Emergence of Ixodes scapularis and Borrelia burgdorferi, the Lyme disease vector and agent, in Ohio.

Lyme disease, the most common vector-borne disease in the United States, is caused by a tick-borne infection with Borrelia burgdorferi. Currently, Ohio is considered by the Centers for Disease Control and Prevention (CDC) to be non-endemic for Lyme disease. The low incidence of Lyme disease in this state was largely attributed to the absence of the transmitting vector, Ixodes scapularis, commonly known as the blacklegged tick. However, a tick surveillance program established by Ohio Department of Health indicated that the number of I. scapularis in Ohio had increased sharply in recent years, from 0 - 5 ticks per year during 1983-2008 to 15 in 2009, 40 in 2010, and 184 in 2011. During the fall deer hunting season, examination of deer heads submitted to Ohio Department of Agriculture found 29 I. scapularis from 7 counties in 2010 and 1,830 from 25 counties in 2011. As of 2012, the tick had been found in 57 of the 88 counties of Ohio. In addition, all three active stages (larva, nymph, and adult) of I. scapularis were found in Tiverton Township of Coshocton County, demonstrating the presence of established tick populations at this central Ohio location. Of 530 nymphal or adult I. scapularis analyzed by quantitative polymerase chain reaction (qPCR), 32 (6.1%) tested positive for the B. burgdorferi flaB gene, ranging from 36 to 390,000 copies per tick. Antibodies to B. burgdorferi antigens were detected in 2 of 10 (20%) field-captured Peromyscus leucopus from Tiverton Township, and in 41 of 355 (11.5%) dogs residing in Ohio. Collectively, these data suggest that the enzootic life cycle of B. burgdorferi has become established in Ohio, which poses risk of Lyme disease to people and animals in the area.

Effect of sugar on male Anopheles gambiae mating performance, as modified by temperature, space, and body size.

BACKGROUND: Anopheles gambiae plant-sugar feeding was thought to be rare and physiologically optional. Unlike adult females, males have no alternative source of energy and soon die with only water, yet they might be competent to inseminate all females within their brief lifespan. This study was designed to detect sugar's effect, if any, on male performance. METHODS: Males with and without 20% sucrose were evaluated at two body sizes and two temperatures, 23 degrees and 27 degrees C. Survival was recorded twice daily, and sexual behaviour was recorded each night after adult emergence. Insemination at a 2:1 male:female ratio was examined in three cage sizes, including walk-in mesocosms. RESULTS: Without sugar, males of both sizes lived longer at 23 degrees than 27 degrees C, and large males lived longer at each temperature. Survival of large males at low temperature averaged 3.7 days, small males at high temperature, 1.9 days. With sugar, males in all four treatments suffered minimal mortality. With sugar, in small cages, large males at 27 degrees C matured most rapidly. A few erected fibrillae and inseminated females on night 1. On night 2, maximal proportions erected fibrillae and swarmed, and over one-third of females became inseminated. Small sugar-fed males at 23 degrees C matured most slowly but had achieved nearly maximal levels of swarming by night 3. By night 5, small males had inseminated more than half the females, and large males had inseminated nearly all of them. Without sugar, large males progressed similarly during the first two nights. On night 3, however, the proportion erecting fibrillae and swarming declined precipitously at 27 degrees C, and to a lesser degree at 23 degrees C. Cumulative insemination never reached high levels. Small males never achieved high levels of fibrillar erection or swarming and inseminated few females, even at 23 degrees C. In larger cages and under more semi-natural conditions, regardless of body size, without sugar male insemination capacity was virtually nonexistent. CONCLUSION: Under some conditions, a limited number of sugar-deprived males can survive long enough to inseminate females. However, in nature males that cannot obtain sugar at frequent intervals will not be competitive with those that can, suggesting that male performance is closely tied to plant communities.

West Nile virus in mosquitoes of Northern Ohio, 2001-2002.

From June 14 to August 30, 2001 and June 10 to August 22, 2002, the mosquitoes of Oberlin, Ohio were surveyed and tested for West Nile virus (WNV). Mosquitoes were trapped weekly using gravid traps and CO(2)-baited Centers for Disease Control light traps at seven sites in 2001 and eight sites in 2002 in woodlots within the city limits. A total of 12,151 mosquitoes, representing 14 species and one species group, were collected in gravid traps, with Culex pipiens/restuans being the most abundant, followed by Ochlerotatus triseriatus. In light traps, 12,510 mosquitoes were collected, with Aedes vexans being the most abundant, followed by Culex pipiens/restuans. All gravid trap collections were tested for WNV via reverse transcriptase-polymerase chain reaction. West Nile virus was first detected in July 2002. Of all species tested, the Cx. pipiens/restuans species group exhibited the highest minimum infection rate (MIR) and the greatest percentage of positive pools. Both the MIR and percent of positive pools increased significantly with the date, although abundance of Cx. pipiens/restuans in gravid trap collections did not.