Presented by

MD Satabul Islam

ID: 25015013

Mst Jannatul Ferdouse

ID: 25015025

Department of Public Health

Canadian University of Bangladesh

Introduction: Discovery and Origins

  • Initial Emergence: The virus first appeared in September 1998 in Ipoh, Perak, Malaysia.
  • Identification: Originally misdiagnosed as Japanese Encephalitis (JE), it was identified in March 1999 by Chua Kaw Bing and named after the village Kampung Sungai Nipah.
  • First Outbreak: Driven by pigs eating fruit contaminated by Pteropus bats; 265 people were infected and 105 died, mostly pig farmers.
  • Most Affected Regions: While it originated in Southeast Asia (Malaysia and Singapore), it is now most frequently seen in South Asia, specifically Bangladesh and India (primarily the state of Kerala and West Bengal).
  • Most Deaths Worldwide: Historically, the 1998–1999 outbreak in Malaysia and Singapore caused over 100 deaths. However, because Bangladesh faces nearly annual outbreaks, it has recorded the highest cumulative number of deaths globally.

Objectives

-To describe the emergence and identification of the Nipah virus, including its initial misdiagnosis and discovery in Malaysia.

-To explain the transmission and impact of the first outbreak, particularly its link to pigs, bats, and human fatalities.

-To analyze the geographical spread and global mortality pattern, highlighting recurrent outbreaks in Bangladesh and India.

Methodology: Tracking the Virus

  • Molecular Epidemiology: Researchers use this to track different strains, specifically the Malaysia strain (NiV-M) and the Bangladesh strain (NiV-B).
  • New Transmission Method: Unlike Malaysia, there were no pigs involved. Humans were infected by drinking raw date palm sap contaminated with bat saliva or urine.
  • Transmission Mapping: Studies focus on how the virus spreads, such as through raw date palm sap or human-to-human (H2H) transmission in hospitals.

Transmission Graph

Map 4: Bangladesh Overview

Discussion: Severity and Public Health Risks

  • Higher Mortality: The Bangladesh strain (NiV-B) is much deadlier, with a mortality rate of 70–90% compared to Malaysia’s 40%.
  • Recent Lethality: All cases identified in 2025 resulted in death, maintaining a 100% mortality rate for that period.
  • Cultural Challenges: The tradition of drinking raw date palm sap (Kacha Khejur Rosh) makes it difficult to prevent spread.
  • Countries with Evidence of the Virus: While major human outbreaks have occurred in the 5 countries above, the virus (or antibodies for it) has been found in bats in many more nations, meaning they are at risk:
  1. Southeast Asia: Thailand, Cambodia, Vietnam, Indonesia.
  2. East Asia: Southern China, Taiwan.
  3. Africa: Madagascar, Ghana (related Henipaviruses).
  4. Oceania: Papua New Guinea, Australia (Hendra virus).

Map 5: District Lethality (2025 Focus)

Map 6: Global Surveillance

Results: Geographic Shift and Current Data

  • The Nipah Belt: Since its first Bangladesh appearance in Meherpur in April 2001, the virus has appeared almost annually.
  • New Geographic Footprint: By January 2026, the virus has expanded to 35 out of 64 districts in Bangladesh, including new detections in coastal areas like Bhola. The districts with the highest infection and death rates include: Faridpur, Rajbari, Naogaon, Lalmonirhat.
  • Seasonal Changes: While typically a winter disease, an August 2025 case in Naogaon (caused by a bat-bitten plum) proved it is no longer strictly seasonal.

Conclusion: Prevention and Future Strategy

  • One Health Approach: Surveillance must move beyond the traditional “Nipah Belt” to include newly affected districts.
  • Behavioral Change: Using maps to target where to distribute “Sap Skirts” (bamboo covers) to protect sap collection pots from bats.
  • No Vaccine: Since no vaccine exists, the focus remains on strengthening PPE for caregivers and changing public habits.