NEW Bat-Borne Virus in Bangladesh: PRV, Not Nipah Health Alert

Over the past few years, health authorities in Bangladesh have been investigating a puzzling illness initially believed to be an outbreak of the deadly Nipah virus. Recent scientific studies, however, have revealed a surprising and concerning truth: this mystery disease is not caused by the Nipah virus at all, but by another bat-borne pathogen known as Pteropine orthoreovirus (PRV) a virus previously underestimated in terms of human health impact. 

The Outbreak and Initial Misdiagnosis

Between December 2022 and March 2023, hospitals in Bangladesh admitted at least five patients exhibiting symptoms that closely mimicked those of known Nipah virus infection including fever, vomiting, headache, severe fatigue, increased salivation, and neurological problems such as disorientation. Because such symptoms have been historically linked to Nipah outbreaks in the region, medical professionals initially suspected a resurgence of the virus.

Most of the patients reported a common exposure: consumption of raw date palm sap (locally called “tari”), a traditional wintertime drink harvested from palm trees. Bats, particularly fruit bats, are known to feed on and contaminate this sap with saliva or urine, making it a well-documented route for bat-to-human virus transmission. Early investigations therefore focused on Nipah virus as the likely cause.

However, diagnostic tests repeatedly came back negative for Nipah, prompting researchers to look deeper. Despite initial hospital discharges within a few weeks, several of these individuals continued to experience long-term health problems  including chronic fatigue, breathing difficulties and issues with movement and one patient eventually died in 2024 after developing unexplained neurological complications.

PRV A Different Bat-Borne Threat

After thorough analysis, scientists identified Pteropine orthoreovirus (PRV) in samples from all five patients. While PRV has been previously detected in human cases in parts of Southeast Asia such as Malaysia, Indonesia and Vietnam those cases were generally associated with milder respiratory symptoms. In contrast, the Bangladesh cases showed more severe and lingering health effects, suggesting the virus may behave differently in this population or environment.

Researchers suspect that the virus has undergone genetic reassortment, a type of mutation or genetic mixing that can alter how viral strains behave. This reassortment could potentially increase the virus’s ability to infect humans, change its virulence (how severe disease it causes), or modify its ability to spread from person to person or from animals to humans.

In addition to raw date palm sap exposure, scientists have found similar PRV strains in bats captured near the homes and environments of the infected patients, particularly around regions of the Padma River basin. This supports the idea that bats  already known as natural reservoirs for many zoonotic viruses remain a key link in transmission chains for emerging infectious diseases.

Why This Matters: Zoonotic Risks and Public Health

The discovery of PRV in human patients highlights a broader concern for zoonotic diseases illnesses that jump from animals to humans. Bats are natural carriers for a wide range of viruses, including rabies, Nipah, Hendra, Marburg, and various coronaviruses. Though PRV has not previously been a major public health focus, these new findings suggest that emerging or previously unrecognized bat-borne pathogens may be silently affecting human populations.

Experts warn that when symptoms resemble those of a high-fatality virus like Nipah, doctors and health workers must also consider other possible causes like PRV to ensure accurate diagnosis and appropriate medical response. PRV’s detection in throat swab samples and laboratory cultures emphasizes the need for broader virological surveillance, especially in regions where human contact with wildlife is common.

Public Health Advice and Research Recommendations

To reduce the risk of future outbreaks or undetected infections, scientists are recommending that regions where raw date palm sap consumption is common such as parts of Bangladesh include PRV and other bat-borne viruses in routine testing when patients present with Nipah-like symptoms.

Additionally, more research is needed to better understand how PRV is transmitted, how widely it circulates among bat populations, and whether it can spread directly between humans. Ongoing surveillance could help health systems detect unusual clusters of illness early and prevent larger outbreaks.

Researchers also emphasize awareness around hygienic collection and processing of raw date palm sap, including measures to prevent bat access to sap collection sites such as physical sap-protection covers to reduce contamination risks. 

Global and Regional Implications

While the immediate human-to-human transmission risk of PRV is still under study, its presence alongside more notorious viruses such as Nipah underscores a larger global health concern: the emergence of previously unrecognized pathogens with pandemic potential.

As global travel, climate change and human encroachment into wildlife habitats increase, scientists warn that countries must enhance their monitoring systems for novel infectious diseases. Understanding bat-borne pathogens and the environmental contexts that facilitate spillover events is a growing priority for international public health agencies.

Staying Vigilant Against Hidden Viral Threats

What was once thought to be another Nipah virus outbreak in Bangladesh has now revealed a more complex and potentially serious public health challenge. The emergence of Pteropine orthoreovirus (PRV) as a cause of human illness shows how important it is to maintain robust surveillance systems, expand diagnostic capabilities, and educate communities about zoonotic disease risks.

Health experts recommend that doctors, researchers and public health authorities stay alert for unusual cases of viral illness, especially in areas where humans and wildlife interact closely. As investigations continue, increased preparedness and proactive prevention strategies remain key to controlling and reducing the impact of emerging infectious diseases around the world.