Detection of human bacterial pathogens in ticks collected from Louisiana black bears (Ursus americanus luteolus)

Abstract

There are 4 major human-biting tick species in the northeastern United States, which include: Amblyomma americanum, Amblyomma maculatum, Dermacentor variabilis, and Ixodes scapularis. The black bear is a large mammal that has been shown to be parasitized by all the aforementioned ticks. We investigated the bacterial infections in ticks collected from Louisiana black bears (Ursus americanus subspecies luteolus). Eighty-six ticks were collected from 17 black bears in Louisiana from June 2010 to March 2011. All 4 common human-biting tick species were represented. Each tick was subjected to polymerase chain reaction (PCR) targeting select bacterial pathogens and symbionts. Bacterial DNA was detected in 62% of ticks (n=53). Rickettsia parkeri, the causative agent of an emerging spotted fever group rickettsiosis, was identified in 66% of A. maculatum, 28% of D. variabilis, and 11% of I. scapularis. The Lyme disease bacterium, Borrelia burgdorferi, was detected in 2 I. scapularis, while one Am. americanum was positive for Borrelia bissettii, a putative human pathogen. The rickettsial endosymbionts Candidatus Rickettsia andeanae, rickettsial endosymbiont of I. scapularis, and Rickettsia amblyommii were detected in their common tick hosts at 21%, 39%, and 60%, respectively. All ticks were PCR-negative for Anaplasma phagocytophilum, Ehrlichia spp., and Babesia microti. This is the first reported detection of R. parkeri in vector ticks in Louisiana; we also report the novel association of R. parkeri with I. scapularis. Detection of both R. parkeri and Bo. burgdorferi in their respective vectors in Louisiana demands further investigation to determine potential for human exposure to these pathogens.

Comparative vertical transmission of Rickettsia by Dermacentor variabilis and Amblyomma maculatum

“…These data are consistent with field surveys in which low prevalence of D. variabilis infected with R. rickettsii and R. montanensis is observed, while infection with R. parkeri is increasingly recognized (Williamson et al, 2010; Fornadel et al, 2011; Stromdahl et al, 2011; Leydet and Liang, 2013; Henning et al, 2014). As the geographical range of A. maculatum increases, the role of this tick in the ecology of TBRDs is less clear (Paddock and Goddard, 2015).…”

Syndromic classification of rickettsioses: an approach for clinical practice

“…58 R. parkeri has also been detected in Amblyomma tigrinum ticks in Cochabamba (Bolivia) 59 and in Ixodes scapularis from Louisiana (USA). 60 …”

A Serosurvey of Multiple Pathogens in American Black Bears (Ursus americanus) in Pennsylvania, USA Indicates a Lack of Association with Sarcoptic Mange

“…Possible explanations include the emergence of a highly-virulent or bear-adapted mite strain, an increasing bear population encouraging the heightened transmission of mites, or a subclinical co-infection or environmental variable making bears more susceptible to clinical disease [18,19]. In addition to S. scabiei, black bears are commonly infected by a wide diversity of bacterial and viral pathogens and other parasites [20][21][22][23][24][25][26][27][28][29]. Infection and subsequent seroconversion from many of these pathogens is common, but clinical disease due to infectious pathogens, other than from S. scabiei, is considered rare in free-ranging black bears [26,30].…”