Nipah virus (NiV) was first recognised in 1999 during an outbreak among pig farmers in Malaysia. In India, its first outbreak was reported in Kozhikode, a district of Kerala, which has spread via Bangladesh. While the first case of NiV was reported three years back, recent news is suggestive of its third outbreak since then.
NiV infection is a zoonotic illness that is transmitted to people from animals and the primary source of the NiV are bats. It can also be transmitted to humans either through contaminated food or can be directly contagious. “While it was also noted that the virus had a tendency to severely affect pigs, consumption of virus infected pork is another attributable factor,” Dr Ashutosh Shukla, Senior Director – Internal Medicine & Medical Advisor says.
Even though it is a known disease, the reappearance of the virus is a matter of concern and thus all possible preventive measures need to be taken before it engulfs the planet just like the COVID pandemic. “In severe infections, a person may die on the spot, but other symptoms may include acute respiratory illness, vomiting, headache and neck stiffness, and the complications increase when the virus starts affecting the brain and the nervous system, leading to swelling in the brain and eventually death,” says Shukla.
According to the World Health Organisation (WHO), Nipah virus infection in humans causes a range of clinical presentations, from asymptomatic infection (subclinical) to acute respiratory infection and fatal encephalitis.
NiV is primarily diagnosed through Polymeric Chain reaction (PCR) as done in cases of dengue or other viral ailments. Early detection and monitoring is the key to prevent complications. Currently, there are no licensed treatments available for NiV infection and it is limited to supportive care, including rest, hydration, and treatment of symptoms as they occur.
WHO reported that initial signs and symptoms of Nipah virus infection are nonspecific, and the diagnosis is often not suspected at the time of presentation. This can hinder accurate diagnosis and creates challenges in outbreak detection, effective and timely infection control measures, and outbreak response activities. In addition, the quality, quantity, type, timing of clinical sample collection and the time needed to transfer samples to the laboratory can affect the accuracy of laboratory results.
The case fatality rate is estimated at 40% to 75%. This rate can vary by outbreak depending on local capabilities for epidemiological surveillance and clinical management. “Usually the infection of Nipah virus occurs through the contaminated bodily fluids. In that case, the infectivity rate is not very high but if it is not maintained in the local spread, it might be of great concern,” says Dr Ankita Baidhya, Consultant, Infectious Diseases, Manipal Hospital, Dwarka, New Delhi.
The symptoms include high fever, vomiting, headache and neck stiffness and the complications increase when the virus starts affecting the brain and the nervous system. Infection can cause mild to severe disease including swelling of the brain leading to death. Symptoms typically appear in 4-14 days following exposure to the virus. “The illness initially presents as 3-14 days of fever and headache, and often includes signs of respiratory illness, such as cough, sore throat, and difficulty in breathing. A phase of brain swelling may follow, where symptoms can include drowsiness, disorientation, and mental confusion, which can rapidly progress to coma within 24-48 hours,” Shukla tells you.
Like in any other disease, early detection and monitoring is a must. And even though communication of the virus through humans is less common, it is more important to follow precautionary steps to prevent it from spreading. If you are living somewhere a lot of bats are found, you should be extra careful. In Kerala, where a lot of bad population is there, people should be careful if any bat in the vicinity is found dead. “If people are reporting fever and headache and some sort of brain infection symptoms like forgetfulness, immediate testing should be done,” Baidhya says.