An ongoing Nipah virus outbreak in India has piqued global interest as the death toll continues to rise. The outbreak, which began earlier this month, has reached 14 confirmed cases, 20 suspect cases, and 12 deaths across two districts. Among the deaths is a nurse who cared for several Nipah patients. Nipah has appeared in India previously, but only in areas near the Bangladesh border. The current outbreak is in the southern state of Kerala, more than 1000 miles from previous outbreaks in India and now the westernmost recorded Nipah outbreak in history. We also provide a quick update on the Ebola outbreak in DRC.

Nipah Virus

Nipah virus was first identified in 1999 as the cause of an outbreak among individuals who worked with pigs in Malaysia. The identified cases were initially believed to be Japanese encephalitis, and the subsequent public health interventions, including mosquito control efforts, had no effect on disease transmission. This outbreak spread to multiple cities in Malaysia, mostly pig-farming communities, and ultimately resulted in 265 cases and 105 deaths (case fatality= 40%) in Malaysia and an additional 11 cases and 1 death in neighboring Singapore. Beyond the human toll, the outbreak necessitated the culling of more than a million pigs, causing substantial damage to the pork market and economy in Malaysia.

Nipah initially presents with flu-like symptoms (eg, fever, headache, muscle pain, sore throat), but the disease can progress to neurological symptoms such as dizziness, drowsiness, and altered mental state or severe respiratory distress. The most severe cases ultimately face encephalitis and associated symptoms such as seizures and coma, potentially leading to death. Symptoms typically present within two weeks of infection, but incubation periods as long as 45 days have been documented in some patients. According to the WHO, approximately 40-75% of Nipah patients die, depending on the outbreak and response capabilities.

There is currently no known treatment or vaccine for Nipah, but the WHO identified Nipah virus as a priority for medical countermeasure research and development in 2015 and reaffirmed that classification earlier this year. Current efforts include a draft “Nipah R&D Roadmap” developed by the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP) [NOTE: open for public comment through June 8, 2018].

While the earliest outbreaks of Nipah were linked to direct contact with infected pigs, the primary animal reservoir is widely believed to be fruit bats, also known as flying foxes. One of the most common modes of zoonotic transmission is via the consumption of fruits or fruit products, including raw palm date sap, that have been contaminated by bat saliva or urine. Human-to-human transmission occurs via close contact with infected individuals, especially contact with bodily fluids. The geographic range of fruit bats extends throughout South and Southeast Asia as well much of Africa and parts of the Middle East and Australia. Nipah outbreaks occur almost annually in Bangladesh, and two outbreaks have been previously reported in West Bengal, India (in 2001 and 2007), which borders Bangladesh.

Current Outbreak and Response

The first death occured on May 18, and the Nipah virus outbreak was confirmed by the Indian Ministry of Health on May 20, upon receipt of laboratory results from the National Institute of Virology. On May 22, MOH officials issued a press release describing the response activities to that point. India’s National Centre for Disease Control (NCDC) deployed a multidisciplinary team of experts to investigate the outbreak and support the local response. Investigators identified multiple bats in the well from which the index patient’s family drew their water, and samples were sent for testing to determine whether this was the source of the infection—60 total specimens were collected and sent for laboratory testing. The MOH is providing guidance and training to local clinicians and ensuring the availability of appropriate personal protective equipment (PPE) and clinical supplies. A May 23 press release indicated that Nipah-specific ambulances will be used to transport suspect patients to designated isolation facilities for testing and treatment.

Response Challenges

As noted above, the current outbreak is more than 1,000 miles from the India-Bangladesh border, in an area that has never seen a case of Nipah. The Kerala Health Minister, K.K. Shailaja, acknowledged that the state had no experience with Nipah but expressed hope that health officials would be able to control the outbreak with support from the Indian MOH and NCDC. As of this writing, Indian health officials have not yet reported the results of the laboratory tests on the bats found in the index patient’s well, but the geographic distribution of fruit bats that can carry Nipah covers Kerala and far beyond. Considering that bats as far away as Ghana and Madagascar have tested positive for Nipah virus infection, it is likely that the emergence of Nipah in a new location was really more a question of when than if.

Like is the case with many emerging infectious disease outbreaks, health officials in India are struggling against fear, stigma, and misinformation. One report indicated that the cremation of the bodies of two Nipah victims was delayed over concerns by the crematorium personnel that they could be infected. Crematorium workers were provided with proper PPE, and the families of Nipah victims have been discouraged attending cremations. There have also been reports of ambulance drivers refusing to transport suspect Nipah patients, resulting in the need to designate specific ambulances for Nipah patients. A tweet from the office of Kerala’s Chief Minister encouraged private hospitals not to deny treatment for suspect Nipah patients.

A MOH press release published today touted the success of the response efforts, including statements that there has not been further geographical spread and that the presence of state- and national-level responders have “instilled a sense of confidence among the public.” While Nipah is new to this area of India, it appears at this point as though Indian health officials are taking the proper measures to contain the outbreak.


UPDATE: Ebola in DRC

In last week’s Outbreak Thursday post, we discussed the emerging Ebola outbreak in the Democratic Republic of Congo. At the time, there were 44 total cases, including 19 deaths. Since that time, the outbreak has climbed to 58 cases and 28 deaths (as of the WHO’s most recent data from May 21). While there is optimism that response efforts will be successful, the outbreak may be at a tipping point. In fact, the WHO Deputy Director for Emergency Preparedness and Response, Dr. Peter Salama, commented that the outbreak is on an “epidemiological knife-edge.”

A vaccination campaign was initiated earlier this week, using an investigational vaccine that has demonstrated some efficacy in previous trials. A ring vaccination strategy is being used—vaccinating healthcare workers and contacts of identified cases—but health officials face challenges with contact tracing protocols, a critical step for ring vaccination. For example, Médecins Sans Frontières (MSF) announced yesterday that 3 Ebola patients in Mbandaka left a local isolation ward to return home with their families—one died in the community, and one was brought back to the hospital and then died. Health officials are trying to quickly identify any potential contacts while these individuals were outside the hospital.

Even if the vaccine proves to be efficacious in preventing Ebola virus disease, the vaccination effort ultimately will not succeed unless new cases and their contacts can be identified, and subsequently vaccinated or if the vaccine cannot be administered before further infections occur. The vaccination effort must be accompanied by outreach, education, and public partnerships to address social, cultural, and religious norms and practices in order to fully address Ebola as a health risk.


Photo: Transmission electron microscope images of Nipah virus; courtesy of CDC/Cynthia Goldsmith.

Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly to allow others to learn from these experiences in order to improve global outbreak response capabilities.


Updated May 27, 2018 to fix grammatical error.