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

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.     

Seroprevalence of toxoplasmosis in the residents of Cheju island, Korea

This study was performed to evaluate the epidemiological status of toxoplasmosis among the residents of Cheju island. The sera of local students from 18 high schools (boys 2110, girls 2460) and those of adults (474 admitted to Cheju Chungang General Hospital) were collected and checked for the IgG antibody titers against Toxoplasma gondii. Serum samples collected from both the students and adults showed sero-positive rate of 5.5% and 12.9%, respectively. Although the rates were not significantly different between the sexes (5.4% for the boys and 5.5% for the girls attending school), the geographical difference showed a significant difference between the urban (4.6-6.9%) and rural areas (5.6-8.8%) (p < 0.05). Based on the high positive rates, it should be necessary to control toxoplasmosis in Cheju island.     

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

Knowledge of the prevalence of human Toxoplasma gondii infection is required in the Republic of Korea. In this study, we surveyed the seroprevalence of T. gondii infection and analyzed the risk factors associated with seropositivity among residents in 2 administrative districts; Seoul and the island of Jeju-do, which have contrasting epidemiologic characteristics. Sera and blood collected from 2,150 residents (1,114 in Seoul and 1,036 in Jeju-do) were checked for IgG antibody titers using ELISA and for the T. gondii B1 gene using PCR. In addition, participants completed a questionnaire that solicited information on gender, age, occupation, eating habits, history of contact with animals, and travel abroad. The T. gondii B1 gene was not detected in all residents examined. However, ELISA showed 8.0% (89 of 1,114 sera) positive for IgG antibodies against T. gondii in Seoul and 11.3% (117 of 1,036 sera) in Jeju-do. In both districts, the positive rates were higher in males than in females, and those 40-79 years of age showed higher rates than other ages. In Seoul, residents older than 70 years of age showed the highest positive rate, 14.9%, whereas in Jeju-do the highest prevalence, 15.6%, was in those in their sixties. The higher seropositive rate in Jeju-do than in Seoul may be related to eating habits and occupations. The present results and a review of related literature are indicative of an increased seroprevalence of T. gondii in Korea in recent years.     

Seroprevalence of Toxoplasma gondii Infection and Characteristics of Seropositive Patients in General Hospitals in Daejeon, Korea

To figure out the epidemiological status and relevance with other diseases in toxoplasmosis, we checked serum IgG antibody titers of 1,265 patients and medical records of seropositive patients. Seropositive rates were 6.6% by latex agglutination test (LAT) and 6.7% by ELISA. No significant differences were detected between sexes and age groups. The peak seroprevalence was detected in the 40-49-year-old age group. According to clinical department, Toxoplasma-positive rates were high in patients in psychiatry, ophthalmology, health management, emergency medicine, and thoracic surgery. Major coincidental diseases in seropositive cases were malignant neoplasms, diabetes mellitus, arthritis, chronic hepatitis B, chronic renal diseases, schizophrenia, and acute lymphadenitis, in the order of frequency. In particular, some patients with chronic hepatitis B and malignant neoplasms had high antibody titers. These results revealed that the seroprevalence of toxoplasmosis in a general hospital-based study was similar to that in a community-based study, and T. gondii seropositivity may be associated with neoplasms, diabetes, and other chronic infections.     

Seroprevalence of Toxoplasma gondii Among Primary School Children in Shandong Province,China

Although Toxoplasma gondii infection in primary school children has been investigated in many countries, limited surveys have been available in primary school children in China. In the present study, we report the seroprevalence of T. gondii infection in primary school children in Shandong province, China. Sera from 6,000 primary school children were evaluated for T. gondii antibodies with ELISA. The overall seroprevalence of T. gondii infection was 16.0% (961/6,000), of which 14.5% (870/6,000) were positive for anti-T. gondii IgG antibodies, 3.4% (206/6,000) positive for IgM, and 1.9% (115/6,000) were positive for both IgG and IgM. The results of the present investigation indicated a high seroprevalence of T. gondii infection in primary school children in Shandong province, China. Therefore, effective measures should be taken to prevent and control T. gondii infection in primary school children in this province. To the best of our knowledge, this is the first report of T. gondii seroprevalence in primary school children in Shandong province, China.     

Maintained seroprevalence of toxoplasmosis among the residents of Jeju island, Korea

Seroepidemiological status of toxoplasmosis among the residents of Jeju island was surveyed and evaluated by ELISA with crude extract of Toxoplasma gondii. The sera of 2,348 residents (male 1,157 and female 1,191) were collected and checked for the IgG antibody titers, which showed 13.2% positive rate (309 sera). The positive rates were increasing gradually according to the age from 4.3% in teenage to 20.6% in seventies. The positive rates were significantly different between the sex by 16.2% for male and 10.2% for female (P<0.05). This positive rate of toxoplasmosis in Jeju island residents is regarded relatively higher than any other regions of Korea. And the high positive rate may be maintained continuously among Jeju island residents without any clear reasons until now but due to some parts peculiar socio-cultural tradition of Jeju island. Therefore, it is necessary to study further the epidemiology of toxoplasmosis of Jeju island.     

High Toxoplasma gondii Seropositivity among Brain Tumor Patients in Korea

Toxoplasma gondii is an intracellular protozoan that can modulate the environment of the infected host. An unfavorable environment modulated by T. gondii in the brain includes tumor microenvironment. Literature has suggested that T. gondii infection is associated with development of brain tumors. However, in Korea, epidemiological data regarding this correlation have been scarce. In this study, in order to investigate the relationship between T. gondii infection and brain tumor development, we investigated the seroprevalence of T. gondii among 93 confirmed brain tumor patients (various histological types, including meningioma and astrocytoma) in Korea using ELISA. The results revealed that T. gondii seropositivity among brain tumor patients (18.3%) was significantly (P<0.05) higher compared with that of healthy controls (8.6%). The seropositivity of brain tumor patients showed a significant age-tendency, i.e., higher in younger age group, compared with age-matched healthy controls (P<0.05). In conclusion, this study supports the close relationship between T. gondii infection and incidence of brain tumors.     

Seroprevalence of toxoplasmosis in Korean pregnant women

This study was performed in order to evaluate the sero-epidemiological status of toxoplasmosis in pregnant Korean women. Among 5,175 sera and 750 amniotic fluid samples obtained from pregnant women, 41 serum samples (0.79%) and 10 (1.33%) amniotic fluid samples tested positive for IgG antibodies by ELISA. Fifty one cases showing a score more than 0.25 on ELISA were tested for PCR reaction against the SAG1 gene. Only one case of the 51 ELISA positive cases exhibited a positive reaction on all tests. This case had a history of acute nephropyelitis during early pregnancy, but fortunately, had delivered a phenotypically healthy baby. In this study, the seroprevalence of toxoplasmosis in pregnant women was found to be comparatively low, consistent with previous reports from Korea. However our trials, performed with a variety of diagnostic tools, were considered to be useful for the precise diagnosis of congenital toxoplasmosis.     

Prevalence of Toxoplasma gondii Infection in Stray and Household Cats in Regions of Seoul, Korea

The principal objective of this study was to investigate the prevalence of toxoplasmosis in household and stray cats in Seoul, Republic of Korea. We collected blood samples from 72 stray and 80 household cats, and all samples were examined by ELISA and nested PCR. The overall positive rates of Toxoplasma gondii in stray cats were 38.9% (28/72), with 15.3% (11/72) in ELISA and 30.6% (22/72) in PCR. The positive rate in male stray cats was slightly higher than that of female stray cats. The highest positive rate of T. gondii infection was noted in Gangnam and Songpa populations in ELISA and in Gwangjin population in PCR. In household cats, however, we could not detect any specific antibodies or DNA for T. gondii. In conclusion, we recognized that the infection rate of toxoplasmosis in stray cats in Seoul was considerably high but household cats were free from infection.     

Seroprevalence of Toxoplasma gondii Infection among HIV/AIDS Patients in Eastern China

Toxoplasmosis, a neglected tropical disease caused by the protozoan parasite Toxoplasma gondii, occurs throughout the world. Human T. gondii infection is asymptomatic in 80% of the population; however, the infection is life-threatening and causes substantial neurologic damage in immunocompromised patients such as HIV-infected persons. The major purpose of this study was to investigate the seroprevalence of T. gondii infection in subjects infected with HIV/AIDS in eastern China. Our findings showed 9.7% prevalence of anti-T. gondii IgG antibody in HIV/AIDS patients, which was higher than in intravenous drug users (2.2%) and healthy controls (4.7%), while no significant difference was observed in the seroprevalence of anti-Toxoplasma IgM antibody among all participants (P>0.05). Among all HIV/AIDS patients, 15 men (7.7%) and 10 women (15.9%) were positive for anti-T. gondii IgG antibody; however, no significant difference was detected in the seroprevalence of anti-Toxoplasma IgG antibody between males and females. The frequency of anti-Toxoplasma IgG antibody was 8.0%, 13.2%, 5.5%, and 0% in patients with normal immune function (CD4⁺ T-lymphocyte count ≥500 cells/ml), immunocompromised patients (cell count ≥200 and <500 cells/ml), severely immunocompromised patients (cell count ≥50 and <200 cells/ml), and advanced AIDS patients, respectively (cell count <50 cells/ml), while only 3 immunocompromised patients were positive for anti-T. gondii IgM antibody. The results indicate a high seroprevalence of T. gondii infection in HIV/AIDS patients in eastern China, and a preventive therapy for toxoplasmosis may be given to HIV/AIDS patients based on CD4⁺ T lymphocyte count.     

Seroprevalence and Incidence of Toxoplasma gondii among Apparently Healthy and Visually or Hearing Disabled Children in Taiz City, Yemen

This cross sectional study was conducted in the city of Taiz, Yemen, during the period from August 2006 to August 2007 in order to investigate the seroprevalence and incidence of toxoplasmosis among apparently healthy children (AHC) and visually and/or hearing disabled children (DC). The seroprevalence was 16.0% among AHC compared to 32.5% among DC. The effect of gender was clear as the seroprevalence rate was significantly higher among females (18.3 and 43.8% for AHC and DC, respectively) than males (13.8 and 25% for AHC and DC, respectively). The seroprevalence was proportionally increased with the age, and the highest rates (20.9 and 53.0%) were reported among the oldest age group (> 10-14 years) for AHC and DC groups, respectively. The incidence rate was also higher (4.2%) in DC group compared to AHC group (2.4%) during 1 year period. These data indicate that the seroprevalence and incidence of toxoplasmosis are significantly higher in DC group than those of AHC group. We need to check further relationship between toxoplasmosis and visual and/or hearing disability.     

Seroprevalence of Toxoplasma gondii Infection in Police Dogs in Shenyang,Northeastern China

In recent years, worldwide surveys of Toxoplasma gondii infection in dogs have been reported. However, only limited surveys of T. gondii infection in police dogs have been available, including China. In the present study, we report the seroprevalence of T. gondii in police dogs in Shenyang, northeastern China. Sera from 291 police dogs were examined for T. gondii antibodies with the modified agglutination test (MAT), and 30.9% animals were tested seropositive. The results of the present study indicated a relatively high prevalence of T. gondii infection in police dogs in Shenyang, China.     

Seropositivity of Toxoplasmosis in Pregnant Women by ELISA at Minia University Hospital,Egypt

Toxoplasmosis is considered as an important risk factor for bad obstetric history (BOH) and one of the major causes of congenitally acquired infections. The present study aimed to estimate the seropositivity of T. gondii infection and associated risk factors among the attendees of high risk pregnancy and low risk antenatal care clinic of Minia Maternity and Pediatric University Hospital, Minia, Egypt. The study was carried out from April 2013 to April 2014 through 2 phases, the first phase was case-control study, and the second phase was follow-up with intervention. A total of 120 high risk pregnant and 120 normal pregnant females were submitted to clinical examinations, serological screening for anti-Toxoplasma IgM and IgG antibodies by ELISA, and an interview questionnaire. Seropositive cases were subjected to spiramycin course treatment. The results showed that the seroprevalence of toxoplasmosis in high-risk pregnancy group was 50.8%, which was significantly different from that of normal pregnancy group (P<0.05). Analysis of seropositive women in relation to BOH showed that abortion was the commonest form of the pregnancy wastage (56.5%). The high prevalence of T. gondii seropositive cases was observed in the age group of 21-30 years. Post-delivery adverse outcome was observed in 80.3% of high-risk pregnancy group compared to 20% of normal pregnancy group. There was a statistically significant relationship between seropositivity and living in rural area, low socioeconomic level, and undercooked meat consumption (P<0.05). Serological screening for anti-Toxoplasma antibodies should be routine tests especially among high-risk pregnant women.     

Clusters of Toxoplasmosis in Ganghwa-gun,Cheorwon-gun,and Goseong-gun,Korea

We find out the clusters with high toxoplasmosis risk to discuss the geographical pattern in Gyodong-myeon and Samsan-myeon of Ganghwa-gun, Cheorwon-gun, and Goseong-gun, Korea. Seroepidemiological data of toxoplasmosis surveyed using rapid diagnostic tests for the residents in the areas in 2019 were analyzed to detect clusters of the infection. The cluster was investigated using the SaTScan program which is based on Kulldorff’s scan statistic. The clusters were found with P-values in each region analyzed in the program, and the risk and patient incidence of specific areas can be examined by the values such as relative risk and log likelihood ratio. Jiseok-ri and Insa-ri were found to be a cluster in Gyodong-myeon and Seokmo-ri was the cluster in Samsan-myeon. Yangji-ri and Igil-ri were found to be a cluster in Cheorwon-gun and Madal-ri and Baebong-ri were the cluster in Goseong-gun. This findings can be used to monitor and prevent toxoplasmosis infections occurring in vulnerable areas.     

Seroprevalence of Encephalitozoon cuniculi and Toxoplasma gondii in domestic rabbits (Oryctolagus cuniculus) in China

The breeding of domestic rabbits (Oryctolagus cuniculus) for human consumption has a long tradition in China. Infections that can affect the production of meat or even be transmitted from animals to humans are important to monitor, especially for public health reasons as well as for their impact on animal health. Thus, a total of 1,132 domestic rabbit sera from 4 regions in China were collected for serological screening for Encephalitozoon cuniculi and for Toxoplasma gondii by ELISA and modified agglutination test (MAT), respectively. Antibodies to E. cuniculi were detected in 248/1,132 (21.9%) sera tested while antibodies against T. gondii revealed a seroprevalence of 51/1,132 (4.5%). We believe that the present results are of epidemiological implications and public health importance due to the acknowledged susceptibility of humans to E. cuniculi and T. gondii infections. Therefore, routine screening tests of domestic rabbits are proposed considering the zoonotic potential of these parasites.     

Seroepidemiological study of Toxoplasma gondii infection in the rural area Okcheon-gun, Korea

There have been some reports about the prevalence of anti-Toxoplasma gondii antibody among Koreans, and most of all data were taken from patients visiting hospitals. However, the epidemiological data of the community-based study in Korea are rare. This study was performed to evaluate the seroprevalence of toxoplasmosis among the inhabitants of the rural area Okcheon-gun, Korea. A total of 1,109 serum samples (499 males, 610 females) were examined for the IgG antibodies by ELISA. To set up the cut-off point for ELISA, we used a commercial latex agglutination (LA) kit. The sensitivity and specificity of ELISA against LA test were 89.5%, and 98.6% respectively. Among 1,109 sera, 6.9% showed seropositivity by ELISA. The positive rates of males and females were 6.0% and 7.2%, respectively. However, there were no significant differences between sexes. Comparing the age groups, the highest seropositive rate showed in the seventies or higher, and their rates had a tendency to increase with age (0.05 < p < 0.3). These results revealed that the seroprevalence of toxoplasmosis in rural inhabitants is similar to previous reports in Korea; however we need further investigation to clarify the prevalence of toxoplasmosis in the general population.     

Prevalence of Toxoplasma gondii in stray cats of Gyeonggi-do, Korea

Toxoplasma gondii is an obligate intracellular zoonotic protozoan with a worldwide distribution. It infects humans as well as a broad spectrum of vertebrate hosts. Cats and wild felidae play crucial roles in the epidemiology of toxoplasmosis. This study was performed to survey the prevalence of T. gondii infection among stray cats in the Gyeonggi-do, Republic of Korea. A total of 174 stray cat blood samples were collected from Gwacheon-si (n=20), Bucheon-si (82), and Yangju-si (72). Positive sera for T. gondii were identified in 14 samples (8.1%) exclusively via the latex agglutination test, 28 (16.1%) via ELISA, and 23 (13.2%) via PCR analysis. The overall infection rate of female stray cats (29.2%) presented as higher than that of male cats (24.0%). This study suggests that T. gondii is widespread in the stray cat population of Gyeonggi-do, Korea. It is urgently needed to control urban stray cat population and to reduce the risk of zoonotic transmission of toxoplasmosis to other animal hosts and humans.     

Seroprevalence of Trichinella sp. in Wild Boars (Sus scrofa) from Yanggu-gun,Gangwon-do,Korea

A total 7 outbreaks of trichinellosis have occurred in Korea, mostly as a result of consumption of raw wild boar (Sus scrofa) meat. Since only 1 serological survey on wild boars had yet been performed in Korea, the present study aimed to estimate the prevalence of trichinellosis in wild boars and some species of rodents by artificial digestion and serological examinations in Yanggu-gun, Gangwon-do, the endemic area of trichinellosis. Both the wild boar and rodent muscle samples revealed no Trichinella larvae by direct examination and artificial digestion method. However, serological examinations revealed that 4 wild boar sera samples out of 118 (3.4%) were positive to Trichinella antigen. Although the recovery of Trichinella larvae ended in a failure, it is proved for the first time that the sylvatic cycle of Trichinella has been maintained in wild boars of Gangwon-do, Korea.     

Seroprevalence of Encephalitozoon cuniculi in Pet Rabbits in Korea

Encephalitozoon cuniculi is a microsporidian parasite commonly found in rabbits that can infect humans, causing encephalitozoonosis. The prevalence of encephalitozoonosis is not well documented, even when many clinics suspect pet rabbits as being highly infected. This study investigated the seropositivity of E. cuniculi using ELISA. The examination of 186 rabbits using ELISA showed that 22.6% (42/186) were seropositive against E. cuniculi. In analysis with healthy status, all 42 seropositive sera were collected from clinically normal rabbits. Moreover, the gender and age of pet rabbits did not have anysignificant effect on E. cuniculi infection. To the best of our knowledge, this is the first report to describe the seroprevalence of E. cuniculi in pet rabbits and suggests that pet rabbits could act as an important reservoir of encephalitozoonosis for both pet animals and humans in Korea.     

A seroepidemiological survey for toxocariasis in apparently healthy residents in Gangwon-do,Korea

We investigated the sero-prevalence of toxocariasis among healthy Korean adults in 1999. A total of 314 sera from normal inhabitants in Whachon-gun, Gangwondo, Korea was examined for specific antibody levels against excretory-secretory products of second stage larvae of Toxocara (TES). The presence of cross-reactions with other helminthiases such as cysticercosis, paragonimiasis, sparganosis or clonorchiasis was also checked by specific IgG ELISA. Sera showing positive reaction against TES were also tested by IgG immunoblot and by IgE ELISA. Out of 314 subjects, 16 was found to be positive by TES IgG ELISA and immunoblot, among whom 12 were also positive by TES IgE ELISA. Among the 16 seropositive samples, two sera showed positive reaction against Paragonimus and sparganum antigen, respectively. These results inferred that cross-reactions were negligible between toxocariasis and other helminthiases. Toxocariasis seroprevalence among Korean rural adults was detected to be approximately 5%.