Tomato flu outbreak in India: Evolution, epidemiology, preventive strategies, and way ahead

Abstract

Introduction: 

Just as the world recovers from the throes of the COVID-19 pandemic, there are reports of monkeypox virus infections in previously unaffected regions. To add another communicable and contagious outbreak to the list, India is witnessing many Pediatric cases of Hand Foot, and mouth disease (HFMD)

Aim: 

To explore the key Epidemiological aspects of Tomato flu, including the difference between the current outbreak and classical HFMD.

Materials and Methods: 

Secondary data from official government sites, press information, latest articles, newspapers, and the WHO website was extracted and discussed in the article. The current Epidemiology of the Tomato flu with a difference from the typical hand foot and mouth disease is highlighted in the study. The most probable factors for the starting point of the emergence of communicable diseases like COVID-19, Monkeypox, and the current tomato flu epidemic in Kerala across the country are also highlighted.

Results: 

Total number of thirty-two articles/government/international websites were assessed. The current study highlights the current epidemiology of Tomato flu, including difference from classical HFMD. The most probable reasons for Kerala being starting point of emerging diseases like COVID-19, Monkey pox and Tomato flu are highlighted. Preventive strategies including steps taken by government and way ahead are also discussed.

Conclusion: 

The study highlights that Current Tomato flu presentation is quite different from classical HFMD. Surveillance, Screening, Personal hand hygiene, and isolation of cases are preventive measures that can be adopted. It is imperative to raise awareness and promote personal hygiene among children, parents, and schools with immediate effect.

For decades since its discovery in 1957, the Hand, Foot, and Mouth Disease (HFMD), earlier thought to be a common cattle disease, has now become a common and rising infection among the paediatric age group.^[1,2] HFMD was first described in Toronto in 1957, as a mild pharyngeal infection caused due to Group A Coxsackie virus and was believed to be just a mild disease.^[3,4] It was the first time that the causative organism of HFMD was identified, and further studies could be undertaken.

Just as the world recovers from the throes of the COVID-19 pandemic, there are reports of monkeypox virus infections in previously unaffected regions. To add another communicable and contagious outbreak to the list, India is witnessing many Pediatric cases of Hand Foot, and mouth disease (HFMD). Many of under the age of five children infected presented with symptoms including an elevated temperature, intense joint pain, and a rash. The children also suffered an eruption of red, painful blisters that grew to the size of a tomato. Scientists have been testing samples from children with tomato flu to try to identify the cause of the disease and the lab results revealed that they were infected with an enterovirus named coxsackie A16.^[5] However, current literature lacks a detailed description of the key Epidemiological aspects of Tomato flu, including the difference between the current outbreak and classical HFMD which have been described in the current study.

Materials and Methods

Secondary data from official government sites, press information, latest articles, newspapers, and the WHO website was extracted and discussed in the article. The current Epidemiology of the Tomato flu with a difference from the typical hand foot and mouth disease is highlighted in the study. The most probable factors for the starting point of the emergence of communicable diseases like COVID-19, Monkeypox, and the current tomato flu epidemic in Kerala across the country are highlighted in Figure 1.

Figure 1:: Kerala as starting point for emerging diseases(Most probable reasons)

Results

Total number of thirty-two articles/government/international websites were assessed. Table 1 highlights the number of cases across the globe. Table 1 represents epidemiological differences between tomato flu and classical hand foot and mouth disease. Timeline of number of cases in India is highlighted in Figure 2. The present outbreak is different from classical Hand foot and mouth disease as highlighted in Table 1. Besides having better surveillance and robust public health infrastructure, the most probable reasons for Kerala being the starting point of the recent emerging diseases like COVID-19, Monkeypox, and Tomato flu are also highlighted [Figure 1]. The preventive strategies and the way ahead is also discussed.

Table 1:: Epidemiological differences between Tomato flu and HFMD(Classical)

Figure 2:: A Timeline of Tomato Flu outbreak across India

Discussion

The present study highlights the key Epidemiological determinants of the Present outbreak of Tomato flu in India, It is different from the classical Hand foot, and mouth disease, probable reasons for Kerala being the starting point of origin of emerging diseases in recent times. The preventive strategies and the way ahead are also discussed.

Epidemiology

Tomato Flu or Tomato Fever was first identified in the Kollam district of Kerala on May 6^th, 2022. This viral infection is currently in its endemic state. As of 26^th July 2022, there are more than eighty-two cases reported in the country.^[6] Currently, Kerala, Tamil Nadu, Odisha, and Haryana are said to be affected.^[7] The timeline of cases of tomato flu reported in India is highlighted in Figure 2.

Tomato flu and classical HFMD

Certain reports considered Tomato flu to be an aftereffect of dengue or chikungunya.^[6] However, viral sequencing from skin lesions of two children returning to the UK from Kerala showed that it is a result of Coxsackie A 16 virus.^[8] Coxsackie A 16 virus belongs to the genus Enterovirus. It is one of the most common pathogens causing hand foot mouth disease, a common childhood illness.^[9] As per the profiling done by the Institute of Advanced Virology in Kerala, both Coxsackie A6 and A16 have been demonstrated in the lesions of tomato flu in the state.^[10] Both these strains have been previously found in cases of Hand foot mouth disease.^[8,11] Hence, tomato flu can be considered as a misnomer or a unique presentation of Hand foot Mouth disease. The key differences between the current tomato flu and Classical HFMD are highlighted in Table 1.

The current viral infection is affecting children below the age group of 5 years. The causative agent, enteroviruses are widespread in the community resulting in older children and adults having immunity against this disease. This could explain why no adults are presenting with this illness.^[12] Similar to hand foot mouth disease, it is said to be spread by close contact with infected persons or even their bedding, clothes, utensils, and other surfaces they have been in contact with^[13] Tomato flu is extremely contagious. It lasts for about 7–10 days.^[12] The name tomato flu has been given due to the red-coloured bullous tomato-shaped blisters appearing on various parts of the body of an affected individual.^[8]

Clinical features

High-grade fever, dehydration, and swollen and painful joints are common complaints associated with this disease. Nausea and vomiting, running nose, sneezing, frequent coughs, patches, and discoloration on various body parts including hands, buttocks, and knees, abdominal pain, cramps, and feeling of tiredness and fatigue are some other symptoms seen.^[6] The disease usually starts with mild fever, poor appetite, malaise, and sore throat. 1 or 2 days following this, small red spots appear which progress to the characteristic tomato-like large blisters.^[14] It is a non-life-threatening disease. A vast majority of the cases are self-limiting. There is a 0.01% chance of neurological complications.^[7] To date, there have been no deaths reported.

Genetic factors

HFMD is known to be caused by different strains of enteroviruses, of which the most common are enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16).^[1,2] Emerging strains include CV-A6 and CV-A10. All of these have similar symptoms, with some that are specific to the strain. For instance, CV-A16 has large vesicular rashes, EV-A71 has petechial rashes, and CV-A6 has atypical symptoms and nail shedding during convalescence.^[3,4] CV-A16 sequence shares the most common recent ancestor with a clade from China (2011–2014) appears to be responsible for the current tomato flu outbreak. It is notable, however, that CV-A6 has been the most common circulating strain of HFMD in South India from 2015 onwards when it surpassed CV-A16 and EV-71.^[5] The tomato flu outbreak could signal the resurgence of CV-A16 in the subcontinent. This knowledge of molecular epidemiology is essential for the development of a vaccine against the disease.

Laboratory diagnosis

The diagnosis of tomato flu is largely clinical – primarily, chikungunya-like symptoms of high fever, joint pain, and rash are seen in patients. In addition, HFMD-associated mouth ulcers (herpangina) may also be present.^[15,16] Laboratory testing may also be performed to confirm the presence of the virus. Throat, stool samples, and skin scrapings may be collected within 48 hours of illness in Viral Transport Medium, as part of an outbreak investigation. CSF samples can also be collected from patients having encephalitis, within 48 hours. The collected samples may be subjected to viral isolation, serology, or molecular studies^[17] Viral isolation is widely regarded as the Gold Standard in the diagnosis of HFMD. Isolation is performed on Vero Rhabdomyosarcoma and MRC 5 monolayer. The presence of cytopathic effect increases suspicion of enteroviruses, which can be confirmed upon immunofluorescence assay.

Serological studies may be performed to measure the neutralizing antibody titers specific to serotype, with a four-fold increase in titers being significant.^[18] Serology is not sensitive enough to make a diagnosis. However, it may be used to monitor recovery. With the advent of the era of molecular diagnosis, RT-PCR is increasingly becoming a preferred mode of laboratory confirmation. Characterization is performed using 5´-UTR and genotyping using the VP1 region.^[19]

Treatment

Tomato flu is a self-limiting illness, with no specific treatment.^[20] Fever is treated with paracetamol, and adequate hydration, rest, and nutrition are ensured. Danger signs that warrant admission includes persistent hyperpyrexia, inability to feed, drowsiness, altered mentation, vomiting, seizures, and hemodynamic compromise.^[21] Several vaccines are under development at present for HFMD however none are available for use present.

Preventive measures

With the increase in the number of cases, the central government has issued an advisory to the states stressing the need for preventive measures to curb the spread of the disease as there is no specific medication or vaccine to cure it. The best measure for prevention is to ensure proper hygiene and sanitation of surroundings. Parents as well as children should be educated about the signs, symptoms, and side effects of this disease. Isolation should be followed for 5–7 days from the onset of any symptom to prevent the spread of infection to other children or adults. Children should be encouraged to not hug or touch sick individuals, stop thumb-sucking or nail-biting and use a handkerchief to cover their mouth while sneezing. A nutritious diet and hydration amongst children should be advocated to boost their immunity. Supportive measures can be initiated in the form of paracetamol for fever, warm water baths, a nutrition-rich diet, and adequate rest with adequate sleep to promote healing. Children should be asked not to scratch or rub the blisters.^[14]

Health education

Public health officials/policymakers must provide health education-related guidelines to the community and apprise health care workers about prevention and modes of transmission, which should also consider risk communication strategies to avoid unnecessary panic in the community.

Steps taken by the Kerala and neighbouring state governments and way ahead

With the initiation and flare-up of the disease in Kerala, the neighbouring states are also on high alert. The Karnataka government has instructed authorities to be vigilant of travellers entering from the affected districts of Kerala as well as children reporting similar symptoms in hospitals. Directions have been given to ensure immediate reporting of such cases^[22] Similarly, the Tamil Nadu government has ramped up its surveillance with a team of health, revenue, and police officials to screen people coming in from Kerala at the Walayar check post.^[20] In Kerala, government officials are now screening across Anganwadi centres. It has been reported that twenty-four mobile teams with health officials have been deployed for the same.^[23] The way ahead to curb the further spread of disease is a primary prevention strategy including health education about modes of transmission and prevention of infection. Secondary prevention in form of early diagnosis, treatment, and isolation of cases. Strict surveillance, exploration for the vaccine, better diagnostics, and definitive treatment may be the futuristic way ahead that can be planned by policymakers and health care officials.

Conclusion

The study highlights there are key differences between Tomato flu and classical HFMD.Surveillance, Screening, Personal hand hygiene, and isolation of cases are preventive measures that can be adopted. It is imperative to raise awareness and promote personal hygiene among children, parents, and schools with immediate effect. All children reporting the above symptoms to be kept away from other children and brought to the health care facility at the earliest to screen for severe and complicated cases.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.