The alveolate protozoan parasite Perkinsus olseni infects a range of marine bivalves inhabiting tidal flats and shallow subtidal zones, causing considerable damage to shellfish industries. Infection by P. olseni is typically assessed using Ray’s fluid thioglycollate medium (RFTM) assay, with gill tissue often employed as a diagnostic proxy for whole-body infection. However, the diagnostic reliability of gill-based assays across diverse ecological settings—particularly under low-infection conditions—remains uncertain. In this study, we investigated tissue-specific distribution and the diagnostic performance of the RFTM assay in detecting P. olseni in Manila clams (Ruditapes philippinarum) collected from 6 tidal flats along Korea’s west and south coast. The assay was applied to 6 different tissues, including gills and visceral mass. Infection prevalence reached 100% at most sites, except at Padori (90%). Whole-body infection intensity ranged from 0.1×104 to 3.7×106 cells per gram of tissue. The visceral mass consistently harbored the largest proportion of parasites (27.8%–49.0%), followed by the mantle (17.4%–30.6%) and gills (19.4%–25.2%). Gill infection levels correlated strongly with whole-body infection intensity (r²=0.6–0.95), supporting their diagnostic value in high-infection areas. However, at Padori—where infection levels were lowest—the efficacy of the gill assay dropped to 56%, resulting in a 44% false negative rate. These results underscore the limitations of relying solely on gill tissue in low-infection environments and highlight the need for a context-dependent diagnostic approach. A dual-tissue strategy incorporating both gill and whole-body samples is recommended to improve diagnostic accuracy in P. olseni surveillance of Manila clam populations.
Citations
Citations to this article as recorded by
First report of mass mortality event caused by Eomarteilia granula in Manila clam Ruditapes philippinarum reared in subtidal and bottom cages on the south coast of Korea Hye-Mi Lee, Hyun-Sil Kang, Nobuhisa Kajino, Hyun-Ki Hong, Young-Ghan Cho, Kwang-Sik Choi Estuarine, Coastal and Shelf Science.2025; 323: 109408. CrossRef
Seungman Cha, Sung-Tae Hong, Jin-Su Lee, Hoo Gn Jeong, In-Sun Kwon, Abd Al Wahab Saed, Mousab Siddig Elhag, Hassan Ahmed Hassan Ahmed Ismail, Mutamad Amin, Young-Ha Lee
Korean J Parasitol 2020;58(4):421-430. Published online August 25, 2020
This study aimed to investigate whether mass drug administration (MDA) intervention has an equivalent effect on reducing the prevalence and intensity of Schistosoma haematobium infection regardless of the baseline values. A repeated cross-sectional survey was performed targeting students of 12 primary schools in Al Jabalain and El Salam districts of White Nile State, Sudan, at both 1 week before and 8 months after the MDA. Prior to the baseline survey, school-aged children in Al Jabalain had received MDA interventions twice in 4 years, while those in El Salam had not. The baseline prevalence was 9.1% in Al Jabalain and 35.2% in El Salam, which were reduced to 1.8% and 5.5% at 8 months after the MDA, respectively. The corresponding reduction rates were 80.3% and 84.4%, not significant difference between both districts. However, changes in the geometric mean intensity (GMI) of egg counts were significantly different between both districts. The baseline GMIs were 14.5 eggs per 10 ml of urine (EP10) in Al Jabalain and 18.5 EP10 in El Salam, which were reduced to 7.1 and 11.2 EP10 after treatment, respectively. The corresponding reduction rates were 51.0% and 39.5%. In conclusion, MDA interventions were found to bring about similar relative reduction in prevalence regardless of the baseline value; however, the relative reduction in infection intensity was more salient in the district with a low baseline value for both prevalence and intensity. This clearly points to the importance of repeated MDA interventions in endemic areas, which will eventually contribute to schistosomiasis elimination.
Citations
Citations to this article as recorded by
Prevalence and Risk Factors of Schistosomiasis in Sudan: A Systematic Review and Meta-Analysis Yousef Alsaafin, Ayman Omer, Osama Felemban, Sarra Modawi, Maydolin Ibrahim, Abdullah Mohammed, Ammar Elfaki, Ahmed Abushara, Maryam A SalahEldin Cureus.2024;[Epub] CrossRef
Programmatic Implications for Schistosomiasis Elimination Based on Community-Based Survey in the Blue Nile, North Kordofan, and Sennar States, Sudan Hassan Ahmed Hassan Ahmed Ismail, Seungman Cha, Yan Jin, Sung-Tae Hong Life.2023; 13(4): 1049. CrossRef
Implications for selecting persistent hot spots of schistosomiasis from community- and school-based surveys in Blue Nile, North Kordofan, and Sennar States, Sudan Hassan Ahmed Hassan Ahmed Ismail, Seungman Cha, Yan Jin, Sung-Tae Hong Parasites, Hosts and Diseases.2023; 61(2): 216. CrossRef
Review of Recent Prevalence of Urogenital Schistosomiasis in Sub-Saharan Africa and Diagnostic Challenges in the Field Setting Sung-Tae Hong Life.2023; 13(8): 1670. CrossRef
Investigation of Intestinal and Blood Parasites in People Returning to Turkey with a History of Traveling Abroad During the Pandemic Abdurrahman Ekici, Esra Gürbüz, Ahmet Hakan Ünlü, Rahmi Yıldız, Selahattin Aydemir, Ahmed Galip Halidi, Nuriz Ödemiş, Sinan Karakuş, Şehriban Yürektürk, Mutalip Çiçek, Hasan Yılmaz Turkish Journal of Parasitology.2022; 46(2): 108. CrossRef
Transmission Dynamics of Schistosoma haematobium among School-Aged Children: A Cohort Study on Prevalence, Reinfection and Incidence after Mass Drug Administration in the White Nile State of Sudan Yan Jin, Young-Ha Lee, Seungman Cha, In-Uk Choi, Hassan Ahmed Hassan Ahmed Ismail, Mousab Siddig Elhag, Sung-Tae Hong International Journal of Environmental Research and Public Health.2021; 18(21): 11537. CrossRef
Urinary schistosomiasis and the associated bladder cancer: update Mohamed S. Zaghloul, Tarek M. Zaghloul, Mai K. Bishr, Brian C. Baumann Journal of the Egyptian National Cancer Institute.2020;[Epub] CrossRef
First
Prev
