Relapsing fever (RF) spirochetes are understudied yet globally prevalent blood-borne pathogens that are often misdiagnosed because of the nonspecific clinical symptoms that occur during infection. In Latin America, evidence based ecological studies are needed to better estimate human health risk and develop vector and pathogen control measures. Recently, the Ornithodoros tick vector of RF spirochetes was collected from bat caves and in urban and rural domestic and peridomestic settings in Panama. This proposal will begin to understand the ecology of RF spirochetes in Panama by implementing innovative approaches that will circumvent complexities of the tick and pathogens' life-cycle. For example, tick vectors are indiscriminant nocturnal rapid feeders (5 - 60 minutes) that return to their den, nest, or crevice upon completing the bloodmeal, and are rarely found on the mammalian host. Thus, to evaluate exposure to RF spirochetes in previously unrecognized small mammal hosts, a serosurveillance approach will be implemented using two diagnostic antigens (GlpQ and BipA) specific for the pathogens. Also, within the blood, the life cycle of RF spirochetes is cyclic, and obtaining novel isolates/species from the mammal is difficult when bacterial densities are low. Taking advantage of the vector's long life span (10 - 20 years) and ability to maintain the pathogens transstadially, the most promising approach to obtain novel bacterial isolates/species is from field collected ticks. The hypothesis of this project is that tik-borne RF spirochetes persist in Panama, and serological detection in rodents and bats will indicate a role of the small mammals in maintaining the pathogens. The following aims are proposed:
Specific Aim 1 : Determine exposure frequencies of small mammals to RF spirochetes. Field studies will be conducted to collect whole blood and serum samples from rodents and bats in regions where Ornithodoros ticks were collected. An ELISA and immunoblotting approach with recombinant diagnostic antigens will evaluate seroconversion to RF spirochetes, which will indicate bacterial propagation in the animals and provide supportive evidence for a role of the small mammals in maintaining the pathogens.
Specific Aim 2 : Obtain novel isolates/species of RF spirochete from field collected Ornithodoros ticks and mammalian blood. Field collected blood samples will be evaluated, and upon spirochete detection, culture media will be inoculated to obtain novel isolates. Also, with the tick vector serving as an arthropod reservoir, field collected ticks will be allowed to engorge on nave (clean) mice. Upon detecting RF spirochetes in murine blood, animals will be sedated, exsanguinated, and culture media inoculated with blood for bacterial isolation. In a region where evidence strongly suggests the continued presence of RF spirochetes, this project coincides with NIAID's mission to better understand and prevent disease. The results will enable future studies to better assess human health risks in a country where the pathogens are neglected.
Estimates from the World Health Organization indicate that nearly half of the global population is at risk of acquiring a vector-borne disease. The purpose of this proposal is to use novel molecular diagnostics to deter- mine the prevalence of a neglected tick-transmitted pathogen in regions of Panama where the arthropod vector has been identified. Understanding a pathogens life history and presence is needed for the development of preventative vaccines and is particularly relevant toward public health.
| Bermúdez, Sergio E; Castillo, Eduardo; Pohlenz, Tyler D et al. (2017) New records of Ornithodoros puertoricensis Fox 1947 (Ixodida: Argasidae) parasitizing humans in rural and urban dwellings, Panama. Ticks Tick Borne Dis 8:466-469 |
| Bermúdez, Sergio E; Gottdenker, Nicole; Krishnvajhala, Aparna et al. (2017) Synanthropic Mammals as Potential Hosts of Tick-Borne Pathogens in Panama. PLoS One 12:e0169047 |
| Lopez, Job E; Krishnavahjala, Aparna; Garcia, Melissa N et al. (2016) Tick-Borne Relapsing Fever Spirochetes in the Americas. Vet Sci 3: |
