Malaria Vector Surveillance in Ganghwa-do, a Malaria-Endemic Area in the Republic of Korea

We investigated the seasonality of Anopheles mosquitoes, including its species composition, density, parity, and population densities of mosquitoes infected with the parasite in Ganghwa-do (Island), a vivax malaria endemic area in the Republic of Korea. Mosquitoes were collected periodically with a dry-ice-tent trap and a blacklight trap during the mosquito season (April-October) in 2008. Anopheles sinensis (94.9%) was the most abundant species collected, followed by Anopheles belenrae (3.8%), Anopheles pullus (1.2%), and Anopheles lesteri (0.1%). Hibernating Anopheles mosquitoes were also collected from December 2007 to March 2008. An. pullus (72.1%) was the most frequently collected, followed by An. sinensis (18.4%) and An. belenrae (9.5%). The composition of Anopheles species differed between the mosquito season and hibernation seasons. The parous rate fluctuated from 0% to 92.9%, and the highest rate was recorded on 10 September 2008. Sporozoite infections were detected by PCR in the head and thorax of female Anopheles mosquitoes. The annual sporozoite rate of mosquitoes was 0.11% (2 of 1,845 mosquitoes). The 2 mosquitoes that tested positive for sporozoites were An. sinensis. Malarial infections in anopheline mosquitoes from a population pool were also tried irrespective of the mosquito species. Nine of 2,331 pools of Anopheles mosquitoes were positive. From our study, it can be concluded that An. sinensis, which was the predominant vector species and confirmed as sporozoite-infected, plays an important role in malaria transmission in Ganghwa-do.

Molecular Epidemiologic Investigation of Norovirus Infections in Incheon City, Korea, from 2005 to 2007

Noroviruses (NoVs) cause major epidemic gastroenteritis in humans. To obtain the molecular epidemiological information on gastroenteritis sporadic cases in Incheon city, Korea, we analyzed the nucleotide sequences of NoV strains detected during 2005~2007. We performed one step RT-PCR amplifying the open reading frame (ORF) 2 (capsid region) followed by semi-nested PCR from the stool samples from acute gastroenteritis patients from 2005 to 2007. Amplicons of the capsid region of norovirus strains were sequenced and analyzed using MegAlign in DNAstar software. Faecal samples were collected from 6,618 acute gastroenteritis patients during the study period. The incidence of NoV infection was about 10.7% (n=708) among patients with acute gastroenteritis and genotypes of the 320 positive samples were determined by sequence analysis. Sequence comparison of NoV strains revealed that 16 genotypes of GII NoV strains were circulated in Incheon city, from 2005 to 2007. Among norovirus strains, the most prevalent genotype GII/4 was most common 69.7% (223 strains), followed by GII/3 17.2% (55 strains), GII/12 4.4% (14 strains), GII/1 2.2% (7 strains), GII/5 1.6% (5 strains), GII/15 1.3% (4 strains) and 0.6% (2 strains) each of GII/9 and GII/16. The GII-3 strains were most frequently detected in Incheon, 2005. From the phylogenetic analysis of NoV strains, we detected 16 genotypes of GII NoV strains during 2005~2007 in Incheon. Our results suggest that various genotypes of human NoV strains in sporadic case of AGE were circulated in Incheon, Korea.