The comparison of spatial variation and risk factors between mosquito-borne and tick-borne diseases: Seroepidemiology of Ehrlichia canis, Anaplasma species, and Dirofilaria immitis in dogs

Canine ehrlichiosis/anaplasmosis and heartworm diseases are vector-borne and zoonotic infections. To compare epidemiology of these vector-borne diseases, a community-based study was conducted to determine the seroprevalence and risk factors of Ehrlichia canis, Anaplasma sp. and Dirofilaria immitis infections among healthy pet dogs. Prevalence distribution patterns were geographically contrasting between tick-borne E. canis/Anaplasma sp. infections and mosquito-borne D. immitis infection. Although highly enzootic communities of ehrlichiosis/anaplasmosis scattered in mountainous environment at elevations between 100 m and 1000 m, those of heartworm disease mainly distributed in urbanized plains. After multiple logistic regression analysis, it further showed that older age group and outdoor housing were associated with higher risk of heartworm infection; being male and having tick infestation associated with higher risk of E. canis infection whereas being male and free-roaming associated with higher risk of Anaplasma infection. These findings may reflect different vectors for disease transmission, and different kinetics of environment–pathogen–host interaction.