[show abstract][hide abstract] ABSTRACT: Although swine origin A/H1N1/2009 influenza virus (hereafter "pH1N1″) has been detected in swine in 20 countries, there has been no published surveillance of the virus in African livestock. The objective of this study was to assess the circulation of influenza A viruses, including pH1N1 in swine in Cameroon, Central Africa. We collected 108 nasal swabs and 98 sera samples from domestic pigs randomly sampled at 11 herds in villages and farms in Cameroon. pH1N1 was isolated from two swine sampled in northern Cameroon in January 2010. Sera from 28% of these herds were positive for influenza A by competitive ELISA and 92.6% of these swine showed cross reactivity with pandemic A/H1N1/2009 influenza virus isolated from humans. These results provide the first evidence of this virus in the animal population in Africa. In light of the significant role of swine in the ecology of influenza viruses, our results call for greater monitoring and study in Central Africa.
[show abstract][hide abstract] ABSTRACT: Critical to the mitigation of parasitic vector-borne diseases is the development of accurate spatial predictions that integrate environmental conditions conducive to pathogen proliferation. Species of Plasmodium and Trypanosoma readily infect humans, and are also common in birds. Here, we develop predictive spatial models for the prevalence of these blood parasites in the olive sunbird (Cyanomitra olivacea). Since this species exhibits high natural parasite prevalence and occupies diverse habitats in tropical Africa, it represents a distinctive ecological model system for studying vector-borne pathogens. We used PCR and microscopy to screen for haematozoa from 28 sites in Central and West Africa. Species distribution models were constructed to associate ground-based and remotely sensed environmental variables with parasite presence. We then used machine-learning algorithm models to identify relationships between parasite prevalence and environmental predictors. Finally, predictive maps were generated by projecting model outputs to geographically unsampled areas. Results indicate that for Plasmodium spp., the maximum temperature of the warmest month was most important in predicting prevalence. For Trypanosoma spp., seasonal canopy moisture variability was the most important predictor. The models presented here visualize gradients of disease prevalence, identify pathogen hotspots and will be instrumental in studying the effects of ecological change on these and other pathogens.
Proceedings of the Royal Society B: Biological Sciences 09/2010; 278(1708):1025-33. · 5.68 Impact Factor
[show abstract][hide abstract] ABSTRACT: Land use changes including deforestation, road construction and agricultural encroachments have been linked to the increased prevalence of several infectious diseases. In order to better understand how deforestation affects the prevalence of vector-borne infectious diseases in wildlife, nine paired sites were sampled (disturbed vs. undisturbed habitats) in Southern Cameroon. We studied the diversity, prevalence and distribution of avian malaria parasites (Plasmodium spp.) and other related haemosporidians (species of Haemoproteus and Leucocytozoon) from these sites in two widespread species of African rainforest birds, the yellow-whiskered greenbul (Andropadus latirostris, Pycnonotidae) and the olive sunbird (Cyanomitra olivacea, Nectariniidae). Twenty-six mitochondrial cytochrome b lineages were identified: 20 Plasmodium lineages and 6 Haemoproteus lineages. These lineages showed no geographic specificity, nor significant differences in lineage diversity between habitat types. However, we found that the prevalence of Leucocytozoon and Haemoproteus infections were significantly higher in undisturbed than in deforested habitats (Leucocytozoon spp. 50.3% vs. 35.8%, Haemoproteus spp. 16.3% vs. 10.8%). We also found higher prevalence for all haemosporidian parasites in C. olivacea than in A. latirostris species (70.2% vs. 58.2%). Interestingly, we found one morphospecies of Plasmodium in C. olivacea, as represented by a clade of related lineages, showed increased prevalence at disturbed sites, while another showed a decrease, testifying to different patterns of transmission, even among closely related lineages of avian malaria, in relation to deforestation. Our work demonstrates that anthropogenic habitat change can affect host-parasite systems and result in opposing trends in prevalence of haemosporidian parasites in wild bird populations.
[show abstract][hide abstract] ABSTRACT: Spatial heterogeneity influences the distribution, prevalence, and diversity of haemosporidian parasites. Previous studies have found complex patterns of prevalence with respect to habitat characteristics and parasite genotype, and their interactions, but there is little information regarding how parasitemia intensity and the prevalence of co-infections may vary in space. Here, using both molecular methods and microscopy, we report an analysis of the variation of parasitemia intensity and co-infections of avian haemosporidian parasites ( Plasmodium and Haemoproteus species) in 2 common African birds species, the yellow-whiskered greenbul ( Andropadus latirostris ) and the olive sunbird ( Cyanomitra olivacea ), at 3 sites with distinct habitat characteristics in Ghana. First, we found an interaction between the site and host species for the prevalence of Plasmodium spp. and Haemoproteus spp. For the olive sunbird, the prevalence of Plasmodium spp., as well as the number of individuals with co-infections, varied significantly among the sites, but these measures remained constant for the yellow-whiskered greenbul. In addition, yellow-whiskered greenbuls infected with Haemoproteus spp. were found only at 1 site. Furthermore, for both bird species, the parasitemia intensity of Plasmodium spp. varied significantly among the 3 sites, but with opposing trends. These results suggest that spatial heterogeneity differently affects haemosporidian infection parameters in these vertebrate-hosts. Environmental conditions here can either favor or reduce parasite infection. We discuss the implications of these discrepancies for conservation and ecological studies of infectious diseases in natural populations.
Journal of Parasitology 10/2009; 96(1):21-9. · 1.32 Impact Factor
[show abstract][hide abstract] ABSTRACT: Plasmodium (Novyella) megaglobularis n. sp. was recorded in the olive sunbird Cyanomitra olivacea, and Plasmodium (Novyella) globularis n. sp. and Haemoproteus (Parahaemoproteus) vacuolatus n. sp. were found in the yellow-whiskered greenbul Andropadus latirostris in rainforests of Ghana and Cameroon. These parasites are described based on the morphology of their blood stages and a segment of the mitochondrial cytochrome b gene, which can be used for molecular identification and diagnosis of these species. Illustrations of blood stages of new species are given, and phylogenetic analysis identifies deoxyribonucleic acid (DNA) lineages closely related to these parasites. Traditional taxonomy of avian pigment-forming haemosporidians of the families Plasmodiidae and Haemoproteidae is discussed based on the recent molecular phylogenies of these parasites. We conclude that further work to increase the number of precise linkages between haemosporidian DNA sequences and their corresponding morphospecies is needed before revising the current classification of haemosporidians. This study emphasises the value of both the polymerase chain reaction and microscopy in the identification of avian haemosporidian parasites.
Parasitology Research 11/2008; 103(5):1213-28. · 2.85 Impact Factor