[Show abstract][Hide abstract] ABSTRACT: Abstract Ixodes scapularis, the blacklegged tick, is capable of transmitting the pathogens that cause Lyme disease (Borrelia burgdorferi), babesiosis (Babesia microti), anaplasmosis (Anaplasma phagocytophilum), and to a lesser extent Powassan encephalitis (deer tick virus [DTV]). These pathogens represent significant public health problems, but little is known about the occurrence and co-infection prevalence of these pathogens in I. scapularis. Here, we used standard PCR and pathogen-specific primers to estimate the prevalence of infection of A. phagocytophilium, B. burgdorferi, B. microti, and Ehrlichia chaffeensis in questing nymph and adult I. scapularis collected from sites in Putnam and Dutchess counties in southern New York in 2011. To detect DTV infection, cell cultures were observed for the presence of cytopathic effects and positive results were confirmed via real time RT-PCR. In 466 individually sampled adult ticks, B. burgdorferi had the highest prevalence of infection (55%) followed by A. phagocytophilum (18.2%), DTV (3.4%), B. microti (3.2%), and E. chaffeensis (1.5%). Infection with two pathogens occurred in 13.3% of ticks, and 10 ticks were infected with three combinations of three pathogens. These results provide an estimate of the rate of co-infection, which then can help inform the epidemiological risk of contracting multiple zoonotic tick-borne pathogens within the Hudson Valley region of New York State.
[Show abstract][Hide abstract] ABSTRACT: Peridomestic exposure to Borrelia burgdorferi-infected Ixodes scapularis nymphs is considered the dominant means of infection with black-legged tick-borne pathogens in the eastern United States. Population level studies have detected a positive association between the density of infected nymphs and Lyme disease incidence. At a finer spatial scale within endemic communities, studies have focused on individual level risk behaviors, without accounting for differences in peridomestic nymphal density. This study simultaneously assessed the influence of peridomestic tick exposure risk and human behavior risk factors for Lyme disease infection on Block Island, Rhode Island. Tick exposure risk on Block Island properties was estimated using remotely sensed landscape metrics that strongly correlated with tick density at the individual property level. Behavioral risk factors and Lyme disease serology were assessed using a longitudinal serosurvey study. Significant factors associated with Lyme disease positive serology included one or more self-reported previous Lyme disease episodes, wearing protective clothing during outdoor activities, the average number of hours spent daily in tick habitat, the subject's age and the density of shrub edges on the subject's property. The best fit multivariate model included previous Lyme diagnoses and age. The strength of this association with previous Lyme disease suggests that the same sector of the population tends to be repeatedly infected. The second best multivariate model included a combination of environmental and behavioral factors, namely hours spent in vegetation, subject's age, shrub edge density (increase risk) and wearing protective clothing (decrease risk). Our findings highlight the importance of concurrent evaluation of both environmental and behavioral factors to design interventions to reduce the risk of tick-borne infections.
PLoS ONE 01/2014; 9(1):e84758. DOI:10.1371/journal.pone.0084758 · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The field of rickettsiology is rapidly evolving. Rickettsiae are small Gram-negative bacteria that can be transmitted to humans by arthropods. In most cases they are transmitted transovarially in the arthropod; human beings are incidental hosts. In recent years the use of cell culture and molecular biology has profoundly changed our knowledge of rickettsiae and has led to the description of several new species. New rickettsial diseases have been found in three main situations: firstly, in places where no new species have been identified, typical rickettsial symptoms have been observed (Japan, China); secondly, typical rickettsioses have been found to be caused by different organisms - in such cases a new Rickettsia species has been misdiagnosed as a previously identified bacterium (for example, R. parkeri was confused with R. rickettsii); thirdly, atypical clinical symptoms have been found to be caused by rickettsial organisms such as R. slovaca. These findings challenge the old dogma that only one tick-borne rickettsiosis is prevalent in one geographical area. Many Rickettsia spp. have been identified in ticks, but have not yet been implicated in human pathology. These rickettsiae should be considered as potential pathogens. All known or suspected rickettsial diseases should be treated (including in children) with doxycycline.
International Health 09/2009; 1(1):17-25. DOI:10.1016/j.inhe.2009.03.003 · 1.13 Impact Factor
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