Use of pMAD Shuttle Vector For Generating Gene Deletions in S . pneumonia

Zoonotic diseases are becoming increasingly important due to the close relationship many people have with companion animals. Ehrlichia chaffeensis is the causative agent of human monocytic ehrlichiosis, a zoonotic tick-borne disease that can also affect dogs. The tick vector for E. chaffeensis, Amblyomma americanum, is readily found in Mississippi. The goal of this project was to evaluate shelter dogs in the Mississippi Delta, a historically unstudied area, for evidence of E. chaffeensis infection and exposure. In addition, dogs were evaluated for zoonotic and other gastrointestinal parasites. We collected whole blood and serum samples from 77 shelter dogs at 4 shelters in the Mississippi Delta. A nested PCR assay was used on DNA extractions of whole blood to detect circulating E. chaffeensis. An indirect fluorescent antibody test was used to detect antibodies in serum or plasma. Additionally, centrifugal floatation was performed on 39 fecal samples to identify gastrointestinal parasite ova. Thus far, 8 of 77 dogs evaluated were positive for E. chaffeensis DNA by PCR. Antibodies to E. chaffeensis were found in 21 of 72 canine samples. Zoonotic parasites identified in fecal samples included Ancylostoma caninum and Toxocara canis. Non-zoonotic parasites including Isospora spp., Sarcocystis spp. and Trichuris vulpis were also observed. Results demonstrate evidence of a zoonotic tick-borne agent in shelter dogs from an understudied region in Mississippi, suggesting humans may be at risk of E. chaffeensis infection here. The gastrointestinal parasites detected were not surprising considering the greater likelihood of exposure and lack of access to treatment in shelter dogs.