Quantitative microbial risk assessment of Cryptosporidium in bivalve samples from Manila Bay, Philippines

In the Philippines, consumption of bivalves is very common due to its year-round availability and cheap price. However, many consume bivalves as lightly-cooked or raw. This might pose health hazards because bivalves are filter-feeders which act as vehicles for transmission of several pathogens such as the protozoan parasite Cryptosporidium, the causative agent of cryptosporidiosis. Cryptosporidiosis in humans is manifested by profuse diarrhea and abdominal pain. To determine the risk of acquiring cryptosporidiosis from consumption of bivalves, quantitative microbial risk assessment (QMRA) should be done. This study aimed to determine the risk associated with the consumption of bivalves which are contaminated with Cryptosporidium oocysts. The results indicate that consumption of at least 21 grams of cooked bivalves contaminated with at least 0.1% viable oocysts might pose a risk to consumers, especially to immunocompromised individuals. This estimated risk of infection exceeded the United States Environmental Protection Agency (US EPA) standards (1.0×10-4). Results call for drive of decision-makers to establish an educational or treatment program to reduce the incidence of gastrointestinal infections of the consumers. Improvement of sanitation techniques and hygienic practices will contribute to the decrease of occurrence of the disease.