Enterovirus 71 (EV71) is a single-stranded RNA virus and 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. Large outbreaks have been reported in Taiwan and Malaysia in 1990s.
EV71 infection is usually found among young children. It most commonly presents with symptoms of HFMD, characterised by fever, sores in the mouth, and a rash with blisters. Usually it begins with fever, poor appetite, malaise and sore throat. One to two days later, painful sores develop in the mouth. The sores are characterised by small red spots with blisters which then often become ulcers. They are usually located on the tongue, gums, and inside of the cheeks. The non-itchy skin rash manifests as flat or raised red spots. The rash is usually found on the palms of the hands and soles of the feet. Asymptomatic infections can occur. Rarely, EV71 may cause more serious diseases, such as viral (aseptic) meningitis, encephalitis, poliomyelitis-like paralysis and myocarditis.
Mode of transmission
EV71 infection is transmitted from person to person by direct contact with nose and throat discharges, saliva, fluid from blisters, or the stool of infected persons. The illness is contagious during the acute stage and perhaps longer, as faecal shedding of virus can continue for several weeks.
The incubation period ranges from 3 to 7 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 spontaneously in one week. Parents should pay attention to the health of their children and seek medical advice if their children having HFMD developing the following symptoms:
Persistent and high fever;
Persistent sleepiness or drowsiness;
Myoclonic jerks or sudden limb weakness.
Infected children should refrain from schools or group activities such as parties, interest classes, swimming until two 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:--
Wash hands before eating and after going to toilet, clearing up vomitus or changing diapers;
Cover nose and mouth while sneezing or coughing, and proper disposal of nasal and mouth discharge;
Never share personal items such as towels and eating utensils;
Maintain good ventilation;
Clean and disinfect frequently touched surface, furniture and toilets regularly with diluted bleach of 1:99 concentration (mixing 1 part of 5.25% household bleach with 99 parts of water);
Disinfect toys/places which are contaminated by secretions or excreta with diluted household bleach of 1:49 concentration;
Avoid close contact with HFMD patients.