Dissecting an outbreak: A clinico-epidemiological study of Nipah virus infection in Kerala, India, 2018

Background: An outbreak of Nipah virus infection was confirmed in Kerala, India in May 2018. Five out of 23 cases including the first laboratory-confirmed case were treated at Baby Memorial Hospital (BMH), Kozhikode. The study describes the clinical characteristics and epidemiology of the Nipah virus outbreak at Kozhikode during May 2018. Objective: To study the clinical and epidemiological profile of Nipah virus epidemic that occurred in Kerala in May 2018. Methods: A collaborative team of physicians and epidemiologists from BMH, Medical College Hospital (MCH) Kozhikode and from the Indian Medical Association (IMA) conducted this study. The clinical and exposure history and the data on outbreak response were gathered from hospital medical records and through interviewing patient relatives and health workers using questionnaires. Results: It was identified that out of the 23 patients with Nipah virus infection, 21 (91.3%) expired. Out of the 21 patients, 18 tested positive for Nipah virus by Real Time polymerase chain reaction (RT-PCR). It has been found that only the index case was infected in the community from fruit bats. Rest of the cases were due to transmission of the virus at three public hospitals. Median age was 45 years. 65% of them were males. Median incubation period was 9.5 days. Fever (100%), altered sensorium (84.2%), tachycardia (63.1%), hypertension (36.8%), segmental myoclonus (15.7%), segmental sweating (15.7%) and shortness of breath (73.6%) were common features. Mean duration of illness was 6.4 days. Conclusion: The rapid spread of infection uncovered the miserable state of health care system in implementing infection control measures. The case fatality and the socio-economic burden warrant developing appropriate treatments, vaccines and diagnostics.