Outbreak of tomato flu in India raising concerns: is it a false alarm or are we welcoming a new pandemic?

Dear Editor,

‘Tomato flu’ recently came to the attention of doctors and other health professionals due to a suspected outbreak in the Kollam District of Kerala, India, in May 20221. Then, the disease spread to the neighboring districts, and new cases were reported in the bordering areas. Most of the reported cases had the presentation of tender and painful, red-colored blisters which enlarged over time and looked like red tomatoes. These blisters are not only found in the mouth, palms, and soles, as the name ‘Hand, Foot, and Mouth Disease’ suggests, but some atypical locations like buttocks and the shedding of the nails have also been recently found related to the disease2. The rest of the symptoms resembled any generalized flu-like viral illness, such as nausea, vomiting, diarrhea, and fever3. Thus, the combination of tomato-like blisters and flu-like symptoms led to the name ‘Tomato flu.’ At present, there is no definitive diagnostic test for this disease. There are many similarities between the presentation of the tomato flu and some other viral illnesses, summarized in Table 1. These diseases need to be ruled out to make the diagnosis of tomato flu.

Table 1.

Differential diagnoses of tomato flu

Differential diagnosis	Causative agent	Cutaneous symptoms	Other features
Hand, foot, and mouth disease	Coxsackievirus	Vesicles and ulcerations in the oral cavity, palms, and soles/painful blisters all over the body that coalesce and enlarge in the form of tomatoes	Generalized body aches, high fever, cough, pain in the joints, nausea, vomiting, and diarrhea
Chikungunya	Chikungunya virus	Diffuse, red-colored rash on trunk, extremities, palms, and soles	High fever, constipation, headache, nausea, and retro-orbital pain
Monkeypox	Human monkeypox virus	Macules, papules, or vesicular rash	Fever, headache, chills, and body aches
Chickenpox/varicella	Varicella-zoster virus	Erythematous rash on the scalp, face, trunk, and extremities; passes through different stages	Fever, headache, and nausea

The disease is raising fears and concerns in public due to its contagious nature and its effect on children less than 5 years of age4. This, along with the ongoing burden of coronavirus disease 2019 (COVID-19) pandemic on healthcare system, can make it difficult to control the outbreak efficiently.

The causative agent of tomato flu is not yet known with certainty. The most popular belief now is that the disease is actually a variant of the previously widespread hand, foot, and mouth disease caused by the coxsackievirus5. It is believed to be transmitted by close contact with the affected person and also through their used items such as clothes, towels, sheets, toys, books, etc6.

On the 6th of May 2022, the district of Kollam, Kerala, reported the first case of tomato flu. Till the 26th of July 2022, the disease was reported in more than 82 children under the age of 5. The Regional Medical Research Centre of Bhubaneswar also reported that 26 children under the age of 9 in the state of Odisha had the illness. To date, only Kerala, Tamil Nadu, and Odisha have reported the cases4. Another suspected case was reported in Nepal. Although the affected person was an adult (in contrast to children being affected in India) and presentation was slightly different, it was reported as tomato flu-like illness, making Nepal the second country to report tomato flu in the world7.

Because the symptoms of COVID-19, chikungunya, and dengue fever are similar to those of tomato flu, doctors warn it might be challenging to diagnose accurately. The relatively high incidence of chikungunya in Kerala adds up to the above challenge. Medical professionals also concur that the virus and its clinical manifestations are evolving since the initial outbreak in Kozhikode in 2001, which makes it further challenging to diagnose. Another challenge is the limitation of the disease surveillance system of India, which might have possibly led to underreporting of the tomato flu cases5. Treatment is mainly supportive with plenty of fluids, rest, and symptomatic management. Managing the outbreak of tomato flu in India is of prime importance since the country is also struggling with COVID-19 and monkeypox pandemics4 (Fig. 1).

Figure 1.

Illustrating challenges in combating tomato flu.

Since tomato flu spreads by respiratory droplets, it is very contagious. So isolation for 5–7 days from the onset of symptoms will prevent transmission4. Now that the concept of isolation is not so new to the general population owing to the COVID-19 pandemic, compliance would be easier. Disinfection of surfaces, toys, clothes, and other items in use by sick children should be performed. Proper surveillance would help in identifying unreported or asymptomatic cases. There is a potential for this disease to spread beyond India. The focus should be on stopping the spread of the virus to other cities and countries. Strict travel advisories, in this regard, would be of paramount importance. All nonaffected states should form standard operating protocols for traveling and reporting potential cases. On a global level, vigilance and international collaboration are important as the world is already going through COVID-19 and monkeypox. Healthcare workers should be trained efficiently to differentiate red blisters of tomato flu from other skin conditions. Adequate provision of medical supplies, hospital beds, and medications should also be ensured. Prevention of spreading misinformation, along with the removal of the stigma attached to infectious diseases, would help to increase the documentation of the incidence of reported cases. The general public should be particularly aware of common symptoms, course of illness, isolation guidelines, and transmission sources. People should be urged to bring the patients to hospitals following standard operating protocols, and at-home treatment should be discouraged. In this regard, the use of television, the Internet, and other resources can work wonders. The most efficacious and cost-effective ways to combat viral infections include drug repurposing and vaccine administration. Up till now, no vaccines or drugs are present against tomato flu4. Moreover, it is high time for extensive research to discover the exact pathophysiology of the disease so that the prevention and treatment guidelines can be standardized. Since India and its neighboring countries have already been afflicted with several outbreaks8–10 this year, this outbreak can prove devastating to the public health of the whole region. If the aforementioned measures are implemented effectively, this outbreak can be contained in a short time.

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A.N., M.A., N.M., A.M., and A.A.W.: writing; A.N.: edited and reviewed with critical comments.

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