The southern Indian state of Kerala is on high alert due to an outbreak of Nipah virus, which has already claimed two lives. According to Kerala Chief Minister Pinarayi Vijayan, the infection has been confirmed in Kozhikode district, resulting in the deaths of two individuals. CNN reports that over 700 people have been tested for potential infection after being identified as close contacts.
State Health Minister Veena George stated that among these contacts, 77 have been deemed “high risk” and have been instructed to isolate at home while their health is closely monitored. Three people, including a child, who tested positive for the virus have been admitted to the hospital for observation.
Nipah virus is a zoonotic virus, meaning it can be transmitted between animals and humans. Preventive measures include avoiding contact with sick bats and pigs, avoiding areas where the virus is present, and refraining from consuming raw date palm sap, which can be contaminated by infected bats. Currently, there is no vaccine available for Nipah virus. The fatality rate for Nipah is estimated to be between 40 to 75 percent, much higher than the approximately 2 percent fatality rate of COVID-19.
In response to the outbreak, several measures have been implemented in Kozhikode district. Seven villages have been declared “containment zones,” while nine villages have seen closure of religious institutions, government buildings, public offices, and educational centers. Public transportation in high-risk areas has been suspended. In the neighboring states of Tamil Nadu and Karnataka, authorities have ordered testing for visitors from Kerala and isolation for individuals displaying influenza symptoms.
State Health Minister Veena George informed Reuters that experts are collecting samples from forested areas that could be potential hotspots for transmission. Samples have been taken from animal droppings, bat urine, and half-eaten fruit from a village near a 300-acre forest inhabited by multiple bat species.
This is the fourth outbreak of Nipah virus in Kerala since 2018. The 2018 outbreak resulted in 17 deaths and over 230 people being tested. In 2019, 300 individuals were placed under surveillance after a man tested positive. In 2021, a third outbreak occurred, leading to the death of a 12-year-old boy. Kerala Chief Minister Pinarayi Vijayan has called for caution and readiness to follow instructions from the Health Department and Police.
The U.S. Centers for Disease Control and Prevention (CDC) states that fruit bats serve as the natural reservoir for Nipah virus in nature. Infection with Nipah virus can cause encephalitis, resulting in mild to severe illness and even death. Annual outbreaks primarily occur in parts of Asia, particularly Bangladesh and India. Symptoms typically appear within four to 14 days after exposure, starting with fever and headache and progressing to respiratory illness symptoms like cough, difficulty breathing, and sore throat. Encephalitis may follow, with symptoms such as drowsiness, disorientation, and mental confusion, which can rapidly lead to coma. The death rate ranges from 40 to 75 percent, and survivors may experience long-term side effects.
Currently, there are no licensed treatments available for Nipah virus. Supportive care, rest, hydration, and symptomatic treatment are the main approaches. The CDC mentions ongoing development and evaluation of immunotherapeutic treatments, such as monoclonal antibody therapies and the potential use of the antiviral treatment remdesivir.
Although Nipah virus outbreaks have been limited to Asia so far, the risk of exposure exists through travel. John Lednicky, a research professor at the University of Florida, expressed concerns related to global travel and its potential to spread unusual pathogens. The first recorded outbreak of Nipah virus occurred in Malaysia and Singapore in 1999, where it infected both pigs and humans, resulting in nearly 300 cases and over 100 deaths. Subsequent outbreaks in India and Bangladesh were associated with the consumption of fruit or fruit products contaminated with saliva or urine from infected fruit bats.