Papers by Charles Masembe
Transboundary and Emerging Diseases, 2019
African swine fever (ASF) is a haemorrhagic fever of pigs that can result in up to 100 per cent m... more African swine fever (ASF) is a haemorrhagic fever of pigs that can result in up to 100 per cent mortality. It is caused by a large DNA virus that is the only known member of the genus Asfivirus and family Asfarviridae (Dixon et al., 2005). Only members of the family Suidae are susceptible to the infection. Confirmation of ASF as a disease that differed from classical swine fever was first obtained in Kenya, where an association with warthogs (Phacochoerus africanus) was recognized (Montgomery, 1921). The epidemiology is complex. Three cycles of transmission have been confirmed in sub-Saharan Africa: two cycles that involve soft ticks of the Ornithodoros moubata complex and a cycle involving circulation among domestic pigs. The virus is believed to have evolved
Uganda is the third largest pig producing country in Africa. However the pig industry in Uganda i... more Uganda is the third largest pig producing country in Africa. However the pig industry in Uganda is currently threatened by African swine fever virus (ASFV) disease, which is a fatal, contagious viral haemorrhagic disease of domestic pigs, causing up to 100% mortality, and the disease has neither vaccine nor treatment. Harnessing the technological, research potential and community outreach strategies, Makerere University in partnership with government agencies, is using a community participatory epidemiology and molecular characterization approach to develop community-derived control strategies and genetic characteristics of the ASF virus. Through this effort the effectiveness of available molecular ASF diagnostic approaches and home ranges of domestic and wild pigs are being investigated. Seventy seven blood samples were collected from pigs during reported ASF outbreaks in selected pig farms in Uganda. The samples were analysed using a variety of molecular diagnostic approaches available at the molecular genetics laboratory at Makerere University. Preliminary results indicate that the samples tested positive for ASFV. In addition tracking collars (GPS/GSM) were used to monitor the movement patterns of free-ranging domestic pigs and wild pigs. Domestic pigs were mostly active during the nights, early mornings and in the evening. The bush pigs were active from the evening and throughout the night wandering between game reserves and farmlands. There was an overlap between free-ranging domestic pigs and bush pig activity times and this might be a contributing factor to the ASFV disease epidemics. The study involves training two MSc and four undergraduate students. It is anticipated that the trained students will add to the pool of home-grown scientists that can contribute to disease diagnostics prevention and control.
Feed accounts for up to 70% of production costs in aquaculture, hence reducing this cost is neede... more Feed accounts for up to 70% of production costs in aquaculture, hence reducing this cost is needed for rural development. Plant ingredients commonly used in feed contain phytic acid that forms indigestible complexes with nutrients thus reducing their use for fish growth. Toasting feed material is widely practiced to reduce antinutrients but its effect on phytic acid remains unclear. In the study, phytic acid, crude protein (CP) and pH in plant-based diets from untoasted and toasted ingredients and their ingesta along the gut were analysed using complex-metric titration, Kjeldahl method and micro pH meter, respectively. Phytic acid in the diet from untoasted and toasted ingredients differed (p ≤ 0.002) while CP and pH did not (p ≥0.06 and p ≤ 0.40, respectively). The content of phytic acid in the diet doubled along the gut, CP halved and pH was 5.30 - 7.78. Diet from untoasted ingredients was not eaten thus no ingesta was analysed. Results showed that toasting plant ingredients had n...
Additional file 1: Table S1. Final List of 40 SSR primers utilized in PCR reactions. Table S2. Va... more Additional file 1: Table S1. Final List of 40 SSR primers utilized in PCR reactions. Table S2. Variation of the final set of 40 SSR loci. Loci Ti1–Ti35 were taken from Tibihika et al. [28] while loci Ti39–Ti61 were developed in the current study. Table S3. List of the linkage group and location/position for each of the primer pairs used. These primers were BLAST against the genome assembly GCF_001858045.2 available in GenBank. The field reference refers to the accession number of the matching Linkage group. Figure S1. Genetic structure based on PCoA within the East African Western Rift Valley lakes, Albert (a) and Edward (b) metapopulations. Figure S2. STRUCTURE HARVESTER analyses for depicting the optimal K values, which is derived from STRUCTURE results. a represents the best K for all populations (K = 10), b best K for all native populations (K = 7), c best K for East African native populations (K = 2), d best K for only Ugandan native populations (K = 2), e best K for all Uganda...
Population morphological variation of the Nile perch
Phylogenetic analyses of the polyprotein coding sequences of serotype O foot-and-mouth disease
African swine fever (ASF) is the most lethal disease of pigs caused by ASF virus (ASFV) with seve... more African swine fever (ASF) is the most lethal disease of pigs caused by ASF virus (ASFV) with severe economic implications and threat to food security in endemic countries. Between 2016 and 2018, several ASF outbreaks were reported throughout pig producing States in Nigeria. This study was designed to identify the ASFV genotypes responsible for these outbreaks and the transmission pathways of the virus during this period. Twenty-two ASFV-positive samples collected during passive surveillance in eight States of Nigeria were characterized using 3 partial genes sequences of the virus. The genes were: p72 capsid protein of the B646L, p54 envelope protein of E183L, and the central variable region (CVR) within B602L of ASFV. Phylogenetic analysis based on p72 and p54 revealed ASFV genotype I as the circulating virus. Sequence analysis of the CVR of B602L revealed genetic variations with six ASFV variants namely: Tet-15, Tet-20a, Tet-21b, Tet-27, Tet-31 and Tet-34, thus increasing the overa...
Theileria parva is a protozoan emo-parasite affecting sub-Saharan Bos taurus and Bos indicus popu... more Theileria parva is a protozoan emo-parasite affecting sub-Saharan Bos taurus and Bos indicus populations. It is the causative agent of East Coast Fever, a major cattle disease causing the death of 1.1∙106 animals per year and an annual loss of 168∙106 USD (Norval et. al., 1992). T. parva geographical occurrence is bound to the presence of susceptible bovine host populations, the main tick vector Rhipicephalus appendiculatus (Neumann 1901), as well as suitable ecological conditions for the survival of both the vector and the parasite. While tick habitat requirements have been extensively investigated (see e.g. Cumming, 2002), studies focusing solely on the environmental conditions determining the parasite occurrence are still lacking. The goal of the study is to define T. parva ecological fundamental niche, thus fostering our understanding of the environmental requirements needed to maintain the parasite-vector-host biological system.
Uganda is one of Africa’s leading fish producers with millions of people deriving their livelihoo... more Uganda is one of Africa’s leading fish producers with millions of people deriving their livelihoods from mainly capture fisheries and related activities. However Climate change is affecting the productivity of many aquatic ecosystems and in the process threatening the Livelihoods of people who depend on fisheries. This threat can only be reduced through knowledge-based adaption and mitigation pathways. In this project we assessed the adaptation and mitigation responses of communities dependent on aquatic ecosystems and evaluated the potential of aquaculture as an innovative alternative to the declining capture fisheries 4. High genetic diversity was observed in both the wild and farmed populations of the African cat fish. Therefore problems of delayed maturity of farmed fish are not genetic as had been previously suspected.
African Journal of Aquatic Science, 2020
This is the final version of the article that is published ahead of the print and online issue Xe... more This is the final version of the article that is published ahead of the print and online issue Xenoestrogens are substances that are similar in chemical composition and structure to steroidal oestrogens, hence they mimic and compete with them, e.g. by binding onto the hormonal receptors in animals such as fish (Roszko et al. 2018; Kanda 2019). In female vertebrates, oestrogens occur in three major forms; oestrone (E1), 17β-estradiol (E2) and estriol (E3), and serve as primary reproductive hormones (Burgos-Aceves et al. 2016; Ashfaq et al. 2019). These hormonal substances have C18 steroidal groups, which are characterised by tetracyclic molecular frameworks of cyclopentane, phenol and two cyclohexanes. Interestingly, this conformation also forms the four ring structures of xenoestrogens (Khanal et al. 2006). The structures of the three hormones (E1, E2 and E3) are named based on the conformational arrangement on C16 and C17. For example, the structure of the 17β-estradiol has two hydroxyl groups, one at position C3, and the other at the 17β position (Figure 1). Therefore, based on the presence of hydroxyl groups, estradiol has been named as E2. E2 is the predominant female sex hormone produced in follicles of ovaries and it is used specifically in vertebrates for the development and maintenance of reproductive tissue, bone, fat and hepatocytes. The E2 synthesis in ovarian follicular cells involves the production of androstenedione, which is converted into oestrone by aromatase and finally into estradiol through a process catalysed by a series of different enzymes (Cui et al. 2013). Moreover, the liver is another site for biosynthesis of the natural oestrogens; it is also the main site for their further biotransformation. Once the oestrogens are synthesised by aromatase in the liver, they are released into circulation. However, in vertebrates, including fish, oestrogens are taken up again by the liver where they are biotransformed into different metabolites under series of enzymes. The quantity and specific type of oestrogen excreted naturally in animals varies, depending mainly on the animal's physiology, reproductive cycle and age. For example, pregnant women and lactating mothers discharge approximately five mg d-1 of 17β-estradiol (Guang-Guo et al. 2002; Khanal et al. 2006), whereas prenatal dairy cows may excrete up to 11.4 mg d-1 of 17α-ethinylestradiol (Khanal et al. 2006). Furthermore, at least 7.0 µg oestrone, 15.2 µg estriol, and 2.4 µg 17β-estradiol have been estimated to be excreted in urine daily by a young woman at the end of the lactating period (Adlercreutz et al. 1986; Liu et al. 2004). As such, oestrogens are continually flushed down in wastewater from homes, hospitals, and abattoirs, and drain into the natural aquatic ecosystems, such as lakes and rivers (Table 1). For pharmaceutical and medical purposes, steroidal estrogenic chemicals like 17α-ethinylestradiol,
Revue d’élevage et de médecine vétérinaire des pays tropicaux, 2019
Les systèmes rudimentaires d’élevage de porcs, non orientés vers le marché, ont été impliqués dan... more Les systèmes rudimentaires d’élevage de porcs, non orientés vers le marché, ont été impliqués dans la persistance de la cysticercose a Taenia spp., maladie endémique présentant un grave problème de santé publique en Ouganda. Nous avons étudié la seroprevalence et les principaux facteurs prédisposant de la maladie à Moyo et à Lira, deux districts producteurs de porcs au nord du pays. Des enquêtes sérologiques transversales ont été menées dans 428 élevages porcins (Moyo, 262 ; Lira, 166). Deux porcs adultes étaient gardés en moyenne par troupeau. En milieu rural ils étaient souvent attachés, la divagation étant occasionnelle. Le confinement en enclos était observé en milieu périurbain. Les animaux étaient principalement alimentés avec des résidus de culture et des fourrages pendant la saison des pluies, et des restes d’aliment des ménages et les résidus de culture en saison sèche. La majorité des éleveurs de l’enquête étaient des femmes (55 %) âgées de plus de 45 ans ; 51 % des éleveu...
Microbiology Resource Announcements, 2018
Complete genome sequences of five African swine fever virus isolates were determined directly fro... more Complete genome sequences of five African swine fever virus isolates were determined directly from clinical material obtained from domestic pigs in Uganda. Four sequences were essentially identical to each other, and all were closely related to the only known genome sequence of p72 genotype IX.
Preventive Veterinary Medicine, 2017
African swine fever (ASF) is one of the most important pig diseases, causing high case fatality r... more African swine fever (ASF) is one of the most important pig diseases, causing high case fatality rate and trade restrictions upon reported outbreaks. In Uganda, a low-income country with the largest pig population in East Africa, ASF is endemic. Animal disease impact is multidimensional and include social and economic impact along the value chain. In low-income settings, this impact keep people poor and push those that have managed to escape poverty back again. If the diseases can be controlled, their negative consequences can be mitigated. However, to successfully argue for investment in disease control, its cost-benefits need to be demonstrated. One part in the cost-benefit equations is disease impact quantification. The objective of this study was therefore to investigate the socioeconomic impact of ASF outbreaks at household level in northern Uganda. In a longitudinal study, structured interviews with two hundred, randomly selected, pig-keeping households were undertaken three times with a six month interval. Questions related to family and pig herd demographics, pig trade and pig business. Associations between ASF outbreaks and economic and social impact variables were evaluated using linear regression models. The study showed that pigs were kept in extreme low-input-low-output farming systems involving only small monetary investments. Yearly incidence of ASF on household level was 19%. Increasing herd size was positively associated with higher economic output. The interaction between ASF outbreaks and the herd size showed that ASF outbreaks were negatively associated with economic output at the second interview occasion and with one out of two economic impact variables at the third interview occasion. No significant associations between the social impact variables included in the study and ASF outbreaks could be established. Trade and consumption of sick and dead pigs were coping strategies used to minimize losses of capital and animal protein. The results indicate that causality of social and economic impact of ASF outbreaks in smallholder systems is complex. Pigs are mostly kept as passive investments rather than active working capital, complicating economic analyses and further disqualifying disease control arguments based only on standard economic models.
BMC veterinary research, Jan 8, 2016
African swine fever (ASF), caused by African swine fever virus (ASFV), is a severe haemorrhagic d... more African swine fever (ASF), caused by African swine fever virus (ASFV), is a severe haemorrhagic disease of pigs, outbreaks of which can have a devastating impact upon commercial and small-holder pig production. Pig production in western Kenya is characterised by low-input, free-range systems practised by poor farmers keeping between two and ten pigs. These farmers are particularly vulnerable to the catastrophic loss of livestock assets experienced in an ASF outbreak. This study wished to expand our understanding of ASFV epidemiology during a period when no outbreaks were reported. Two hundred and seventy six whole blood samples were analysed using two independent conventional and real time PCR assays to detect ASFV. Despite no recorded outbreak of clinical ASF during this time, virus was detected in 90/277 samples analysed by conventional PCR and 142/209 samples analysed by qPCR. Genotyping of a sub-set of these samples indicated that the viruses associated with the positive samples...
American Journal of Clinical and Experimental Medicine, 2015
Goat production is of great importance especially to the rural farmers in Uganda, serving a numbe... more Goat production is of great importance especially to the rural farmers in Uganda, serving a number of socioeconomic functions. Among the limitations of goat production in Uganda are Gastro Intestinal Nematodes (GINs). These are usually controlled using commercial Anthelmintic compounds. Due to continual improper usage of these drugs by the farmers, evolution of resistant strains has resulted thus affecting their effectiveness in controlling the GINs. The aim of this study was to determine the efficacy of four commercially available anthelmintics used for controlling Gastro Intestinal Nematodes (GINs) in goats on natural pastures in the south western highlands of Uganda. A mini survey was conducted prior to the current study to get information about the most commonly used anthelmintics in the study area. Initially, 240 goats were enrolled into the study and, 210 were used in the final analysis. The goats were randomly allocated to 5 different treatment groups at district level namely; untreated controls (CTRL), Albendazole 10% (ABZ), Ivermectin (IVE), Levamisole (LEV) and Closantel (CL). Faecal and blood samples were collected from each animal at 0, 14, 28 and 42 days post-treatment respectively and analysed for faecal egg counts (FEC) using the modified McMaster method. The percentage reduction, FECR % was calculated from the arithmetic mean and difference in FEC between breeds, district and age were assessed by univariate analysis of variance in SPSS. Results at day zero indicated that age and district had significant effect on FEC (P-value= 0.001 and 0.035respectively) while breed had no significant effect (P-value=0.465). At 14 days post-treatment, district, breed and treatment had significant effects on FEC (P-value=0.00, 0.02 and 0.05 respectively) while age was not (P=0.931). Albendazole and Levamizol were the most used drugs in the study area while Closantel and Ivermectin were the least used. Drug efficacy varied between districts, with the highest mean Fecal Egg Count Reduction (FECR) achieved with Closantel (FECR%=100%), while the lowest mean FECR observed with Albendazole (FECR%=49%) in Rukungiri and Kisoro districts respectively. Ivermectin was effective in all the four districts (FECRT% > 95%). Our study confirmed presence of Anthelmintic resistance (AR) by GIN in goats in the south western highlands of Uganda. Closantel is highly effective against GINs, but albendazole is not due to its wide spread usage. Further research is necessary to find and validate alternative strategies for the control of GINs in goats.
Parasites & Vectors, 2015
Background: Glossina fuscipes fuscipes is the main vector of African Trypanosomiasis affecting bo... more Background: Glossina fuscipes fuscipes is the main vector of African Trypanosomiasis affecting both humans and livestock in Uganda. The human disease (sleeping sickness) manifests itself in two forms: acute and chronic. The Lake Victoria basin in Uganda has the acute form and a history of tsetse re-emergence despite concerted efforts to control tsetse. The government of Uganda has targeted the basin for tsetse eradication. To provide empirical data for this initiative, we screened tsetse flies from the basin for genetic variation at the mitochondrial DNA cytochrome oxidase II (mtDNA COII) gene with the goal of investigating genetic diversity and gene flow among tsetse, tsetse demographic history; and compare these results with results from a previous study based on microsatellite loci data in the same area. Methods: We collected 429 Gff tsetse fly samples from 14 localities in the entire Ugandan portion of the Lake Victoria coast, covering 40,000 km 2. We performed genetic analyses on them and added data collected for 56 Gff individuals from 4 additional sampling sites in the basin. The 529pb partial mitochondrial DNA cytochrome oxidase II (mtDNA COII) sequences totaling 485 were analysed for genetic differentiation, structuring and demographic history. The results were compared with findings from a previous study based on microsatellite loci data from the basin. Results: The differences within sampling sites explained a significant proportion of the genetic variation. We found three very closely related mtDNA population clusters, which co-occurred in multiple sites. Although Φ ST (0-0.592; P < 0.05) and Bayesian analyses suggest some level of weak genetic differentiation, there is no correlation between genetic divergence and geographic distance (r = 0.109, P = 0.185), and demographic tests provide evidence of locality-based demographic history. Conclusion: The mtDNA data analysed here complement inferences made in a previous study based on microsatellite data. Given the differences in mutation rates, mtDNA afforded a look further back in time than microsatellites and revealed that Gff populations were more connected in the past. Microsatellite data revealed more genetic structuring than mtDNA. The differences in connectedness and structuring over time could be related to vector control efforts. Tsetse re-emergence after control interventions may be due to re-invasions from outside the treated areas, which emphasizes the need for an integrated area-wide tsetse eradication strategy for sustainable removal of the tsetse and trypanosomiasis problem from this area.
Livestock Research for Rural Development
Uganda has the largest pig industry in eastern Africa, with majority of farmers still smallholder... more Uganda has the largest pig industry in eastern Africa, with majority of farmers still smallholders. African swine fever (ASF) is arguably one of the major constraints in the region, where it is considered endemic. Although the sylvatic cycle exists here, the pig-pig cycle of transmission is more important. The pig value chain is one critical area where there is need for study of the role it plays in the spread of ASF. In this study, different practices and their association with the transmission of ASF within and between farms were investigated on 101 pig farms in Uganda. Practices by 30 traders in pigs and pig products (slaughter slab, pork butchery and roasted pork restaurant operators) were investigated in the districts of Kabarole, Mityana, Moyo, Mukono, Soroti, and Tororo. Key informant interviews with the District Veterinary Officers (DVOs) about pig trade, pig slaughter infrastructure, ASF status and its management in the districts were conducted as well between May-November ...
The NextGen project investigates disease resistance in indigenous Ugandan cattle. Since populatio... more The NextGen project investigates disease resistance in indigenous Ugandan cattle. Since population structure and stratification may produce biased results, we have investigated the genomic structure of sampled animals genotyped with the BovineSNP50 Genotyping Beadchip.
Parasites & Vectors, 2014
Background: Non-clinical Theileria parva infection among indigenous cattle occurs upon recovery f... more Background: Non-clinical Theileria parva infection among indigenous cattle occurs upon recovery from primary disease during the first year of life. Continuous exposure to infection through contaminated tick infestations with absence of clinical disease gives rise to endemic stability. Endemic stable populations may become sources of infection if contaminated tick vectors are shared with susceptible exotic cattle. This study aimed at establishing a nationwide distribution of non-clinical T. parva infection among indigenous cattle populations to inform novel control strategies. Methods: The occurrence of non-clinical T. parva infection among apparently healthy 925 indigenous cattle from 209 herds spread out in 10 agro-ecological zones (AEZs) was determined using a nested PCR assay. The influence of AEZ, breed, sex, age and farmers' ranking of ECF importance were interrogated for influence of non-clinical parasite occurrence. Results: The overall prevalence of non-clinical T. parva infection was 30% (278/925). A gradual increase of non-clinical T. parva infection was observed ranging from 17% (95% CI: 0.03-0.23) to 43% (95% CI: 0.3-0.55) in the North Eastern Savannah Grasslands (NESG) to the Western Highland Ranges (WHR) respectively. A similarly associated 18% (95% CI: 0.07-0.28) and 35% (95% CI: 0.3-0.39) non-clinical parasite prevalence was observed among the East African shorthorn Zebu (EASZ) and Ankole cattle respectively. Average herd level non-clinical T. parva prevalence was 28%, ranging from zero to 100%. The likelihood of non-clinical T. parva infection was 35.5% greater in the western highlands compared to the northeastern semi-arid AEZs. Conclusions: Non-clinical T. parva occurs countrywide, structured along patterns of AEZ and breed gradients. These findings may guide policy formulation, deployment of integrated control strategies and local cattle improvement programs.
Virology Journal, 2012
Background: The rising demand for pork has resulted in a massive expansion of pig production in U... more Background: The rising demand for pork has resulted in a massive expansion of pig production in Uganda. This has resulted in increased contact between humans and pigs. Pigs can act as reservoirs for emerging infectious diseases. Therefore identification of potential zoonotic pathogens is important for public health surveillance. In this study, during a routine general surveillance for African swine fever, domestic pigs from Uganda were screened for the presence of RNA and DNA viruses using a high-throughput pyrosequencing method. Findings: Serum samples from 16 domestic pigs were collected from five regions in Uganda and pooled accordingly. Genomic DNA and RNA were extracted and sequenced on the 454 GS-FLX platform. Among the sequences assigned to a taxon, 53% mapped to the domestic pig (Sus scrofa). African swine fever virus, Torque teno viruses (TTVs), and porcine endogenous retroviruses were identified. Interestingly, two pools (B and C) of RNA origin had sequences that showed 98% sequence identity to Ndumu virus (NDUV). None of the reads had identity to the class Insecta indicating that these sequences were unlikely to result from contamination with mosquito nucleic acids. Conclusions: This is the first report of the domestic pig as a vertebrate host for Ndumu virus. NDUV had been previously isolated only from culicine mosquitoes. NDUV therefore represents a potential zoonotic pathogen, particularly given the increasing risk of human-livestock-mosquito contact.
Uploads
Papers by Charles Masembe