Researchers studying infectious diseases have identified the Pteropine orthoreovirus (PRV), a virus carried by bats, in stored throat swabs and viral cultures from five patients in Bangladesh. Initially, these individuals were suspected of having Nipah virus infection, but subsequent tests returned negative results. This discovery expands the list of animal-to-human viruses detected in the country and highlights the need to consider PRV when diagnosing illnesses with symptoms similar to Nipah infection. The study’s findings were published in the journal Emerging Infectious Diseases.

Link to Consumption of Date Palm Sap

All five patients had consumed raw date palm sap—a sweet liquid typically collected in winter and often visited by bats—shortly before falling ill. This sap is already known as the main route of Nipah virus transmission in Bangladesh. Bats are recognized as natural reservoirs for many zoonotic viruses, including rabies, Nipah, Hendra, Marburg, and SARS-CoV-1. As noted by Nishay Mishra, Associate Professor of Epidemiology at the Center for Infection and Immunity (CII) at Columbia University’s Mailman School of Public Health and senior author of the study, the risk of diseases linked to raw date palm sap consumption extends beyond Nipah virus. This underscores the importance of broad surveillance programs to detect and reduce public health risks from new bat-borne viruses.

Study Process and Diagnostic Methods

From December 2022 to March 2023, five patients were hospitalized with symptoms typical of Nipah virus infection: fever, vomiting, headache, fatigue, increased salivation, and neurological manifestations. Despite these signs, laboratory tests using PCR and serology ruled out Nipah virus. For further analysis, scientists applied high-throughput viral sequencing (VCS) to patient samples, which enabled them to detect PRV genetic material in archived throat swabs. In three cases, the virus was successfully cultured, confirming active infection.

The patients were identified through a Nipah virus surveillance program jointly run by the Institute of Epidemiology, Disease Control and Research (IEDCR, Bangladesh), the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), and the US Centers for Disease Control and Prevention (CDC).

Sequencing Technologies and Their Significance

Viral sequencing (VCS) is a patented method developed at Columbia University’s CII. It allows scientists to detect all known viral infections in vertebrates, including those carried by bats. This technology is as sensitive as standard PCR testing but can simultaneously search for thousands of viruses and generate nearly complete genome sequences. A related tool, bacterial sequencing (BCS), identifies pathogenic bacteria and genes associated with antibiotic resistance. Both technologies are approved for clinical and research use.

Clinical Features and Epidemiological Conclusions

All five patients experienced severe illness. In contrast, PRV infections reported in neighboring countries have often been milder, suggesting that less severe cases in Bangladesh may go undetected.

According to Tahmina Shirin, Director of the IEDCR and the National Influenza Center (NIC) in Bangladesh, this new zoonotic infection causes respiratory and neurological complications after consuming raw date palm sap, alongside Nipah virus infection.

Tracing the Source of Infection and Further Research

In a later study supported by the US Department of Agriculture, Mishra and colleagues identified a likely source of infection by finding genetically similar Pteropine orthoreovirus in bats captured near the site of human cases along the Padma River basin (unpublished data).

Ariful Islam, an ecologist and epidemiologist specializing in bat-borne diseases (Charles Sturt University, Australia), notes that the study provides important evidence linking bat reservoirs to human infection. Researchers are now working to understand the mechanisms of transmission from bats to humans and domestic animals, as well as studying the ecology of new bat-borne viruses in communities along the Padma River basin.

Participants and Funding

The study involved Sharmeen Sultana, Associate Professor of Virology and Senior Scientist at IEDCR in Bangladesh, along with other experts from CII, IEDCR, icddr,b, CDC, and the US Department of Agriculture. Funding was provided through agreements between the US Department of Agriculture and Columbia University.