To probe the potential role of Th1 versus Th2 reactivity underlying the hygiene hypothesis, intrinsic levels of Th1‐associated and Th2‐associated antibodies in the serum of wild rodents were compared with that in various strains of laboratory rodents. Studies using rat lung antigens as a target indicated that wild rats have substantially greater levels of autoreactive, polyreactive immunoglobulin G (IgG), but not autoreactive, polyreactive IgM than do laboratory rats, both on a quantitative and qualitative basis. Increased levels of serum IgG and IgE were observed in both wild rats and wild mice relative to their laboratory‐raised counterparts, with the effect being most pronounced for IgE levels. Further, wild rats had greater intrinsic levels of both Th1‐ and Th2‐associated IgG subclasses than did lab rats. The habitat (wild versus laboratory raised) had a more substantial impact on immunoglobulin concentration than did age, strain or gender in the animals studied. The presence in wild rodents of increased intrinsic, presumably protective, non‐pathogenic responses similar to both autoimmune (autoreactive IgG, Th1‐associated) and allergic (IgE, Th2‐associated) reactions as well as increased levels of Th1‐associated and Th2‐associated IgG subclasses points toward a generally increased stimulation of the immune system in these animals rather than a shift in the nature of the immunoreactivity. It is concluded that, at least to the extent that feedback inhibition is a controlling element of immunoreactivity, an overly hygienic environment may affect the threshold of both types of immune responses more so than the balance between the different responses.

Summary Wild animals, unlike their laboratory counterparts, live amidst an abundance of pathogens and parasites. The presence of such immune stimulation from the time of birth likely has a profound effect on the development and stasis of the immune system. To probe potential differences between the immune systems of wild and laboratory animals, the response to mitogen (Con A) of splenocytes from wild rats was evaluated in vitro and compared with results from lab-rat-derived splenocytes. Although the response to mitogen is ubiquitous in splenocytes from laboratory animals regardless of strain or even species, splenocytes derived from wild rats were unresponsive to mitogen as judged by upregulation of activation markers and proliferation. Further, splenocytes from wild rats produced almost 10-fold less IL-2 and TNF-a in response to mitogen than did splenocytes from laboratory rats. In addition, mitogen stimulation resulted in an almost 100-fold greater production of IL-4 in wild-rat-derived splenocytes than in lab-rat-derived splenocytes. Perhaps surprisingly, these differences were observed in the absence of differences between wild and laboratory animals in the ratio of CD4 1 /CD8 1 T cells or in the relative numbers of T cells, B cells and monocytes in the splenocyte population. These observations may have substantial implications for the hygiene hypothesis and provide considerable insight into the roles played by the environment during immune system development and modulation.

Ixodes affinis, which is similar morphologically to Ixodes scapularis, is widely distributed in North Carolina. Collections have documented this species in 32 of 41 coastal plain counties, but no piedmont or mountain counties. This coastal plain distribution is similar to its distribution in Georgia and South Carolina, where it is considered an enzootic vector of Borrelia burgdorferi sensu stricto. An updated list of hosts for I. affinis in the U.S.A. is included, increasing the number to 15 mammal and one bird species. The presence of questing adults of I. affinis from April to November reinforces the need for confirmed identifications of suspected tick vectors of Borrelia spirochetes collected during warm months. Journal of Vector Ecology 35 (1): 174-179. 2010.

A rapid assessment was conducted in July-August 2007 to determine the impact of heavy rains and early summer floods on the mosquitoes and arbovirus activity in 4 southeastern Kansas counties. During 10 days and nights of collections using different types and styles of mosquito traps, a total of 10,512 adult female mosquitoes representing 29 species were collected, including a new species record for Kansas (Psorophora mathesoni). High numbers of Aedes albopictus were collected. Over 4,000 specimens of 4 Culex species in 235 species-specific pools were tested for the presence of West Nile, St. Louis, and western equine encephalitis viruses. Thirty pools representing 3 Culex species were positive for West Nile virus (WNV). No other arboviruses were detected in the samples. Infection rates of WNV in Culex pipiens complex in 2 counties (10.7/1,000 to 22.6/1,000) and in Culex salinarius in 1 county (6.0/1,000) were sufficiently high to increase the risk of transmission to humans. The infection rate of WNV in Culex erraticus was 1.9/1,000 in one county. Two focal hot spots of intense WNV transmission were identified in Montgomery and Wilson counties, where infection rates in Cx. pipiens complex were 26/ 1,000 and 19.9/1,000, respectively. Despite confirmed evidence of WNV activity in the area, there was no increase in human cases of arboviral disease documented in the 4 counties for the remainder of 2007.

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