Occurrence of Cryptosporidium oocysts in commercial oysters in southern Thailand

Mayuna Srisuphanunt; Polrat Wilairatana; Nateelak Kooltheat; Thanis Damrongwatanapokin; Panagiotis Karanis

doi:10.1016/j.fawpar.2023.e00205

Occurrence of Cryptosporidium oocysts in commercial oysters in southern Thailand

Food Waterborne Parasitol. 2023 Jul 27:32:e00205. doi: 10.1016/j.fawpar.2023.e00205. eCollection 2023 Sep.

Authors

Mayuna Srisuphanunt^{1

2

3}, Polrat Wilairatana⁴, Nateelak Kooltheat^{1

3}, Thanis Damrongwatanapokin^{5

2}, Panagiotis Karanis⁶

Affiliations

¹ Department of Medical Technology, School of Allied Health Sciences, Walailak University, Nakhon Si Thammarat 80160, Thailand.
² Centre for One Health, Walailak University, Nakhon Si Thammarat 80161, Thailand.
³ Hematology and Transfusion Science Research Center, School of Allied Health Sciences, Walailak University, Nakhon Si Thammarat 80160, Thailand.
⁴ Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand.
⁵ Akkhraratchakumari Veterinary College, Walailak University, Nakhon Si Thammarat 80160, Thailand.
⁶ University of Nicosia Medical School, Department of Basic and Clinical Sciences, Egkomi 2408, Cyprus.

Abstract

The enteric parasite Cryptosporidium is spread through the fecal-oral pathway, most commonly by the consumption of contaminated water but also through food. Because eating raw or barely cooked shellfish might put consumers at risk for cryptosporidiosis, identifying the parasite in oysters is important for public health. A total of 240 oysters, collected from two shellfish aquaculture sites in Thailand's Gulf coast, Nakhon Si Thammarat and Surat Thani, were tested for the presence of Cryptosporidium. Escherichia coli, enterococci, and thermotolerant coliform total levels were measured to assess seawater quality in the shellfish production regions. Oocysts of Cryptosporidium spp. were detected in 13.8% of the samples processed by immunofluorescence analyses. The detection of Cryptosporidium spp. oocysts in oysters obtained from Surat Thani (17.5%) was higher than in those obtained from Nakhon Si Thammarat (9.2%). The difference in detection of positive samples obtained from Nakhon Si Thammarat and those obtained from Surat Thani may be attributed to the effects of physical, ecological, and anthropogenic conditions, resulting in an increased level of marine water contamination by Cryptosporidium spp. oocysts. These findings demonstrate that native commercial oysters obtained from Thailand's southern Gulf coast contained Cryptosporidium spp. oocysts which might serve as a source of human infection. Consequently, these findings pose a serious public health concern and suggest that more quality control measures need to be implemented by the oyster aquaculture business to ensure the safety of seafood.

Keywords: Coastal gulf; Cryptosporidium; Detection; Oysters; Thailand.