Investigation of Seroprevalence and the Risk Factors of Ehrlichia and Anaplasma Species Along the Texas-Mexico Border.

BACKGROUND

Ehrlichiosis and anaplasmosis are emerging tick-borne bacterial zoonotic diseases resulting from infections with Ehrlichia and Anaplasma species, respectively, within the family Anaplasmataceae. These tick-borne pathogens represent a growing public health problem in the United States.

MATERIALS AND

METHODS

To assess their seroprevalence and risk factors for infection along the Texas-Mexico border, we conducted a cross-sectional seroprevalence study using plasma samples obtained from 616 adults residing in Starr County, Texas. Plasma samples were screened for IgG reactivity to Ehrlichia and Anaplasma antigens using a dual-spot indirect immunofluorescent assay. Ticks were also collected from this region and tested for Anaplasmataceae DNA.

RESULTS

Seroprevalence was higher for cases of Anaplasma spp. (10.4%) than Ehrlichia spp. (4.8%) and Anaplasmataceae unspecified (6.9%). Age and gender were both significantly associated with seropositivity. PCR testing of the collected ticks revealed a 12.4% (12/97) positivity for Ehrlichia canis, all detected in Rhipicephalus sanguineus (Brown dog) ticks, but none were positive for Anaplasma species.

CONCLUSION

These findings suggested that Ehrlichia and Anaplasma species are endemic in the region and highlighted the need for ongoing surveillance and public health interventions.