# Occurrence of Clostridium perfringens in Shellfish

## TL;DR

This study finds that Clostridium perfringens is commonly found in shellfish, posing a public health risk, especially in countries like Spain and China.

## Contribution

The study provides a global assessment of Clostridium perfringens prevalence in shellfish and highlights the need for its inclusion in quality monitoring.

## Key findings

- The overall prevalence of C. perfringens in shellfish is 54.12%.
- Oysters, mussels, and clams show the highest contamination rates.
- Spain has the highest C. perfringens contamination rate in shellfish at 87.79%.

## Abstract

Clostridium perfringens constitutes an important foodborne risk in shellfish globally. The current study aimed at assessing the occurrence of C. perfringens in shellfish. The overall prevalence of C. perfringens in shellfish was 54.12%. There is also a 32.02% chance of contracting its toxigenic strains in shellfish. Generally, the mollusc shellfish had more C. perfringens contamination than the crustaceans. Common shellfish such as oysters (85.97%), mussels (71.81%), and clams (50.38%) harbour more C. perfringens contamination than other shellfish groups, also, C. perfringens contamination in shellfish is common in Spain (87.79%), China (47.01%), Japan (43.91%), and the USA (10.44%); and in South America (51.36%), Asia (44.77%), Europe (21.97%), and North America (10.44%). The presence of C. perfringens in shellfish, often consumed raw or undercooked, constitutes a significant public health risk. Thus, it will be beneficial to include C. perfringens in shellfish quality monitoring as an auxiliary quality indicator in addition to established indicators.

Background: Clostridium perfringens is an infectious agent of concern in wild/farmed shellfish. Hence, this study assessed shellfish-borne Clostridium perfringens (ShbCp) prevalence. Methods: A total of 1469 ShbCp from 2336 shellfish were modelled using hierarchical generalized linear and 1000-permutation-based-mixed-effects, meta-regression models. Results: The overall ShbCp prevalence was 54.12% (19.73–84.99) with a 32.02% (14.52–56.64) toxigenic rate and a higher estimate in 2020–2025 (41.01%, 17.00–70.23) versus 1970–2019 (20.01%, 4.49–57.08). Culture media significantly affect ShbCp recovery, with cooked meat medium and thioglycollate medium registering higher estimates (77% and 25.15%, respectively) than selective agars (<7%). The molluscans had a higher ShbCp rate (60.68%) than crustaceans (1.57%) and cephalopods (0.14%); oysters (85.97%) than mussels (71.81%), clams (50.38%), slug/snails (48.23%), scallops (16.24%), crabs (11.91%), shrimps (1.05%), and squids (0.42%); and Crassostrea gigas (89.27%) versus Ruditapes philippinarum (45.92%) versus Mytilus galloprovincialis (30.14%). ShbCp differed significantly by nations but not by continent with Spain (87.79%) having the highest rate, then China (47.01%), Japan (43.91%), the USA (10.44%), and Greece (0.00%); South America (51.36%), then Asia (44.77%), Europe (21.97%), and North America (10.44%). Sample size, growth medium, nation, and shellfish class significantly explained 27.58%, 72.30%, 67.52%, and 28.51% (R2) variance in ShbCp prevalence, respectively. Conclusions: The present study estimated a high ShbCp prevalence, suggesting a significant public health risk. It recommends that C. perfringens should be incorporated as a supplemental indicator into shellfish safety/shellfish water quality monitoring alongside traditional indicators. Also, geographical data gaps from Africa, Latin America, the Middle East, and Oceania underline the need for national and global monitoring attention and priority on C. perfringens in shellfish/shellfish beds.