A faunistic survey of digenean larvae infecting freshwater snails Biomphalaria, Radix and Bulinus species in the Lake Victoria and Mindu dam, Morogoro in Tanzania

Biomphalaria and Bulinus spp have been reported in Tanzania as vectors of Schistosoma mansoni and Schistosoma haematobium respectively. Thus most schistosomiasis control efforts have focussed on elimination of these molluscs in freshwater systems or deworming infected persons. In addition almost there is limited information of larval trematodes infecting freshwater snails in Tanzania and whether the trematode antagonism found elsewhere could be used for control of schistosomiasis. We report and describe larval digeneans infecting Biomphalaria pfeifferi, Bulinus spp and Radix natalensis, snails collected at Mindu dam, Morogoro and Mwanza gulf of the Lake Victoria from January 2011 to January 2012. Out of a total 9194 snails, belonging to Biomphalaria pfeifferi, Bulinus tropicus and Radix natalensis, collected from Mindu dam and the Mwanza gulf, Lake Victoria, 678 (7.34%) were infected with 14 larval trematode species: 3 xiphidiocercariae, 6 furcocercariae, l gymnocephalous cercariae, 1 amphistome, 2 echinostome and 1 undescribed metacercaria. From 386 infected B. pfeifferi 67 (1.69%) were infected with S. mansoni, the causative agent of intestinal schistosomiasis. These findings show that despite the increased effort to control schistosomiasis and other neglected tropical diseases in Tanzania, the diseases are still highly prevalent in freshwater systems. However, the absence of trematode antagonism or low multiple infections mean redia cannot coexist with sporocysts, hence can be used for control of schistosomiasis.Keywords: Bulinus, Biomphalaria, Radix, Digenean larvae, neglected tropical disease

Spread of Tylodelphys mashonense (digenea: diplostomidae) by grey heron Ardea cinerea and great white egret a. Alba in Lake Victoria, Tanzania

Despite the fact that Tylodelphys mashonense, parasites of the cranial cavity of the catfish Clarias gariepinus, are ubiquitous in freshwater systems, little is known on their spread. As such, we examined a total of 152 piscivorous birds, belonging to 6 species; 43 great cormorant Phalacrocorax carbo, 33 grey heron Ardea cinerea, 26 hamerkop Scopus umbretta, 22 great white egret Ardea alba, 15 marabou stork Leptoptilos crumeniferus and 13 pied kingfisher Ceryle rudis foraging in the Lake Victoria. Out of the six bird species only A. cinerea and A. alba were found infected by T. mashonense with prevalence of 42.4% and 9.1%, respectively. These findings report T. mashonense in A. alba for the first time and its occurrence in A. cinerea in Tanzania is the first record outside Zimbabwe.Keywords: Ardeidae, Ardea cinerea, Ardea alba, intestinal digenean

A Survey of Fish Parasites from Pangani Catchment and Lake Kitangiri in Singida, Tanzania

Inland water fisheries are a significant source of dietary protein to human populations, and consequently they are essential economic activities worldwide. However, both natural waters and aquaculture systems, which form the freshwater fisheries are faced with a problem of fish parasitic diseases which may result in reduced productivity and market value. The present study, therefore, carried out a survey on fish parasites from the Pangani catchment (Nyumba ya Mungu dam and Lake Jipe) and Lake Kitangiri in Singida Region in Tanzania to seal the gap of occurrence, diversity and abundance of helminths. Three species of fish viz. 111 African sharptooth catfish (Clarias gariepinus), 36 African butter catfish (Schilbe mystus) and 9 cichlid tilapia (Oreochromis amphimelas) were examined for parasites. Most fishes were co-infected with two helminth genera, Contracaecum in the abdominal cavities and Tylodelphys in the cranial cavities with prevalences higher than 70%, while a few fish were infected with Diplostomum in the eyes’ vitreous humour and unidentified trematodes in the intestines. Pangani catchment and Lake Kitangiri were recorded as new localities for Tylodelphys species, and O. amphimelas as a new host species. Keywords: Fish; Helminths; Nyumba ya Mungu Dam; Lakes Kitangiri; Lake Jip

Cryptic intermediate snail host of the liver fluke Fasciola hepatica in Africa

Background: Snails such as Galba truncatula are hosts for trematode flukes causing fascioliasis, a zoonosis that is a major public health problem. Galba truncatula has recently been shown to be a cryptic species complex. African populations of Galba spp. are not yet studied using molecular assessments and is imperative to do so and reconstruct the centre of origin of Galba and to understand when and by what means it may have colonized the highlands of Africa and to what extent humans might have been involved in that process. Methods: Samples from all known sub-ranges throughout Africa and new samples from Europe and Asia were obtained. We used a combination of two mitochondrial (cox1 and 16S) and one nuclear (ITS2) markers and phylogenetic, divergence time estimates and phylogeographical methods to determine the identity and biogeographical affinities. We also reconstructed the colonization history including the likely mode of dispersal and tested for the presence of cryptic Galba species in Africa. Results: Galba truncatula is restricted to the Palaearctic region of the continent, namely Morocco. All sub-Saharan populations proved to be a distinct species according to the phylogenetic analyses and genetic distance. We propose to use the existing name Galba mweruensis (Connolly, 1929) for this species which is morphologically indistinguishable from the other two species hitherto known to occur in northern Africa, i.e. G. truncatula and G. schirazensis. Sub-tropical Africa has been colonized only once in either the Pliocene and possibly Miocene. Diversification within G. mweruensis is dated to the Plio-Pleistocene and thus human-mediated dispersal can be ruled out for the initial colonization of the isolated mountain ranges. There are potentially even more cryptic species in high altitude areas of Africa as outlined by the distinctness of the population found at the top of Mt. Elgon, Uganda. Conclusions: From a novel genetic inspection of available African material, a hitherto neglected distinct species, G. mweruensis, now appears a major host of F. hepatica throughout sub-Saharan Africa. A closer examination of trematode parasites hosted by this species is needed in order to understand transmission patterns in highlands throughout eastern and southern Africa. We encourage future studies to inspect other high altitudes areas in Africa in light of parasites of either veterinary or medical importance

Intercontinental distributions, phylogenetic position and life cycles of species of Apharyngostrigea (Digenea, Diplostomoidea) illuminated with morphological, experimental, molecular and genomic data

When subjected to molecular study, species of digeneans believed to be cosmopolitan are usually found to consist of complexes of species with narrower distributions. We present molecular and morphological evidence of transcontinental distributions in two species of Apharyngostrigea Ciurea, 1924, based on samples from Africa and the Americas. Sequences of cytochrome c oxidase I and, in some samples, internal transcribed spacer, revealed Apharyngostrigea pipientis (Faust, 1918) in Tanzania (first known African record), Argentina, Brazil, USA and Canada. Sequences from A. pipientis also match previously published sequences identified as Apharyngostrigea cornu (Zeder, 1800) originating in Mexico. Hosts of A. pipientis surveyed include definitive hosts from the Afrotropic, Neotropic and Nearctic, as well as first and second intermediate hosts from the Americas, including the type host and type region. In addition, metacercariae of A. pipientis were obtained from experimentally infected Poecilia reticulata, the first known record of this parasite in a non-amphibian second intermediate host. Variation in cytochrome c oxidase I haplotypes in A. pipientis is consistent with a long established, wide-ranging species with moderate genetic structure among Nearctic, Neotropic and Afrotropic regions. We attribute this to natural dispersal by birds and find no evidence of anthropogenic introductions of exotic host species. Sequences of CO1 and ITS from adult Apharyngostrigea simplex (Johnston, 1904) from Egretta thula in Argentina matched published data from cercariae from Biomphalaria straminea from Brazil and metacercariae from Cnesterodon decemmaculatus in Argentina, consistent with previous morphological and life-cycle studies reporting this parasite—originally described in Australia—in South America. Analyses of the mitochondrial genome and rDNA operon from A. pipientis support prior phylogenies based on shorter markers showing the Strigeidae Railliet, 1919 to be polyphyletic.Facultad de Ciencias Naturales y MuseoCentro de Estudios Parasitológicos y de Vectore

Serological Analyses of Human Brucellosis in Ngara and Kibondo Districts, Tanzania

Brucellosis, a zoonotic disease transmitted by Brucella species, is transmitted to humans from infected animals through handling dairy products like milk, blood, and semen. Although some human communities in Tanzania live close to livestock, the status of human brucellosis in Ngara and Kibondo Districts in Kagera and Kigoma regions, respectively, is poorly understood. As such, the present study aimed to investigate the status of human brucellosis in north-western Tanzania, particularly Ngara and Kibondo Districts, where the risk of contracting zoonotic diseases, including brucellosis, is high due to the abundance of livestock. Among the screened sera (n = 450), the prevalence was 13.11% with an incidence rate of 6.22% in 581,378 population size intimating that the risk is alarming. Brucellosis patients admitted in dispensaries and other lower health facilities ranged from 6% to 26%, while those admitted in hospitals ranged from 4% to 14%  indicating that communities prefer primary health facilities to hospitals when they show symptoms of brucellosis. The present study has also revealed that communities engaged in slaughtering, milking, skinning and helpers during births of livestock are at high risk of acquiring Brucella spp. because the odds ratios’ of these activities range between 1.583 and 8.400. Therefore, awareness and education should be enhanced by veterinary officers and associated stakeholders. A comprehensive study of brucellosis using molecular techniques to reveal species-specific in north-western Tanzania is highly recommended. Keywords: brucellosis; prevalence; incidence; risk factors; seru

Optimal control and cost effectiveness analysis for Newcastle disease eco-epidemiological model in Tanzania

CITATION: Hugo, A., et al. 2017. Optimal control and cost effectiveness analysis for Newcastle disease eco-epidemiological model in Tanzania. Journal of Biological Dynamics, 11(1):190-209, doi:10.1080/17513758.2016.1258093.The original publication is available at https://www.tandfonline.comIn this paper, a deterministic compartmental eco- epidemiological model with optimal control of Newcastle disease (ND) in Tanzania is proposed and analysed. Necessary conditions of optimal control problem were rigorously analysed using Pontryagin’s maximum principle and the numerical values of model parameters were estimated using maximum likelihood estimator. Three control strategies were incorporated such as chicken vaccination (preventive), human education campaign and treatment of infected human (curative) and its’ impact were graphically observed. The incremental cost effectiveness analysis technique used to determine the most cost effectiveness strategy and we observe that combination of chicken vaccination and human education campaign strategy is the best strategy to implement in limited resources. Therefore,NDcan be controlled if the farmers will apply chicken vaccination properly and well in time.https://www.tandfonline.com/doi/full/10.1080/17513758.2016.1258093Publisher's versio