Nipah virus: Past outbreaks, scrutiny helped in case detection
Nipah is mainly a zoonotic disease — when a pathogen jumps from a non-human host to humans — with some documented cases of transmission among humans
A combination of familiarity with symptoms, adherence to protocols laid down during previous outbreaks and effective contact tracing measures helped officials in Kerala detect cases of Nipah virus in time, experts said on Thursday, a day after a 24-year-old health worker tested positive taking the total number of cases to five.
It began on August 30, when a 47-year-old man died at a private hospital in Kozhikode with symptoms including fever that gradually turned into pneumonia.
On September 10, four of his relatives — his son (9), daughter, brother-in-law (24), and the brother-in-law’s son, were rushed to the Aster MIMS hospital in Kozhikode with fever.
“The man’s son soon suffered shortness of breath and seizures. Normal fever tests and other respiratory tests returned negative. That’s when we suspected that this was something different,” Dr Anoop Kumar AS, director of critical care medicine at the Aster hospital, said.
“Doctors treating the nine-year-old boyfound that his father had also experienced symptoms like disorientation before his death,” Dr Kumar, who was involved in management of the virus during the last outbreak in 2018, said.
On September 11, another man, 40, was admitted to the hospital with “symptoms of pneumonia which led to his death within minutes”, Dr Kumar said.
Dr Kumar’s experience from 2018 turned out to be instrumental in alerting authorities.
“The unusual symptoms were similar to those of Nipah, as we learnt in the past outbreak, and that is why I immediately alerted the authorities,” he said.
Kozhikode district medical officer Dr KK Rajaram added that unlike the 2018 outbreak, patients were also showing respiratory distress.
Nipah is mainly a zoonotic disease — when a pathogen jumps from a non-human host to humans — with some documented cases of transmission among humans.
In humans, at the start (5-14 days after exposure) it manifests with initial symptoms of headache and fever. Some patients also show respiratory illness during the early phases, according to a factsheet on the viral disease by CDC. It is followed by neurological symptoms like drowsiness, disorientation, confusion and epilepsy. These symptoms can progress to coma within 24-48 hours, eventually causing death by encephalitis — swelling of the brain — and acute respiratory distress syndrome.
About the 40-year-old, health officials said that he displayed symptoms like “vomiting and disorientation” at previous hospitals and clinics.
“He had displayed symptoms like vomiting, fits and disorientation which was also seen in other Nipah-positive patients. The deterioration of his condition was also quick. He died within 4-5 days of first complaining of fever. After his death, doctors conducted detailed postmortem studies whose results indicated the presence of the virus,” Dr Rajaram said.
Samples of the 40-year-old as well as the family members of the 47-year-old were sent to National Institute of Virology lab in Pune on September 11.
In the meantime, officials began efforts to find a common point of contact between the two men as they were not related and hailed from different areas. The 47-year-old man who died on August 30 was a resident of Maruthonkara, the 40-year-old who died on September 11 lived in Ayancheri.
“Through questioning of their family members, we found that they were both at a private hospital at the same time. The 40-year-old was accompanying his ailing father-in-law at the hospital where the 47-year-old was treated. They were likely in the same ward or room. That was the epidemiological point of contact,” said Dr Rajaram.
By the evening of September 12, three of the five samples sent from Kerala to the Pune lab came back positive for Nipah, confirming the suspicions of doctors and health officials.
While the samples of the 40-year-old, the son and brother-in-law of the 47-year-old returned positive, it was assumed that the 47-year-old was the index case in the outbreakand likely spread the infection to others.
His samples were never tested.
Frantic contact tracing measures were then afoot to locate all those who might have come in contact with the two patients who died, as well as the three currently under treatment.
The contact list, consisting of both high-risk and low-risk individuals, currently has 787 names and is likely to get bigger.
“Since the incubation period of the virus is 6-14 days extending up to 20 days, we will have to keep a close watch on the contacts for some time. Symptomatic high-risk contacts have been shifted to the Medical College hospital,” said Dr Rajaram.
“Right now, it’s a 24-hour operation. We had intensified our measures right after the second death. We already have a good system in place for surveillance and contact tracing. There are 16 committees formed to look at various aspects of the outbreak. Just today, our local health workers visited nearly 4800 homes in the district as part of surveillance,” said the top district health officer.
Officials said that all three active cases are under treatment at private hospitals, including the 24-year-old male nurse who tested positive on September 13.
While he is currently asymptomatic, a nine-year-old boy, who tested positive on September 12 in Kozhikode, remains on a ventilator support with his condition showing neither improvement nor deterioration.