Expert reaction: What do we know about 'tomato flu'?

Professor Vasso Apostolopoulos is Pro Vice-Chancellor, and Immunology and Translational Group Leader at Victoria University. She is also an author on The Lancet Respiratory Medicine paper which described the outbreak in India.

"We are still trying to identify exactly what this virus is. Its symptoms are similar to dengue fever and Chikungunya virus, which are common in the area, but it doesn’t appear to be them. Similarly, it also shares symptoms with hand, foot and mouth disease.

There is a case study of one child returning to the UK from India, who has these symptoms and tested positive for enterovirus, which is one cause of hand foot and mouth disease. In this single case, the enterovirus shared 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. However, this is one case study, and it needs to be confirmed with more cases. Hopefully, within the next week or so we should be able to confirm exactly what it is.

It has been called tomato virus because the symptoms include small grapelike blisters, that can actually grow as big as a tomato, and are red like a tomato. It's got nothing to do with tomatoes or eating tomatoes.

At the moment it looks like the virus is mild and goes 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. At the moment it is still isolated and doesn’t appear to have spread beyond India.”

Professor Andreas Suhrbier is Group Leader, Inflammation Biology at QIMR Berghofer Medical Research Institute

“Early indications are that tomato flu is actually hand foot and mouth disease (HFMD) caused by Coxsackievirus A16, the virus that is most commonly associated with HFMD. The virus and disease are common worldwide, including Australia, mostly causing illness in children.

The disease is generally mild, lasting 7-10 days, with symptoms including fever, rash, sometimes mouth sores, and joint pains. The virus can spread rapidly and can be transmitted on unwashed hands, surfaces contaminated by faeces, and via droplets from sneezing or coughing.”

Ashley Quigley is a Senior Research Associate (Epidemiology Team Leader) in Global Biosecurity at the Kirby Institute, UNSW.

"Little is known about tomato flu in India. 'Tomato Flu' has been used as a long-standing colloquial term to describe fever and rash in children and was detected by EPIWATCH, a system which uses the power of Al and open-source data to capture early epidemic signals globally and enables early detection of epidemics, in early May 2022.

Tomato flu could be an after-effect of chikungunya or dengue fever in children, with the presentation also similar to the viral hand, foot and mouth disease which infects children aged 1-5 years. The actual ways in which the infection spreads are still being studied but it is believed to be highly contagious.

It is unclear if these outbreaks are caused by a single virus or more than one virus. Urgent laboratory testing and genotyping of any virus identified is therefore needed to confirm whether Tomato Flu is in fact a new virus.

In light of the COVID-19 pandemic, hyper vigilance and improvement in surveillance techniques and reporting may be picking up more infections, however the long-term effects of COVID-19 could lead to an increase in illnesses in an already weakened immune system and so we need to be cautious until more is known about this infection."