Evolving epidemiology of Nipah virus infection in Bangladesh: evidence from outbreaks during 2010-2011.

Drinking raw date palm sap is the primary route of Nipah virus (NiV) transmission from bats to people in Bangladesh; subsequent person-to-person transmission is common. During December 2010 to March 2011, we investigated NiV epidemiology by interviewing cases using structured questionnaires, in-depth interviews, and group discussions to collect clinical and exposure histories. We conducted a case-control study to identify risk factors for transmission. We identified 43 cases; 23 were laboratory-confirmed and 20 probable. Thirty-eight (88%) cases died. Drinking raw date palm sap and contact with an infected person were major risk factors; one healthcare worker was infected and for another case transmission apparently occurred through contact with a corpse. In absence of these risk factors, apparent routes of transmission included drinking fermented date palm sap. For the first time, a case was detected in eastern Bangladesh. Identification of new epidemiological characteristics emphasizes the importance of continued NiV surveillance and case investigation.

Integrated cluster- and case-based surveillance for detecting stage III zoonotic pathogens: an example of Nipah virus surveillance in Bangladesh.

This paper explores the utility of cluster- and case-based surveillance established in government hospitals in Bangladesh to detect Nipah virus, a stage III zoonotic pathogen. Physicians listed meningo-encephalitis cases in the 10 surveillance hospitals and identified a cluster when ⩾2 cases who lived within 30 min walking distance of one another developed symptoms within 3 weeks of each other. Physicians collected blood samples from the clustered cases. As part of case-based surveillance, blood was collected from all listed meningo-encephalitis cases in three hospitals during the Nipah season (January-March). An investigation team visited clustered cases' communities to collect epidemiological information and blood from the living cases. We tested serum using Nipah-specific IgM ELISA. Up to September 2011, in 5887 listed cases, we identified 62 clusters comprising 176 encephalitis cases. We collected blood from 127 of these cases. In 10 clusters, we identified a total of 62 Nipah cases: 18 laboratory-confirmed and 34 probable. We identified person-to-person transmission of Nipah virus in four clusters. From case-based surveillance, we identified 23 (4%) Nipah cases. Faced with thousands of encephalitis cases, integrated cluster surveillance allows targeted deployment of investigative resources to detect outbreaks by stage III zoonotic pathogens in resource-limited settings.

Evaluation of alternative diagnostic techniques for diagnosis of cerebral malaria in a tertiary referral hospital in Bangladesh.

Five alternative techniques for diagnosis of malaria were evaluated in 124 clinically diagnosed cerebral malaria cases admitted in a tertiary hospital in Bangladesh. Clinical diagnosis of cerebral malaria was done by WHO criteria. The tests were conventional routine malaria microscopy; prolonged microscopy; dipstick antigen capture assay (Para Sight TM-F test); pigments in peripheral leucocytes and routine microscopy repeated at 12 hours interval. First four tests were done at 0 hours of hospital admission and repeat routine microscopy was added at 12 hours interval. Diagnostic capability of the test was 64%, 65%, 69%, 27% and 63% respectively. None of the tests except pigments in peripheral leucocytes was superior at initial evaluation. Only the dipstick test added 5% more diagnostic possibility compared with routine microscopy as standard. Stratification of diagnostic capability in different ways improved diagnosis 15% and 11% in smear negative cases by dipstick and prolonged microscopy respectively. It was increased by 50% (5/10 patients) with dipstick test in the smear negative patients with history of anti-malarials prior to hospital admission.