Patterns of helminth infection in Kenyan elephant populations

Remotely sensed localised primary production anomalies predict the burden and community structure of infection in long-term rodent datasets

The increasing frequency and cost of zoonotic disease emergence due to global change have led to calls for the primary surveillance of wildlife. This should be facilitated by the ready availability of remotely sensed environmental data, given the importance of the environment in determining infectious disease dynamics. However, there has been little evaluation of the temporal predictiveness of remotely sensed environmental data for infection reservoirs in vertebrate hosts due to a deficit of corresponding high-quality long-term infection datasets. Here we employ two unique decade-spanning datasets for assemblages of infectious agents, including zoonotic agents, in rodents in stable habitats. Such stable habitats are important, as they provide the baseline sets of pathogens for the interactions within degrading habitats that have been identified as hotspots for zoonotic emergence. We focus on the enhanced vegetation index (EVI), a measure of vegetation greening that equates to primary productivity, reasoning that this would modulate infectious agent populations via trophic cascades determining host population density or immunocompetence. We found that EVI, in analyses with data standardised by site, inversely predicted more than one-third of the variation in an index of infectious agent total abundance. Moreover, in bipartite host occupancy networks, weighted network statistics (connectance and modularity) were linked to total abundance and were also predicted by EVI. Infectious agent abundance and, perhaps, community structure are likely to influence infection risk and, in turn, the probability of transboundary emergence. Thus, the present results, which were consistent in disparate forest and desert systems, provide proof-of-principle that within-site fluctuations in satellite-derived greenness indices can furnish useful forecasting that could focus primary surveillance. In relation to the well-documented global greening trend of recent decades, the present results predict declining infection burden in wild vertebrates in stable habitats; but if greening trends were to be reversed, this might magnify the already upwards trend in zoonotic emergence.

Markers of inflammation in free-living African elephants (Loxodonta africana): Reference intervals and diagnostic performance of acute phase reactants

INTRODUCTION

Acute phase reactants (APRs) have not been investigated in free-living African elephants (Loxodonta africana), and there is little information about negative APRs albumin and serum iron in elephants.

OBJECTIVES

We aimed to generate reference intervals (RIs) for APRs for free-living African elephants, and to determine the diagnostic performance of APRs in apparently healthy elephants and elephants with inflammatory lesions.

METHODS

Stored serum samples from 49 apparently healthy and 16 injured free-living elephants were used. The following APRs and methods were included: albumin, bromocresol green; haptoglobin, colorimetric assay; serum amyloid A (SAA), multispecies immunoturbidometric assay, and serum iron with ferrozine method. Reference intervals were generated using the nonparametric method. Indices of diagnostic accuracy were determined by receiver-operator characteristic (ROC) curve analysis.

RESULTS

Reference intervals were: albumin 41-55 g/L, haptoglobin 0.16-3.51 g/L, SAA < 10 mg/L, and serum iron 8.60-16.99 μmol/L. Serum iron and albumin concentrations were lower and haptoglobin and SAA concentrations were higher in the injured group. Serum iron had the best ability to predict health or inflammation, followed by haptoglobin, SAA, and albumin, with the area under the ROC curve ranging from 0.88-0.93.

CONCLUSIONS

SAA concentrations were lower in healthy African vs Asian elephants, and species-specific RIs should be used. Serum iron was determined to be a diagnostically useful negative APR which should be added to APR panels for elephants.

Diversity of gastrointestinal parasites in sympatric mammals in Moukalaba-Doudou National Park, Gabon

Background and Aim: Gastrointestinal parasites identified in the wild can negatively affect host fitness, lower performance, and growth. On the other side, sympatric mammals that share habitat and resources may also cross-transmit parasites, which are often zoonotic and can contribute to morbidity and mortality. This study aimed to characterize the diversity of gastrointestinal parasites circulating in mammalian hosts in Moukalaba-Doudou National Park. Materials and Methods: We screened a total of 25 fecal samples collected from nine wild mammalian species, namely, western gorilla (Gorilla gorilla gorilla), chimpanzee (Pan troglodytes), putty-nosed monkey (Cercopithecus nictitans), African forest elephant (Loxodonta cyclotis), African buffalo (Syncerus caffer), blue duiker (Philantomba monticola), bay duiker (Cephalophus dorsalis), and red river hog (Potamochoerus porcus) as well as people working as trackers (Homo sapiens) using direct microscopic observations following a sedimentation technique to concentrate the fecal material. Results: Of the total 25 fecal samples screened, 15 (60%) were positive for parasitic gastrointestinal infection. Based on the morphology of parasite eggs and cysts, we identified a rich diversity of nematodes, protozoans, trematodes, and cestodes, including unidentified strongyles (73%), Oesophagostomum spp. (53%), Ancylostoma spp. (27%), Trichuris spp. (13%), Ascaris spp. (13%), Mammomonogamus spp. (13%), Strongyloides spp. (47%), Balantidium coli (20%), Entamoeba coli (20%), Endolimax nana (6%), Fasciola hepatica (6%), Paramphistomum spp. (13%), and Taenia spp. (6%). Conclusion: All parasites were found at least once in one of the hosts, and most were potentially zoonotic and responsible for several diseases of public health concern. Because of the small sample size, our findings should not be considered conclusive. Nevertheless, they highlight the diversity of gastrointestinal parasites in this area.