Nipah outbreak in Bangladesh: are we paying enough heed?

Introduction While the norm is to celebrate New Year with festivities, Bangladesh had to see yet another outbreak of Nipah virus (NiV), causing concern about another growing zoonotic epidemic. With the first case reported on January 4 and a total of 11 cases with 8 fatalities as of February 13, the case-fatality ratio (CFR) is 73%. The reported cases are spread over 7 districts across the 2 divisions of Dhaka and Rajshahi, the latter also bordering India, posing threats of cross-border spread1. The outbreak is despicably unfortunate as 2023 marks 25 years since the first NiV outbreak in Malaysia and 22 years since that in Bangladesh in 2001. Nearly a quarter of a century since then, we stand with minimal research about NiV, and hence, no success in the development of a vaccine and any substantial pharmacotherapy for NiV so far2. NiV, a member of henipavirus genus of the family paramyxoviridae, is a bat-borne virus. Pterous bats form the reservoir. Though the virus has had regional outbreaks in India, Philippines, Singapore, Malaysia, and Bangladesh, its zoonotic as well as person-to-person transmission makes it a potential pandemic-causing pathogen provided the suitable circumstances. It is, without a doubt, this reason that NiV is one of the WHO’s most sought-after pathogens in terms of research and other developments. Even though the number of cases reported each year is small, the mortality rate varies from 40% in Malaysia to as high as 70% in India and Bangladesh. The disease presentation also varies from asymptomatic cases to those with severe respiratory illnesses or neurological symptoms2. Epidemiology, etiology, and transmission NiV spreads in 3 major ways. The first mode of transmission is from its host reservoir, that is, bats to humans. It includes the consumption of food or food products contaminated by the urine and saliva of infected bats (as seen in outbreaks in Bangladesh and India). It was this very mode responsible for the 2023 NiV outbreak in Bangladesh after people unknowingly ingested date palm sap contaminated by bats’ spillover. The other 2 include transmission to humans by contact with NiV- permissive animals, and spread through close contact with the infected persons or their body fluids (urine, blood, nasal, or respiratory droplets), putting their close ones and health care workers at a high risk of getting infected1,3. The number of cases, mortality, and CFR in NiV outbreaks in Bangladesh has varied throughout the years. The total number of cases reported from 2021 to 2023 is 335, of which 237, that is, 70% succumbed to the disease. CFR was at its peak in 2005, 2010, and 2019, again rising to a comparable magnitude in the current 2023 outbreak1. A comparison of NiV and SARS-CoV-2 NiV being a zoonotic pathogen is quite like SARS-CoV-2. Both resemble in their modes of transmission and some of the symptoms they produce. On the other hand, they are very distinct other characters. Their similarities as well as discriminating features have been summarized in Table 14. Table 1 - Comparision of NiV to SARS-CoV-2-similarities and differences4. Nipah virus (NiV) SARS-CoV-2 Similarities Both are zoonotic pathogens and are bat-borne.Both give rise to respiratory complications. Contrasting features NiV causes severe neurological complications resulting from encephalitis SARS-CoV-2 produces distinct dysgeusia and parosmia NiV-affected patient is likely to transmit infection at the peak of his symptoms For SARS-CoV-2, the time at which the patients demonstrate the maximum infectious potential is the asymptomatic stage NiV has a deadlier fatality ratio of 40%–45%. SARS-CoV-2 has a fatality ratio of 0.1%–19% Challenges There are various challenges when it comes to containing NiV outbreaks in a country like Bangladesh. The information about NiV is limited to just 2 strains3. The need for a human vaccine is absolutely essential for the prevention and control of any future outbreaks. Even though there are vaccines available for the livestock that have contracted NiV, they are of little to no use in Bangladesh since the outbreaks developed mostly due to bats spillovers directly and not due to any NiV-infected domestic animals (which could have been vaccinated and helped contain the viral spread otherwise)5. There is no licensed treatment for NiV. However; ribavirin and acyclovir have been used with some effectiveness in treating NiV-encephalitis in Malaysia and Singapore. The only treatment option thus, is supportive4. Another challenge comes with the diagnosis. The Rare and Impored Pathogen Laboratory (RIPL) in the United Kingdom is the appointed center for having NiV PCR. The sample collection and transportation lead to a several weeks delay in NiV screening, adding to the problems being faced in the surveillance of the disease6. Efforts and recommendations After this brief insight into NiV, it is not surprising to say the world is in danger of another pandemic if appropriate measures are not taken. Pandemics require intense measures like lockdowns, putting a huge burden on a country’s economy, not to mention that of a developing country, already crippled by the recent SARS-CoV-2 pandemic. The mantra of “prevention is better than cure” is the only way to get through until vaccinations and targeted drugs are developed. Religious use of protective personal equipment and strict hand-washing practices are by far the most effective preventive strategies. Media in all its forms should be employed to educate the vulnerable populations as well as the masses at large about NiV and the possible precautions4. Surveillance programs [currently ongoing under the National Rapid Response Team (NRRT) in Bangladesh in collaboration with ICDDR, B]1 need to be reviewed and planned in a way to ensure accurate reporting of the cases, isolating the individuals, tracing close contacts, the surveillance limited not to Bangladesh but South East Asia as a whole. This part of the subcontinent has been affected by NiV the most and the surveillance would help determine any patterns in the occurrence of the outbreaks. The government of Bangladesh (and other countries at acute risk) should work together with WHO for the introduction of well-equipped laboratories to aid research, provision of diagnostic facilities (often inaccessible and expensive), the appointment of health care professionals proficient in NiV disease management as well as the launch of training programs. NiV infection being a zoonotic infection has to be dealt with through “one health program,” incorporating risk factors related to humans, animals, and the environment into a single integrated plan1,7. Conclusion In a nutshell, public education campaigns should be launched in Bangladesh. The government and Ministry of Health should allocate the necessary resources and funds to help speed up vaccine trials and suitable antiviral development. Providing pharmaceutical companies with incentives will also aid in furthering the process. In the meanwhile, adopting precautionary measures on an individual, societal, and global level will help nip this evil in the bud and curb the disease. These, when followed closely, will help contain the virus and save us from another pandemic. Ethical approval None. Sources of funding None. Author contribution S.A.: study concept and design. U.A.R., M.H., H.S.J., and A.L.: writing manuscript. Conflicts of interest disclosure The authors declare that they have no financial conflict of interest with regard to the content of this report. Research registration unique identifying number (UIN) None. Guarantor Abdul Latif.