Monday, 18 November 2002 - 2:24 PM

This presentation is part of : Student Competition Ten-Minute Papers, Section D. Medical and Veterinary Entomology

Confirmation of the presence of Rickettsia africae in Amblyomma variegatum from Antigua

Jennilee B. Robinson1, Marina E. Eremeeva2, Patrick E. Olson3, Scott A. Thornton3, Michael J. Medina3, John W. Sumner1, Tehnaz Parakh1, and Gregory A. Dasch1. (1) Centers for Disease Control and Prevention, Viral & Rickettsial Zoonoses Branch, 1600 Clifton Rd., MS-G13, Atlanta, GA, (2) University of Maryland School of Medicine, Department of Microbiology and Immunology, 655 West Baltimore Street, Baltimore, MD, (3) U.S. Navy Environmental and Preventive Medicine Unit No. 5, 3235 Albacore Alley, Naval Station, San Diego, CA

Amblyomma variegatum, the tropical bont tick, is distributed in 12-14 islands in the Caribbean and in Subsahelian Africa. Imported from Africa to Guadeloupe and Antigua in the 19th century, it has been spread since 1970 by inter-island transport of cattle and possibly by migrating cattle egrets, Bubulcus ibis. Recently, Rickettsia africae was detected in A. variegatum from Guadeloupe. This rickettsia is the etiologic agent of African tick bite fever, a common disease in Africa and the probable cause of illness in one patient from Guadeloupe. During an annual military exercise, New Horizons, on Antigua in July 2000, we collected 75 A. variegatum and 6 Boophilus microplus from cattle at a St. Johns abattoir. The ticks were crushed in saline and the extracts absorbed on a Nobotu filter strip, air dried, and methanol fixed. DNA extracted from the strips was purified with a Qiagen DNAeasy kit. Rickettsial DNA was detected by polymerase chain reaction with both rOmpA and gltA primers. No rickettsia was found in Boophilus, while 84% of Amblyomma had rickettsial DNA by rOmpA and 52% by gltA assays. The agent was identified as R. africae by restriction fragment length polymorphism analysis of the rOmpA amplicon, and by DNA sequencing of a 17 kDa gene amplicon. The continued presence of A. variegatum in the Caribbean poses a strong risk of infection in cattle by transmission of Ehrlichia ruminantium and Dermatophilus and in humans by R. africae. Eradication efforts are essential to prevent the spread of A. variegatum to the mainland.

Species 2: Acari Ixodidae Amblyomma variegatum (Tropical Bont Tick)
Species 3: Acari Ixodidae Boophilus microplus
Keywords: Tick eradication

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