Survey of Zoonotic Trematode Metacercariae in Fish from Water systems of Geum-gang (River) in Republic of Korea

The infection status of zoonotic trematode metacercariae (ZTM) was surveyed in freshwater fishes from the water systems of Geum-gang (River) in the Republic of Korea (Korea). A total of 1,161 freshwater fishes from 6 local sites of Geum-gang were examined with the artificial digestion method for 4 years (2012–2015). Clonorchis sinensis metacercariae were detected in 122 (37.2%) out of 328 fishes in the positive fish species from 4 surveyed areas, and their mean intensity was 43 per fish infected. Metagonimus spp. metacercariae were found in 432 (51.7%) out of 835 fishes in the positive fish species from all 6 surveyed areas, and their mean intensity was 30 per fish infected. Centrocestus armatus metacercariae were detected in 285 (75.0%) out of 380 fishes in the positive fish species from 6 surveyed areas, and their mean intensity was 2,100 per fish infected. Echinostoma spp. metacercariae were found in 56 (19.7%) out of 284 fishes in the positive fish species from 5 surveyed areas, and their mean intensity was 10 per fish infected. Clinostomum complanatum metacercariae were detected in 98 (57.3%) out of 171 fishes in the positive fish species from only 2 surveyed areas, and their mean intensity was 11 per fish infected. Conclusively, the endemicity of ZTM is not so high in fishes from water systems of Geum-gang in Korea although it is more or less different by fish species, surveyed areas and ZTM species.     

Endemicity of Zoonotic Trematode Metacercariae in Fish from Deokcheon-gang (River) in Sancheong-gun,Gyeongsangnam-do,Republic of Korea

The endemicity of zoonotic trematode metacercariae (ZTM) was investigated with total 871 freshwater fishes (19 species) from Deokcheon-gang (a branch stream of Gyeongho-gang) in Sancheong-gun, Gyeongsangnam-do, Korea for 3 years (2018–2020). All fishes were examined with the artificial digestion method. The metacercariae of Clonorchis sinensis (CsMc) were detected in 233 (36.3%) out of 642 fish in 11 positive fish species (PFS), and their infection intensity was 27 per fish infected (PFI). Especially, in index fish, Puntungia herzi, of CsMc infection, prevalence was 64.2% and infection intensity was 37 PFI. Metagonimus spp. metacercariae (MsMc) were found in 760 (87.5%) out of 869 fish in 18 PFS and their infection intensity was 228 PFI. In sweet smelt, Plecoglossus altivelis, the prevalence of MsMc was 97.6% and their infection intensity was 3,570 PFI. Centrocestus armatus metacercariae were detected in 209 (29.4%) out of 710 fish in 8 PFS and their infection intensity was 1,361 PFI. Echinostoma spp. metacercariae were found in 293 (42.6%) out of 688 fish in 15 PFS and their infection intensity was 5 PFI. Metacercariae of Clinostomum complanatum and Metorchis orientalis were also detected in 2.7% and 21.2% fish in 4 PFS and their infection intensities were 3.1 and 3.4 PFI respectively. By the present study, it was confirmed that some species of ZTM including CsMc and MsMc are more or less prevalent in fishes from Deokcheon-gang in Sancheong-gun, Gyeongsangnam-do, Korea.     

Intestinal parasite infections at an institution for the handicapped in Korea

Stool and cellotape anal swab examinations were carried out in August 1997 on handicapped people at an institution located in Chorwon-gun, Kangwon-do, Korea. A total of 112 stool samples (78 males and 34 females) revealed three cases of Trichuris trichiura infection and one case of Enterobius vermicularis infection. Other helminth eggs were not detected. The overall prevalence rate was 35.7% (38.5% for males and 29.4% for females). More than two different kinds of parasites were found in 42.0% of the positive stool samples (17 cases). The infection rates for protozoan cysts are as follow: Entamoeba coli (25.0%), E. histolytica (1.8%), Endolimax nana (21.4%), Iodoamoeba bütschlii (1.8%) and Giardia lamblia (0.9%). In cellotape anal swab examinations (165 samples), the prevalence rate of E. vermicularis was 20.6% (25.7% of males and 9.6% of females). In conclusion, the handicapped people in the institution showed higher infection rates of protozoan parasites and E. vermicularis, possibly due to more accessibility to the infection.     

Distribution of Gastrointestinal Parasitic Infection in Domestic Pigs in the Republic of Korea: Nationwide Survey from 2020–2021

This study aimed to examine the distribution of gastrointestinal parasitic infections in domestic pigs in the Republic of Korea. From May 2020 to October 2021, 364 pig fecal samples were collected from 75 farms in 7 Provinces and microscopically examined. A total of 170 (46.7%) pigs were infected with at least one of the following parasites: Balantioides coli, strongyles, Ascaris suum, Trichuris suis, and coccidia. By parasite species, B. coli, strongyles, A. suum, T. suis, and coccidia oocysts or eggs were detected in 144 (39.6%), 24 (6.6%), 14 (3.8%), 4 (1.1%), and 1 (0.3%) samples, respectively. One hundred fifty-four, 15, and 1 cases showed single, double, and triple infections, respectively. Of the swine fecal samples from 75 farms, 69 specimens (92.0%) were infected with 1 or more parasites. All surveyed farms across the country exhibited a positive rate of over 30%, among which the highest positive rate was 65.0% in Chungcheongnam-do, and Jeollabuk-do was followed by 61.9%. Winter showed a statistically lower prevalence than other seasons. This study showed that gastrointestinal parasites are prevalent in pigs in Korea, although the diversity of parasites is low.     

Schistosoma mansoni in a low-prevalence area in Brazil: the importance of additional methods for the diagnosis of hard-to-detect individual carriers by low-cost immunological assays

Schistosomiasis diagnosis is based on the detection of eggs in the faeces, which is laborious and lacks sensitivity, especially for patients with a low parasite burden. Immunological assays for specific antibody detection are available, but they usually demonstrate low sensitivity and/or specificity. In this study, two simple immunological assays were evaluated for the detection of soluble Schistosoma mansoni adult worm preparation (SWAP) and egg-specific IgGs. These studies have not yet been evaluated for patients with low parasite burdens. Residents of an endemic area in Brazil donated sera and faecal samples for our study. The patients were initially diagnosed by a rigorous Kato-Katz analysis of 18 thick smears from four different stool samples. The ELISA-SWAP was successful for human diagnosis with 90% sensitivity and specificity, confirming the Kato-Katz diagnosis with nearly perfect agreement, as seen by the Kappa index (0.85). Although the ELISA-soluble S. mansoni egg antigen was 85% sensitive, it exhibited low specificity (80%; Kappa index: 0.75) and was more susceptible to cross-reactivity. We believe that immunological assays should be used in conjunction with Kato-Katz analysis as a supplementary tool for the diagnosis of schistosomiasis for patients with low infection burdens, which are usually hard to detect.     

Survey of Zoonotic Trematode Metacercariae in Fish from Irrigation Canal of Togyo-jeosuji (Reservoir) in Cheorwon-gun,Gangwon-do,Republic of Korea

The infection status of zoonotic trematode metacercariae (ZTM) was investigated in total 568 freshwater fishes (19 species) from the irrigation canal of Togyo-jeosuji (Reservoir) in Cheorwon-gun, Gangwon-do, the Republic of Korea for 3 years (2018–2020). All fishes were examined using the artificial digestion method. The metacercariae of Clonorchis sinensis (CsMc) were detected in 180 (43.8%) out of 411 fish of positive species, and their infection intensity was 38 per fish infected (PFI). Especially, in 2 fish species, i.e., Pseudorasbora parva and Puntungia herzi, the prevalence was 82.1% and 31.3%, and the infection intensity with CsMc was 88 and 290 PFI, respectively. Metagonimus spp. metacercariae (MsMc) were found in 403 (74.1%) out of 544 fish of positive species, and their infection intensity was 62 PFI. In the pale chub, Zacco platypus, the prevalence of MsMc was 98.6%, and their infection intensity was 144 PFI. Centrocestus armatus metacercariae were detected in 171 (38.9%) out of 440 fish of positive species, and their infection intensity was 1,844 PFI. Echinostoma spp. metacercariae were found in 94 (19.6%) out of 479 fish of positive species, and their infection intensity was 3 PFI. Metorchis orientalis metacercariae were detected in 43 (29.3%) out of 147 fish of positive species, and their infection intensity was 4 PFI. By the present study, it has been confirmed that some species of ZTM, including CsMc and MsMc, are prevalent in fishes from the irrigation canal of Togyo-jeosuji in Cheorwon-gun, Gangwon-do, Korea.     

Spatio-temporal variation in post-recovery dynamics in a large Peregrine Falcon (Falco peregrinus) population in the Jura mountains 2000–2020†

After spectacular population crashes in the 1960 and 1970s, Peregrine Falcon Falco peregrinus populations recovered worldwide, and in the 2000s many study populations were back to normal. However, post-recovery trends have been documented less well. We combined three long-term population studies covering the entire Jura mountain range (16 304 km²) to examine spatio-temporal variation in population dynamics during 2000–2020 in 420 known nesting sites in five regions: Ain, Jura and Doubs in France, and Jura Sud and Jura Nord in Switzerland. Every year about 60% of all sites were surveyed at least once, and this proportion increased over time. We used Bayesian occupancy modelling to investigate site persistence and colonization probabilities and correct status and trend estimates for bias due to non-random site coverage. Based on the average of two models correcting for preferential sampling, we estimated that population size peaked in 2002 (Jura), 2005 (Doubs), 2007 (Ain, Jura Nord) and in 2007 for the Jura as a whole. Thereafter, the population declined significantly in four regions and in the Jura as a whole, with the strongest decline found in the Jura Nord ( –38%, 95% credible interval –34%/–41%) during 2007–2020. Thus, we found considerable spatial heterogeneity in post-recovery trends and widespread post-recovery declines. Reasons for the latter may include Eagle Owl Bubo bubo predation, illegal persecution and human disturbance. Our results illustrate how quickly positive population trends may be reversed, such that continuous long-term monitoring even for species seemingly ‘out of danger’ remains invaluable. Our study also emphasizes the importance of correcting for both coverage bias in general and preferential sampling in particular when assessing population trends in studies where not every territory can be surveyed in all years.     

Prevalence of chytrid parasitism among diatom populations in the lower Columbia River (2009–2013)

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Epidemiological study of clonorchiasis and metagonimiasis along the Geum-gang (River) in Okcheon-gun (county), Korea

The endemic status of clonorchiasis and metagonimiasis along the Geum-gang (River) in Okcheon-gun (County) in Korea was examined. From February to December 2000, stools of total 1,081 inhabitants living in 5 villages were examined. Each stool specimen was examined by both the cellophane thick smear method and the formalin-ether sedimentation technique. Egg-positive cases were further analyzed by Stoll's egg-counting technique, and praziquantel was administered to positive cases. The egg-positive rates for Clonorchis sinensis and Metagonimus species were 9.3% and 5.5%, respectively, and the double infection rate was 3.5%. The numbers of eggs per gram (EPG) of feces of C. sinensis and Metagonimus sp. were 918 +/- 1,463 and 711 +/- 947, respectively. The egg-positive rates for C. sinensis and Metagonimus sp. in the riverside area were 14.2% and 8.4%, respectively, which were significantly higher than those of the inland area (3.2% and 1.7%, respectively). The egg-positive rates of C. sinensis and Metagonimus sp. in males (16.7% and 10.0%) were significantly higher than those of females (3.5% and 1.8%). However, there were no significant differences of EPG values between localities and sexes. The prevalence of clonorchiasis and metagonimiasis in this survey was significantly lower than that in the previous reports. However, there is still a high prevalence of infection with C. sinensis and Metagonimus sp. in this region, especially in the riverside area.     

Enterobius vermicularis Infection among Preschool Children: A 12-Year (2008–2019) Survey in Large Cities and Provinces of the Republic of Korea

A 12-year nationwide survey (2008–2019) was performed to investigate the prevalence of Enterobius vermicularis infection among preschool children in Seoul, 4 large cites (Busan, Incheon, Daegu, and Ulsan), and 9 provinces (grouped into 5 localities) in the Republic of Korea (=Korea). The survey was carried out once a year by 16 regional offices of the Korea Association of Health Promotion. The cello-tape perianal swab method (1 smear per child) was applied to detect eggs of E. vermicularis and other helminths. According to the results, the egg positive rate of E. vermicularis infection in 2008–2009 was 1.8–2.0%, but it decreased gradually to 0.6% in 2019 (P<0.05). The prevalence was significantly higher in boys (0.7–5.0%, mean 1.8%) than in girls (0.5–2.8%, mean 1.3%) (P<0.05). The 2 most southern localities, Jeju-do (Province) and Jeolla-do (inclusive of Jeollabuk-do and Jeollanam-do) and a mid-western province, Gyeonggi-do, revealed higher prevalences, whereas Seoul and Gangwon-do showed lower prevalences. The results indicate that a low-grade prevalence of E. vermicularis infection (less than 4%) has been maintained for the recent 12 years among preschool children in Korea. Continuous monitoring of enterobiasis in the child age group is necessary in Korea.     

Seroprevalence of Plasmodium vivax in the Republic of Korea (2003-2005) using Indirect Fluorescent Antibody Test

Plasmodium vivax reemerged in the Republic of Korea (ROK) in 1993, and is likely to continue to affect public health. The purpose of this study was to measure levels of anti-P. vivax antibodies using indirect fluorescent antibody test (IFAT) in border areas of ROK, to determine the seroprevalence of malaria (2003-2005) and to plan effective control strategies. Blood samples of the inhabitants in Gimpo-si, Paju-si, and Yeoncheon-gun (Gyeonggi-do), and Cheorwon-gun (Gangwon-do) were collected and kept in Korea Centers for Disease Control and Prevention (KCDC). Out of a total of 1,774 serum samples tested, the overall seropositivity was 0.94% (n=17). The seropositivity was the highest in Paju-si (1.9%, 7/372), followed by Gimpo-si (1.4%, 6/425), Yeoncheon-gun (0.67%, 3/451), and Cheorwon-gun (0.19%, 1/526). The annual parasite incidence (API) in these areas gradually decreased from 2003 to 2005 (1.69, 1.09, and 0.80 in 2003, 2004, and 2005, respectively). The highest API was found in Yeoncheon-gun, followed by Cheorwon-gun, Paju-si, and Gimpo-si. The API ranking in these areas did not change over the 3 years. The seropositivity of Gimpo-si showed a strong linear relationship with the API of 2005 (r=0.9983, P=0.036). Seropositivity data obtained using IFAT may be useful for understanding malaria prevalence of relevant years, predicting future transmission of malaria, and for establishing and evaluating malaria control programs in affected areas.     

Application of the Maryblyt Model for the Infection of Fire Blight on Apple Trees at Chungju,Jecheon, and Eumsung during 2015–2020

To preventively control fire blight in apple trees and determine policies regarding field monitoring, the Maryblyt ver. 7.1 model (MARYBLYT) was evaluated in the cities of Chungju, Jecheon, and Eumseong in Korea from 2015 to 2020. The number of blossom infection alerts was the highest in 2020 and the lowest in 2017 and 2018. And the common feature of MARYBLYT blossom infection risks during the flowering period was that the time of BIR-High or BIR-Infection alerts was the same regardless of location. The flowering periods of the trees required to operate the model varied according to the year and geographic location. The model predicts the risk of “Infection” during the flowering periods, and recommends the appropriate times to control blossom infection. In 2020, when flower blight was severe, the difference between the expected date of blossom blight symptoms presented by MARYBLYT and the date of actual symptom detection was only 1–3 days, implying that MARYBLYT is highly accurate. As the model was originally developed based on data obtained from the eastern region of the United States, which has a climate similar to that of Korea, this model can be used in Korea. To improve field utilization, however, the entire flowering period of multiple apple varieties needs to be considered when the model is applied. MARYBLYT is believed to be a useful tool for determining when to control and monitor apple cultivation areas that suffer from serious fire blight problems.     

The state of the leprosy epidemic in Yunnan,China 2011–2020: A spatial and spatiotemporal analysis,highlighting areas for intervention

BackgroundDespite public health efforts to reduce the leprosy burden in Yunnan, China, leprosy remains an important public health problem in some specific areas. We analyzed the epidemiological characteristics and spatial distribution of leprosy in Yunnan, China, and provide data to guide disease prevention and control efforts.Methodology/principal findingsThe surveillance data of newly detected leprosy cases in Yunnan, China, during 2011–2020 were extracted from the LEPROSY MANAGEMANT INFORMATION SYSTEM IN CHINA (LEPMIS), and spatial distribution analysis, spatial autocorrelation analysis, and spatiotemporal scanning were performed with ArcGIS 10.6.1, GeoDa 1.8.8, and SaTScan 9.4.3 software, respectively. A total of 1907 newly detected leprosy cases were reported in Yunnan, China, during 2011–2020. The new case detection rate (NCDR) decreased from 0.62 in 2011 to 0.25 in 2020, with an annual incidence of 0.41/100,000 population. The proportions of multibacillary (MB) cases, cases in female patients, cases causing grade 2 physical disability (G2D), and cases in pediatric patients were 67.07%, 33.93%, 17.99%, and 2.83%, respectively. The number of counties with an incidence above 1/100,000 population decreased from 30 in 2011 to 8 in 2020. The Moran’s I of leprosy in Yunnan, China, during 2011–2020 ranged from 0.076 to 0.260, indicating the presence of spatial clusters. Local spatial autocorrelation (LSA) analysis showed that high-high cluster areas (hot spots) were mainly distributed in the southeastern, northern, and northwestern regions. Spatiotemporal scanning showed three clusters with high NCDRs. The probably primary clusters, occurring during January 1, 2011–December 31, 2015, covered 11 counties in the southeastern region (RR = 5.046515, LRR = 271.749664, P = 0.000).ConclusionThe number of leprosy cases in Yunnan decreased overall, although some high-NCDR regions remained. Geographic information system (GIS) analysis coupled with spatial analysis indicated regions with leprosy clusters. Continuous leprosy prevention and control strategies in Yunnan Province should be established, and interventions in high-risk regions should be prioritized and further strengthened.     

Mongooses (Urva auropunctata) as reservoir hosts of Leptospira species in the United States Virgin Islands, 2019–2020

During 2019–2020, the Virgin Islands Department of Health investigated potential animal reservoirs of Leptospira spp., the bacteria that cause leptospirosis. In this cross-sectional study, we investigated Leptospira spp. exposure and carriage in the small Indian mongoose (Urva auropunctata, syn: Herpestes auropunctatus), an invasive animal species. This study was conducted across the three main islands of the U.S. Virgin Islands (USVI), which are St. Croix, St. Thomas, and St. John. We used the microscopic agglutination test (MAT), fluorescent antibody test (FAT), real-time polymerase chain reaction (lipl32 rt-PCR), and bacterial culture to evaluate serum and kidney specimens and compared the sensitivity, specificity, positive predictive value, and negative predictive value of these laboratory methods. Mongooses (n = 274) were live-trapped at 31 field sites in ten regions across USVI and humanely euthanized for Leptospira spp. testing. Bacterial isolates were sequenced and evaluated for species and phylogenetic analysis using the ppk gene. Anti-Leptospira spp. antibodies were detected in 34% (87/256) of mongooses. Reactions were observed with the following serogroups: Sejroe, Icterohaemorrhagiae, Pyrogenes, Mini, Cynopteri, Australis, Hebdomadis, Autumnalis, Mankarso, Pomona, and Ballum. Of the kidney specimens examined, 5.8% (16/270) were FAT-positive, 10% (27/274) were culture-positive, and 12.4% (34/274) were positive by rt-PCR. Of the Leptospira spp. isolated from mongooses, 25 were L. borgpetersenii, one was L. interrogans, and one was L. kirschneri. Positive predictive values of FAT and rt-PCR testing for predicting successful isolation of Leptospira by culture were 88% and 65%, respectively. The isolation and identification of Leptospira spp. in mongooses highlights the potential role of mongooses as a wildlife reservoir of leptospirosis; mongooses could be a source of Leptospira spp. infections for other wildlife, domestic animals, and humans.     

Distribution of overwintering mosquitoes (Diptera: Culicidae) in grassy fields in the Republic of Korea, 2007–2008

Overwintering mosquitoes in a grassy field were surveyed at 13 different localities from December 2007 to February 2008 in the Republic of Korea (ROK). Mosquitoes were collected by putting a white colored tent on the grass, without the base, and heating the inside of the tent. A total of 784 female adults comprising seven species were collected during the study period, including 395 (45.6%) Anopheles pullus, 338 (43.2%) An. sinensis, 21 (2.7%) An. belenrae, 2 (0.3%) An. kleini, 43 (5.5%) Culex tritaeniorhynchus, 20 (2.5%) Cx. inatomii, and 1 (0.3%) Cx. pipiens complex. The mosquitoes showed different overwintering distributions by temperature zone and locality. Predominant species, the malaria vectors An. pullus and An. sinensis, showed different overwintering distributions. Anopheles pullus had a 90.9% collection rate except for Youngju and an average – 0.6°C temperature between December and February. Anopheles pullus showed >50% collection rate in most regions maintained below an average of ?1.4°C, and the rate of An. sinensis showed more than 50% collection rate in all regions maintained at an average above ?1.1°C. Other species showed regional characteristics; An. belenrae was distributed in the northwest part of the ROK, and An. kleini was collected rarely at one locality in the middle part of ROK. Culex tritaeniorhynchus, a Japanese encephalitis virus vector, was distributed in the southern and costal region and maintained at an above average of ?1.0°C. Culex inatomii was collected on the coastal region of the ROK.     

Zoonotic Intestinal Trematodes in Stray Cats (Felis catus) from Riverside Areas of the Republic of Korea

The present study was performed to survey the infection status of zoonotic intestinal trematode (ZIT) in stray cats from 5 major riverside areas in the Republic of Korea. Total 400 stray cats were captured with live-traps in riverside areas of Seomjingang (‘gang’ means river) (203 cats) from June to October 2010, and of Yeongsangang (41), Nakdonggang (57), Geumgang (38), and Hangang (61 cats) from June to October 2011, respectively. Small intestines resected from cats were opened with a pair of scissors in a beaker with 0.85% saline and examined with naked eyes and under a stereomicroscope. More than 16 ZIT species were detected in 188 (92.6%) cats from Seomjingang areas, and the number of worms recovered was 111 per cat infected. In cats from riverside areas of Yeongsangang, Nakdonggang, Geumgang, and Hangang, more than 9, 8, 3, and 5 ZIT species were recovered, and the worm burdens were 13, 42, 11, and 56 specimens per infected cat, respectively. As the members of family Heterophyidae, more than 10 species, i.e., Metagonimus spp., Pygidiopsis summa, Heterophyes nocens, Stellantchasmus falcatus, Heterophyopsis continua, Acanthotrema felis, Centrocestus armatus, Procerovum varium, Cryptocotyle concava, and Stictodora lari, were recovered. More than 5 species of echinostomes, i.e., Echinostoma hortense, Echinochasmus japonicus, Echinochasmus sp., Echinoparyphium sp., and unidentified larval echinostomes, were collected. Plagiorchis spp. were detected in cats from areas of Seomjin-gang and Yeongsangang. From the above results, it has been confirmed that stray cats in 5 major riverside areas of Korea are highly infected with various species of ZITs.     

New horizons in drug discovery of lymphocyte-specific protein tyrosine kinase (Lck) inhibitors: a decade review (2011–2021) focussing on structure–activity relationship (SAR) and docking insights

Lymphocyte-specific protein tyrosine kinase (Lck), a non-receptor Src family kinase, has a vital role in various cellular processes such as cell cycle control, cell adhesion, motility, proliferation, and differentiation. Lck is reported as a key factor regulating the functions of T-cell including the initiation of TCR signalling, T-cell development, in addition to T-cell homeostasis. Alteration in expression and activity of Lck results in numerous disorders such as cancer, asthma, diabetes, rheumatoid arthritis, atherosclerosis, and neuronal diseases. Accordingly, Lck has emerged as a novel target against different diseases. Herein, we amass the research efforts in literature and pharmaceutical patents during the last decade to develop new Lck inhibitors. Additionally, structure-activity relationship studies (SAR) and docking models of these new inhibitors within the active site of Lck were demonstrated offering deep insights into their different binding modes in a step towards the identification of more potent, selective, and safe Lck inhibitors.     

Seasonal Prevalence of Mosquitoes Collected from Light Traps in Gyeongsangnam Province,Republic of Korea (2013–2014)

Adult mosquito surveillance was conducted from 2013 through 2014 at four cattle sheds, a wild bird refuge, and two residential areas located in Gyeongnam Province in the Republic of Korea. Adult mosquitoes were collected in black light traps from April 1, through November 30. Mosquito surveillance was conducted to figure out population densities of vector mosquitoes, possibly invaded mosquitoes and identify various virus infections at the selected sites. A total of 107,466 females comprising 14 species and 7 genera were collected from 2013 to 2014. The most common species collected were Culex tritaeniorhynchus Giles (63.8%), Anopheles sinensis s.l. (18.9%), Aedes vexans nipponii (Theobald) (7.7%), and Culex pipiens Coquillett (5.1%). Trap indices (TIs) varied widely for species over their range, due to geographical distribution and degree of association with rural and urban communities . The most collected An. sinensis s.l. and Cx. tritaeniorhynchus appeared at a cow shed in Hapcheon (TI 347.5) and a pigsty in Daejeo‐1‐dong, Busan (TI 1,040.8), respectively, due in part to their situation near breeding sites such as rice paddies. The bi‐weekly population densities for mosquito species were variable for each of the years, apparently as a result of variable annual weather conditions. None of the mosquito species collected tested for the flavivirus including Japanese Encephalitis Virus, West Nile Virus, Dengue Virus, and Zika Virus infections by polymerase chain reaction (PCR) assay were positive.     

Three‐year surveillance (2016–2018) of chigger mites vector for tsutsugamushi disease in the Hwaseong‐Si area of Gyeonggi‐Do,Republic of Korea

Owing to climate change, the global resurgence of vector‐borne infectious diseases has emerged as a critical public health issue. Orientia tsutsugamushi is the etiological agent of tsutsugamushi disease (scrub typhus) a mite‐borne acute febrile disease occurring in the Asia‐Pacific region. We investigated the prevalence of tsutsugamushi disease transmitted by chigger mite vectors living on rodents. Using sticky‐type chigger traps for three months during 2016–2018, 1,057 chigger mites were collected (chigger mite index, 1.31) from four locations in the Hwaseong‐si area of Gyeonggi‐do, Republic of Korea. Five species distributed among three genera were identified. In addition, 94 rodents were captured (collection rate: 7.83%) using Sherman live traps over the course of three months (April, October, and November) during 2016–2017. Three rodent species were captured and identified and the striped field mouse (Apodemus agrarius) was the dominant rodent host species in the surveyed area. A total of 10,469 ectoparasitic chigger mites were recovered from the 94 rodents, from which 13 species distributed among four genera were identified. Of the 5,250 chigger mites examined, Leptotrombidium pallidum was most abundant (n = 2,558), followed by L. orientale, L. scutellare, L. zetum, Euschoengastia koreaensis, L. subintermedium, and Neotrombicula tamiyai. Of the examined chigger mites, no groups recovered from rodent hosts tested positive for O. tsutsugamushi. This study provides fundamental regional information on vector‐borne disease data collection in the Hwaseong‐si area, Gyeonggi‐do, and will further contribute to formulating disease control and prevention strategies.