Feeding period required by Amblyomma aureolatum ticks for transmission of Rickettsia rickettsii to vertebrate hosts

• Published in: Emerging infectious diseases Vol. 20; no. 9; pp. 1504 - 1510
• Main Authors: Saraiva, Danilo G, Soares, Herbert S, Soares, João Fábio, Labruna, Marcelo B
• Format: Journal Article
• Language: English
• Published: United States U.S. National Center for Infectious Diseases 01-09-2014; Centers for Disease Control and Prevention
• Subjects: Amblyomma aureolatum; Animals; Arthropod Vectors - microbiology; Brazil - epidemiology; Disease Models, Animal; Disease Reservoirs - parasitology; Disease transmission; Dogs; Female; Guinea Pigs; Health aspects; Humans; Ixodidae - microbiology; Ixodidae - physiology; Male; Mortality; Nymph - microbiology; parasite; Physiological aspects; Rickettsia; Rickettsia rickettsii; Rickettsia rickettsii - isolation & purification; Risk factors; Rocky Mountain spotted fever; Rocky Mountain Spotted Fever - epidemiology; Rocky Mountain Spotted Fever - mortality; Rocky Mountain Spotted Fever - transmission; ticks; vectorborne; Brazil
• ISSN: 1080-6040; 1080-6059
• DOI: 10.3201/eid2009.140189

Rocky Mountain spotted fever is endemic to the São Paulo metropolitan area, Brazil, where the etiologic agent, Rickettsia rickettsii, is transmitted to humans by adult Amblyomma aureolatum ticks. We determined the minimal feeding period required by A. aureolatum nymphs and adults to transmit R. rickettsii to guinea pigs. Unfed nymphs and unfed adult ticks had to be attached to the host for >10 hours to transmit R. rickettsii. In contrast, fed ticks needed a minimum of 10 minutes of attachment to transmit R. rickettsii to hosts. Most confirmed infections of Rocky Mountain spotted fever in humans in the São Paulo metropolitan area have been associated with contact with domestic dogs, the main host of A. aureolatum adult ticks. The typical expectation that transmission of tickborne bacteria to humans as well as to dogs requires ≥2 hours of tick attachment may discourage persons from immediately removing them and result in transmission of this lethal bacterium.