Hand, Foot and Mouth Disease (HFMD)

Hand, foot and mouth disease (HFMD) is a viral infection caused by agents of Enterovirus family. Common causes of HFMD are Coxsackievirus A16, Coxsackievirus A6, and Enterovirus 71 (EV-A71). It is a common viral illness of infants and children and uncommon in adults.

Transmission

HFMD is moderately contagious. Infection is spread from person to person by direct contact with nose and throat discharges, saliva, fluid from blisters, or the stool of infected persons. Rarely, infection by swallowing recreational water, such as water in swimming pools. This can happen if the water is not properly treated with chlorine and becomes contaminated with feces from a person who has HFMD.

Clinical features

HFMD is mucocutaneous manifestation that usually affects persons in their preteen and teenage years. Serotypes CVA16 and EV71 are responsible for most epidemic cases of HFMD, but occasionally may be associated with CVA4-CVA7, CV9, CVA10, CVB1-CVB3, CVB5, and echovirus 4. 

After an incubation period of 3-6 days, a prodrome characterized by low fever, malaise, and abdominal or respiratory symptoms precedes the mucosal lesions by 12-24 hours. Adult cases have been associated with severe symptoms and occasional onychomadesis.

Oral lesions typically appear first and are most common on the hard palate, tongue, and  buccal mucosa. The lesions can vary in number from 1 to 10 and typically begin as macules that rapidly progress to 2 to 3 mm vesicles and then to shallow, yellow-grey painful ulcers with an erythematous halo.

Cutaneous vesicles appear concomitantly with or soon after the oral lesions and are most prevalent on the hands and feet, including the palms and soles, but can appear on the face, legs, and buttocks. The lesions can vary in number from a few to over 100. Cutaneous lesions also begin as erythematous macules, but are larger (3-7mm) and develop into cloudy, white oval vesicles with a red halo. Both oral and cutaneous lesions are usually tender or painful and resolve in 5-10 days without treatment or scarring.

HFMD can cause neurologic manifestations that range from aseptic meningitis to acute flaccid paralysis and brainstem encephalitis, which can be associated with systemic features such as severe pulmonary edema and shock. 

Laboratory diagnosis

In mild cases of HFMD, particularly in patients with a high probability of having the disease based on their clinical characteristics and sick contacts, laboratory testing is not necessary. Testing is usually reserved for severe cases and epidemiological studies.

Samples collected : Throat and vesicle specimens are considered to be the most useful sources for diagnostic purpose. Other samples collected include blood, rectal swabs, stool. 

Laboratory tests include: Viral culture, Polymerase chain reaction and ELISA.

Prevention

• Frequent washing of hands with soap and water after changing diapers, after using toilets, after using blowing nose, coughing or sneezing , and before and after caring for someone who is sick.
• Clean and disinfect frequently touched surfaces and shred items including toys and doorknobs.
• Avoid touching eyes, nose and mouth with unwashed hands
• Avoid close contact with sick people

Treatment

No proven antiviral treatment exists for HFMD. Thus, the goal of treatment are typically supportive, as for any self limited viral syndrome.