Eastern equine encephalomyelitis virus (EEEV) is perpetuated in eastern North America in a mosquito-wild bird maintenance cycle that involves Culiseta melanura (Coquillett) as the principal enzootic vector and passerine birds as the primary amplifying hosts. We examined the role of birds in the EEEV cycle at a site in southern New Jersey where EEEV cycles annually at high levels. Birds and mosquitoes were sampled during three epiornitics and one season of limited virus activity. We examined antibody prevalence in birds in relation to eight physical and natural history characteristics. Our goal was to compare EEEV cycling in C. melanura and the primary avian hosts better to understand the mechanisms that initiate annual epiornitics. Antibody prevalence was highest in the Blue Jay (62%), Wood Thrush (60%), and Tufted Titmouse (44%). Resident status of birds was the natural history characteristic most closely linked to participation in the EEEV cycle. Species spending the greatest amount of time at our study site (permanent residents, summer residents) had the highest antibody rates. We captured viremic birds as early as 25 May, 51 d before we first detected virus in C. melanura. We recaptured 10 after hatching year adults and one hatching year (HY) bird that seroconverted before we detected virus in C. melanura. We also found EEEV antibody in 15 HY birds up to 31 d before we isolated EEEV from C. melanura. We provide evidence that a cryptic cycle develops weeks before epiornitic cycling is detected in C. melanura by traditional laboratory techniques, indicating that the early season cycle is initiated by the recrudescence of latent virus in previously infected birds.

Zoonotic mosquito-borne viruses, such as the West Nile virus (WNV) and eastern equine encephalitis virus (EEEV), are major public health threats in the United States. Early detection of virus transmission and targeted vector management are critical to protect humans against these pathogens. Sentinel chickens and pool screening of mosquitoes, the most widely used methods of arbovirus early detection, have technical time-lags that compromise their early-detection value. The exploitation of sugar-feeding by trapped mosquitoes for arbovirus surveillance may represent a viable alternative to other methods. Here we compared effectiveness of sugar-impregnated nucleic-acid preserving substrates (SIPS) and sentinel chicken program for detecting WNV, EEEV, and St. Louis encephalitis virus in gravid traps, CO-baited light traps, and resting traps at 10 locations in two Florida counties. In St. Johns County, comparable numbers of EEEV detections were made by SIPS traps (18) and sentinel chickens (22), but fewer WNV detections were made using SIPS (1) than sentinel chickens (13). In Volusia County, seven arbovirus detections were made via the sentinel chicken program (one EEEV and six WNV), whereas only one arbovirus detection (WNV) was made using SIPS. CO-baited light traps captured >90% of total mosquitoes, yet yielded <30% of arbovirus detections. Resting traps and gravid traps captured a fraction of total mosquitoes, yet yielded roughly equivalent numbers of arbovirus detections, as did light traps. Challenges to successful deployment of SIPS include optimization of traps for collecting all vector species, increasing sugar-feeding rates of trapped vectors, and developing tractable methods for arbovirus detection.

To study the susceptibility of wading birds to eastern equine encephalitis (EEE) virus and to determine their potential as reservoir or amplifying hosts, fledgling glossy ibises (Plegadis falcinellus) and snowy egrets (Egretta thula) were captured in New Jersey (USA) and shipped to Colorado (USA) where they were experimentally inoculated with EEE virus. All 16 snowy egrets and 14 (93%) of 15 of the glossy ibises inoculated became viremic with moderate titers, and all survivors developed neutralizing antibody. Six ibises and two egrets died during the first week after inoculation, and EEE virus was isolated from the tissues of three birds. Our experimental results support field evidence about the relative involvement of glossy ibises and snowy egrets in the epizootiology of EEE virus in New Jersey.

Background Aedes (Stegomyia) albopictus (Skuse) impacts human outdoor activity because of its aggressive biting behavior, and as a major vector of mosquito-borne diseases, it is also of public health importance. Although most mosquito species exhibit crepuscular activity by primarily host seeking at dawn and dusk, Ae. albopictus has been traditionally characterized as a diurnal or day-biting mosquito. With the global expansion and increased involvement of Ae. albopictus in mosquito-borne diseases, it is imperative to elucidate the diel activity of this species, particularly in newly invaded areas. Methodology and principal findings Human sweep netting and carbon dioxide-baited rotator traps were used to evaluate the diel activity of Ae. albopictus in two study sites. Both trapping methods were used in New Jersey’s Mercer County, USA (temperate/urban), while only human sweep netting was used in Florida’s Volusia County, USA (subtropical/suburban). Human sweep netting was performed to determine adult mosquito activity at Sunrise, Solar Noon, Sunset, and Lunar Midnight. Because New Jersey is in a temperate area, diel activity was investigated during the early season (3–19 July), peak season (25 July-19 September), and late season (22 September- 22 October). Aedes albopictus showed the highest activity during peak and late seasons at Solar Noon (P < 0.05). At Sunrise and Sunset during the peak season, Ae. albopictus activity was similar. Lunar Midnight activity was significantly lower than Sunrise and Solar Noon (P < 0.05) but was similar to that of Sunset. In the late season, the highest activity was observed during Solar Noon while the least activity was observed during Sunrise and Lunar Midnight (P<0.05). Bottle rotator traps used in conjunction with the human sweep net technique exhibited similar results. Seasonal activity was not differentiated in Florida due to the consistent subtropical climate. The highest adult activity was observed at Sunrise using human sweep netting, but it was not significantly different from Solar Noon and Sunset. The lowest adult activity was observed at Lunar Midnight; however, it was not significantly different from Solar Noon and Sunset. These results provide evidence that the diel activity of Ae. albopictus, contrary to the common perception of its diurnal activity, is much more varied. Conclusion/Significance Involvement of Ae. albopictus in the transmission of debilitating mosquito-borne pathogens such as chikungunya, dengue, and Zika virus, coupled with its affinity to thrive in human peridomestic environments, substantiates that our findings have global implications in areas where Ae. albopictus populations established. It also highlights the importance of behavioral studies of vector species which will not only help mosquito control professionals plan the timing of their control efforts but also provides empirical evidence against conventional wisdoms that may unjustly persist within public health stewards.

Females of Culex coronator were collected in Mobile, AL, during surveillance to direct mosquito control operations following Hurricane Katrina. A total of 249 specimens of this species were collected in light traps at 15 widely separated sites in the county. These represent the first confirmed specimens of Cx. coronator in Alabama.