Enterovirus 71 (EV71) is a single-stranded RNA virus and is one of the causative agents for hand, foot and mouth disease (HFMD). The disease occurs commonly in Southeast Asian areas, especially in summer and early autumn. Outbreaks have been reported in Australia, Mainland China, Malaysia, Singapore, Taiwan etc.
EV71 infection is usually found among young children. It commonly presents with symptoms of HFMD, characterised by fever, sores in the mouth, and a rash with blisters. It usually begins with fever, poor appetite, tiredness and sore throat. One or two days after fever onset, painful sores develop in the mouth. They begin as small red spots with blister and then often become ulcers. They are usually located on the tongue, gum, and inside of the cheeks. There may also be skin rash that is non-itchy and, some with blisters. The rash is usually located on the palms of the hands and soles of the feet; it may also appear on the buttocks and/or genitalia. A person with HFMD may not have symptoms, or may have only the rash or only mouth ulcers. EV71 may cause more serious diseases, such as viral (aseptic) meningitis, encephalitis, poliomyelitis-like paralysis and myocarditis.
Mode of transmission
The disease mainly spreads by contact with an infected person’s nose or throat discharges, saliva, fluid from vesicles or stool, or after touching contaminated objects. The illness is contagious during the acute stage and perhaps longer, as faecal shedding of virus can continue for several weeks.
The incubation period commonly ranges from 3 - 5 days.
Currently, no specific treatment is available for EV71 infection. Some symptomatic treatments can relieve fever and pain from the ulcers. In most cases, the illness is self-limiting. Symptoms including fever, rash and ulcers subside in 1 week. Parents should pay attention to the health of their children and seek medical advice immediately if their children having HFMD developing the following symptoms:
- persistent and high fever
- repeated vomiting
- persistent sleepiness or drowsiness
- myoclonic jerks or sudden limb weakness
Infected children are advised to refrain from schools or group activities such as parties, interest classes, swimming until 2 weeks after fever has subsided and all the vesicular lesions have dried and crusted to prevent the spread of disease. Protect other family members, especially children, from getting the infection through strict personal and environmental hygiene (see advice on prevention below).
Vaccine is not available at the moment. Good personal and environmental hygiene are the most important measures to prevent EV71 infection. While in Hong Kong or during travel, members of the public are advised to:
- maintain good personal hygiene;
- wash hands with liquid soap and water especially:
- before touching nose and mouth;
- before eating or handling food;
- after touching blister;
- after using the toilet;
- when hands are contaminated by respiratory secretions e.g. after coughing or sneezing;
- after changing diapers or handling soiled articles;
- cover both the nose and mouth with tissue paper when coughing or sneezing, and wash hands thoroughly afterwards. Dispose of soiled tissue paper properly in a lidded rubbish bin;
- do not share towels and other personal items;
- regularly clean and disinfect frequently touched surfaces such as furniture, toys and commonly shared items with 1:99 diluted household bleach (mixing 1 part of 5.25% bleach with 99 parts of water), leave for 15 - 30 minutes, and then rinse with water and keep dry. For metallic surface, disinfect with 70% alcohol;
- use absorbent disposable towels to wipe away obvious contaminants such as respiratory secretions, vomitus or excreta, and then disinfect the surface and neighbouring areas with 1:49 diluted household bleach (mixing 1 part of 5.25% bleach with 49 parts of water), leave for 15 - 30 minutes and then rinse with water and keep dry. For metallic surface, disinfect with 70% alcohol;
- avoid group activities when HFMD outbreak occurs in the school or institution. Besides, minimise staff movement and arrange the same group of staff to take care of the same group of children as far as possible; and
- avoid close contact (such as kissing, hugging) with infected persons.