Anthropogenic disturbance may lead to the spread of vector-borne diseases through effects on pathogens, vectors, and hosts. Identifying the type and extent of vector response to habitat change will enable better and more accurate management strategies for anthropogenic driven disease spread. I reviewed empirical studies to summarize patterns among flea and rodent diversity, flea abundance, several measures of flea infestation (fleas/parasitized rodent, fleas/rodent species, fleas species/rodent species, percent infested rodents), and host specificity in 70 small mammal communities of 6 habitat types and 3 levels of human disturbance: 1) remote/wild areas; 2) agricultural areas; and 3) urban areas. I classified habitats according to modified versions of Olson's (2001) terrestrial biome scheme and Ellis and Ramankutty’s (2008) anthropocentric biome classification scheme, both available in GoogleEarth.
Results/Conclusions
Eleven of 14 rodent and flea characteristics showed a significant effect of disturbance category (8), habitat type (4), or both (2). Seven variables had a significant interaction effect. For rodent-flea communities in forest habitats (39 of the 70 communities in my sample), disturbance affected all 14 characteristics. Overall, flea and mammal richness and diversity were higher in low disturbance versus high disturbance sites. Most measures of flea infestation, including percent of infested rodents and fleas/rodent and rodent species increased with increasing disturbance and peaked at intermediate levels of disturbance. In addition, host use increased, and the number of specialist fleas decreased, as human disturbance increased. Of the three most common habitat types (forest, grassland/savanna, desert), desert communities were most sensitive to disturbance. Anthropogenic disturbance was associated with conditions conducive to increased transmission of flea-borne diseases. Sites of intermediate disturbance contained the highest diversity of hosts and fleas and also exhibit characteristics associated with increased disease spread. Management efforts should recognize that disturbance promotes flea host switching and potentially the rate of flea-borne disease spread among rodents and ultimately to humans. In addition, disturbance processes may exacerbate the negative consequences of climate change for vector borne disease spread within some habitats.
