Ecological characteristics and current status of infectious disease vectors in South Korea

In light of global climate change, the seasonal and geographical distribution of vector species, especially mosquitoes, chigger mites, and ticks, are of great importance for human beings residing in rural and urban environments. A total of 12 species belonging to 4 genera have been identified as vector mosquitoes in the Republic of Korea. The most common of the 56 mosquito species in this country from 2013 through 2015 was found to be a malaria vector, Anopheles sinensis s.l. (species ratio [SR] 52%); followed by a potential vector of West Nile virus, Aedes vexans nipponii (SR 38%); a Japanese encephalitis vector, Culex tritaeniorhynchus (SR 6%); a West Nile virus vector, Culex pipiens (SR 3%); and a dengue and Zika virus vector, Ae. albopictus (SR 0.3%). Of the scrub typhus vectors, Leptotrombidium scutellare is the predominant chigger mite in Gyongnam province and Jeju island, whereas L. pallidum is the predominant species in other areas of Korea. Ticks were found to be prevalent in most environmental conditions, and high levels of their activity were consistently observed from May to September. Haemaphysalis species of ticks were mostly collected in grasslands, whereas Ixodes species were frequently found in coniferous forests. Haemaphysalis longicornis, known as the main vector of severe fever with thrombocytopenia syndrome, was the predominant species and was widely distributed throughout the country.

A New Species of Chigger Mite (Acari: Trombiculidae) from Rodents in Southwest China

This paper describes a new species of chigger mite (Acari: Trombiculidae), Gahrliepia cangshanensis n. sp., from rodents in southwest China. The specimens were collected from Yunnan red-backed voles, Eothenomys miletus (Thomas, 1914), and a Chinese white-bellied rat, Niviventer confucianus (Milne-Edwards, 1871) in Yunnan Province. The new species is unique mainly in its number of dorsal setae (n=21), and it has the following features: fT (formula of palpotarsus)=4B (B=branched), fp (formula of palpal seta)=B/N/N/N/B (N=naked), a broad tongue-shaped scutum with an almost straight posterior margin, and 17 PPLs (posterior posterolateral seta) with a length of 36-43 microm. This chigger mite may also infect other rodent hosts and may be distributed in other localities.

Trombiculidae distribution associated to tsutsugamushi in Quang Ninh province

From 2000 to 2002, 449 tsutsugamushi patients were admitted to Uong Bi Hospital of Quang Ninh province. The disease occurred mainly in Uong Bi town, Dong Trieu district, Yen Hung district, and Cam Pha town. It occurred sporadically during the year but more frequently between May and Octorber. 14 species of Trombiculidae were found to parasitize in mice in almost all surveyed sites, especially in the places with many more tsutsugamushi patients. The main clinical signs were biting spots 94.2%, fever 100%, peripheral glands 98.7%, and rash 52.2%. Three effective regimes in treatment of tsutsugamushi were (1) chloramphenicol 30-50mg/kg/24 hours x 5-7 days; (2) tetracycline 30-40mg/kg/24 hours x 5-7 days; and (3) doxycycline 4mg/kg/24 hours x 3-5 days