Beriberi outbreak investigation in commercial fishermen in Ranong Province,Thailand, January 2016

Abstract

On January 12, 2016 Office of Disease Prevention and Control Region 11, Nakhon Si Thammarat (DPC 11 NST) was notified about 4 unspecified deaths among commercial fishermen by Ranong Provincial Health Office. DPC 11 NST and Bureau of Epidemiology jointly investigated the outbreak. The aims were to verify the diagnosis, describe epidemiological characteristics and factors or conditions related to the illness, and provide prevention and control measures. Clinical interview and physical examination, laboratory study, autopsy, and testing for toxic substances and heavy metals in food and water samples were performed. Thirty-two fishermen (25 Cambodian and 7 Thai) clinically compatible with beriberi deficiency were found among 115 fishermen from 6 ships (attack rates = 27.8%). Among those cases, 24 were confirmed, 5 were probable and 3 were suspected cases. Six of them died (case-fatality rates 18.8%). All of them were male and median age was 31.5 years (ranged from 18-65 years). Dyspnea was presented dominantly and followed with muscle weakness, chest pain/chest discomfort, numbness, muscle pain and edema (63%, 59%, 56%, 53%, 50% and 39%, respectively). Twenty-four cases got blood testing and all of them were confirmed vitamin B1 deficiency. Twenty-five samples of food and water were tested for heavy metals. Most laboratory results were in acceptable level except Thai tobacco in which its cadmium level was higher than traditional medicine standard. Autopsy was performed in 6 deaths. The results confirmed that five of them had cardiac enlargement which is compatible with cardiac beriberi and 1 case had abnormal myocardial tissue. The study indicated that this outbreak caused by vitamin B1 deficiency and probable factors related to the outbreak included insufficiency nutrient intake during 9-months period at sea, raw food intake behavior, and labor working. Providing supplementary vitamin B1 for crewmembers who work over 30 days on the sea should be established.