Clonorchiasis, caused by direct contact with Clonorchis sinensis worms and their excretory-secretory products (ESPs), is associated with chronic inflammation, malignant changes in bile ducts, and even cholangiocarcinogenesis. Our previous report revealed that intracellular free radicals enzymatically generated by C. sinensis ESPs cause NF-κB-mediated inflammation in human cholangiocarcinoma cells (HuCCT1). Therefore, the present study was conducted to examine the role of upstream Toll-like receptors (TLRs) on the initial host innate immune responses to infection. We found that treatment of HuCCT1 cells with native ESPs induced changes in TLR mRNA levels in a time-dependent manner, concomitant with the generation of free radicals. ESP-mediated free radical generation was markedly attenuated by preincubation of the cells with TLR1-4-neutralizing antibodies, indicating that at least TLR1 through 4 participate in stimulation of the host innate immune responses. These findings indicate that free radicals triggered by ESPs are critically involved in TLR signal transduction. Continuous signaling by this pathway may function in initiating C. sinensis infection-associated inflammation cascades, a detrimental event leading to progression to more severe hepatobiliary diseases.
Antibodies ; Bile Ducts ; Cholangiocarcinoma* ; Clonorchiasis ; Clonorchis sinensis* ; Free Radicals ; Humans ; Immunity, Innate ; Inflammation ; RNA, Messenger ; Signal Transduction ; Toll-Like Receptors

Clonorchiasis, caused by direct contact with Clonorchis sinensis worms and their excretory-secretory products (ESPs), is associated with chronic inflammation, malignant changes in bile ducts, and even cholangiocarcinogenesis. Our previous report revealed that intracellular free radicals enzymatically generated by C. sinensis ESPs cause NF-κB-mediated inflammation in human cholangiocarcinoma cells (HuCCT1). Therefore, the present study was conducted to examine the role of upstream Toll-like receptors (TLRs) on the initial host innate immune responses to infection. We found that treatment of HuCCT1 cells with native ESPs induced changes in TLR mRNA levels in a time-dependent manner, concomitant with the generation of free radicals. ESP-mediated free radical generation was markedly attenuated by preincubation of the cells with TLR1-4-neutralizing antibodies, indicating that at least TLR1 through 4 participate in stimulation of the host innate immune responses. These findings indicate that free radicals triggered by ESPs are critically involved in TLR signal transduction. Continuous signaling by this pathway may function in initiating C. sinensis infection-associated inflammation cascades, a detrimental event leading to progression to more severe hepatobiliary diseases.
Antibodies ; Bile Ducts ; Cholangiocarcinoma* ; Clonorchiasis ; Clonorchis sinensis* ; Free Radicals ; Humans ; Immunity, Innate ; Inflammation ; RNA, Messenger ; Signal Transduction ; Toll-Like Receptors

Plasmodium vivax is more challenging to control and eliminate than P. falciparum due to its more asymptomatic infections with low parasite densities making diagnosis more difficult, in addition to its unique biological characteristics. The potential re-introduction of incidence cases, either through borders or via human migrations, is another major hurdle to sustained control and elimination. The Republic of Korea has experienced re-emergence of vivax malaria in 1993 but is one of the 32 malaria-eliminating countries to-date. Despite achieving successful nationwide control and elimination of vivax malaria, the evolutionary characteristics of vivax malaria isolates in the Republic of Korea have not been fully understood. In this review, we present an overview of the genetic variability of such isolates to increase understanding of the epidemiology, diversity, and dynamics of vivax populations in the Republic of Korea.
Asymptomatic Infections ; Diagnosis ; Epidemiology ; Genetic Variation ; Human Migration ; Incidence ; Korea ; Malaria ; Malaria, Vivax ; Parasites ; Plasmodium vivax ; Plasmodium ; Population Characteristics ; Republic of Korea

Malaria remains one of the leading health burdens in the developing world, especially in several sub-Saharan Africa countries; and Uganda has some of the highest recorded measures of malaria transmission intensity in the world. It is evident that the prevalence of malaria infection, the incidence of disease, and mortality from severe malaria remain very high in Uganda. Although the recent stable political and economic situation in the last few decades in Uganda supported for a fairly good appreciation of malaria control, the declines in infection, morbidity, and mortality are not sufficient to interrupt transmission and this country is among the top 4 countries with cases of malaria, especially among children under 5 years of age. In fact, Uganda, which is endemic in over 95% of the country, is a representative of challenges facing malaria control in Africa. In this study, we evaluated an active case detection program in 6 randomly selected villages, Uganda. This program covered a potential target population of 5,017 individuals. Our team screened 12,257 samples of malaria by active case detection, every 4 months, from February 2015 to January 2017 in the 6 villages (a total of 6 times). This study assessed the perceptions and practices on malaria control in Kiyuni Parish of Kyankwanzi district, Uganda. Our study presents that the incidence of malaria is sustained high despite efforts to scale-up and improve the use of LLINs and access to ACDs, based on the average incidence confirmed by RDTs.
Africa ; Africa South of the Sahara ; Child ; Health Services Needs and Demand ; Humans ; Incidence ; Malaria ; Mortality ; Prevalence ; Uganda

Incidence of tsutsugamushi disease (scrub typhus) caused by Orientia tsutsugamushi, is steadily increasing. It is a mite-borne disease transmitted by chigger mites. In this study, the chigger mites were collected from field small mammals in Hwaseong-si (city), Gyeonggi-do (province), Korea, 2019 and 2020. The field small mammals captured were 56 Apodemus agrarius (94.9%) and 3 Crocidura lasiura (5.1%). A total of 7,531 chigger mites were collected from the captured small mammals. Using PCR test, 153 chigger mite pools were examined and 17 pools were reported positive for O. tsutsugamushi. The O. tsutsugamushi were identified to 5 strains; Jecheon strain was most prevalent, followed by Boryong strain. The other strains were OI011, Taguchi, and Shimokoshi. Collectively, these results provide essential regional information on mite-borne tsutsugamushi disease in the Hwaseong-si, and further contribute to bring awareness and rapid diagnosis for the tsutsugamushi disease.

Incidence of tsutsugamushi disease (scrub typhus) caused by Orientia tsutsugamushi, is steadily increasing. It is a mite-borne disease transmitted by chigger mites. In this study, the chigger mites were collected from field small mammals in Hwaseong-si (city), Gyeonggi-do (province), Korea, 2019 and 2020. The field small mammals captured were 56 Apodemus agrarius (94.9%) and 3 Crocidura lasiura (5.1%). A total of 7,531 chigger mites were collected from the captured small mammals. Using PCR test, 153 chigger mite pools were examined and 17 pools were reported positive for O. tsutsugamushi. The O. tsutsugamushi were identified to 5 strains; Jecheon strain was most prevalent, followed by Boryong strain. The other strains were OI011, Taguchi, and Shimokoshi. Collectively, these results provide essential regional information on mite-borne tsutsugamushi disease in the Hwaseong-si, and further contribute to bring awareness and rapid diagnosis for the tsutsugamushi disease.

In 2005, we reported the infection status of 438 stray cats with various species of intestinal helminths, including nematodes (4 species), trematodes (23 species), and cestodes (5 species) in the Republic of Korea. However, morphologic details of each helminth species have not been provided. In the present study, we intended to describe morphologic details of 13 trematode species which were either new fauna of cats (10 species) or new fauna of not only cats but also all animal hosts (3 species). The worms were fixed in 10% neutral buffered formalin under a cover slip pressure, stained with Semichon's acetocarmine, and then observed using a light microscope equipped with a micrometer. The 13 subjected species included members of the Heterophyidae (Stellantchasmus falcatus, Stictodora fuscata, Stictodora lari, Centrocestus armatus, Procerovum varium, and Cryptocotyle concava), Echinostomatidae (Echinostoma hortense, Echinostoma revolutum, Echinochasmus japonicus, and Stephanoprora sp.), Diplostomidae (Neodiplostomum seoulense), Plagiorchiidae (Plagiorchis muris), and Dicrocoeliidae (Eurytrema pancreaticum). By the present study, Cryptocotyle sp. and Neodiplostomum sp. recored in our previous study were identified as C. concava and N. seoulense, respectively. Three species, P. varium, C. concava, and Stephanoprora sp., are new trematode fauna in Korea.
Animals ; Cat Diseases/*epidemiology/parasitology ; Cats ; Helminthiasis/epidemiology/parasitology ; Intestinal Diseases/epidemiology/parasitology/*veterinary ; Intestine, Small/*parasitology ; Microscopy ; Parasitology ; Republic of Korea/epidemiology ; Trematoda/anatomy & histology/classification/*isolation & purification ; Trematode Infections/epidemiology/parasitology/*veterinary

This study was conducted to investigate the prevalence of intestinal parasites among students from Goseong-gun, Gangwon-do and Hadong-gun, Gyeongsangnam-do as typical low and high endemic counties. From May to July 2017, a total of 2,033 fecal samples were collected at 27 elementary, 10 junior high, and 8 high schools from 2 counties and examined by the Kato-Katz technique for egg-positive surveys (Collection rate: 37.02% [2,033/5,492]). Of the participants examined, 13 (0.64%) were found to harbor eggs of 3 parasitic species, Trichuris trichiura, Clonorchis sinensis and Metagonimus yokogawai. Based on the regional distribution, the egg-positive rate in Goseong-gun was 0% (0/550) and that in Hadong-gun was 0.88% (13/1,483). The positive rates for C. sinensis, M. yokogawai, and T. trichiura in Hadong-gun were 0.20% (3/1,483), 0.61% (9/1,483), and 0.07% (1/1,483), respectively. The present survey showed that the prevalence of parasitic infection among students is currently very low even in remote, previously endemic areas, and the present status of parasitic diseases can be summarized as some transmission of fish/food-borne trematodes. Thus, it is necessary to carefully, continuously monitor the trematode infection status, particularly of C. sinensis and M. yokogawai.
Clonorchis sinensis ; Eggs ; Gangwon-do ; Gyeongsangnam-do ; Helminths ; Heterophyidae ; Humans ; Korea ; Ovum ; Parasites ; Parasitic Diseases ; Prevalence ; Trematode Infections ; Trichuris

Korea is successfully controlled intestinal parasitic infections owing to economic development and high health consciousness. The Division of Vectors and Parasitic Diseases (formerly the Division of Malaria and Parasitology) is in the Center for Laboratory Control of Infectious Diseases of the Korea Centers for Disease Control and Prevention. It has been the governmental agency responsible for controlling and leading scientific research on parasitic diseases. The Division of Vectors and Parasitic Diseases has conducted and funded basic research and disseminated the research results to various medical fields, ultimately promoting public health in Korea. Among the noteworthy achievements of this division are the national surveillance of healthcare-associated parasitic infections, prevention and control for parasitic infections, and the elimination of lymphatic filariasis from Korea. On a broader scale, the division's research programs and academic supports were influential in preventing and treating infectious parasitic diseases through public policies and laws. In this review, we summarize the past and present role of the Division of Vectors and Parasitic Diseases in preventing and treating infectious parasitic diseases in Korea.
Centers for Disease Control and Prevention (U.S.) ; Communicable Disease Control ; Communicable Diseases ; Consciousness ; Economic Development ; Elephantiasis, Filarial ; Financial Management ; Jurisprudence ; Korea ; Malaria ; Parasitic Diseases ; Public Health ; Public Policy

Entamoeba histolytica, which causes amoebic colitis and occasionally liver abscess in humans, is able to induce host cell death. However, signaling mechanisms of colon cell death induced by E. histolytica are not fully elucidated. In this study, we investigated the signaling role of NOX in cell death of HT29 colonic epithelial cells induced by E. histolytica. Incubation of HT29 cells with amoebic trophozoites resulted in DNA fragmentation that is a hallmark of apoptotic cell death. In addition, E. histolytica generate intracellular reactive oxygen species (ROS) in a contact-dependent manner. Inhibition of intracellular ROS level with treatment with DPI, an inhibitor of NADPH oxidases (NOXs), decreased Entamoeba-induced ROS generation and cell death in HT29 cells. However, pan-caspase inhibitor did not affect E. histolytica-induced HT29 cell death. In HT29 cells, catalytic subunit NOX1 and regulatory subunit Rac1 for NOX1 activation were highly expressed. We next investigated whether NADPH oxidase 1 (NOX1)-derived ROS is closely associated with HT29 cell death induced by E. histolytica. Suppression of Rac1 by siRNA significantly inhibited Entamoeba-induced cell death. Moreover, knockdown of NOX1 by siRNA, effectively inhibited E. histolytica-triggered DNA fragmentation in HT29 cells. These results suggest that NOX1-derived ROS is required for apoptotic cell death in HT29 colon epithelial cells induced by E. histolytica.
*Cell Death ; Cell Line ; Entamoeba histolytica/*pathogenicity ; Epithelial Cells/metabolism/*parasitology/*physiology ; *Host-Pathogen Interactions ; Humans ; NADPH Oxidase/*metabolism ; Reactive Oxygen Species/metabolism/*toxicity ; Signal Transduction