Excretion patterns of coccidian oocysts and nematode eggs during the reproductive season in Northern Bald Ibis (Geronticus eremita)

Individual reproductive success largely depends on the ability to optimize behaviour, immune function and the physiological stress response. We have investigated correlations between behaviour, faecal steroid metabolites, immune parameters, parasite excretion patterns and reproductive output in a critically endangered avian species, the Northern Bald Ibis (Geronticus eremita). In particular, we related haematocrit, heterophil/lymphocyte ratio, excreted immune-reactive corticosterone metabolites and social behaviour with parasite excretion and two individual fitness parameters, namely, number of eggs laid and number of fledglings. We found that the frequency of excretion of parasites’ oocysts and eggs tended to increase with ambient temperature. Paired individuals excreted significantly more samples containing nematode eggs than unpaired ones. The excretion of nematode eggs was also significantly more frequent in females than in males. Individuals with a high proportion of droppings containing coccidian oocysts were more often preened by their partners than individuals with lower excretion rates. We observed that the more eggs an individual incubated and the fewer offspring fledged, the higher the rates of excreted samples containing coccidian oocysts. Our results confirm that social behaviour, physiology and parasite burden are linked in a complex and context-dependent manner. They also contribute background information supporting future conservation programmes dealing with this critically endangered species

Classifying chimpanzee (Pan troglodytes) landscapes across large scale environmental gradients in Africa

Primates are sometimes categorized in terms of their habitat. Although such categorization can be over-simplistic, there are scientific benefits from the clarity and consistency that habitat categorization can bring. Chimpanzees (Pan troglodytes) inhabit various environments, but researchers often refer to ‘forest’ or ‘savanna’ chimpanzees. Despite the wide use of this forest-savanna distinction, clear definitions of these landscapes for chimpanzees, based on environmental variables at study sites or determined in relation to existing bioclimatic classifications, are lacking. The robustness of the forest-savanna distinction thus remains to be assessed. We review 43 chimpanzee study sites to assess how the landscape classifications of researchers fit with the environmental characteristics of study sites and with three bioclimatic classifications. We use scatterplots and Principal Components 15 Analysis to assess the distribution of chimpanzee field sites along gradients of environmental 16 variables (temperature, rainfall, precipitation seasonality, forest cover and satellite-derived 17 Hansen tree cover). This revealed an environmental continuum of chimpanzee study sites 18 from savanna to dense forest, with a rarely acknowledged forest mosaic category in between, 19 but with no natural separation into these three classes and inconsistencies with the bioclimatic 20 classifications assessed. The current forest–savanna dichotomy therefore masks a progression 21 of environmental adaptation for chimpanzees, and we propose that recognizing an additional, 22 intermediate ‘forest mosaic’ category is more meaningful than focusing on the ends of this 23 environmental gradient only. Future studies should acknowledge this habitat continuum, place their study sites on the forest–savanna gradient, and include detailed environmental data to support further attempts at quantification

One Health and Neglected Tropical Diseases—Multisectoral Solutions to Endemic Challenges

One Health is defined as an approach to achieve better health outcomes for humans, animals, and the environment through collaborative and interdisciplinary efforts [...

One Health and Neglected Tropical Diseases—Multisectoral Solutions to Endemic Challenges

One Health is defined as an approach to achieve better health outcomes for humans, animals, and the environment through collaborative and interdisciplinary efforts. Increasingly, the One Health framework is being applied to the management, control, and even elimination of neglected tropical diseases (NTDs). NTDs are a set of debilitating and often chronic infectious diseases that, collectively, affect more than one billion people in almost 150 countries, with disproportionate impact on the extremely poor [1,2]. In this Special Issue, we present a diverse body of work united under the One Health ideology and a desire to mitigate the devastating effects of NTDs. The numerous diseases, methodologies, and landscapes presented highlight the interconnected and increasingly overlapping existence of humans, animals, and their pathogens

Summary of apparent prevalence of schistosome eggs in participants sampled from Gombe National Park and its neighbouring villages: actively sampled (school children), passively sampled (self-selected adults), and accompanying children (non-school children that were sampled along with the passively sampled adults).

<p>Summary of apparent prevalence of schistosome eggs in participants sampled from Gombe National Park and its neighbouring villages: actively sampled (school children), passively sampled (self-selected adults), and accompanying children (non-school children that were sampled along with the passively sampled adults).</p

Estimating the prevalence and intensity of <i>Schistosoma mansoni</i> infection among rural communities in Western Tanzania: The influence of sampling strategy and statistical approach

<div><p>Background</p><p><i>Schistosoma mansoni</i> is a parasite of major public health importance in developing countries, where it causes a neglected tropical disease known as intestinal schistosomiasis. However, the distribution of the parasite within many endemic regions is currently unknown, which hinders effective control. The purpose of this study was to characterize the prevalence and intensity of infection of <i>S</i>. <i>mansoni</i> in a remote area of western Tanzania.</p><p>Methodology/Principal findings</p><p>Stool samples were collected from 192 children and 147 adults residing in Gombe National Park and four nearby villages. Children were actively sampled in local schools, and adults were sampled passively by voluntary presentation at the local health clinics. The two datasets were therefore analysed separately. Faecal worm egg count (FWEC) data were analysed using negative binomial and zero-inflated negative binomial (ZINB) models with explanatory variables of site, sex, and age. The ZINB models indicated that a substantial proportion of the observed zero FWEC reflected a failure to detect eggs in truly infected individuals, meaning that the estimated true prevalence was much higher than the apparent prevalence as calculated based on the simple proportion of non-zero FWEC. For the passively sampled data from adults, the data were consistent with close to 100% true prevalence of infection. Both the prevalence and intensity of infection differed significantly between sites, but there were no significant associations with sex or age.</p><p>Conclusions/Significance</p><p>Overall, our data suggest a more widespread distribution of <i>S</i>. <i>mansoni</i> in this part of Tanzania than was previously thought. The apparent prevalence estimates substantially under-estimated the true prevalence as determined by the ZINB models, and the two types of sampling strategies also resulted in differing conclusions regarding prevalence of infection. We therefore recommend that future surveillance programmes designed to assess risk factors should use active sampling whenever possible, in order to avoid the self-selection bias associated with passive sampling.</p></div

Map of the study area, showing the arrangement of villages sampled in relation to Gombe National Park.

<p>The inset shows the location of the study area within Tanzania.</p

Box and whisker plots of the observed faecal egg counts within each age category for each site for the actively sampled data.

<p>The overlaid dashed line shows the relationship between age and site for the truly infected individuals, as estimated by the ZINB2 model.</p

Fitted estimates and p-values for the relevant effects estimated from the final NB model for the passively sampled data.

<p>Note that there are no zero-inflation terms for the NB model because any observed zeros are assumed to reflect a failure to detect eggs in truly infected individuals.</p

The apparent prevalence based on the raw data and estimated prevalence based on the ZINB2 model for the actively sampled (school children) and passively sampled (self-selected adults) data.

<p>The apparent prevalence based on the raw data and estimated prevalence based on the ZINB2 model for the actively sampled (school children) and passively sampled (self-selected adults) data.</p