Higher risk of gastrointestinal parasite infection at lower elevation suggests possible constraints in the distributional niche of Alpine marmots

Alpine marmots Marmota marmota occupy a narrow altitudinal niche within high elevation alpine environments. For animals living at such high elevations where resources are limited, parasitism represents a potential major cost in life history. Using occupancy models, we tested if marmots living at higher elevation have a reduced risk of being infected with gastrointestinal helminths, possibly compensating the lower availability of resources (shorter feeding season, longer snow cover and lower temperature) than marmots inhabiting lower elevations. Detection probability of eggs and oncospheres of two gastro-intestinal helminthic parasites, Ascaris laevis and Ctenotaenia marmotae, sampled in marmot feces, was used as a proxy of parasite abundance. As predicted, the models showed a negative relationship between elevation and parasite detectability (i.e. abundance) for both species, while there appeared to be a negative effect of solar radiance only for C. marmotae. Site-occupancy models are used here for the first time to model the constrains of gastrointestinal parasitism on a wild species and the relationship existing between endoparasites and environmental factors in a population of free-living animals. The results of this study suggest the future use of site-occupancy models as a viable tool to account for parasite imperfect detection in ecoparasitological studies, and give useful insights to further investigate the hypothesis of the contribution of parasite infection in constraining the altitudinal niche of Alpine marmots

Intestinal parasitic infections in three geographical zones of Rivers State, Nigeria

The distribution of intestinal parasitic infections among school-age children was assessed in three geographical zones (rural, semi-urban and urban) in Rivers State, Nigeria. Stool samples were collected following ethical approval and consent from parents and teachers of the pupils and analyzed using both wet saline/iodine and formol-ether concentration methods. A total of 3,828 stool samples were collected from school children in thirty-six primary schools from thirteen Local Government Areas of Rivers State. Of the 3,828 stool samples examined, a total of 1,059 (27.66%) were positive for different intestinal parasites. Of the geographical zones, prevalence of infection was higher in the Rural area (35.32%), followed by the Urban area (34.75%) and semi-urban (29.93%). The differences were not statistically significant (p>0.05). Sex-related infection shows that infections occurred more among boys (35.57%) in the rural area, followed by urban (34.43%) and semi-urban (30.0%). More females (35.19%) were infected in Urban followed by Rural (34.97%) and semiurban (29.94%). This high prevalence is of public health concern hence control measures and awareness strategy to improve sanitation should be developed.Keywords: intestinal parasitic infections, distributions, geographical zones, Rivers State, Nigeri

Seasonally timed treatment programs for Ascaris lumbricoides to increase impact-An investigation using mathematical models.

There is clear empirical evidence that environmental conditions can influence Ascaris spp. free-living stage development and host reinfection, but the impact of these differences on human infections, and interventions to control them, is variable. A new model framework reflecting four key stages of the A. lumbricoides life cycle, incorporating the effects of rainfall and temperature, is used to describe the level of infection in the human population alongside the environmental egg dynamics. Using data from South Korea and Nigeria, we conclude that settings with extreme fluctuations in rainfall or temperature could exhibit strong seasonal transmission patterns that may be partially masked by the longevity of A. lumbricoides infections in hosts; we go on to demonstrate how seasonally timed mass drug administration (MDA) could impact the outcomes of control strategies. For the South Korean setting the results predict a comparative decrease of 74.5% in mean worm days (the number of days the average individual spend infected with worms across a 12 month period) between the best and worst MDA timings after four years of annual treatment. The model found no significant seasonal effect on MDA in the Nigerian setting due to a narrower annual temperature range and no rainfall dependence. Our results suggest that seasonal variation in egg survival and maturation could be exploited to maximise the impact of MDA in certain settings