Role of dog behaviour and environmental fecal contamination in transmission ofEchinococcus multilocularisin Tibetan communities

Abstract

On the Eastern Tibetan Plateau region (Sichuan province, China) dogs are regarded as important definitive hosts of Echinococcus multilocularis. We studied dog spatial behaviour in 4 Tibetan villages in order to determine the role of dogs in environmental contamination and their potential interactions with small mammal intermediate hosts. We identified definitive host species and Echinococcus spp. infection status of feces collected in the field by PCR methods and analysed the spatial distribution of canid feces. Nocturnal space utilization of GPS collared dogs in and around villages was also undertaken. E. multilocularis DNA was amplified in 23% of dog feces (n=142) and in 15% of fox feces (n=13) but this difference was not significant. However, dog feces were more frequently observed (78% of collected feces) than fox feces and are therefore assumed to largely contribute to human environment contamination. Feces were mainly distributed around houses of dog owners (0-200 m) where collared dogs spent the majority of their time. Inside villages, the contamination was aggregated in some micro-foci where groups of dogs defecated preferentially. Finally, small mammal densities increased from the dog core areas to grasslands at the periphery of villages occasionally used by dogs; male dogs moving significantly farther than females. This study constitutes a first attempt to quantify in a spatially explicit way the role of dogs in E. multilocularis peri-domestic cycles and to identify behavioural parameters required to model E. multilocularis transmission in this region.

Trophic ecology, behaviour and host population dynamics in Echinococcus multilocularis transmission

“…By contrast, no difference in faeces density was observed between villages and sampling years in China. The density of dog faeces significantly decreased with increasing distance from households, with a maximum at 50 m from houses (one quadrat reached a score of 354 faeces/ha) and a minimum of less than 14 faeces/ha in quadrats located farther than 200 m (Vaniscotte et al, 2011). The proportion of copro-PCR positive faeces did not vary between samples collected within and outside villages in China (37/180).…”

“…However, a few dogs per village had an excursive behaviour and travelled more than 500 m away from their release point. Interestingly, the relative density of small mammals in the excursive areas (15.5-56.6% of positive transect intervals) was significantly higher than in the core areas (2.9-36.8% of positive transect intervals) (Vaniscotte et al, 2011). It is therefore suspected that domestic dogs spent part of their time in areas outside villages where they could predate small mammals.…”

“…A few studies investigated the contamination of dog populations with E. multilocularis on the mid-and high-altitude grasslands (2000-4500 m) of central Asia, including southeast Kyrgyzstan and central and western China (Sichuan, Qinghai and Xinjiang provinces) where pastoralism is the main activity (Budke et al, 2005;Wang et al, 2007Wang et al, , 2010Ziadinov et al, 2008;Vaniscotte et al, 2011;Van Kesteren et al, 2013). These open landscapes are known to favour population outbreaks of a variety of small mammal species shown to be E. multilocularis intermediate hosts: Ochotona curzoniae and Ochotona cansus, Microtus limnophilus, Cricetulus kamensis in the eastern Tibetan plateau of central China, Ellobius tancrei and Microtus gregalis in Kyrgyzstan .…”

“…The distribution of carnivore faeces and the activity patterns of dogs in the villages of the high altitude endemic areas of the eastern Tibetan plateau in China and of southeast Kyrgyzstan were quantified by Vaniscotte et al (2011) and Van Kesteren et al (2013), respectively. The density of faeces measured using quadrat counts was highly variable (median ranged between 22 and 120 faeces/ha), differed among villages and was generally higher in May than October in Kyrgyzstan (Van Kesteren et al, 2013).…”

“…The median distance travelled per dog from the household in Kyrgyzstan significantly varied among villages (range: 20-62 m), with maximum distances as high as almost 2 km (Van Kesteren et al, 2013). In China, 50% of GPS-collared dogs spent 80% of their time (core area) within less than 0.16 ha and did not travel more than 36 m away from the owner's house (Vaniscotte et al, 2011). However, a few dogs per village had an excursive behaviour and travelled more than 500 m away from their release point.…”