A Surge in the Seroprevalence of Toxoplasmosis among the Residents of Islands in Gangwha-gun, Incheon, Korea

Abstract

Seroepidemiological changes of Toxoplasma gondii infection among the residents of the islands of Gangwha-gun, Incheon for 2 years were surveyed and evaluated by ELISA using a crude extract antigen. In 2010, sera of 919 adult residents in Gyodong-myeon and 313 adults in Samsan-myeon were collected and checked for IgG antibody titers, which showed 14.5% (133 sera) and 19.8% (62 sera) positive rates, respectively. In 2011, sera of 955 adults in Gyodong-myeon and 341 adults in Samsan-myeon were examined, which showed an increase of positive rates to 23.8% (227 sera) and 31.7% (108 sera), respectively. Totally, the seroprevalence of the first year was 15.8% and it increased rapidly to 25.8% in the second year. The positive rates of both sexes increased simultaneously with the significant ratio of males to females by 1.7-2.2 fold (P<0.05). In both myeons, 661 sera were collected every year and showed changes in optical density (OD) in 177 sera; newly found as positives in 73 persons (11.0%), negative conversion in 10 persons (1.5%), and maintained or increased in 94 persons (14.2%). This rapid increase in the prevalence of toxoplasmosis in Gangwha islands may be due to in part peculiar changes in the toxoplasmic environment of the islands and presumably the consumption of the pork bred domestically within the islands or imported from high endemic nations. It is necessary to find out symptomatic toxoplasmic patients and confirm the risk factors for further infection in the islands of Gangwha-gun.

High Seroprevalence of Toxoplasmosis Detected by RDT among the Residents of Seokmo-do (Island) in Ganghwa-Gun, Incheon City, Korea

“…Some of them may have been imported from high endemic nations. Indeed, pork has been imported without any inspection on T. gondii infection in Korea [15]. …”

“…Many surveys on the seroprevalence of toxoplasmosis among various patient groups have been performed in Korea using various test methods [10–15]. The seroprevalence resulted in the range from 1.9 to 5.8% with indirect latex agglutination (ILA) test [10] and up to 7.7% with the more sensitive ELISA [11].…”

Serologic Survey of Toxoplasmosis in Seoul and Jeju-do, and a Brief Review of Its Seroprevalence in Korea

“…2). Particularly, on islands in Gangwha-gun, the seroprevalence among residents were 15.8% in 2010 and 25.8% in 2011 which was the highest figure ever reported [23]. Subsequently, in Cheorwon-gun, the IgG ELISA seropositive rate was also high, at 17.0% [24].…”

“…In the Republic of Korea (hereafter referred to as Korea), the seroprevalence of toxoplasmosis has been studied by many researchers [6-23]. From 1960 until 1999, residents, children, and hospital patients in Korea usually showed relatively lower prevalences, ranging from 1.1-7.7%, compared to American and European locales [3,5,6-13].…”

“…Thereafter, the reported seroprevalence in Korean residents have been, with the exception of one report [21], higher than this figure, ranging from 13.2-25.8% [22-24]. In this respect, it has been assumed that the seroprevalence of toxoplasmosis in Korea is presently increasing, presumably due to an increased consumption of domestic or imported pork, or other animal meat at risk of T. gondii infection [23]. …”