Investigation and analysis of melioidosis outbreak after Typhoon Nanmadol in Southern Taiwan, 2011

Abstract

Background: Melioidosis caused by Burkholderia pseudomallei is a common zoonotic disease of tropical climates, especially in Southeast Asia and northern Australia. It is spread through inhalation, ingestion or direct contact between a wound and the contaminated source. In Taiwan, melioidosis outbreaks are often associated with typhoon floods. Past outbreaks occurred mostly in southern Taiwan after typhoons passed through in 2005, 2008, 2009, and 2010. In this study, we investigated the melioidosis outbreak after Typhoon Namadol struck Taiwan in August, 2011 to identify high risk groups and the transmission route, and provide public prevention measures. Methods: The data was collected by Taiwan CDC. One month after Typhoon Namadol occurred during August 27 and 31, 2011, cases were confirmed in southern Taiwan. Taiwan FETP interviewed the cases (or their family members); determined whether the residence was flooded and whether the case had any skin wound and exposure to soil during the typhoon; and reviewed the cases’ medical records and demographic characteristics. Results: During September 6 and 28, 2011, 17 melioidosis cases were confirmed in southern Taiwan. In this outbreak, the case number peaked three weeks after the typhoon hit. The mean age of the cases was 63 years. The male to female ratio was 1.43:1. All cases had chronic diseases such as diabetes, renal disease, malignant tumor or liver disease. All cases were found to have no wound and no exposure history to soil. Four of 17 cases (23.5%) died despite of proper medical care. The most common clininal syndrome was pneumonia (n = 12, 71%). Conclusion: Melioidosis is highly fatal. All cases had no exposure to soil and most developed pneumonia, which indicated that the infection was associated with inhalation of contaminated dust or vapor caused by typhoon. Patients with history of chronic diseases are at increased risk for melioidosis, especially elderly. During the typhoon season, health authorities should reinforce promoting melioidosis awareness by spreading important health education messages to patients at risk and advising public to remain vigilant against melioidosis.