Risk Factors for Melioidosis Mortality and Epidemics: A Multicentre, 10-Year Retrospective Cohort Study in Northern Hainan

INTRODUCTION: Burkholderia pseudomallei is a gram-negative environmental bacterium and aetiological agent of melioidosis, a tropical infectious disease with diverse clinical presentations. We aimed to describe the epidemiological and clinical characteristics of melioidosis in northern Hainan and to determine the meteorological factors affecting its morbidity. METHODS: We conducted a retrospective, multicentre, observational cohort study of 90 patients with melioidosis admitted to four general hospitals in northern Hainan from 2010 to 2020. Epidemiological, clinical presentation, laboratory and treatment outcome data were collected and analysed. The monthly incidence of melioidosis and meteorological data, including precipitation, temperature, humidity, air pressure and wind speed, for the same period were collected to analyse the relationship between meteorological factors and the incidence of melioidosis. RESULTS: Of the 90 patients included in the study, 79 (87.78%) were male. Patient age ranged from 10 to 81 years old, but most patients, namely, 78 (86.67%), were middle-aged and elderly people aged 41–81 years old. Forty-six patients (51.11%) were farmers. The number of cases increased significantly after 2014, with the highest numbers occurring in 2014 and 2016. The highest number of cases occurred in summer and autumn and were associated with abundant rainfall, and 58 cases (64.44%) occurred from July to December. The patients showed diverse presentations and abnormal laboratory parameters: 69 patients (76.67%) had a history of diabetes mellitus; bacteremia was present in 50 patients (55.56%), sepsis was present in 39 patients (43.33%) and pneumonia in 19 patients (21.11%). An average high-sensitivity C-reactive protein (hs-CRP) level of 149.57 ± 13.65 mg/L and a median procalcitonin (PCT) level of 1.31 (0.39, 6.21) ng/mL were observed. Among all the cases, 21 (23.33%) were identified as acute infections, 51 (56.67%) as subacute infections and 18 (20.00%) as chronic infections. Six patients (6.67%) died of illness; five of these patients were male, and five of these patients were middle-aged and elderly patients. The monthly average precipitation was significantly positively correlated with the monthly average incidence of melioidosis (r = 0.74, P < 0.01). CONCLUSION: Male patients, farmers and especially middle-aged and elderly individuals with a history of diabetes mellitus accounted for most of the patients. The majority of cases were concentrated in coastal areas. Most cases of melioidosis occurred during the rainy seasons, and the monthly average precipitation was an independent factor affecting the average monthly incidence of melioidosis.