What is ‘tomato flu?’

Last week, The Lancet reported on the outbreak of a new viral infection spreading among children under five in Kerala, India.
 
Described as rare and non-life-threatening, the report has nonetheless generated widespread media attention due to it causing red and painful blisters throughout the body that can gradually enlarge to the size of a tomato.
 
The infection was detected by EPIWATCH, a system which uses the power of Al and open-source data to capture early epidemic signals globally, in early May 2022.
 
But while the extent of its spread is not yet known, at least 82 cases have been reported by local government hospitals since the infection was first identified, prompting concerns it could soon reach Australia.
 
So what do GPs need to know?
 
According to Professor Vasso Apostolopoulos, Immunology and Translational Group Leader at Victoria University and co-author of The Lancet paper, scientists 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,’ she said.
 
‘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.
 
‘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.’
 
She also pointed out that tomato flu 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,’ Professor Apostolopoulos said.
 
‘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.’
 
Meanwhile, Epidemiology Team Leader in Global Biosecurity at the Kirby Institute, Ashley Quigley, explains that while the ways in which the infection spreads are still being studied, it is believed to be ‘highly contagious’.
 
‘It is unclear if these outbreaks are caused by a single virus or more than one virus,’ she said.
 
‘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.’
 
Aside from the red blisters, the primary symptoms observed in children with tomato flu are similar to those of chikungunya, which include high fever, rashes, and intense pain in joints. The blisters are also said to resemble those seen with the monkeypox virus in young individuals.
 
‘As with other viral infections, further symptoms include, fatigue, nausea, vomiting, diarrhoea, fever, dehydration, swelling of joints, body aches, and common influenza-like symptoms, which are similar to those manifested in dengue,’ The Lancet paper reports.
 
‘In children with these symptoms, molecular and serological tests are done for the diagnosis of dengue, chikungunya, zika virus, varicella-zoster virus, and herpes; once these viral infections are ruled out, contraction of tomato virus is confirmed.’
 
Isolation should be followed for 5–7 days from symptom onset ‘to prevent the spread of infection to other children or adults’.
 
Proper hygiene and sanitisation of the surrounding necessities and environment as well as preventing the infected child from sharing toys, clothes, food, or other items with other non-infected children, are identified as the ‘best’ solutions for prevention.
 
As yet, no antiviral drugs or vaccines are available for tomato flu, and the paper’s authors recommend similar treatments to those utilised for chikungunya, dengue, and hand, foot, and mouth disease – isolation, rest, plenty of fluids, and hot water sponge for the relief of irritation and rashes.
 
Supportive therapy of paracetamol for fever and bodyache and other symptomatic treatments are required, The Lancet paper states.
 
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