Distribution of malaria vectors and incidence of vivax malaria at Korean army installations near the demilitarized zone, Republic of Korea

Abstract

BackgroundAs a result of the reintroduction of malaria in the Republic of Korea (ROK) in 1993 and the threat to military and civilian populations, the Korea Military National Defense (MND) increased emphasis on vector control in 2012 at ROK Army (ROKA) installations located near the DMZ, while decreasing chemoprophylaxis, fearing potential drug resistance. Mosquito surveillance demonstrated a need for continuous monitoring of disease patterns among ROKA soldiers and vector malaria infection rates to ensure positive outcomes.MethodsAnopheles spp. were collected from May–October at three ROKA installations in three locations near the DMZ. Each of the areas included one installation <2 km and two installations 11–12 km from the DMZ in Paju and Yeoncheon counties, Gyeonggi Province. Anopheles spp. were identified by polymerase chain reaction (PCR) techniques and then assayed for the presence of vivax malaria sporozoites. The ROK MND reported vivax malaria patients monthly to Korea Centers for Disease Control and Prevention. Correlations for the incidence of Plasmodium vivax patients and infected Anopheles species were analysed using the Wilcoxon rank sum test, Pearson correlation test and liner regression analysis.ResultsA total of 4282 Anopheles spp. were collected. Anopheles kleini (69.5 %) was the most commonly collected, followed by Anopheles pullus (17.3 %), Anopheles belenrae (4.5 %), Anopheles sineroides (4.2 %), Anopheles sinensis sensu stricto (2.7 %), and Anopheles lesteri (1.9 %). Overall, 21 malaria patients were reported by the ROK MND. The monthly incidence of the malaria patients correlated with the monthly number of Plasmodium vivax sporozoite positive Anopheles spp. The monthly numbers of An.kleini demonstrated the highest correlations to the numbers of ROKA malaria patients throughout the mosquito season (P < 0.01). Anopheles spp. positive for P. vivax and malaria patients at ROKA installations located <2 km from the DMZ were higher than for ROKA installations located 11–12 km from DMZ.ConclusionThe number of Anopheles spp. positive for P. vivax sporozoites correlated with the monthly number of malaria cases and exposure of ROKA soldiers from May–October to P. vivax malaria infections. Malaria vector surveillance and vector control is warranted as part of an effective malaria management program at ROKA installations located near DMZ.

Seasonal dynamics ofAnophelesspecies at three locations in the Republic of Korea

“…sinensis was the predominant mosquito collected at all sites, and populations peaked just after the remotely sensed period of maximum greenness at all sites. By contrast, Chang et al () caught more An. kleini, An.…”

“…Periods when mosquito longevity was predicted to exceed the EIP (i.e., when P. vivax transmission is possible) included: Wks 29, 31, 34, and towards the end of the season (Wks 36–37). If yearly variation is minimal, only the elevated risk predicted during Wk 29 would be relevant to the July, 2011 peak in vivax malaria cases reported by Chang et al (). Anopheles birth rate generally declined towards the end of the trapping season, but otherwise each location displayed a different pattern for calculated birth rate and mortality.…”

“…Future studies relating times of risk for malaria transmission, when longevity exceeds the EIP, to concurrent data on human malaria cases or infections of field‐collected mosquitoes, could serve to validate the use of mosquito demography as an estimator of risk. Chang et al () reported PCR identified vivax infections of Anopheles species collected from blacklight traps, which suggests that a validation experiment could be conducted focused on malarious areas near the DMZ. However, care must be taken to ensure that oocyst DNA contamination of mosquito head and thorax (Foley et al ) and false positivity of PCRs as reported by Harrison et al () is minimized or eliminated.…”

Colonization and Maintenance of Anopheles belenrae and Anopheles pullus From the Republic Of Korea

“…sinensis s.l. as the potential malaria vector and highlighted the need to evaluate each of the cryptic species for their ability to vector P. vivax (Joshi et al 2009(Joshi et al , 2011Phasomkusolsil et al 2014;Chang et al 2016;Ubalee et al 2016). Establishing colonies of mosquitoes in countries, such as Thailand where P. vivax is endemic, is important as it provides for mosquito species to be evaluated for susceptibility to malaria by collecting blood samples from infected patients, feeding infectious blood aliquots to multiple batches of mosquitoes, and then measuring infection rates, numbers of oocysts, and numbers of salivary gland sporozoites.…”

Trends in Infectious Disease Mortality, South Korea, 1983–2015

“…Despite these changes, persons in South Korea remain vulnerable to infectious diseases that typically impose great burdens on healthcare systems (7). Particularly vulnerable populations are disproportionately affected by endemic infections from tuberculosis (TB) and vectorborne pathogens (8,9). The emergence of pandemic influenza A(H1N1) in 2009 and Middle East respiratory syndrome in 2015 substantially affected not only overall health outcomes but also societal stability (10,11).…”