Dr. Thulani Pattiyakumbura (Registrar in Medical Virology)
Outbreaks of hand, foot, and mouth disease (HFMD) was reported from several parts of the country mainly in Western and Southern Provinces in last couple of weeks. Hand, foot, and mouth disease is considered a self-limiting illness. It primarily affects infants and young children; however, it can also affect adolescents and adults. The hands, feet, and mouth are commonly affected, occasionally even the genitalia and buttocks are affected [1]. HFMD is a viral exanthem. It is mostly caused by the coxsackievirus and enterovirus of the Enterovirus family. Coxsackievirus (CV) A4, A6, A7, A9, A10, and B1 to B3, and B5 and enteroviruses have been identified as the causative viruses[2],[3]. However, coxsackievirus A16 (CV-A16) and enterovirus A71 (EV-A71) are most implicated as causative agents. Recently, CV-A6 and CV-A10 have partially replaced CV-A16 and EV-A71 as the main pathogens associated with HFMD.
HFMD cases often occur more frequently globally in the late spring and early summer[4]. However, in tropical/ subtropical countries outbreaks occur year around. The HFMD epidemic has been continuously reported over the world for the past three decades. Recently, HFMD has become an increasing burden in the Asia-pacific region including Japan, Malaysia, Singapore, Vietnam, and China [2]. However, the case fatality rates for patients under the age of five are considered as less than 0.1% [2].
The transmission is mediated by oral ingestion of the virus from the gastrointestinal or upper respiratory tract of infected hosts. The infection can also spread via contact of vesicle fluid/ oral secretions by direct or indirect methods[5]. After ingestion, the virus replicates in the pharynx and lymphoid tissue of the lower intestine. Then it spreads to the regional lymph nodes and to multiple organs, including the central nervous system (CNS), heart, liver, and skin [2]. The disease begins with a prodrome of low-grade fever, loss of appetite, general malaise, and throat pain. The incubation period ranges between 3 to 6 days. The cutaneous manifestations include the presence of vesicles surrounded by a thin halo of erythema. The lesions are about 2 mm to 6 mm in size and are usually non-pruritic and are not painful. They last about ten days, then tend to rupture, and result in painless and shallow ulcers that do not leave a scar. The cutaneous manifestations commonly involve the dorsum of the hand, feet, buttocks, legs, and arms. Oral lesions commonly involve buccal and tongue ulcers and may also involve the soft palate. However, the cutaneous manifestations can occasionally be macular or papular in addition to being vesicular. Most patients recover within a few weeks without any residual sequelae. Acute illness usually lasts 10 to 14 days, and the infection rarely recurs or persists causing pneumonia, myocarditis, pancreatitis, pulmonary edema, and serositis [6].HFMD occasionally causes severe diseases including meningitis, encephalitis, and polio-like paralysis [5],[2]. The diagnosis is usually made clinically. For atypical/ complicated cases, nasopharyngeal swabs/ oropharyngeal swabs or sometimes fecal samples can be subjected to real-time reverse transcriptase polymerase chain reaction (rRT-PCR)[2].
Currently, no approved specific antiviral treatment is available, although Pleconaril (a newer antiviral) has shown some promising action against EV-71. Most of the cases are managed with symptomatic measures including hydration and analgesics. Several vaccine candidates have been developed against HFMD. Currently, the inactivated whole-virus vaccine against EV-71 has been approved in China. Bivalent EV71/CA16 vaccines are still under development [1], [2]. Additionally, maintaining good hand hygiene, staying away from infected patients, avoiding touching eyes/ mouth/ nose, and health education are important to prevent the transmission of the infection.
References
[1] S. Esposito and N. Principi, “Hand, foot and mouth disease: current knowledge on clinical manifestations, epidemiology, aetiology and prevention,” Eur. J. Clin. Microbiol. Infect. Dis., vol. 37, no. 3, pp. 391–398, Mar. 2018, doi: 10.1007/s10096-018-3206-x.
[2] A. M. Guerra, E. Orille, and M. Waseem, “Hand Foot And Mouth Disease,” in StatPearls, Treasure Island (FL): StatPearls Publishing, 2022. Accessed: Oct. 25, 2022. [Online]. Available: http://www.ncbi.nlm.nih.gov/books/NBK431082/
[3] J. E. Bennett, R. Dolin, and M. J. Blaser, Mandell, douglas, and bennett’s principles and practice of infectious diseases E-book. Elsevier Health Sciences, 2019.
[4] X.-F. WANG, J. LU, X.-X. LIU, and T. DAI, “Epidemiological Features of Hand, Foot and Mouth Disease Outbreaks among Chinese Preschool Children: A Meta-analysis,” Iran. J. Public Health, vol. 47, no. 9, pp. 1234–1243, Sep. 2018.
[5] CDC, “Symptoms and Diagnosis of Hand, Foot & Mouth Disease,” Centers for Disease Control and Prevention, Aug. 10, 2022. https://www.cdc.gov/hand-foot-mouth/about/signs-symptoms.html
[6] “Hand, foot and mouth disease,” nhs.uk, Oct. 18, 2017. https://www.nhs.uk/conditions/hand-foot-mouth-disease
