DETECTION OF ANAPLASMA PHAGOCYTOPHILUM, BABESIA MICROTI AND BORRELIA BURGDORFERI IN IXODES SCAPULARIS COLLECTED FROM LOCATIONS SURROUNDING THE RESIDENCE OFA LOCALLY-ACQUIRED CASE OF HUMAN BABESIOSIS IN MARYLAND, USA
Ellen Y. Stromdahl1, Katherine Feldman2, Siok-Bi Wee2, Maniphet Xayavong3, Alexandre Dasilva3
1U.S. Army Public Health Command, Aberdeen Proving Ground, MD, United States, 2Maryland Department of Health and Mental Hygiene, Baltimore, MD, United States, 3Division of Parasitic Diseases and Malaria, Atlanta, GA, United States
The Delmarva Peninsula has long been recognized as home to populations of Ixodes scapularis infected with Borrelia burgdorferi, although reports of tick surveillance are few. Babesia microti has never been reported from I. scapularis there, although there is only one published investigation of Ba. microti in the area.
In 2009, Maryland Department of Health and Mental Hygiene (DHMH) reported the investigation of an autochthonous case of human babesiosis on the Maryland Eastern Shore of the Delmarva Peninsula. The patient was also infected with B. burgdorferi.
Subsequently, a team from DHMH and U.S. Army Public Health Command (USAPHC) performed a preliminary investigation of vector ticks in locations surrounding the patient’s residence.
Sixteen I. scapularis adults were collected by flagging at the patient’s yard and a nearby site.
PCR testing at the USAPHC detected B. burgdorferi in 8/16 of the ticks; 2 of these 8 were coinfected with Ba. microti, and 1 of the 8 was coinfected with A. phagocytophilum.
PCR positives were reconfirmed with second PCR at USAPHC, and Ba. microti positive tick samples were sent to Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, for reconfirmation with nested primers targeting the ss-rDNA gene.
To our knowledge, these are the first Ba. microti positive I. scapularis collected in Maryland, and the human case is the first locally acquired babesiosis infection reported from Maryland.
B. burgdorferi infection can be quite robust in the mid-Atlantic region, so finding 50% of these ticks positive for B. burgdorferi was not completely unexpected.
However, the regional prevalence of infection with A. phagocytophilum is low (2-3%), and Ba. microti has never been reported from I. scapularis in Maryland, so detection of these pathogens in a small sample of ticks was remarkable. Further investigation at this location of nymphal I. scapularis, the stage most likely to transmit human diseases, is warranted.
Page 30- November 2014