An Outbreak of Trichinosis with Molecular Identification of Trichinella sp. in Vietnam

The 5th outbreak of trichinosis occurred in a mountainous area of North Vietnam in 2012, involving 24 patients among 27 people who consumed raw pork together. Six of these patients visited several hospitals in Hanoi for treatment. Similar clinical symptoms appeared in these patients within 5-8 days after eating infected raw pork, which consisted of fever, muscle pain, difficult moving, edema, difficult swallowing, and difficult breathing. ELISA revealed all (6/6) positive reactions against Trichinella spiralis antigen and all cases showed positive biopsy results for Trichinella sp. larvae in the muscle. The larvae detected in the patients were identified as T. spiralis (Vietnamese strain) by the molecular analysis of the mitochondrial cytochrome c oxidase subunit III (cox3) gene.     

Trichinosis Caused by Ingestion of Raw Soft-Shelled Turtle Meat in Korea

Reptiles, unlike mammals, have been considered to be unsuitable hosts of Trichinella spp., though larvae have been detected in their muscles and human outbreaks related to their consumption have, in fact, occurred. Herein we report 2 Korean cases of trichinosis, possibly transmitted via consumption of reptile meat. Both patients suffered from myalgia, headache, and facial edema. Laboratory examinations revealed leukocytosis with eosinophilia (54% and 39%, respectively) and elevated creatinine phosphokinase. ELISA was performed under the suspicion of trichinosis, showing positivity at the 29th and 60th day post-infection. Since they had consumed raw soft-shelled turtle meat, turtle was strongly suggested to be an infection source of trichinosis in Korea next to the wild boar and badger.     

Seroprevalence of antibodies against Anisakis simplex larvae among health-examined residents in three hospitals of southern parts of Korea

The present study was performed to estimate the seroprevalence of larval Anisakis simplex infection among the residents health-examined in 3 hospitals in southern parts of Korea. A total of 498 serum samples (1 serum per person) were collected in 3 hospitals in Busan Metropolitan city, Masan city, and Geoje city in Gyeongsangnam-do (Province) and were examined by IgE-ELISA and IgE-western blotting with larval A. simplex crude extract and excretory-secretory products (ESP). The prevalence of antibody positivity was 5.0% and 6.6% with ELISA against crude extracts and ESP, respectively. It was also revealed that infection occurred throughout all age groups and higher in females than in males. A specific protein band of 130 kDa was detected from 10 patients with western blot analysis against crude extract and ESP among those who showed positive results by ELISA. Our study showed for the first time the seroprevalence of anisakiasis in Korea. The allergen of 130 kDa can be a candidate for serologic diagnosis of anisakiasis.     

A Hospital-Based Serological Survey of Cryptosporidiosis in the Republic of Korea

The seroprevalence of cryptosporidiosis was examined using patients'' sera collected from hospitals located in 4 different areas of the Republic of Korea. ELISA was used to measure antibody titers against Cryptosporidium parvum antigens from a total of 2,394 serum samples, which were collected randomly from patients in local hospitals; 1) Chungbuk National University Hospital, 2) Konkuk University Hospital, 3) local hospitals in Chuncheon, Gangwon-do (province), 4) Jeonnam National University Hospital, from 2002 through 2003. Of the 2,394 samples assayed, 34%, 26%, and 56% were positive for C. parvum-specific IgG, IgM, and IgA antibodies, respectively. Positive IgG titers were most common in sera from Jeonnam National University Hospital, Gwangju, Jeollanam-do, and positive IgM titers were most common in sera from Chungbuk National University Hospital, Cheongju, Chuncheongbuk-do. The seropositivity was positively correlated with age for both the IgG and IgA antibodies but was negatively correlated with age for the IgM antibodies. Western blotting revealed that 92%, 83%, and 77% of sera positive for IgG, IgM, and IgA ELISA reacted with 27-kDa antigens, respectively. These results suggested that infection with Cryptosporidium in hospital patients occurs more commonly than previously reported in the Republic of Korea.     

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.     

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.     

Therapeutic Potential of Myrrh and Ivermectin against Experimental Trichinella spiralis Infection in Mice

Trichinosis is a parasitic zoonosis caused by the nematode Trichinella spiralis. Anthelmintics are used to eliminate intestinal adults as well as tissue-migrating and encysted larvae. This study aimed to investigate the effects of ivermectin and myrrh obtained from the aloe-gum resin of Commiphora molmol on experimental trichinosis. Ninety albino mice were orally infected with 300 T. spiralis larvae. Drugs were tested against adult worms at day 0 and day 5 and against encysted larvae on day 15 and day 35 post-infection (PI). Mature worms and encysted larvae were counted in addition to histopathological examination of muscle specimens. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), total protein, albumin, globulin, urea, and creatinine values were estimated. Significant reductions in mean worm numbers were detected in ivermectin treated mice at day 0 and day 5 PI achieving efficacies of 98.5% and 80.0%, while efficacies of myrrh in treated mice were 80.7% and 51.5%, respectively. At days 15 and 35 post-infection, ivermectin induced significant reduction in encysted larval counts achieving efficacies of 76.5% and 54.0%, respectively, while myrrh efficacies were 76.6% and 35.0%, respectively. AST, ALT, urea, and creatinine levels were reduced, while total proteins were increased in response to both treatments compared to their values in the infected non-treated mice. Ivermectin use for controlling T. spiralis could be continued. Myrrh was effective and could be a promising drug against the Egyptian strains of T. spiralis with results nearly comparable to ivermectin.     

Extraintestinal Migration of Centrorhynchus sp. (Acanthocephala: Centrorhynchidae) in Experimentally Infected Rats

Reptiles were known to serve as paratenic hosts for Centrorhynchus (Acanthocephala: Centrorhynchidae) in Korea, but the infection course in experimental animals was not elucidated yet. In this study, the tiger keelback snakes (Rhabdophis tigrinus) were collected and digested with artificial pepsin solution, and the larvae of Centrorhynchus were recovered from them. Then, the collected larvae were orally infected to rats for developmental observations. In rats, all the larvae were observed outside the intestine on day 3 post-infection (PI), including the mesentery and abdominal muscles. As for the development in rats, the ovary of Centrorhynchus sp. was observed at day 15 PI, and the cement glands were 3 in number. Based on the morphological characteristics, including the arrangement of proboscis hooks, these larvae proved to be a species of Centrorhynchus, and more studies were needed for species identification.     

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%.     

Mucosal Immune Responses of Mice Experimentally Infected with Pygidiopsis summa (Trematoda: Heterophyidae)

Mucosal immune responses against Pygidiopsis summa (Trematoda: Heterophyidae) infection were studied in ICR mice. Experimental groups consisted of group 1 (uninfected controls), group 2 (infection with 200 metacercariae), and group 3 (immunosuppression with Depo-Medrol and infection with 200 metacercariae). Worms were recovered in the small intestine at days 1, 3, 5, and 7 post-infection (PI). Intestinal intraepithelial lymphocytes (IEL), mast cells, and goblet cells were counted in intestinal tissue sections stained with Giemsa, astra-blue, and periodic acid-Schiff, respectively. Mucosal IgA levels were measured by ELISA. Expulsion of P. summa from the mouse intestine began to occur from days 3-5 PI which sustained until day 7 PI. The worm expulsion was positively correlated with proliferation of IEL, mast cells, goblet cells, and increase of IgA, although in the case of mast cells significant increase was seen only at day 7 PI. Immunosuppression suppressed all these immune effectors and inhibited worm reduction in the intestine until day 7 PI. The results suggested that various immune effectors which include IEL, goblet cells, mast cells, and IgA play roles in regulating the intestinal mucosal immunity of ICR mice against P. summa infection.     

Antigenemia and Specific IgM and IgG Antibody Responses in Rabbits Infected with Toxoplasma gondii

In this experiment, the correlation between antigenemia and specific antibody responses in Toxoplasma gondii-infected rabbits was assessed. We injected 1,000 T. gondii tachyzoites (RH) subcutaneously into 5 rabbits. Parasitemia, circulating antigens, and IgM and IgG antibody titers in blood were tested by ELISA and immunoblot. For detection of parasitemia, mice were injected with blood from rabbits infected with T. gondii and mice died between days 2 and 10 post-infection (PI). Circulating antigens were detected early on day 2 PI, and the titers increased from day 4 PI and peaked on day 12 PI. Anti-Toxoplasma IgM antibody titers increased on day 6 PI and peaked on days 14-16 PI. IgG was detected from day 10 PI, and the titers increased continuously during the experiment. The antigenic protein patterns differed during the infection period, and the number of bands increased with ongoing infection by the immunoblot analysis. These result indicated that Toxoplasma circulating antigens during acute toxoplasmosis are closely related to the presence of parasites in blood. Also, the circulating antigen levels were closely correlated with IgM titers, but not with IgG titers. Therefore, co-detection of circulating antigens with IgM antibodies may improve the reliability of the diagnosis of acute toxoplasmosis.     

Serodiagnosis of Echinococcosis by ELISA Using Cystic Fluid from Uzbekistan Sheep

According to increase of travel, the cases of imported echinococcosis have been increasing in Korea. The present study was undertaken to develop a serodiagnostic system for echinococcosis in Korea. For diagnosis of echinococcosis, the fluid of Echinococcus granulosus hydatid cysts was collected from naturally infected sheep in Uzbekistan. Also serum samples of infected patients who were surgically confirmed were collected in a hospital in Tashkent, Uzbekistan. According to the absorbance of 59 echinococcosis positive and 39 negative control serum samples, the cut-off value was determined as 0.27. The sensitivity and specificity of ELISA with hydatid fluid antigen were 91.5% and 96%, respectively. The antigen cross-reacted with the serum of some cysticercosis or clonorchiasis patients. However, immunoblot analysis on the cystic fluid recognized antigenic proteins of 7-, 16-, and 24-kDa bands in their dominant protein quantity and strong blotting reactivity. In conclusion, the present ELISA system using hydatid cyst fluid antigen from Uzbekistan sheep is sensitive and specific for diagnosis of echinococcosis cases.     

Prevalence of Toxoplasma gondii Infection in Household Cats in Korea and Risk Factors

Several epidemiological surveys have reported the prevalence of Toxoplasma gondii infection in stray cats in Korea, but little information is available on T. gondii infection in household cats. The aim of the present study was to assess the prevalence and risk factors of T. gondii infection among household cats reared in Seoul, Korea. A total of 474 blood samples were collected from clinically healthy household cats. All samples were tested using ELISA and PCR. The risk factor analysis was based on a questionnaire filled out by the owners. The overall positive rate for ELISA and PCR assays was 2.2% (10/437) and 2.1% (10/474), respectively. With regard to the origin of cats, the positive rates among cats adopted from the animal shelter and veterinary clinic for stray cats were significantly different (P<0.05). Our study demonstrated that the positive rate of T. gondii infection in household cats was low and that this low prevalence was assumed to be associated with keeping the cats indoors and restriction of eating raw food and uncooked meat. Therefore, we suggest that the owners check the origin of the cats prior to adoption to prevent infection of other animals, including humans.     

Growth and development of Gymnophalloides seoi in immunocompetent and immunosuppressed C3H/HeN mice

The growth and development of Gymnophalloides seoi were studied in C3H/HeN mice and effects of immunosuppression of the host on the worm development were observed. Two hundred metacercariae of G. seoi were orally administered to each mouse, and worms were recovered on days 1, 3, 5, 7, 14 and 21 post-infection (PI). The worm recovery rate was significantly higher in immunosuppressed (ImSP) mice than in immunocompetent (ImCT) mice except on days 1 and 3 PI. The worms attained sexual maturity by day 3 PI with eggs in the uterus, and worm dimensions and the number of uterine eggs continuously increased until day 14 PI in ImSP mice. Worms recovered from ImSP mice were significantly larger in size than those from ImCT mice on days 1 and 3 PI, and the number of uterine eggs was significantly larger in ImSP mice on days 5 and 7 PI. Genital organs such as the ovary, testes, and vitellaria, that were already developed in the metacercarial stage, grew a little in size until day 14 PI. The results show that the C3H/HeN mouse is, though not excellent, a suitable laboratory host for G. seoi.     

An Outbreak of Trichinellosis by Consumption of Raw Soft-Shelled Turtle Meat in Korea

Trichinellosis transmission to humans via the consumption of reptile meat is rare worldwide. In Korea, however, 2 such outbreaks, possibly via consumption of soft-shelled turtle meat, have occurred in 2 successive years. In 17 August 2014, 6 patients were admitted to Wonju Severance Christian Hospital complaining of myalgia, fever, and headache. Eosinophilia was the indication of the initial laboratory results, and they were eventually diagnosed as trichinellosis by ELISA. All of the patients worked at the same company and had eaten raw soft-shelled turtle meat at a company dinner 10 days prior to their admission. They were treated with albendazole for 2 weeks, upon which all of their symptoms disappeared. This is the 8th report on human trichinellosis in Korea, and the second implicating raw soft-shelled turtle meat.     

Detection of vivax malaria sporozoites naturally infected in Anopheline mosquitoes from endemic areas of northern parts of Gyeonggi-do (Province) in Korea

We investigated population densities of mosquitoes infected with sporozoites in three highly epidemic areas of Josan-ri and Jangpa-ri (Paju City) and Dongjung-ri (Yeoncheon County) in Korea. Anopheline mosquitoes were collected from both indoors and outdoors by human baiting collection method during the period of the first week of June to the second week of September 1999. Total 13,296 female mosquitoes were collected and 8,650 (65.1%) were Anophelines. Thirty seven percent (3,199) of the Anopheline mosquitoes were captured outdoors and 63.9% (5,531) indoors. Employing a sandwich enzyme-linked immunosorbent assay (ELISA), we analyzed a total of 7,820 Anopheline mosquitoes and found that 7 Anopheline mosquitoes were infected with sporozoites. The positive rate in Josan-ri was 0.14% (5/3,500) and 0.15% (2/1,370) in Jangpa-ri. The total positive rate in all three surveyed areas was 0.09% (7/7,820). The mosquitoes infected with the sporozoites were detected on June 28th (n = 2), July 5th (n = 1), July 19th (n = 1), August 9th (n = 1), September 6th (n = 1), and the last one on September 13th (n = 1). They were all classified as Anopheles sinensis, which showed positive reaction in ELISA test. Therefore it might be concluded that Anopheles sinensis plays an important role in re-emerging malaria transmission in Korea.     

Serological Detection of Borrelia burgdorferi among Horses in Korea

Lyme disease is a tick-borne zoonotic infectious disease caused by Borrelia burgdorferi. The present study assessed the infection status of B. burgdorferi among horses reared in Korea using ELISA and PCR. Between 2009 and 2013, blood samples were collected from 727 horses throughout Korea. Data for each animal including age, gender, breed, and region of sample collection were used for epidemiological analysis. Overall, 38 (5.2%; true prevalence: 5.5%) of 727 horses were seropositive by ELISA. There were statistically significant differences according to breed and region (P<0.001) whose differences might be attributed to the ecology of vector ticks and climate conditions. Using 2 nested PCR, none of the samples tested positive for B. burgdorferi. Thus, a positive ELISA result can indicate only that the tested horse was previously exposed to B. burgdorferi, with no certainty over the time of exposure. Since global warming is likely to increase the abundance of ticks in Korea, continuous monitoring of tick-borne diseases in Korean horses is needed.     

Enzyme-linked immunosorbent assay for detection of Trichinella spiralis antibodies and the surveillance of selected pig breeding farms in the Republic of Korea

Trichinellosis is a parasitic zoonosis of public health importance. It is caused by Trichinella spiralis which has a wide host range including humans. In the present communication, the ELISA technique was employed on a total of 803 blood samples from 7 selected pig breeding farms in 1996 for diagnosis and surveillance of trichinellosis. Out of the entire 803 samples, nine were found to be suspected while one was positive by ELISA. But western blot analyses employed for further confirmation have shown that all of 10 samples did not react to larval excretory-secretory product antigens. These results indicate that pig breeding farms included in the present study are free from trichinellosis. However, it does not mean Korea is free from trichinellosis since human trichinellosis has recently been reported. The necessity of continued surveillance for trichinellosis in both pigs and wild animals was discussed.     

A case of acute gastric anisakiasis provoking severe clinical problems by multiple infection

Acute gastric anisakiasis with multiple anisakid larvae infection is reported. A 68-year-old woman residing in Busan, Korea, had epigastric pain with severe vomiting about 5 hours after eating raw anchovies. Four nematode larvae penetrating the gastric mucosae in the great curvature of the middle body and fundus were found and removed during gastro-endoscopic examination. Another one thread-like moving larva was found in the great curvature of upper body on the following day. On the basis of their morphology, the worms were identified as the 3rd stage larvae of Anisakis simplex. This case is acute gastric anisakiasis provoking severe clinical problems by the multiple infection and the greatest number of anisakid larvae found in a patient in Korea.     

Antibody levels in goats fed Toxoplasma gondii oocysts

Outbred goats were fed 10(5) Toxoplasma gondii oocysts and were monitored twice weekly for 8 wk for rectal temperature, clinical signs, parasitemia, and antibody levels by indirect fluorescence antibody test (IFAT), latex agglutination test (LAT), and indirect enzyme-linked immunosorbent assay (ELISA). After 8 wk, all goats were killed, and samples of heart, skeletal muscle, brain, lymph nodes, kidneys, and liver were bioassayed in mice. Anorexia, fever, and lethargy were observed from day 3 to day 7 postinfection (PI). Parasitemia was detected by bioassay in 50% of infected goats from day 7 to day 14 PI. Viable T. gondii organisms were isolated from all infected goats. Antibodies to T. gondii were detected in some animals on day 10 PI by IFAT and LAT and on day 14 PI by ELISA. The infected goats were seropositive on day 17 PI.