Borrelia burgdorferi not detected in widespread Ixodes scapularis (Acari: Ixodidae) collected from white-tailed deer in Tennessee.

Lyme disease (LD), caused by the bacterium Borrelia burgdorferi and transmitted in the eastern United States by blacklegged ticks, Ixodes scapularis Say, is classified as nonendemic in Tennessee and surrounding states in the Southeast. Low incidence of LD in these states has been attributed, in part, to vector ticks being scarce or absent; however, tick survey data for many counties are incomplete or out of date. To improve our knowledge of the distribution, abundance, and Borrelia spp. prevalence of I. scapularis, we collected ticks from 1,018 hunter-harvested white-tailed deer (Odocoileus virginianus (Zimmerman)) from 71 of 95 Tennessee counties in fall 2007 and 2008. In total, 160 deer (15.7%) from 35 counties were infested with adult I. scapularis; 30 of these counties were new distributional records for this tick. The mean number of I. scapularis collected per infested deer was 5.4 +/- 0.6 SE. Of the 883 I. scapularis we removed from deer, none were positive for B. burgdorferi and one tested positive for B. miyamotoi. Deer are not reservoir hosts for B. burgdorferi; nevertheless, past surveys in northern LD-endemic states have readily detected B. burgdoreferi in ticks collected from deer. We conclude that I. scapularis is far more widespread in Tennessee than previously reported. The absence of detectable B. burgdorferi infection among these ticks suggests that the LD risk posed by I. scapularis in the surveyed areas of Tennessee is much lower than in LD-endemic areas of the Northeast and upper Midwest.

First isolation of La Crosse virus from naturally infected Aedes albopictus.

La Crosse (LAC) virus, a California serogroup bunyavirus, is the leading cause of pediatric arboviral encephalitis in the United States and an emerging disease in Tennessee, West Virginia, and North Carolina. Human cases of LAC encephalitis in Tennessee and North Carolina have increased above endemic levels during 1997 to 1999 and may represent an expansion of a new southeastern endemic focus. This report describes the isolation of LAC virus from the exotic mosquito Aedes albopictus. The discovery of LAC virus in wild populations of Ae. albopictus coupled with its expanding distribution in the southeastern United States, suggests that this mosquito may become an important accessory vector, potentially increasing the number of human cases in endemic foci or expanding the range of the disease.

Newly recognized focus of La Crosse encephalitis in Tennessee.

La Crosse virus is a mosquito-borne arbovirus that causes encephalitis in children. Only nine cases were reported in Tennessee during the 33-year period from 1964-1996. We investigated a cluster of La Crosse encephalitis cases in eastern Tennessee in 1997. Medical records of all suspected cases of La Crosse virus infection at a pediatric referral hospital were reviewed, and surveillance was enhanced in the region. Previous unreported cases were identified by surveying 20 hospitals in the surrounding 16 counties. Mosquito eggs were collected from five sites. Ten cases of La Crosse encephalitis were serologically confirmed. None of the patients had been discharged from hospitals in the region with diagnosed La Crosse encephalitis in the preceding 5 years. Aedes triseriatus and Aedes albopictus were collected at the case sites; none of the mosquitos had detectable La Crosse virus. This cluster may represent an extension of a recently identified endemic focus of La Crosse virus infection in West Virginia.

Sucking lice (Anoplura) of mammals of Tennessee.

Twenty-five species of sucking lice are recorded from wild and domestic mammals, including humans, from Tennessee. Collections of 10 of these species (Haematopinus eurysternus, Hoplopleura captiosa, Hoplopleura hirsuta, Hoplopleura oryzomydis, Hoplopleura trispinosa, Linognathus africanus, Linognathus setosus, Linognathus vituli, Neohaematopinus sciuropteri and Polyplax auricularis) represent newly documented state records. Host specificity was exhibited by 22 species of lice with each of these species being recovered from just one mammal species. Louse infestation prevalences are included for large samples of hosts. A host-parasite list for Tennessean sucking lice is included.

Ehrlichiosis in a golf-oriented retirement community.

BACKGROUND: Ehrlichiosis due to Ehrlichia chaffeensis usually occurs sporadically or in small clusters, with an annual incidence estimated at 3 to 5 cases per 100,000 population in areas of endemic disease. The putative principal vector is the Lone Star tick (Amblyomma americanum). We investigated an outbreak of ehrlichiosis that occurred in June 1993 among members of a golf-oriented retirement community (community A) in Tennessee. The community is densely wooded and borders a wildlife-management area where deer are numerous. METHODS: We conducted a case-control study, using medical-history reviews, serologic testing, and testing with the polymerase chain reaction for E. chaffeensis infection. We also surveyed a sample of 10 percent of the households in community A and in another golf-oriented community (community B) more than 20 miles (32 km) from the wildlife-management area. Survey participants completed a questionnaire and provided specimens for serologic testing. In both communities, searches for ticks were undertaken. RESULTS: Eleven cases of symptomatic ehrlichiosis were identified in the case-control study, 10 of which were in community A (attack rate, 330 per 100,000). Of 311 surveyed residents of community A, 12.5 percent had serologic evidence of past E. chaffeensis infection, as compared with 3.3 percent of 92 in community B (relative risk in community A as compared with community B, 3.9; 95 percent confidence interval, 1.2 to 12.2). The risk of infection was associated with tick bites, exposure to wildlife, golfing, and among golfers, retrieving lost golf balls from the rough. Persons who never used insect repellent were more likely to have had infection than persons who did. In community A, thousands of Lone Star ticks were found; in community B, only three ticks were found. CONCLUSIONS: The high rate of E. chaffeensis infection in community A resulted from its proximity to a wildlife reserve. When outdoor recreational activities are common and concentrations of ticks are high, outbreaks of arthropod-borne zoonoses can be anticipated.

The role of face flies in an episode of infectious bovine keratoconjunctivitis.

Cattle partially protected from face flies (Musca autumnalis) had much less infectious bovine keratoconjunctivitis and yielded fewer isolated of hemolytic Moraxella bovis than did similar cattle that received no face fly protection. The number of new isolated of M bovis from the unprotected cattle was highly correlated with the number of face files observed on the cattle. Close physical proximity to cattle infected with M bovis was important in the spread of the bacteria to previously uninfected cattle; however, it did not require physical contact among the cattle to spread from herd to herd. Moraxella bovis first began to spread from herd to herd after face fly populations exceeded 10/animal for 1 month. Keratoconjunctivitis was not observed in 53% of the cattle from which M bovis was isolated. Moraxella bovis was isolated from 4 of 45 pools of face files collected from animals in the untreated herds.