Tomato flu is a viral illness that emerged in India in 2022, primarily affecting children under five years old. It is characterized by flu-like symptoms and distinctive red blisters resembling tomatoes, which has led to its colloquial name1 . Although the exact cause remains under investigation, many experts believe tomato flu is a variant or atypical presentation of hand, foot, and mouth disease (HFMD), a common childhood infection caused by enteroviruses such as Coxsackievirus A162 .
The tomato flu outbreak highlights the importance of active surveillance and molecular epidemiology to distinguish new viral strains from atypical manifestations of known diseases. Accurate diagnosis is essential to avoid unnecessary panic and ensure appropriate public health responses11 4.
Unusual Presentation of a Common Childhood Illness
Hand, foot, and mouth disease (HFMD) is a frequent childhood illness caused by enteroviruses, predominantly Coxsackievirus A16 (CA16), Coxsackievirus A6 (CA6), and enterovirus 71 (EV-A71) 3. Typically, HFMD presents with fever, oral ulcers, and a rash on the palms, soles, and sometimes buttocks. However, the "tomato flu" outbreak in India has shown an unusual clinical manifestation of HFMD, with larger, more prominent red blisters resembling tomatoes4 .
💡 Did You Know?
Tomato flu is named for the red blisters resembling tomatoes that appear on infected children in India1 .
HFMD is a disease that people are very familiar with; the only slight difference is that adults are getting it now, though the disease is much milder in adults11 .
The atypical presentation includes:
- Larger, round, red skin lesions that can resemble tomatoes in size and appearance1 .
- Vesicular rashes on the hands, feet, and legs, sometimes accompanied by oral lesions causing painful eating or drinking1 5.
- Flu-like symptoms such as high fever, fatigue, nausea, vomiting, diarrhea, dehydration, and body aches2 6.
- Joint swelling and intense joint pain, mimicking symptoms of chikungunya2 6.
- Unlike typical HFMD, some cases show no fever or systemic symptoms despite rash presence7 .
Atypical HFMD presentations are increasingly recognized and may include diffuse rashes, purpuric lesions, and even adult-age predilection, which differs from the usual pediatric pattern8 . While EV-A71 strains can cause severe and sometimes fatal HFMD cases, CA16 is generally associated with mild symptoms such as blisters or ulcers9 .
The tomato flu blisters have also been compared to those seen in monkeypox, although the diseases are distinct6 . The larger blister size in tomato flu cases initially led to confusion and speculation about a novel virus, but molecular testing has identified Coxsackievirus A16 as the causative agent in several cases7 5.
Tomato flu cases in India have raised public health concerns due to their unusual blister size and symptom overlap with other viral infections. However, evidence suggests that tomato flu is an atypical presentation of HFMD caused by Coxsackievirus A16, not a novel virus. Preventive measures focus on hygiene, isolation, and awareness to control spread among children10 1115.
Treatment for tomato flu aligns with the supportive care used for HFMD and similar viral infections:
- Isolation of affected children to prevent spread10 .
- Rest and hydration to support recovery10 .
- Use of acetaminophen or paracetamol for fever and body aches2 6.
- Hot water sponging to relieve irritation from rashes10 6.
No specific antiviral drugs or vaccines are currently available for tomato flu or HFMD7 6. The disease is self-limiting, with most children recovering without hospitalization or complications1 7.
Need for More Data on Cases in India
The first reported cases of tomato flu appeared in Kerala, India, in May 2022, with over 80 confirmed cases in children under five by August 202212 . Additional cases have been reported in Tamil Nadu, affecting children under nine years old1 . Despite the growing number of cases, the exact etiological agent remains under investigation, and more detailed epidemiological and molecular data are needed to clarify whether tomato flu represents a new viral strain or an atypical form of HFMD4 13.
Calling the virus new and sensationalizing HFMD as 'tomato flu' through correspondence in Lancet Respiratory Medicine, without taking into account data in published literature or facts on the ground, is the issue here11 .
The clinical features of tomato flu overlap with other viral infections endemic to India, such as dengue and chikungunya, complicating differential diagnosis10 . Key overlapping symptoms include:
- High fever
- Red, painful blisters or rashes
- Flu-like symptoms such as fatigue, nausea, vomiting, and diarrhea
- Joint swelling and pain
Because of these similarities, tomato flu may be misdiagnosed as chikungunya, dengue, or HFMD10 14. Molecular testing of swabs from affected children has identified Coxsackievirus A16 as the causative agent in some cases, supporting the hypothesis that tomato flu is a variant of HFMD rather than a novel virus11 75.
Public health responses in India have focused on:
- Promoting hygiene and sanitation to reduce transmission15 .
- Isolating infected children for 5–7 days from symptom onset to prevent spread6 .
- Raising awareness among parents, schools, and healthcare providers about the disease and its management15 .
- Closing schools temporarily if outbreaks occur to limit viral transmission11 .
Just as we are dealing with the probable emergence of fourth wave of COVID-19, a new virus known as tomato flu, or tomato fever, has emerged in India in the state of Kerala in children younger than 5 years6 .
Transmission is believed to occur through close contact and contact with contaminated objects such as clothing, bedding, towels, toys, and books2 . The disease is highly contagious among children, especially those under five years old, who are at increased risk due to frequent viral infections in this age group6 .
Despite concerns raised by media reports, leading Indian clinicians emphasize that tomato flu is not a new disease and that HFMD is well understood as a self-limiting illness with rare complications11 . No deaths or severe cases have been reported in the tomato flu outbreaks so far2 7.
| Aspect | Tomato Flu / HFMD Characteristics | Notes |
|---|---|---|
| Age group affected | Mostly children under 5 years, some cases in older children | Adults can get milder HFMD11 |
| Causative agent | Coxsackievirus A16 and A6 enteroviruses | Confirmed by molecular testing11 5 |
| Symptoms | Fever, red blisters, flu-like symptoms, joint pain | Overlaps with chikungunya and dengue10 |
| Contagiousness | Highly contagious through close contact and fomites | Isolation recommended6 |
| Treatment | Supportive care: rest, fluids, fever control | No specific antivirals or vaccines7 |
| Outcome | Self-limiting, no hospitalizations reported | Rare complications1 7 |
