Kazuko Miyamoto1, Masashi Kirinoki2, Hajime Matsuda3, Naoko Hayashi2, Yuichi Chigusa2, Muth Sinuon4, Char Meng Chuor4, Viroj Kitikoon5. 1. School of Nursing, Dokkyo Medical University Tochigi, Japan. Electronic address: mkazu@dokkyomed.ac.jp. 2. Laboratory of Tropical Medicine and Parasitology, Dokkyo Medical University, Tochigi, Japan. 3. Center for International Cooperation, Dokkyo Medical University, Tochigi, Japan. 4. National Center for Malaria Control, Parasitology and Entomology (CNM), Ministry of Health (MOH), Cambodia. 5. Former Head, Department of Social and Environmental Medicine, Faculty of Tropical Medicine, Mahidol University, Thailand.
Abstract
BACKGROUND: Opisthorchiasis is endemic in Thailand and Lao People's Democratic Republic and constitutes a major public health problem throughout the Mekong Basin. Although Cambodia is located in the Mekong Basin, the status of O. viverrini infection in that country was not previously clarified. This research was conducted to document the extent and distribution of O. viverrini infection in Cambodia. METHODS: Surveillance was conducted in 55 villages in five Cambodian provinces. Research tools included stool examination using the Kato-Katz thick-smear technique, identification of intermediate hosts, and interviews covering factors related to O. viverrini infection. Some larvae and egg-positive stool samples were examined using PCR to detect O. viverrini DNA. RESULTS: A total of 16,082 stool samples from the 55 villages were examined, of which 1232 were egg positive. In 15 villages with egg-positive rates of greater than 10%, eggs were found in 998 of 3585 stool samples, for an egg-positive rate of 27.8%. PCR analysis showed that 30 of 33 samples were positive for O. viverrini DNA from five villages in Kampong Cham and Kampong Thom provinces. The first intermediate host Bithynia siamensis siamensis was identified in the target areas of Takaev, Kandal, and Kampong Cham provinces. Cercariae were identified morphologically as O. viverrini and some were confirmed using PCR. Metacercariae of O. viverrini were identified by morphologic observations, animal experiments, or PCR in six species of fish in the target areas. DISCUSSION AND CONCLUSIONS: Four Cambodian provinces were identified as endemic areas of O. viverrini infection. Careful planning is necessary for effective field surveys, because complex environmental factors might be involved in the distribution of O. viverrini infection-endemic areas in Cambodia. Many problems remain to be resolved regarding the status of O. viverrini infection in Cambodia, and a nationwide baseline survey is necessary.
BACKGROUND: Opisthorchiasis is endemic in Thailand and LaoPeople's Democratic Republic and constitutes a major public health problem throughout the Mekong Basin. Although Cambodia is located in the Mekong Basin, the status of O. viverriniinfection in that country was not previously clarified. This research was conducted to document the extent and distribution of O. viverriniinfection in Cambodia. METHODS: Surveillance was conducted in 55 villages in five Cambodian provinces. Research tools included stool examination using the Kato-Katz thick-smear technique, identification of intermediate hosts, and interviews covering factors related to O. viverriniinfection. Some larvae and egg-positive stool samples were examined using PCR to detect O. viverrini DNA. RESULTS: A total of 16,082 stool samples from the 55 villages were examined, of which 1232 were egg positive. In 15 villages with egg-positive rates of greater than 10%, eggs were found in 998 of 3585 stool samples, for an egg-positive rate of 27.8%. PCR analysis showed that 30 of 33 samples were positive for O. viverrini DNA from five villages in Kampong Cham and Kampong Thom provinces. The first intermediate host Bithynia siamensis siamensis was identified in the target areas of Takaev, Kandal, and Kampong Cham provinces. Cercariae were identified morphologically as O. viverrini and some were confirmed using PCR. Metacercariae of O. viverrini were identified by morphologic observations, animal experiments, or PCR in six species of fish in the target areas. DISCUSSION AND CONCLUSIONS: Four Cambodian provinces were identified as endemic areas of O. viverriniinfection. Careful planning is necessary for effective field surveys, because complex environmental factors might be involved in the distribution of O. viverriniinfection-endemic areas in Cambodia. Many problems remain to be resolved regarding the status of O. viverriniinfection in Cambodia, and a nationwide baseline survey is necessary.
Authors: Catrin E Moore; Phot Nget; Mao Saroeun; Suy Kuong; Seng Chanthou; Varun Kumar; Rachel Bousfield; Johanna Nader; J Wendi Bailey; Nicholas J Beeching; Nicholas P Day; Christopher M Parry Journal: PLoS One Date: 2015-05-07 Impact factor: 3.240