Biological Sciences Collection

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    Mosquito diversity and virus infection in Kilombero valley in South-eastern Tanzania
    (Sokoine University of Agriculture, 2015) Shayo, John Mariana
    Mosquito-borne viruses are an important cause of human and domestic diseases worldwide. As crucially important emerging pathogens, they have caused multiple, notable and unnoticed epidemics of human disease over recent decades. All mosquito-borne viruses circulate within sylvatic cycles among wildlife and forest mosquitoes and may cause diseases in rural and urban populations after spillover transmission to human and domestic animals. The aim of this study was to determine mosquito diversity and transmission of Rift Valley fever virus (RVFV), dengue virus (DENV) and Chikungunya virus (CHIKV) in South-eastern Tanzania. In the present cross-sectional study, a total of 1320 adult mosquitoes were collected using Biogent (BG) sentinel traps and battery-powered aspirators. In addition, a total of 31 larvae were collected using a dipping technique and allowed to hatch into adults. Morphological identification of mosquitoes showed the presence of 12 different species which were unevenly distributed among different ecological zones within the two districts. Culex mosquitoes were found to be dominant at all mosquito collection sites and represented 89.1% followed by 10.1% Aedes and 0.8% Mansonia. Aedes mosquitoes were pooled into groups of 20 mosquitoes resulting into a total of 12 pools. No mosquito pool was positive for DENV or CHIKV when Aedes mosquito pools were screened for these viruses. However, RVFV was found in two pools of mosquitoes including one of Aedes aegypti and another of Aedes pembaensis. Furthermore, when Aedes mosquito pools were screened, eight pools were positive for Flavivirus and six pools were positive for Alphavirus respectively. The positivity to Flavivirus and Alphavirus with concurrent absence of DENV and CHIKV in these mosquitoes indicates the presence of viruses other than DENV and CHIKV. Results obtained from this study show that mosquitoes in Kilombero Valley carry viruses of iii serious public health importance. It is recommended that mosquito-borne viruses be screened in febrile patients presenting at points of care in order to improve prognosis.
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    Mosquito diversity and virus infectivity in Kinshasa, Democratic Republic of Congo
    (Sokoine university of agriculture, 2015) Mbanzulu, Kennedy, M
    Mosquito species distribution patterns and their ecology is gaining importance, because global climate changes are thought to lead to the emergence of mosquito-borne diseases; which are of considerable medical and veterinary importance because of their high morbidity and mortality. This study was conducted in five municipalities of Kinshasa to determine mosquito diversity, and arboviruses infection within. Mosquitoes were collected using BG-Sentinel traps, battery-powered aspirator for adult and a dipping technique for larvae. One part (adults and larvae-hatched adults) served for species identification, using morphological keys and Ae. aegypti were further identified by PCR using primers targeting the guanylate cyclase (GUA) and phosphoglycerate kinase (PGK) genes. Another part (adults only) was pooled into groups according to mosquitoes’ genus and sampling sites. Each group was preserved in RNA later and screened for bunyaviruses, alphaviruses and flaviviruses. Positive groups were then tested for the presence of specific viruses using reverse transcriptase polymerase chain reaction (RT-PCR) assays. In total, 5714 mosquitoes were collected. Of these, 2814 adults and larvae-hatched adults were identified and belonged to 4 genera (Culex, Aedes, Anopheles and Mansonia), representing 12 mosquito species. Culex quiquenfiasciatus was the most predominant species, followed by Ae. aegypti, while Ae. luteocephalus seems to be reported for the first time in Kinshasa. 2900 mosquitoes were pooled in 29 groups of 100 mosquitoes and 12 pools were positive either for alphavirus or flavivirus or bunyavirus including mixed infection. Chikungunya, O’nyong’nyong and Rift valley fever viruses were mainly found in Aedes groups. A high frequency of arboviruses was found in agricultural areas around Ndjili River. The present study shows that mosquitoes in Kinshasa carry several arboviruses that may have serious public health implications. Such study in the human population of Kinshasa is needed.
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    Relationship between diet digestibility and morphology of digestive system of local Zebu cattle finished on agro – processing by products
    (Sokoine University of Agriculture., 2015) Juma, Kulwa
    The relationship between diets digestibility and morphology of digestive systems, were studied in local Tanzanian Short Horn Zebu (TSHZ) cattle finished on agro industrial by products. Forty five TSHZ were weighed and randomly allocated to five dietary treatments in a completely randomized design, and nine grazer animals were used as a control group which made a total of fifty four animals. The feedlot animals were fed on hay as a basal diet and supplemented with concentrate, the control group was fed on natural pasture. Animals under Treatments 1 – 5 were fed adlibitum with five concentrates formulated to contain Molasses + Maize meal (T1), Molasses + Maize bran (T2), Maize meal + Maize bran (T3), Molasses + Rice polishing (T4) and Maize meal + Rice polishing (T5). In addition, cotton seedcake, mineral mix, salt and urea were included in all Treatment diets, to meet the requirements for CP and minerals. Digestibility of the diets was measured using Acid Insoluble Ash as a marker. The Morphology of the rumen, duodenum, small intestine and liver from the animals were evaluated after slaughter using ruler and light microscope. Animals under Treatment 2 exhibited significantly higher apparent digestibility of DM (63.9%) and OM (58.8%) than those fed on T1 (62.2% and 55.3%) and lowest values were observed on control group (35.7% and 32.6%) respectively. Higher digestibility values for NDF and ADF (P<0.01) were observed in cattle under T2 (57.4% and 54.8%) and T1 (54.3% and 49.9%) than the other treatments. Rumen papillae length (16.1 mm) and width (3.4mm) for the cattle assigned to Treatment 2 were longest (P<0.01) and widest than those of other Treatments. The villi length (78.5 μm), and crypt depth (29.7 μm) of the small intestine from cattle under Treatment 2 were significantly (P<0.01) longer than those from cattle under the other iii Treatments while the control had the shortest villi (54.2 μm) and narrowest crypt depth (17.5 μm). Cattle under Treatment 2 had heavier carcass (153kg), liver weight (3.86kg) and glycogen level (55.1%) than cattle assigned to the other Treatments. Treatment 5 had the lowest carcass weight (133kg), liver weight (3.03kg) and glycogen level (33.0%). At same time, there was a positive correlation between DM and OM digestibility with carcass, liver weight and glycogen level at (P<0.05), also NDF and ADF digestibility had significant (P<0.05) correlation with carcass and liver weight. Also there was a simple correlation coefficient between papillae (length and width), villi (crypt and depth) with a series of DM, OM, NDF and ADF apparent digestibility (P<0.05). From the above findings, it seems that, for better animal performance, cattle should be fed the well digested feed, which can lead to high morphological improvement. Treatment 2 was the best in categories of digestibility and morphology of digestive system and carcass weight; so it is recommended to be used for beef cattle fattening under feedlot system.
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    Assessing the genetic diversity of five Tanzanian chicken ecotypes using molecular tools
    (South African Society for Animal Science, 2013-12-21) Lyimo, Charles Moses; Weigend, Annett; Janßen-Tapken, Ulrike; Msoffe, Peter Lawrence; Simianer, Henner; Weigend, Steffen
    The study aimed to evaluate the genetic diversity of Tanzanian chicken populations through phylogenetic relationship, and to trace the history of Tanzanian indigenous chickens. Five ecotypes of Tanzanian local chickens (Ching'wekwe, Kuchi, Morogoro-medium, Pemba and Unguja) from eight regions were studied. Diversity was assessed based on morphological measurements and 29 microsatellite markers recommended by ISAG/FAO advisory group on animal genetic diversity. A principal component analysis (PCA) of morphological measures distinguished individuals most by body sizes and body weight. Morogoro Medium, Pemba and Unguja were grouped together, while Ching'wekwe stood out because of their disproportionate short shanks and ulna bones. Kuchi formed an independent group owing to their comparably long body sizes. Microsatellite analysis revealed three clusters of Tanzanian chicken populations. These clusters encompassed i) Morogoro-medium and Ching'wekwe from Eastern and Central Zones ii) Unguja and Pemba from Zanzibar Islands and iii) Kuchi from Lake Zone regions, which formed an independent cluster. Sequence polymorphism of D-loop region was analysed to disclose the likely maternal origin of Tanzanian chickens. According to reference mtDNA haplotypes, the Tanzanian chickens that were sampled encompass two haplogroups of different genealogical origin. From haplotype network analysis, Tanzanian chickens probably originated on the Indian subcontinent and in Southeast Asia. The majority of Kuchi chickens clustered in a single haplogroup, which was previously found in Shamo game birds sampled from Shikoku Island of Japan in the Kochi Prefecture. Analysis of phenotypic and molecular data, as well as the linguistic similarity of the breed names, suggests a recent introduction of the Kuchi breed to Tanzania.