Parasite infection and host group size: a meta-analytical review

Abstract

SUMMARYMany studies have identified various host behavioural and ecological traits that are associated with parasite infection, including host gregariousness. By use of meta-analyses, we investigated to what degree parasite prevalence, intensity and species richness are correlated with group size in gregarious species. We predicted that larger groups would have more parasites and higher parasite species richness. We analysed a total of 70 correlations on parasite prevalence, intensity and species richness across different host group sizes. Parasite intensity and prevalence both increased positively with group size, as expected. No significant relationships were found between host group size and parasite species richness, suggesting that larger groups do not harbour more rare or novel parasite species than smaller groups. We further predicted that the mobility of the host (mobile, sedentary) and the mode of parasite transmission (direct, indirect, mobile) would be important predictors of the effects of group sizes on parasite infection. It was found that group size was positively correlated with the prevalence and intensity of directly and indirectly transmitted parasites. However, a negative relationship was observed between group size and mobile parasite intensity, with larger groups having lower parasite intensities. Further, intensities of parasites did not increase with group size of mobile hosts, suggesting that host mobility may negate parasite infection risk. The implications for the evolution and maintenance of sociality in host species are discussed, and future research directions are highlighted.

Digging for answers: contributions of density- and frequency-dependent factors on ectoparasite burden in a social mammal

“…Conversely, the dispersal constraints posed by the subterranean lifestyle of the study species that lead to an impaired mobility of the host in the arid habitat are likely to account for the greater ectoparasite burden as has been suggested previously (Côté and Poulin 1995;Patterson and Ruckstuhl 2013). Hence, colony stability seems to maintain higher parasite burdens at the population level.…”

“…Nevertheless, three meta-analyses have demonstrated across a broad range of host species and parasite taxa that hosts living in larger groups generally suffer higher levels of parasitism (Côté and Poulin 1995;Rifkin et al 2012;Patterson and Ruckstuhl 2013). The strength of these patterns depends on the mode of transmission of the parasite with positive correlations being more apparent for directly transmitted parasites (Côté and Poulin 1995;Rifkin et al 2012;Patterson and Ruckstuhl 2013).…”

“…The strength of these patterns depends on the mode of transmission of the parasite with positive correlations being more apparent for directly transmitted parasites (Côté and Poulin 1995;Rifkin et al 2012;Patterson and Ruckstuhl 2013). In addition, it has been suggested that host mobility may be important with group sizedependent increases in parasite burden being more pronounced for sedentary host species than those that range over large areas.…”

The sociality–health–fitness nexus: synthesis, conclusions and future directions

“…While we might expect that animals living in a group will experience some increased exposure to infectious disease [18,21], the same is not true of social stress, where heterogeneity in responses might be more marked (e.g. in relation to dominance rank, see [7], with possibilities for both positive and negative effects).…”

Sensing parasites: Proteomic and advanced bio-detection alternatives

“…In this sense, the interest in understanding disease transmission among wild and domestic animals, and between them and human population has grown, resulting in the emergence of the "one health approach", which aims to model the transmission of parasitic diseases [7,8]. Detection and transmission control constitute significant components to the overall management of many pathogen infections (including parasites).…”