Hand, Foot And Mouth Disease

Introduction

Hand, Foot, and Mouth Disease (HFMD) is a viral illness occurring mainly in infants and children. Occasionally, young adults and adults may develop the disease. The causative virus is usually Coxsackievirus A16 from the genus Enterovirus, family Picornaviridae. Enterovirus 71 along with other coxsackievirus types A4-A7, A9, A10, B1-B3, and B5 are responsible for some sporadic cases.¹

Mode of transmission: The disease is contagious, transmission occurs by the following routes:

• Direct contact with nasal and/or oral secretions,
• Fecal-oral
• Aerosolized droplets in a fecal-oral or oral-oral route

During epidemics, transmission from mother to fetus also occurs.

Incubation period: 3-7 days

Age: It is common in children, especially infants and children under 5 years of age. The severity of disease as well as complications are more in this age group.

Sex: Males and females are equally affected

Geographical distribution: It occurs worldwide. HFMD shows a seasonal variance only in temperate countries, with cases spiking in summer. However, in tropical countries like India, there is no seasonal pattern.

The disease occurs both sporadically as well as in the form of epidemics.

Recent outbreaks: Southeast Asia has seen the maximum number of cases in the recent past. Taiwan (1998) and Singapore (2000) recorded epidemics of HFMD. Recently, an increase in the number of HFMD cases has been reported from Indian cities like Mumbai² and Vadodara³.

Risk factors: Contact with HFMD, large family number, and rural residence are risk factors in the setting of an epidemic.

Pathogenesis

The virus particles are implanted initially in the buccal and ileal mucosa. From here, they spread into the bloodstream via the regional lymph nodes. Within 72 hours, viremia is established and the virus reaches the skin and oral mucosa causing the characteristic lesions.⁴

Symptoms

Initially, the presentation is with constitutional symptoms like fever, malaise, body ache, anorexia, and sore throat. This is followed by the development of oral and skin lesions. Patients present with very small blisters on hands, feet, and diaper area. The rash may be painful if pressed.

Signs

Oral lesions: These are seen on the labial and buccal mucosal surfaces. Other sites -Tongue, gums, uvula, anterior tonsillar pillars, palate.

Nature of lesions: Yellow ulcers surrounded by red halos.

Skin lesions: These are typically seen on the dorsal aspects of the hands and feet as well as the diaper area. They may appear on the ventral and inter-digital surfaces as well. The rash may be asymptomatic or pruritic. Initially, erythematous macules that rapidly progress to thick-walled grey vesicles with an erythematous base.⁵ The rash resolves by itself within 3-6 days.

Differential Diagnosis

Herpangina, Herpetic gingivostomatitis, Aphthous stomatitis, Stevens-Johnson's syndrome are some of the conditions which need to be differentiated from HMFD.

Investigations

Typically, a clinical evaluation is sufficient to diagnose HFMD. Lab tests which may prove useful are:

• Virus isolation: Swabs taken from the vesicles, ulcers or stool can be utilized for isolating the virus. It can then be cultured on viral tissue media or inoculated into mice to obtain a larger sample for demonstration
• Serologic tests:
• Acute phase: Neutralizing antibodies can be detected;
• Convalescent phase: For retrospective diagnosis, complement-fixing antibodies can be detected
• PCR can be used to distinguish between coxsackievirus A16 and enterovirus 71⁶. It has prognostic significance. The usefulness of this technique lies in the fact that epidemics caused by enterovirus 71 tend to be more severe and are associated with more complications and fatalities.

Treatment

The main aim of treatment in HFMD is to reduce the severity and duration of symptoms. As such, there is no curative therapy. Hence, care is purely supportive. Topical antihistamines like diphenhydramine are useful to treat pruritis. NSAIDs (Ibuprofen, paracetamol) may be used for pain relief and control of fever. Aspirin is NOT to be used in children under 12 years of age as it carries the risk of precipitating Reye's syndrome. Antipyretics are given as and when required. Fluids should be given to maintain hydration. Since the oral ulcers are very pain sensitive, the child may refuse feeds. Juices and carbonated beverages are not recommended as they contain significant acid content which causes pain. Hence, cold milk preparations like ice cream are ideal feeds.

Prognosis

Complete recovery is the norm in HFMD

Complications

The main complication that can occur is a secondary skin infection. Rarely, cardiopulmonary and CNS complications like a cardiopulmonary failure, aseptic meningitis, etc. may occur. These are associated with outbreaks caused by Enterovirus 71.