Did you hear about a new virus sweeping through kids in India? It’s called “tomato flu,” and according to some reports we all should be very concerned. But it turns out “tomato flu” is not new, has potentially been around in some form for at least 15 years, and is probably just a relatively novel manifestation of a common childhood virus.
On August 17th, a correspondence letter was published in the journal The Lancet Respiratory Medicine. The letter, titled "Tomato flu outbreak in India," reported on the potential emergence of a “new virus,” with 82 children diagnosed with a mystery illness between early May and late July.
Red flags could be found in the letter's very first paragraph as its authors described this viral illness as “new”, “emerging” and “endemic” – terms one researcher described as entirely contradictory. How can a virus be new and emerging but also simultaneously in an endemic state?
The letter went on to characterize tomato flu as an illness similar to COVID-19 – with symptoms of fever, fatigue and body aches - but also presenting with large and painful blisters that can reach the size of tomatoes. Hence the name, tomato flu.
Although the letter did speculate the illness could potentially be anything from a new form of a common childhood infection to a type of post-viral condition, it essentially framed the whole idea of “tomato flu” as a “new virus.” However, no actual laboratory data was offered to back up this suggestion and the main references to “tomato flu” cited in the letter were news reports from local Indian websites.
These kinds of correspondence letters to journals are not peer-reviewed, despite coming with the veneer of being in a journal such as The Lancet. They are published without any oversight and often serve as valuable sirens to other scientists, highlighting things that are worthy of closer investigation. But in a post-COVID world, news of a potential “new virus” could never stay quiet for the few weeks scientists would need to actually verify the suggestion.
Within days the story was amplified via hundreds of articles, and tomato flu had become a real thing based on this single correspondence with no actual lab-verified evidence. Headlines loudly declared, "India on Alert as Rare Viral Illness Tomato Flu Spreads," and other outlets warned the “mysterious new illness” was likely to spread to your country and infect your children.
While these hyperbolic stories were spreading, several researchers began to question the veracity of this initial research letter. Australian epidemiologist Gideon Meyerowitz-Katz quickly published a response to the letter, arguing there is no evidence these illnesses in India are caused by a new virus and that the current news cycle seems mostly based on “hot air.”
“All of the news is essentially based on a single case-report from a public official describing an outbreak of something that is apparently locally called 'tomato flu,'” explained Meyerowitz-Katz. “But that’s … really not a lot to go on. The authors don’t even provide evidence that this is, indeed, a virus, leaving the door open to other pathogens that might cause a similar rash.”
Meyerowitz-Katz and other researchers quickly pointed to a letter published in the Pediatric Infectious Disease Journal, two days after The Lancet correspondence. This letter, from a team of infectious disease researchers in the United Kingdom, reported on two suspected “tomato flu” cases.
The two children, a five-year-old boy and a 13-month-old girl, developed signs of the mystery “tomato flu” illness a week after returning from a family holiday in Kerala, India. Lab testing revealed the children did not have a mystery new virus, but in fact were infected with a common childhood enterovirus named coxsackie A16.
“Coxsackie A16 causes hand, foot and mouth disease (HFMD), so-called because the patient has blisters on the palms of their hands, soles of their feet and in their mouth,” explained microbiologist Sarah Pitt in The Conversation. “So it seems that tomato flu is actually HFMD. It is not a type of influenza, has nothing to do with tomatoes and is not a new disease at all.”
Not only that, but the UK researchers indicated the particular viral strain wasn’t even especially unique. Genomic testing connected the viral samples to a strain of coxsackie A16 previously identified in China a decade ago.
Meyerowitz-Katz said this UK data isn’t a “slam dunk” allowing us to entirely write off concerns over a new disease emerging in India, but it is enough evidence to make a reasonable scientist hesitant about claiming “tomato flu” is a whole new thing. And perhaps even more relevant is the simple fact that the terms “tomato flu” and “tomato fever” have long been used in India to reference outbreaks of unexplained illness.
Back in 2007, for example, several thousand people in Kerala were diagnosed with a mystery illness that at the time was called “tomato fever.” Symptoms included fever, rashes and, “tomato like wounds especially on hands and legs, from which fluid oozes out.”
During this mystery outbreak the illness was suspected as being a post-viral condition following earlier infection with a mosquito-borne virus called Chikungunya. The hypothesis was the "tomato fever" illness could be an after-effect of the earlier viral infection.
And now, some researchers are already speculating this wave of “tomato flu” could be related to COVID-19. Sarah Pitt said viruses have been behaving strangely since the COVID-19 pandemic began, from the outbreak of hepatitis in children last year to the recent global spread of monkeypox.
Ashley Quigley, a research associate in Global Biosecurity at the Kirby Institute, said her team’s AI-driven epidemic watch system has picked up signals of unusual disease activity in India but that doesn’t mean “tomato flu” is some kind of new virus. Instead, it is possible SARS-CoV-2 infections have weakened immune systems to the point where a pre-existing virus is manifesting in new or unusual ways.
“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,” noted Quigley.
Virologist Angela Rasmussen has been particularly frank in her criticism of the media over recent coverage of “tomato flu.” According to Rasmussen, the recent reports of “tomato flu” are certainly interesting from an epidemiological perspective, and worthy of investigation, but “alarmist”, “unhelpful” and “sensationalized” news stories are a great example of “how not to report on an infectious disease.”
“After 2.5 years of this s**t, I expect journalists to know better than to uncritically report on “novel tomato flu virus.” It says a lot about what an outlet values in its coverage of health and science: clicks or truth,” Rasmussen tweeted.
