HFMD is highly infectious. It can spread from one person to another through direct contact with discharge from the nose and throat, saliva, infected stools, or fluid from a blister. It takes up to a week for symptoms to appear once a person is infected, though not all infected people develop symptoms.
HFMD usually begins with a low-grade fever and general fatigue. A rash of tiny, painful red spots will appear within a couple of days and will soon begin to blister and sometimes form ulcers. These spots may appear:
- inside the mouth (on the tongue, gums, or cheeks)
- on the palms of the hands or on the fingers
- on the soles of the feet or on the toes
- on the buttocks
The rash is not generally itchy and, in some cases, may develop on other parts of the body. Lymph nodes in the neck may also become swollen. The virus can cause the throat to feel sore and painful.
Rarely, dehydration may occur as the pain due to the blisters in the mouth can make drinking difficult. Infection by EV71 has been known to cause encephalitis or viral meningitis in rare cases.
Children and adolescents are the most commonly affected people. Adults are rarely infected, although pregnant women who have not been exposed to the virus before have a higher chance of becoming infected. Daycare centres, parks, nursery schools, and other places where children play with each other are potential sites for the infection to be transmitted from one child to another. HFMD is most common in the summer and early fall.
A pregnant woman who is infected may show mild or no signs of illness. If she is infected just before her delivery, the infection can be transmitted to the newborn resulting in only a mild illness in the baby. Rarely, multiple-organ infections occur.
During the acute phase, a person can infect others through secretions from the nose and throat. Discharge due to coughing and sneezing can cause the virus to be transmitted easily. Young children who tend to drool can also transmit the infection through their saliva.
Until the blisters dry, a person should be regarded as infectious. Fluid from the blisters contains the virus. The virus is also present in the feces for several weeks after symptoms of illness have vanished. An infected person who does not develop the illness will also have the virus present in the stools.