Outbreak of Haff Disease caused by consumption of crayfish (Procambarus clarkii), Nanjing, Jiangsu Province, China

- We described the investigation of a crayfish-related Haff disease outbreak in China.
- This study incorporated both epidemiological and chemical analysis.
- Consuming more than 10 pieces of crayfish was related to increased Haff disease risk.
- Chemical analysis of samples did not show any possible toxins, drugs and hazardous elements.

Haff disease is a rare syndrome characterized by rhabdomyolysis following consumption of cooked fish or crustaceans. We present the investigation of an outbreak of Haff disease in Nanjing, Jiangsu Province, China incorporating both epidemiological and chemical analysis. Structured questionnaires were sent to 20 case-patients and 25 diners who ate with case-patients. Eleven samples of crayfish (Procambarus clarkii) from the local markets, blood and urine samples from two case-patients were collected and sent for chemical testing. The case-control study revealed that all cases and controls had eaten crayfish during the exposure period. Consuming more than 10 pieces of crayfish was related to increased disease risk (p < 0.001). Chemical analysis of crayfish, blood and urine samples did not show any possible toxins, drugs and hazardous elements. This 2010 Nanjing outbreak of Haff disease was attributed to the consumption of crayfish. Improved surveillance and understanding of etiology should help further our understanding of this disease and improve management of future disease outbreaks.