Nematodes of the small intestine of African buffaloes, Syncerus caffer, in the Kruger National Park, South Africa

Epidemiology and diversity of gastrointestinal tract helminths of wild ruminants in sub-Saharan Africa: a review

This review summarises studies on distribution, diversity, and prevalence of gastrointestinal helminth infections in wild ruminants in sub-Saharan Africa. The results showed that 109 gastrointestinal tract (GIT) helminth species or species complexes were recorded in 10 sub-Saharan African countries. South Africa reported the highest number of species because most studies were carried out in this country. Eighty-eight nematode species or species complexes were recorded from 30 wild ruminant species across eight countries. The genus Trichostrongylus recorded the highest number of species and utilised the highest number of wild ruminant species, and along with Haemonchus spp., was the most widely distributed geographically. Fifteen trematode species or species complexes were reported from seven countries. The genus Paramphistomum recorded the highest number of species, and Calicophoron calicophoron was the most commonly occurring species in sub-Saharan African countries and infected the highest number of hosts. Six cestode species or species complexes from one family were documented from 14 wild hosts in seven countries. Moniezia spp. were the most commonly distributed in terms of host range and geographically. Impala were infected by the highest number of nematodes, whilst Nyala were infected by the highest number of trematode species. Greater kudu and Impala harbored the largest number of cestodes. The prevalence amongst the three GIT helminths taxa ranged between 1.4% and 100% for nematodes, 0.8% and 100% for trematodes, and 1.4% and 50% for cestodes. There is still limited information on the distribution and diversity of GIT helminths in wild ruminants in most sub-Saharan African countries.

Pathological findings in African buffaloes (Syncerus caffer) in South Africa

The African buffalo (Syncerus caffer) is an iconic species of South African megafauna. As the farmed buffalo population expands, the potential impacts on population health and disease transmission warrant investigation. A retrospective study of skin biopsy and necropsy samples from 429 animals was performed to assess the spectrum of conditions seen in buffaloes in South Africa. Determination of the cause of death (or euthanasia) could not be made in 33.1% (136/411) of the necropsy cases submitted due to autolysis or the absence of significant lesions in the samples submitted. Infectious and parasitic diseases accounted for 53.5% (147/275) of adult fatal cases and non-infectious conditions accounted for 34.9% (96/275). Abortions and neonatal deaths made up 11.6% (32/275) of necropsy cases. Rift Valley fever, bovine viral diarrhoea, malignant catarrhal fever, tuberculosis, bacterial pneumonia, anaesthetic deaths, cachexia and hepatotoxic lesions were the most common causes of death. The range of infectious, parasitic and non-infectious diseases to which African buffaloes were susceptible was largely similar to diseases in domestic cattle which supports concerns regarding disease transmission between the two species. The similarity between diseases experienced in both species will assist wildlife veterinarians in the diagnosis and treatment of diseases in captive African buffaloes. The present study likely does not represent accurate disease prevalence data within the source population of buffaloes, and diseases such as anthrax, brucellosis and foot and mouth disease are under-represented in this study. Hepatic ductal plate abnormalities and haemorrhagic septicaemia have not, to our knowledge, been previously reported in African buffaloes.

A Revised Checklist of Cooperia Nematodes (Trichostrogyloidea), Common Parasites of Wild and Domestic Ruminants

This review updates the current knowledge on the taxonomy of intestinal nematodes of the genus Cooperia parasitizing in wild and domestic ruminants. The emphasis is put on revision of 19 valid species belonging to the genus. This analysis focuses on main features of the genus Cooperia, including its geographic occurrence and the life cycle details. The most widespread congeners are Cooperia curticei, C. oncophora, C. pectinata, and C. punctata, having nearly worldwide distribution. The fifth species, referred by electronic databases from the European territory as Cooperia asamatiSpiridonov, 1985, is unveiled here originally as nomen nudum.

A review of wildlife tourism and meta-analysis of parasitism in Africa's national parks and game reserves

The recent increase of parasitic diseases associated with wildlife tourism can be traced to human contact with wildlife and intense modification of wildlife habitat. The continental estimates of parasitic diseases among visited wildlife-tourists and mammalian wildlife present in conservation areas are lacking; therefore, a general review was necessary to provide insights into Africa's parasitic disease burden and transmission between humans and wildlife. A two-step analysis was conducted with searches in Ovid MEDLINE, EMBASE, PubMed, Web of Science and Global Health. All diseases reported without prevalence were grouped and analysed as categorical data while meta-analysis of prevalence rates of parasitic diseases in wildlife from national parks and reserves in Africa was conducted. Only 4.7% of the tourist centres reported routine wildlife diagnosis for parasitic diseases. Disease intensity shows that cryptosporidiosis and seven other parasitic diseases were observed in both human and wildlife; however, no significant difference in intensity between human and wildlife hosts was observed. Schistosomiasis intensity reports showed a significant increase (P < 0.05) while entamoebiasis showed a significant decrease (P < 0.05) in humans as compared to wildlife. Visiting tourists were more infected with malaria, while wildlife was more infected with parasitic gastroenteritis (PGE). The meta-analysis of wildlife revealed the highest prevalence of PGE with mixed parasites and lowest prevalence of Giardia spp. at 99.9 and 5.7%, respectively. The zoonotic and socioeconomic impact of some of these parasites could pose a severe public threat to tourism. Pre- and post-travel clinical examinations are important for tourists while routine examination, treatment and rational surveillance are important for these animals to improve wildlife tourism.

Uncertain links in host-parasite networks: lessons for parasite transmission in a multi-host system

For many parasites, the full set of hosts that are susceptible to infection is not known, and this could lead to a bias in estimates of transmission. We used counts of individual adult parasites from historical parasitology studies in southern Africa to map a bipartite network of the nematode parasites of herbivore hosts that occur in Botswana. Bipartite networks are used in community ecology to represent interactions across trophic levels. We used a Bayesian hierarchical model to predict the full set of host-parasite interactions from existing data on parasitic gastrointestinal nematodes of wild and domestic ungulates given assumptions about the distribution of parasite counts within hosts, while accounting for the relative uncertainty of less sampled species. We used network metrics to assess the difference between the observed and predicted networks, and to explore the connections between hosts via their shared parasites using a host-host unipartite network projected from the bipartite network. The model predicts a large number of missing links and identifies red hartebeest, giraffe and steenbok as the hosts that have the most uncertainty in parasite diversity. Further, the unipartite network reveals clusters of herbivores that have a high degree of parasite sharing, and these clusters correspond closely with phylogenetic distance rather than with the wild/domestic boundary. These results provide a basis for predicting the risk of cross-species transmission of nematode parasites in areas where livestock and wildlife share grazing land.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'.

Nematode-coccidia parasite co-infections in African buffalo: Epidemiology and associations with host condition and pregnancy

Co-infections are common in natural populations and interactions among co-infecting parasites can significantly alter the transmission and host fitness costs of infection. Because both exposure and susceptibility vary over time, predicting the consequences of parasite interactions on host fitness and disease dynamics may require detailed information on their effects across different environmental (season) and host demographic (age, sex) conditions. This study examines five years of seasonal health and co-infection patterns in African buffalo (Syncerus caffer). We use data on two groups of gastrointestinal parasites, coccidia and nematodes, to test the hypothesis that co-infection and season interact to influence (1) parasite prevalence and intensity and (2) three proxies for host fitness: host pregnancy, host body condition, and parasite aggregation. Our results suggest that season-dependent interactions between nematodes and coccidia affect the distribution of infections. Coccidia prevalence, coccidia intensity and nematode prevalence were sensitive to factors that influence host immunity and exposure (age, sex, and season) but nematode intensity was most strongly predicted by co-infection with coccidia and its interaction with season. The influence of co-infection on host body condition and parasite aggregation occurred in season-dependent manner. Co-infected buffalo in the early wet season were in worse condition, had a less aggregated distribution of nematode parasites, and lower nematode infection intensity than buffalo infected with nematodes alone. We did not detect an effect of infection or co-infection on host pregnancy. These results suggest that demographic and seasonal variation may mediate the effects of parasites, and their interactions, on the distribution and fitness costs of infection.

Mixed-host aggregations and helminth parasite sharing in an East African wildlife-livestock system

Parasitic infections transmitted between livestock and wildlife pose a significant risk to wildlife conservation efforts and constrain livestock productivity in tropical regions of the world. Gastrointestinal helminths are among the most ubiquitous parasites, and many parasites within this taxon can readily infect a wide range of host species. Factors shaping bidirectional transmission of parasites in wildlife-livestock systems are understudied. In this study, we investigate the prevalence and diversity of helminth infections in an East African community of wild and domestic ungulates. We also identify pairs of host species between which transmission may be possible based on shared parasite taxa, and explore the role of multi-host aggregations in shaping patterns of parasite sharing. Helminth taxa detected included Trichostrongylus, Trichuris, Paramphistomum, Skrjabinema, Strongyloides, Strongylus spp., and other strongyle-type nematodes. We found that nearly 50% of individuals harbored at least one species of helminth, but certain species, such as zebra and impala, exhibited higher prevalence than others. High canopy feeders, like giraffe, had lower prevalence than hosts feeding at medium and low foraging heights. For helminths, patterns of parasite sharing likely emerge from shared space use, which is mediated in part by mixed-species aggregations. The frequency with which host species associated together in mixed-species aggregations was positively correlated with the number of parasite taxa shared. We suggest that variation among species in their tendency to form mixed-species aggregations creates heterogeneity in transmission opportunities, and consequently, parasite sharing across ungulate species. These results enhance our understanding of the role of spatiotemporal relationships among host species in shaping parasite communities in mixed wildlife-livestock grazing systems.