Interacting parasites

[lou]

Science. 2010 Oct 8;330(6001):243-6. doi: 10.1126/science.1190333.

Species interactions in a parasite community drive infection risk in a wildlife population.

Telfer S1, Lambin X, Birtles R, Beldomenico P, Burthe S, Paterson S, Begon M.


Abstract
Most hosts, including humans, are simultaneously or sequentially infected with several parasites. A key question is whether patterns of coinfection arise because infection by one parasite species affects susceptibility to others or because of inherent differences between hosts. We used time-series data from individual hosts in natural populations to analyze patterns of infection risk for a microparasite community, detecting large positive and negative effects of other infections. Patterns remain once variations in host susceptibility and exposure are accounted for. Indeed, effects are typically of greater magnitude, and explain more variation in infection risk, than the effects associated with host and environmental factors more commonly considered in disease studies. We highlight the danger of mistaken inference when considering parasite species in isolation rather than parasite communities.


https://www.ncbi.nlm.nih.gov/pubmed/20929776

extracts:

"Likewise, animals with ongoing A. phagocytophilum infections (infected at t−1 and t0) were less likely to become infected with B. microti, but risk was not reduced in animals that had recently cleared an infection "

"Strong decreases in susceptibility caused by other infections were also observed. The largest effect overall was reduced susceptibility to Bartonella spp. in individuals infected with B. microti and was especially apparent in chronically infected animals, where the odds of infection were 15% of those of uninfected animals (Figs. ​(Figs.11 and ​and2B).2B). B. microti also decreases the length of Bartonella taylorii infections (10). Reciprocally, current Bartonella spp. infections were associated with reduced susceptibility to B. microti (Figs. ​(Figs.11 and ​and2C).2C). Resource depletion may play a role here because both species target erythrocytes "

"Specifically, where interactions are antagonistic, control that targets one parasite species may result in unexpected increases in a second parasite species. To predict and control parasites and disease in natural populations, we need to understand community interactions among parasites and not just single host-parasite interactions."

[lou]

I do wonder about the statement that a bartonella infection decreases the chance of a concurrent B. microti infection. There certainly are people with both. Would people and animals as in this study react differently?