Effects of mammal host diversity and density on the infection level of Trypanosoma cruzi in sylvatic kissing bugs

Abstract

Several reports have described host species diversity and identity as the most important factors influencing disease risk, producing either dilution or amplification of the pathogen in a host community. Triatomine vectors, mammals and the protozoan Trypanosoma cruzi (Trypanosomatida: Trypanosomatidae) Chagas are involved in the wild cycle of Chagas disease, in which infection of mammals occurs by contamination of mucous membranes or skin abrasions with insect-infected faeces. We examined the extent to which host diversity and identity determine the infection level observed in vector populations (i.e. disease risk in humans). We recorded infection in triatomine colonies and on the coexisting host mammalian species in semi-arid Chile. Host diversity, and total and infected host species densities are used as predictor variables for disease risk. Disease risk did not correlate with host diversity changes. However, the densities of each infected rodent species were positively associated with disease risk. We suggest that the infected host density surrounding the vector colonies is a relevant variable for disease risk and should be considered to understand disease dynamics. It is crucial to pay attention on the spatial scale of analysis, considering the pattern of vector dispersal, when the relationship between host diversity and disease risk is studied.

Drivers of Intensity and Prevalence of Flea Parasitism on Small Mammals in East African Savanna Ecosystems

“…Multiple studies have argued that high host diversity and low levels of anthropogenic disturbance tend to lead to lower intensities and prevalence of parasitism and disease in a wide range of systems (Keesing et al, 2010;Haas et al, 2011;Lacroix et al, 2014;Venesky et al, 2014), with vector-borne diseases in rodents being one important study system (LoGiudice et al, 2003;Friggens and Beier, 2010). However, other studies have failed to find a causal relationship (Giraudoux et al, 2013;Oda et al, 2014), or they have found idiosyncratic relationships across hosts, parasites, and environmental conditions (Froeschke et al, 2013;Salkeld et al, 2013;Young et al, 2013a;Kedem et al, 2014). Here, in contrast to other studies on fleas and flea-borne disease (Thamm et al, 2009;Friggens and Beier, 2010), we find no substantial support for a general effect of either disturbance or host diversity on frequency or levels of flea parasitism.…”

Prehistoric earth oven facilities and the pathoecology of Chagas disease in the Lower Pecos Canyonlands

“…Triatoma brasiliensis is found in different habitats in the Brazilian caatinga and cerrado environments (Valença-Barbosa et al, 2014) and Mepraia spp. are found in the Pacific coast of northern Chile, in the Atacama desert (Oda et al, 2014), both inhabiting rocks piles, among other different places. However, in the caatinga of Brazil, T. brasiliensis prefers wood accumulations to rock piles.…”

Spatial distribution of an infectious disease in a small mammal community

“…Relating this to the IDI result, the significant effect detected may be caused by O. degus philopatric colony persistence in time and space, as what happens with vector colonies. P. darwini was the most abundant rodent species in the study site, highly infected with T. cruzi and a previous study documented that is one of the main blood sources for M. spinolai populations (Oda et al 2014). A. olivaceus was also highly infected, but it much less abundant.…”

“…1 Effects of the combined distance and colony prevalence (expressed as the infection distance index) on infection status. P positive, N negative) relatively high longevity and communal nursing (Previtali et al 2010), with potential vertical transmission of T. cruzi (Oda et al 2014), lead to a cumulative infection at the population level. Relating this to the IDI result, the significant effect detected may be caused by O. degus philopatric colony persistence in time and space, as what happens with vector colonies.…”

“…Contrary to O. degus, P. darwini and A. olivaceus are solitary, nocturnal and short-lived rodents potentially less exposed to M. spinolai attacks, constituting a less easy target than O. degus. Notwithstanding, for future studies it would be necessary to assess host reservoir competence, considering parasitic loads to determine host infectivity (Oda et al 2014;Brunner et al 2008).…”