Nipah Virus can be detected in bodily fluids such as blood, cerebrospinal fluid, throat swabs, and urine through RP PCR.
Published Aug 05, 2024 | 7:00 AM ⚊ Updated Aug 05, 2024 | 7:00 AM
Nipah virus outbreak in Kerala
In a recent development concerning the death of a 14-year-old boy who was infected with the Nipah virus, on Sunday, 4 August, the presence of the virus was detected in bat samples collected from Pandikkad in Kerala’s Malappuram district.
The boy died on 21 July and a total of 472 people were traced to be in his contact list, all of who tested negative according to the test conducted as per the Nipah protocol. Of them, 261 individuals who have completed the mandatory 21-day isolation period have been removed from the list.
According to Health Minister Veena George, antibodies were found in six of the 27 fruit bat samples collected within a five-kilometre radius. Authorities continue to monitor the situation closely, following established Nipah virus protocols to ensure public safety.
While primary contacts are tested after 21 days, secondary contacts will need to be tested only if they present symptoms of Nipah. Currently, no one under incubation is exhibiting any symptoms.
The Health Minister is expected to hold a meeting with the Nipah unit on Monday, 5 August at Malappuram. There is no current information or special guidelines given to the health workers regarding the presence of antibodies in bats, but further details are likely to be published tomorrow.
Apart from releasing guidelines in Pandikkad to avoid panic, a panchayat-level meeting will also be held to address this. Since antibodies have been detected in bats in the Pandikkad residential area, these guidelines will serve as the initial step. As of now, no further instructions have been issued by the health department regarding subsequent actions, said Sreejith Ambrakkatt, Pandikkad Health Inspector, to South First.
Kerala has seen cases of this infection in 2018, 2019, 2021 and 2023. The Kerala government started to heighten surveillance ever since the minor’s death in July and unveiled a year-round calendar to deal with this virus.
NiV first emerged in Kerala in 2018, causing significant concern. The World Health Organisation defines NiV as a zoonotic virus transmitted from animals to humans. It can also be transmitted through contaminated food or directly between people. In infected people, it causes a range of illnesses from asymptomatic (subclinical) infection to acute respiratory illness and fatal encephalitis.
Fruit bats, scientifically known as flying foxes, serve as natural hosts for the Nipah virus. The virus is transmitted to humans also through infected animals, such as bats and pigs, or food contaminated with saliva, urine, and excreta of infected animals. It can also be transmitted directly from person to person through close contact with an infected person, although this represents a less common transmission route.
Nipah Virus can be detected in bodily fluids such as blood, cerebrospinal fluid, throat swabs, and urine through RP PCR. ELISA test can also help detect NiV-specific IgM and IgG antibodies in the blood. CSF is an important part of the work up and also helps rule out other possible causes of Encephalitis.
Routine blood investigations may show thrombocytopenia, leukopenia and transaminitis, explains Dr Rahul Chawla.
MRI Brain does not have any characteristic signature finding but may have discrete high-signal-intensity lesions in the subcortical and deep white matter of the cerebral hemispheres, he adds.
Nipah virus encephalitis does not have any specific antiviral treatment and management primarily involves supportive or Intensive Care. Patients with severe respiratory distress or encephalitis may require mechanical ventilation. Anticonvulsant therapy may be required to control or prevent seizures in patients with encephalitis.
This is not the first time, Nipah virus has been found in bats in Kerala. It should be mentioned that in a study published in 2023, Nipah Virus were found in 20.9 percent of bats in Kerala.
The study done by ICMR-NIV published in Frontiers in Microbiology conducted a surveillance of Nipah virus in Pteropus medius bats in Kerala state during February, July, and September 2023. The study found an overall seroprevalence of 20.9 percent in 272 P. medius bats tested.
While the throat and rectal swab samples of 321 bats were negative for Nipah virus RNA, 4 out of 44 P. medius bats tested positive for the virus in their liver/spleen samples.
The study cautions that there is a spillover risk in the region and necessary precautions should be taken. The partial N gene retrieved showed more than 99 percent similarity with the earlier reported Nipah virus genome from Kerala state, India.
The study was motivated by the history of Nipah virus outbreaks in Kerala, with four outbreaks reported since 2018. The Pteropus medius bats are known reservoirs for the virus, and the research aimed to assess the prevalence of NiV in this bat population in regions affected by previous outbreaks.
Bats were sampled in three phases (February, July, and September 2023) from areas around Kozhikode, where outbreaks had occurred. A total of 289 P. medius bats were captured, and various samples (throat, rectal, and serum) were collected. Additionally, organ samples were taken from a subset of bats for further analysis.
The findings highlight a significant risk of spillover from bats to humans in the region. The study emphasised the need for ongoing surveillance and preventive measures to mitigate the potential for future outbreaks. The presence of antibodies in bats suggests that they are exposed to the virus and could transmit it to humans under certain conditions.
The research had underscored the importance of monitoring bat populations in areas with a history of Nipah virus outbreaks. The close genetic relationship of the detected viral strains to those previously identified in human cases in Kerala raises concerns about the ongoing risk of zoonotic transmission.
(Edited by Neena)
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