Toxoplasma gondii Infection in Alpine Red Deer (Cervus elaphus): Its Spread and Effects on Fertility

Abstract

In contrast to the depth of knowledge on the pathological effects of parasitism in domestic animals, the impact of the vast majority of parasites on wildlife hosts is poorly understood and, besides, information from domestics is rarely usable to disclose the parasites’ impact on free-ranging populations’ dynamics. Here we use Toxoplasmosis as a study model since, until now, the infection process and the protozoan’s effects in natural conditions has received little attention. We analysed 81 sera from red deer (Cervus elaphus) sampled in Italian Alps and through generalized linear models we evaluated (1) the epidemiological factors influencing T. gondii infection dynamics; (2) its impact on female fertility. High seroprevalence of T. gondii infection was recorded in yearling (1 year-old; prevalence = 52.4%) and adult (>2 year-old; prevalence = 51.3%) red deer, while calves (<1 year-old) did not contract the infection suggesting horizontal transmission as the main route of infection. The stable prevalence between yearlings and adults and the higher serological titres of younger individuals lead to two alternative infection processes suggesting a difference between age classes or in acquiring the infection or in responding to the pathogen. No associations between T. gondii serological titres and pregnancy status was observed indicating no direct effect on the probability of being pregnant; nevertheless a relation between females’ higher serological titres and lower foetal development emerged, suggesting potential effects of the parasite infection on deer reproduction. The results demonstrate high seroprevalence of T. gondii infection in free-ranging red deer and, furthermore, the effect on foetal development suggests the potential impact of the parasite on red deer fertility and thus on its population dynamics.

Interaction of diet and habitat predicts Toxoplasma gondii infection rates in wild birds at a global scale

“…Cases of severe morbidity and mortality observed in some wildlife species have clear wildlife conservation implications, but the chronic morbidity imparted by naturally acquired T. gondii infections could be equally consequential for long‐term population stability. Subclinical T. gondii infections have impacted fetal development in red deer ( Cervus elaphus ) (Formenti et al, 2015) and reduced the resilience to other environmental stressors and mortality factors, such as co‐infections in sea otters ( E. lutri s) (Gibson et al, 2011), roadkill frequency in Tasmanian pademelons ( Thylogale billardierii ) (Hollings et al, 2013) and cold weather mortality in hares ( Lepus sp.) (Jokelainen, Isomursu, Näreaho, & Oksanen, 2011).…”

“…Wildlife epidemics with high mortality can lead to dramatic population declines, as seen with amphibian chytridiomycosis and white‐nose syndrome in bats (Macphee & Greenwood, 2013). Pathogens can also threaten long‐term population fitness more subtly by reducing reproductive outputs (Formenti et al, 2015), altering sex ratios (Kaňková et al, 2007) and increasing susceptibility to other stressors, such as trauma (Hollings, Jones, Mooney, & McCallum, 2013), predation (Berdoy, Webster, & Macdonald, 2000), contaminants (Provencher, 2013) and co‐infections (Gibson et al, 2011). The demographic impact of pathogens on wildlife populations may be exacerbated further when combined with other factors, such as landscape degradation, climate change and invasive species.…”

Consumer preferences for red deer meat: a discrete choice analysis considering attitudes towards wild game meat and hunting

“…Considering the microbiological safety issue, wild game meat consumption may present some risks related to Toxoplasma spp. (Formenti et al, 2016;Formenti et al, 2015), Hepatitis E Virus (HEV) (Martelli et al, 2017), Cryptosporidium spp. e Giardia duodenalis (De Liberato et al,…”

The cooler the better? Indirect effect of spring–summer temperature on fecundity in a capital breeder

“…Parasites, among the others, may play an important role in shaping fecundity variation, and their effect may be influenced by age, density, and temperature according to the transmission routes of the pathogen (Carlsson et al 2018). In fact, our study population showed some evidence of negative consequences of Toxoplasma gondii infection on fetal development, and this effect changed with hind age (Formenti et al 2015). Whether the inclusion of further parameters will enable a better prediction of deer fecundity, and whether increasing temperatures in the future years could have long-term effects on the life history of our study population, however, still remain to be investigated.…”

“…In fact, our study population showed some evidence of negative consequences of Toxoplasma gondii infection on fetal development, and this effect changed with hind age (Formenti et al. ). Whether the inclusion of further parameters will enable a better prediction of deer fecundity, and whether increasing temperatures in the future years could have long‐term effects on the life history of our study population, however, still remain to be investigated.…”