rattus (captured in houses) and L. flavopunctatus were the potential rodent reservoirs of plague in the western Usambara Mountains. Grammomys dolichurus and Praomys sp. tested negative for plague, but more specimens will be tested to confirm this finding.
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.
Short communication - effects of azadirachta indica (neem) extract on livestock fleas in Morogoro district, Tanzania
(International Centre of Insect Physiology and Ecology, 2001) Kilonzo, B. S.; Ngomuo, A. J.; Sabuni, C. A.; Mgode, G. F.
Aqueous neem seed kernels extracts (NSKE) were used to treat flea-infested goats in Morogoro, Tanzania to determine their efficacy for flea control. Mean population densities of the insects were significantly lower in the treated goats compared to their untreated counterparts (P < 0.05). It was concluded that NSKE has potential in controlling livestock fleas, but further studies are needed to determine the active principals against fleas and their mode of action.
Spatio-temporal patterns in the distribution of the multi-mammate mouse, Mastomys natalensis, in rice crop and fallow land habitats in Tanzania
(Mammalia, 2015) Mulungu, L. S.; Sixbert, V.; Ngowo, V.; Mdangi, M.; Katakweba, A. S.; Tesha, P.; Mrosso, F. P.; Mchomvu, M.; Kilonzo, B. S.; Belmain, S. R.
: An understanding of the dispersion patterns of a pest is an important pre-requisite for developing an effective management programme for the pest. In this study, rodents were trapped in two rice fields and two fallow fields for three consecutive nights each month from June 2010 to May 2012. Mastomys natalensis was the most abundant rodent pest species in the study area, accounting for > 95% of the trapped rodent community. Rattus rattus, Dasymys incomtus, Acomys spinosissimus and Grammomys dolichurus comprised relatively small proportions of the trapped population. Morisita’s index of dispersion was used to measure the relative dispersal pattern (aggregate, random, uniform) of individuals across each trapping grid as a means of comparing rodent distribution in rice and fallow fields over time. This analysis revealed that the rodents in rice fields generally exhibited an aggregated spatio-temporal distribution. However, the rodents in fallow fields were generally less aggregated, approaching a random distribution in some habitats and seasons. Heat maps of trapping grids visually confirmed these dispersal patterns, indicating the clumped or random nature of captured rodents. ANOVA showed that the parameters of habitat (rice, fallow), crop stage (transplanting, vegetative, booting, maturity) and cropping season (wet, dry) all significantly impacted the number of rodents captured, with the vegetative, dry season, fallow habitat having the highest number of rodents; and the transplanting, wet season, rice habitat with the least number of rodents. Therefore, such spatio-temporal patterns can serve as a tool for developing stratified biodiversity sampling plans for small mammals and decision making for rodent pest management strategies.