County Records for Aedes japonicus in Georgia.

Consolidating and updating distributional data for mosquito species within a state is a good practice. These updates have an immediate impact by providing documented species distribution information for public use and by serving as a resource to researchers who need background information about a species's state distribution. In Georgia, Aedes japonicus, an introduced species, was peer review reported from 7 counties (2002-06): Fulton, Habersham, Lumpkin, Rabun, Towns, Union, and White. No further records were found in peer-reviewed journals or in the Symbiota Collections of Arthropods Network. This study consolidated the 7 peer-reviewed county records for Ae. japonicus with 73 new county records from surveillance data collected by the Georgia Department of Public Health. This study documented the presence of Ae. japonicus in 80 of the 159 counties in Georgia.

Haemagogus equinus in Kinney County, Texas.

Larvae collected from an oak tree hole east of Brackettville, Kinney County, Texas, resulted in the collection of 3 species: Aedes triseriatus, Ae. zoosophus, and Haemagogus equinus. One larva and 1 female of Hg. equinus were recovered from this sample. This is the first report of Hg. equinus in Kinney County and the first report of this species being collected in Texas since 1962. Samples collected from other sites documented the presence of Ae. epactius, Culex nigripalpus, and Psorophora signipennis in Kinney County.

Aedes japonicus japonicus in Nebraska and Texas.

Aedes japonicus japonicus continues to spread westward and in this study, its presence is documented in 8 counties in Nebraska and in Bowie County, TX. In 1998, Ae. japonicus was collected in Connecticut, New Jersey, and New York for the 1st records of this species in North America. Except for Louisiana, it has been reported from all states that border or are east of the Mississippi River. In Canada, it has been reported in Ontario and all eastern provinces. In the Pacific Northwest, it has been reported in Washington, Oregon, and British Columbia, and in the midwestern states that do not border the Mississippi River, Kansas, Oklahoma, and South Dakota are the only states to have reported its presence in peer-reviewed journals.

Ornithodoros turicata (Dugès) on a Feral Hog in Real County, Texas, USA.

The potential introduction of African swine fever virus (ASFV) into the US has researchers evaluating routes of potential transmission and the establishment of sylvatic cycles. To help document vector-host associations related to ASFV transmission, the finding of O. turicata on a feral hog in Real County, Texas is reported.

A Checklist of the Mosquito Species in 13 Counties West of San Antonio, Texas.

The aim of this study was to consolidate mosquito information for 13 counties west of San Antonio, Bexar County, Texas, and to create a species checklist for future regional studies. The resulting checklist established a baseline for local mosquito-borne disease surveillance and can serve as a resource for public health officials. The 13 counties in this region were Bandera, Edwards, Kendall, Kerr, Kimble, Kinney, Maverick, Medina, Real, Sutton, Uvalde, Val Verde, and Zavala counties. To develop the checklist, county-level mosquito species data were extracted from 38 peer-reviewed publications and government documents, university reference collections, private collections, and the Texas Department of State Health Services' historical collection data. These data were combined with author field collections to create a comprehensive species list. Overall, 339 county-level records were documented through field studies with a total of 36 species representing 8 genera confirmed as being present in this region. An additional 14 species listed in historical surveillance records were not collected during this study.

County-Level Records for Culex stigmatosoma and Culex thriambus in Texas.

Populations of Culex stigmatosoma and Cx. thriambus have been documented in the southwestern USA with a southward range extension to northern South America and Central America, respectively. Studies conducted in California indicate both species are potential vectors of West Nile virus. However, vector competence studies are lacking for other parts of the USA. During a multicounty regional surveillance study west of San Antonio, Texas, multiple errors were observed in the Texas distributional literature of these species. These errors involved incorrect distributional information in Texas and US publications. Evidence to correct these errant records was found upon further analysis of Texas literature and curated specimens. Therefore, the aims of this study were to present that evidence and then combine the corrected records with additional records from the Texas Department of State Health Services and from larval collections made during other Texas surveillance studies.

Distribution of Culex coronator in the USA.

In 1920, Culex coronator was reported from San Benito, Texas, and later in Arizona, New Mexico, and Oklahoma. In 2005, this species was reported to be spreading across the southeastern USA. Now reported in 14 states, it has been found as far north as northern Oklahoma; Memphis, TN; and Suffolk, VA. The public health significance of Cx. coronator is not firmly established, even though it has been implicated as a potential vector of several arboviral diseases. This study aims to document additional Cx. coronator county-level records, to provide information about its continued expansion across the southern USA, and to provide a short research update into its vector potential. Data acquired through multistate collaborations and author collections resulted in 146 new county records from Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, and Texas. No new county records were presented for Arizona, New Mexico, Tennessee, or Virginia, which had previously reported this species. With these new data, this species has been documented in 386 counties in 14 states of the continental USA.

Distribution of Culex coronator in Texas.

The distribution of Culex coronator Dyar and Knab by county in Texas was updated by combining data from peer-reviewed literature, military and government reports, and university and private collections, and by collecting specimens from counties where data had not been reported. With 254 counties in Texas, the initial collection effort was focused on counties east of US Highway 277, which runs from Val Verde County on the US and Mexico border to Wichita County on the Texas and Oklahoma border. The study resulted in 127 counties with Cx. coronator presence data. The remaining 127 counties need to be surveyed for this species.

Seasonal distribution of ticks in four habitats near the demilitarized zone, Gyeonggi-do (Province), Republic of Korea.

This study describes the seasonal distribution of larvae, nymph, and adult life stages for 3 species of ixodid ticks collected by tick drag and sweep methods from various habitats in the Republic of Korea (ROK). Grasses less than 0.5 m in height, including herbaceous and crawling vegetation, and deciduous, conifer, and mixed forests with abundant leaf/needle litter were surveyed at United States (US) and ROK operated military training sites and privately owned lands near the demilitarized zone from April-October, 2004 and 2005. Haemaphysalis longicornis Neumann adults and nymphs were more frequently collected from April-August, while those of Haemaphysalis flava Neumann and Ixodes nipponensis Kitaoka and Saito were collected more frequently from April-July and again during October. H. longicornis was the most frequently collected tick in grass habitats (98.9%), while H. flava was more frequently collected in deciduous (60.2%) and conifer (57.4%) forest habitats. While more H. flava (54.1%) were collected in mixed forest habitats than H. longicornis (35.2%), the differences were not significant. I. nipponensis was more frequently collected from conifer (mean 8.8) compared to deciduous (3.2) and mixed (2.4) forests.

Comparison of dragging and sweeping methods for collecting ticks and determining their seasonal distributions for various habitats, Gyeonggi Province, Republic of Korea.

As part of the 65th Medical Brigade tick-borne disease surveillance program to determine the abundance, geographical and seasonal distributions, and tick-borne pathogens present in the Republic of Korea, dragging and sweeping methods were compared to determine their efficiency for collecting ticks in grass and deciduous, conifer, and mixed forest habitats at military training sites and privately owned lands in northern Gyeonggi Province near the demilitarized zone from April-October, 2004-2005. Three species of Ixodid ticks, Haemaphysalis longicornis, Haemaphysalis flava, and Ixodes nipponensis, were collected. Overall, H. longicornis adults and nymphs were most frequently collected from grass and deciduous forest habitats, accounting for 98.2 and 66.2%, respectively, of all ticks collected. H. flava adults and nymphs were most frequently collected from conifer and mixed forests, accounting for 81.6, and 77.8%, respectively, of all ticks collected. I. nipponensis adults and nymphs accounted for 9.3% of all ticks collected from mixed forests, were less commonly collected from deciduous (4.1%) and conifer (4.1%) forests, and infrequently collected from grass habitats (0.9%). Overall, there were no significant differences between dragging and sweeping methods for the three species when the areas sampled were similar (sweeping = 2 x the area over the same transect). Adults and nymphs of H. longicornis were most commonly collected from April-August, while those of H. flava and I. nipponensis were most commonly collected during April-July and again during October. Larvae of all three species were most frequently observed from July-September.

Hantaan virus surveillance in small mammals at firing points 10 and 60, Yeoncheon, Gyeonggi Province, Republic of Korea.

We used epidemiological data and indirect fluorescent antibody tests to determine the Hantaan virus (HTNV) antibody-positive (Ab+) prevalence in small mammals captured at firing point 10 (FP-10) and firing point 60 (FP-60), Gyeonggi Province, near the demilitarized zone, Republic of Korea (ROK), from 2001 to 2005. We used these data, combined with the partial M segment amplified from HTNV recovered from lung tissues of Apodemus agrarius, to clarify the genetic diversity and phylogenetic relationships among HTNV strains in the ROK. Of the eight species of rodents and one insectivore species captured, A. agrarius accounted for 93.4% and 88.5% at FP-10 and FP-60, respectively. Only two species of rodents, A. agrarius and Micromys minutus, were HTNV Ab+. The overall HTNV Ab+ prevalence for A. agrarius captured at FP-10 and FP-60 was 23.3% (121/520) and 14.5% (94/647), respectively. The hantaviral reverse transcription-polymerase chain reaction-positive rate of Ab+ A. agrarius was 74.2% (167/215), and the phylogenetic trees, based on the 269-nucleotide G2-encoding M segment, demonstrated that HTNV strains from FP-10 and FP-60 were distantly segregated from HTNV of other geographic regions in Korea and China. These data are useful in the development of risk reduction strategies for the prevention of hantavirus infections among military personnel, especially during training or the event of hostilities, and civilian populations.

Distribution and larval habitats of Anopheles species in northern Gyeonggi Province, Republic of Korea.

A total of 180 larval collection sites (e.g., rice paddies, marshes, ground pools, ponds, stream margins, and irrigation and drainage ditches) was surveyed within a 2 km radius from Warrior Base training area, 5 km south of Panmunjeom (Joint Security Area, demilitarized zone), Gyeonggi Province, Republic of Korea (ROK), from May through October, 2007 to characterize larval habitat distributions of members of the Anopheles Hyrcanus Group (An. sinensis, An. lesteri, An. pullus, An. belenrae, An. kleini, and An. sineroides). A total of 5,859 anopheline larvae was collected from 84.4% of the sites surveyed, of which 4,071 were identified to species by polymerase chain reaction (PCR) using the ribosomal DNA internal transcribed spacer 2 (rDNA ITS2). Anopheles sinensis (52.6%) was the most frequently collected, followed by An. kleini (29.4%), An. sineroides (9.8%), An. pullus (6.7%), An. belenrae (1.1%), and An. lesteri (0.5%). Anopheles pullus and An. kleini were collected in greater proportions in May and from May - July, respectively. Few An. sinensis were collected from May - June, but it was the predominant species collected by August, and accounted for >80% of all larvae from September - October. Anopheles kleini was found in all habitats sampled; however, it was collected most frequently in young growth rice paddies, while An. sinensis was collected more frequently in mature and post-harvest paddies. Anopheles pullus was associated with pre-cultivated rice paddies, including water-filled tire ruts left from the previous fall's harvest.

Detection of Rickettsia felis and Rickettsia typhi and seasonal prevalence of fleas collected from small mammals at Gyeonggi Province in the Republic of Korea.

Fleas were collected from live-captured small mammals to identify flea-borne pathogens, host associations, and seasonal prevalence of flea species, as part of the 65th Medical Brigade rodent-borne disease surveillance program at 20 military installations and training sites, Gyeonggi Province, Republic of Korea, 2005-2007. A total of 1251 fleas were recovered from 2833 small mammals. Apodemus agrarius, the striped field mouse, accounted for 93.1% (2,637/2,833) of all small mammals captured, followed by Crocidura lasiura (3.1%), Mus musculus (1.3%), Microtus fortis (0.7%), Myodes regulus (0.7%), Micromys minutus (0.5%), Rattus norvegicus (0.4%), Tscherskia triton (0.1%), Apodemus peninsulae (< 0.1%), Rattus rattus (< 0.1%), and Mogera robusta (< 0.1%). A total of 6/11 species of mammals captured were infested with fleas with infestation rates ranging from a high of 26.3% (A. agrarius and M. regulus) to a low of 5.3% (M. fortis). Flea indices among infested mammals were highest for R. norvegicus (2.50), followed by C. lasiura (2.20), A. agrarius (1.71), M. regulus (1.20), M. musculus (1.0), and M. fortis (1.0). The predominant flea species collected were Stenoponia sidimi (56.5%), followed by Ctenophthalmus congeneroides (38.3%) and Rhadinopsylla insolita (3.9%). The minimum field infection rates [number of positive pools/total number of fleas (600)] for Rickettsia typhi and for Rickettsia felis were 1.7% and 1.0%, respectively.

Prevalence of tick-borne encephalitis virus in ticks from southern Korea.

The prevalence of tick-borne encephalitis virus (TBEV) in southern Korea was determined by collecting ticks using tick drags. A total of 4,077 of 6,788 ticks collected were pooled (649 pools) according to collection site, species, and developmental stage and assayed for TBEV. The TBEV protein E and NS5 gene fragments were detected using RT-nested PCR in six pools of nymphs collected from Jeju Island (2,491 ticks). The minimum field detection rates for TBEV were 0.17% and 0.14% for Haemaphysalis longicornis and Haemayphysalis. flava nymphs, respectively. The 252 bp NS5 and 477 bp protein E gene amplicons were sequenced. Phylogenetic analysis showed that the NS5 and protein E genes of the Jeju strain were clustered with Western subtype (98.0% and 99.4% identity, respectively). The Western subtype of TBEV is endemic in Korea, including Jeju Island. The study of vector and zoonotic host susceptibility to TBEV is required to better understand its potential impact on public health.

Serological surveillance of scrub typhus, murine typhus, and leptospirosis in small mammals captured at Twin Bridges Training Area, Gyeonggi Province, Republic of Korea, 2005-2007.

Soldiers from the Republic of Korea and the United States conduct armistice military operations at Twin Bridges Training Area (TBTA) located near the demilitarized zone (DMZ) and are exposed to zoonotic disease pathogens that small mammals and their potentially disease-carrying ectoparasites transmit. TBTA is a 36 km2 rural training site with small villages and various forms of agriculture along its boundary. At TBTA, rodents, insectivores, and their ectoparasites are commonly found in association with unmanaged habitats of various densities of tall grasses, herbaceous plants, shrubs, briars, and crawling vegetation. Rodents and insectivores were collected during the winter (November-December 2005 and December 2006) and early spring (March 2007), and serologically tested for the presence of scrub typhus, murine typhus, and leptospirosis antibodies. Of the six species of small mammals collected, Apodemus agrarius, the common striped field mouse and known reservoir of scrub typhus, was the most frequently collected (96.1%), followed by Crocidura lasiura (2.5%), Micromys minutus (0.5%), Myodes regulus (0.5%), Mus musculus (0.3%), and Rattus rattus (0.1%). A. agrarius (56.1%), M. musculus (66.7%), M. minutus (25%), and R. rattus (100%) were positive for scrub typhus antibodies. Only A. agrarius (14.7%) and C. lasiura (4.5%) were positive for murine typhus antibodies, whereas only A. agrarius (1.5%) was seropositive for leptospirosis. Seroprevalence rates of scrub typhus and murine typhus based on weight and sex of A. agrarius are presented.

Serological surveillance of scrub typhus, murine typhus, and leptospirosis in small mammals captured at firing points 10 and 60, Gyeonggi province, Republic of Korea, 2001-2005.

Soldiers from the Republic of Korea and the United States conducting peacetime military operations at various training sites and multiple range complexes located near the demilitarized zone separating North and South Korea are exposed to rodents and their potentially disease-carrying ectoparasites. These diseases include scrub typhus, murine typhus, and leptospirosis. Many of the training sites are rural or semi-rural, surrounded or co-located with various forms of agriculture, and are infested with rodents and insectivores (as well as their ectoparasites), which are commonly found in association with unmanaged tall grasses, scrub, and crawling vegetation habitats. For 5 years, rodents and insectivores were collected seasonally (spring, summer, fall, and winter) at firing points 10 and 60 near the demilitarized zone and serologically tested for the presence of scrub typhus, murine typhus, and leptospirosis antibodies. Of the nine species of small mammals collected, Apodemus agrarius, the common striped field mouse and known reservoir of scrub typhus, was the most frequently collected (90.6%). Only four of the nine species captured, A. agrarius (60.9%), Micromys minutus (100%), Mus musculus (55.6%), and Rattus norvegicus (46.7%), were positive for scrub typhus. Of all the small mammals captured, only A. agrarius was positive for murine typhus (0.3%) and leptospirosis (1.3%). Seasonal and annual prevalence rates based on weight and sex are presented.

Malaria in the Republic of Korea, 1993-2007. Variables related to re-emergence and persistence of Plasmodium vivax among Korean populations and U.S. forces in Korea.

Malaria was eradicated and the Republic of Korea (ROK) declared "malaria free" in 1979. However, in 1993, a temperate strain of vivax malaria, expressing both latent and nonlatent disease populations, re-emerged near the demilitarized zone (DMZ), rapidly spread to civilian sectors near the DMZ, and increased exponentially in ROK military, veteran, and civilian populations through 1998. Malaria among all ROK populations decreased 5-fold from a high of 4142 cases in 2000 to a low of 826 cases in 2004, before increasing again to 2180 cases by 2007. Each malaria case in the ROK is reported in the metropolitan area/province where the diagnosis is made, which may be at some distance from the area where infection occurred. Therefore, it is difficult to ascertain transmission sites since approximately 60% of vivax malaria in Korea is latent with symptoms occurring >1 month to 24 months after infection. A review of case diagnosis for civilian, veteran, and military populations shows that nearly all malaria south of Gyeonggi and Gangwon Provinces is the result of veterans exposed in malaria high-risk areas along the DMZ and returning to their hometowns where they later develop malaria. Thus, malaria currently remains localized near the DMZ with limited transmission in provinces south of Seoul and has not spread throughout Korea as previously hypothesized. This report describes the reemergence of vivax malaria cases in civilian and military ROK populations and U.S. military personnel and assesses variables related to its transmission and geographic distribution.

Plasmodium vivax malaria among U.S. forces Korea in the Republic of Korea, 1993-2007.

Malaria is a significant health threat to U.S. combat forces that are deployed to malaria-endemic regions. From 1979, when the Republic of Korea (ROK) was declared malaria free, malaria did not present a health threat to U.S. forces deployed to Korea until the early 1990s. In 1993, a temperate strain of vivax malaria expressing both latent (long prepatent incubation periods of usually 6-18 months after infection) and nonlatent (short prepatent incubation periods < 30 days after infection) disease reemerged near the demilitarized zone (DMZ) and once again presented a primary health threat to U.S. military populations in the ROK. Following its reemergence, malaria rates increased dramatically through 1998 and accounted for > 44% of all malaria cases among U.S. Army soldiers from 1997 to 2002. More than 60% of all Korean-acquired malaria among U.S. soldiers was identified as latent malaria. Nearly 80% of all latent malaria attributed to exposure in Korea was diagnosed in the U.S. or other countries where soldiers were deployed. These data illustrate the requirement for a comprehensive malaria education program, especially for those soldiers residing or training in malaria high-risk areas, to inform soldiers and providers of the risk of developing malaria after leaving Korea.

Geographic distribution and ecology of potential malaria vectors in the Republic of Korea.

Environmental geospatial data and adult and larval mosquito collection data for up to 106 sites throughout the Republic of Korea (ROK) were used to develop ecological niche models (ENMs) of the potential geographic distribution for eight anopheline species known to occur there. The areas predicted suitable for the Hyrcanus Group species were the most extensive for Anopheles sinensis Wiedemann, An. kleini Rueda, An. belenrae Rueda, and An. pullus Yamada, intermediate for An. sineroides Yamada, and the most restricted for An. lesteri Baisas and Hu and the non-Hyrcanus Group species An. koreicus Yamada and Watanabe and An. lindesayi Yamada. The relative vectorial importance of these species is unknown, and all, except An. koreicus and An. lindesayi, are predicted to occur widely in the northwest of the ROK where malaria transmission has been sporadic since its resurgence in 1993. Our ENMs suggest that it is unlikely that An. koreicus and An. lindesayi are vectors, but we do not document consistent geographic differentiation that might incriminate any of the other species as vectors. Because all species are predicted to occur in North Korea, we also cannot reject the hypothesis that malaria infected mosquitoes from North Korea may have been the cause of the resurgence of malaria in the ROK. Ecological differentiation of the eight species is inferred from collection locations and 34 environmental layers based on remote sensing and global climatic averages. Interspecific differences were noted, and characterizing mosquito habitats by ground-based and remote sensing methods is proposed.