Detection of Babesia microti and Borrelia burgdorferi in host-seeking Ixodes scapularis (Acari: Ixodidae) in Monmouth County, New Jersey.

The etiological agents that cause human babesiosis (Babesia microti) and Lyme disease (Borrelia burgdorferi) share a common tick vector (Ixodes scapularis Say) and rodent reservoir (Peromyscus leucopus), but because the geographical distribution of babesiosis is more restricted than Lyme disease, it was not considered a nationally notifiable disease until 2011. Although recent studies have shown dramatic increases in the number of cases of babesiosis and expansion of its range, little is known about infection and coinfection prevalence of these pathogens in the primary tick vector. Of the 478 I. scapularis nymphs collected within six Monmouth County, NJ, municipalities between 2004 and 2006, 4.0 and 10.0% were infected with B. microti and B. burgdorferi, respectively, while 2.9% were coinfected. Analysis of the 610 I. scapularis adults collected during the same period yielded an infection prevalence of 8.2% for B. microti and 45.2% for B. burgdorferi, while 6.2% were coinfected. The potential public health importance of these findings is discussed.