Nipah virus as a biological weapon
Nipah virus is an RNA virus belonging to the henipavirus group and is classified as a Category C agent by the U.S. Centers for Disease Control and Prevention, indicating its potential use as a biological weapon. First identified in 1998 during an outbreak among pigs in Malaysia, Nipah virus has since caused significant mortality in both animals and humans, particularly in regions of South Asia. The virus is primarily transmitted from fruit bats to animals and humans, with symptoms ranging from respiratory distress to severe neurological complications, often resulting in a mortality rate exceeding 50%.
While there is currently no specific treatment for Nipah virus infection, supportive care is essential, and research into vaccines shows promise. Notably, outbreaks can occur beyond the natural habitats of fruit bats, potentially arising from exposure to infected animals or meat, underscoring the need for vigilance in animal husbandry and food safety. The possibility of human-to-human transmission and the risk of bioterrorism prompt ongoing research and public health preparedness efforts to mitigate the impact of this emerging pathogen.
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Nipah virus as a biological weapon
DEFINITION: RNA virus of the henipavirus group in the family Paramyxoviridae that causes disease characterized by fever and severe influenza-like symptoms with high mortality in animals and humans.
SIGNIFICANCE: Nipah virus is an emerging pathogen with an increasing incidence of deaths in humans and domestic animals. The US Centers for Disease Control and Prevention classify the Nipah virus as a Category C agent, the lowest of three categories of possible bioterrorism agents.
The Nipah virus was first discovered in 1998 when domestic pigs in Malaysia experienced an outbreak of disease initiated by fruit-eating bats. Subsequent outbreaks occurred in India and Bangladesh. Outbreaks of the closely related Hendra virus, another henipavirus also spread by fruit bats, have occurred in horses in Australia. All these outbreaks were characterized by transmission from animals to humans, with high mortality. Regions of the world where fruit bats (also called flying foxes) are found include much of South Asia, from Madagascar to Australia. These regions can be anticipated as sites of natural outbreaks of Nipah virus and Hendra virus, especially wherever domestic animals are raised in proximity to fruit bats.
Nipah virus is identified by its epidemiology, pathology with high mortality, and laboratory tests on the blood and tissue of victims. It can be detected by serological tests that identify antibodies to viral proteins in the blood. The virus has also been isolated from patients and grown in cells in culture, then further identified by antibody reactions to surface proteins of the virus and through its ultrastructure as seen in the electron microscope. Nipah virus RNA (ribonucleic acid) is detectable by the reverse transcriptase-polymerase chain reaction (RT-PCR) method. Forensic labs should retain blood and tissue samples from suspected victims of the virus for future tests and should take care to preserve the chain of evidence.
In animals, the symptoms of Nipah virus are mainly respiratory; in humans, symptoms are both respiratory and neurological. In humans, symptoms begin with fever and headaches, progressing to nausea, vomiting, weakness, coughing, and ultimately to respiratory distress and possibly very high fever and encephalitis. No effective treatment has yet been developed beyond supportive care. The mortality rate for humans who contract the Nipah virus is often more than 50 percent. Vaccines have been developed that show promise; tests with hamsters, cats, and horses indicate that they offer significant protection from the disease.
Transmission of the Nipah virus from fruit bats to animals most likely takes place through exposure to bat saliva, urine, or feces. Transmission to humans is likely from saliva and respiratory exudates in aerosols, with the further possibility of human-to-human transmission.
Outbreaks of Nipah virus infection outside the regions of fruit bat territory may be expected to have different causes, such as exposure to infected meat or to animals shipped from affected regions. One outbreak in humans took place because workers in a Singapore slaughterhouse were exposed to infected pigs from neighboring Malaysia in 1999. In the twenty-first century, a number of outbreaks occurred in India, and in early 2023, an outbreak in Bangladesh resulted in eleven infections and eight deaths. Potential exists for other episodes to take place outside the regions where Nipah virus occurs naturally, such as through transmission from travelers exposed during stays in fruit bat territory, through accidents in clinical or research laboratories, or through bioterrorist attacks.
Bibliography
Anderson, Burt, Herman Freedman, and Mauro Bendinelli, eds. Microorganisms and Bioterrorism. New York: Springer, 2006. Print.
Flint, S. J., L. W. Enquist, V. R. Racaniello, and A. M. Skalka. Principles of Virology: Molecular Biology, Pathogenesis, and Control of Animal Viruses. 2nd ed. Washington, DC: ASM, 2004. Print.
Hsu, V. P., et al. “Nipah Virus Encephalitis Reemergence, Bangladesh.” Emerging Infectious Diseases 10 (2004): 2082–087. Print.
"Nipah Virus Infection - Bangladesh." World Health Organization, 17 Feb. 2023, www.who.int/emergencies/disease-outbreak-news/item/2023-DON442. Accessed 16 Aug. 2024.
Sun, Yan-Qun, et al. "Mapping the Distribution of Nipah Virus Infections: A Geospatial Modelling Analysis." Lancet, vol. 8, no. 7, July 2024, doi.org/10.1016/S2542-5196(24)00119-0. Accessed 16 Aug. 2024.