Tackling a global epidemic threat: Nipah surveillance in Bangladesh, 2006-2021.

Human Nipah virus (NiV) infection is an epidemic-prone disease and since the first recognized outbreak in Bangladesh in 2001, human infections have been detected almost every year. Due to its high case fatality rate and public health importance, a hospital-based Nipah sentinel surveillance was established in Bangladesh to promptly detect Nipah cases and respond to outbreaks at the earliest. The surveillance has been ongoing till present. The hospital-based sentinel surveillance was conducted at ten strategically chosen tertiary care hospitals distributed throughout Bangladesh. The surveillance staff ensured that routine screening, enrollment, data, and specimen collection from suspected Nipah cases were conducted daily. The specimens were then processed and transported to the reference laboratory of Institute of Epidemiology, Disease Control and Research (IEDCR) and icddr,b for confirmation of diagnosis through serology and molecular detection. From 2006 to 2021, through this hospital-based surveillance platform, 7,150 individuals were enrolled and tested for Nipah virus. Since 2001, 322 Nipah infections were identified in Bangladesh, 75% of whom were laboratory confirmed cases. Half of the reported cases were primary cases (162/322) having an established history of consuming raw date palm sap (DPS) or tari (fermented date palm sap) and 29% were infected through person-to-person transmission. Since the initiation of surveillance, 68% (218/322) of Nipah cases from Bangladesh have been identified from various parts of the country. Fever, vomiting, headache, fatigue, and increased salivation were the most common symptoms among enrolled Nipah patients. Till 2021, the overall case fatality rate of NiV infection in Bangladesh was 71%. This article emphasizes that the overall epidemiology of Nipah virus infection in Bangladesh has remained consistent throughout the years. This is the only systematic surveillance to detect human NiV infection globally. The findings from this surveillance have contributed to early detection of NiV cases in hospital settings, understanding of Nipah disease epidemiology, and have enabled timely public health interventions for prevention and containment of NiV infection. Although we still have much to learn regarding the transmission dynamics and risk factors of human NiV infection, surveillance has played a significant role in advancing our knowledge in this regard.

An epidemic of chikungunya in northwestern Bangladesh in 2011.

BACKGROUND: In November 2011, a government hospital physician in Shibganj sub-district of Bangladesh reported a cluster of patients with fever and joint pain or rash. A multi-disciplinary team investigated to characterize the outbreak; confirm the cause; and recommend control and prevention measures. METHODS: Shibganj's residents with new onset of fever and joint pain or rash between 1 September and 15 December 2011 were defined as chikungunya fever (CHIKF) suspect cases. To estimate the attack rate, we identified 16 outpatient clinics in 16 selected wards across 16 unions in Shibganj and searched for suspect cases in the 80 households nearest to each outpatient clinic. One suspect case from the first 30 households in each ward was invited to visit the nearest outpatient clinic for clinical assessment and to provide a blood sample for laboratory testing and analyses. RESULTS: We identified 1,769 CHIKF suspect cases from among 5,902 residents surveyed (30%). Their median age was 28 (IQR:15-42) years. The average attack rate in the sub-district was 30% (95% CI: 27%-33%). The lowest attack rate was found in children <5 years (15%). Anti-CHIKV IgM antibodies were detected by ELISA in 78% (264) of the 338 case samples tested. In addition to fever, predominant symptoms of serologically-confirmed cases included joint pain (97%), weakness (54%), myalgia (47%), rash (42%), itching (37%) and malaise (31%). Among the sero-positive patients, 79% (209/264) sought healthcare from outpatient clinics. CHIKV was isolated from two cases and phylogenetic analyses of full genome sequences placed these viruses within the Indian Ocean Lineage (IOL). Molecular analysis identified mutations in E2 and E1 glycoproteins and contained the E1 A226V point mutation. CONCLUSION: The consistently high attack rate by age groups suggested recent introduction of chikungunya in this community. Mosquito control efforts should be enhanced to reduce the risk of continued transmission and to improve global health security.

Outbreak of Sudden Death with Acute Encephalitis Syndrome Among Children Associated with Exposure to Lychee Orchards in Northern Bangladesh, 2012.

Recurrent outbreaks of acute encephalitis syndrome (AES) among children in lychee growing areas in Asia highlight the need to better understand the etiology and the context. We conducted a mixed-methods study to identify risk factors for disease, and behaviors and practices around lychee cultivation in an AES outbreak community in northern Bangladesh in 2012. The outbreak affected 14 children; 13 died. The major symptoms included unconsciousness, convulsion, excessive sweating, and frothy discharge. The median time from illness onset to unconsciousness was 2.5 hours. The outbreak corresponded with lychee harvesting season. Multiple pesticides including some banned in Bangladesh were frequently used in the orchards. Visiting a lychee orchard within 24 hours before onset (age-adjusted odds ratio [aOR] = 11.6 [1.02-109.8]) and 3 days (aOR = 7.2 [1.4-37.6]), and family members working in a lychee orchard (aOR = 7.2 [1.7-29.4]) and visiting any garden while pesticides were being applied (aOR = 4.9 [1.0-19.4]) in 3 days preceding illness onset were associated with illness in nearby village analysis. In neighborhood analysis, visiting an orchard that used pesticides (aOR = 8.4 [1.4-49.9]) within 3 days preceding illness onset was associated with illness. Eating lychees was not associated with illness in the case-control study. The outbreak was linked to lychee orchard exposures where agrochemicals were routinely used, but not to consumption of lychees. Lack of acute specimens was a major limitation. Future studies should target collection of environmental and food samples, acute specimens, and rigorous assessment of community use of pesticides to determine etiology.