Health experts are monitoring an outbreak of a viral infection detected in children in the southern Indian state of Kerala earlier this year that has now spread to two other regions.
More than 82 children aged under five had been diagnosed with the virus as of July 26, according to the Lancet Respiratory Medicine journal.
Researchers say the illness dubbed 'tomato flu' is non-life threatening but a "highly infectious" disease that appears to be a variant of hand foot mouth diseases — but this is yet to be confirmed.
Scientists are still trying to identify exactly what the virus is. Here is what they have said so far.
What do we know about 'tomato flu'?
Its symptoms are similar to dengue fever and chikungunya virus, which are common in the area, but it doesn't appear to be them, Victoria University's Vasso Apostolopoulos said.
Professor Apostolopoulos is the university's immunology and translational group leader and co-authored the Lancet paper.
"Similarly, it also shares symptoms with hand, foot and mouth disease," Professor Apostolopoulos said.
The first two illnesses are known to be spread by mosquitoes. And hand, foot, and mouth disease is a common infectious disease affecting mostly children aged between one and five years and immunocompromised adults.
Professor Apostolopoulos said it looked like the virus was mild and went away on its own.
"But most people who have had this infection are young, and we don't really know what might happen in an immunocompromised person or if it spreads to elderly people," she said.
She said children are at increased risk of exposure to tomato flu as viral infections are common in this age group.
Why the name?
It's been called tomato virus because of the eruption of red and painful blisters throughout the body and some can grow as big as a tomato and are red like the fruit.
"It's got nothing to do with tomatoes or eating tomatoes," Professor Apostolopoulos said.
Given its similarities to hand, foot, and mouth disease, the Lancet says if tomato flu in children is not controlled and prevented, transmission might lead to serious consequences by spreading in adults as well.
When was the virus first identified?
In May this year it was first identified in the Kollam district of Kerala, India.
More than 82 children younger than five with the infection have been reported by the local government hospitals.
"We are still trying to identify exactly what this virus is," Professor Apostolopoulos said.
There is a case study of a 13-month-old and her five-year-old brother returning to the UK from India, who had these symptoms and tested positive for enterovirus, which is one cause of hand foot and mouth disease.
"[It] shares some sequences with a strain of virus called coxsackie A16 but it is not entirely the same, although it appears it is probably from the clade of this virus," Professor Apostolopoulos said.
In this case, she says it’s likely that tomato flu could be a variant of hand foot and mouth disease, but this "needs to be confirmed with more cases and genome analysis".
How does the virus affect people?
The primary symptoms observed in children include high fever, rashes, and joint pain.
Tomato flu blisters resemble those seen with the monkeypox virus in young individuals and rashes also appear on the skin that lead to skin irritation.
Intense joint pain is another symptom association with the virus.
Similar to other viral infections, other symptoms include fatigue, nausea, vomiting, diarrhoea, dehydration and bodyaches.
What are the known treatments for tomato flu?
There are no antiviral drugs or vaccines available for the treatment or prevention of tomato flu.
The recommendation is that isolation should be followed for five to seven days from symptom onset to prevent the spread of infection to other children or adults, according to the Lancet.
It states the best means of prevention is the "maintenance of proper hygiene and sanitisation" as well as preventing infected children from sharing toys, clothes, food, or other items with other non-infected people.
Where are the cases?
Cases have now been reported in neighbouring Tamil Nadu state and in Odisha in the east, where children as old as nine have been infected, even though the virus usually affects children aged under five.
To date, apart from Kerala, Tamilnadu, and Odisha, no other regions in India have been affected by the virus.
"At the moment it is still isolated and doesn't appear to have spread beyond India," Professor Apostolopoulos said.
Precautionary measures are being taken by the Kerala Health Department to monitor the spread of the viral infection and prevent its spread in other parts of India.
Professor Apostolopoulos says there is no need to be alarmed at present, but it's important to understand tomato flu's prevention, symptoms and management.
