Hand, Foot, and Mouth Disease
HFMD is often confused with foot-and-mouth disease of cattle, sheep, and swine. Although the names are similar, the two diseases are not related and are caused by different viruses.
Signs and Symptoms
The incubation period (the time between infection with the virus that causes HFMD and the appearance of symptoms) is generally between three to five days. Most people infected with the virus have no symptoms. If symptoms do occur, they usually begin as a mild illness with the following:
- Low-grade fever
- Poor appetite
- Malaise ("feeling sick")
- Sore throat
One to two days after the fever begins, painful sores develop in the mouth. The sores begin as small red spots that become blisters and then often become shallow ulcers. These sores are typically located on the tongue, gums, and inside of the cheeks.
In 75% to 100% of people who get HFMD, a skin rash can develop at about the same time as the sores in the mouth. The skin rash begins as flat or raised red spots which can develop into blisters. The rash does not itch but it can be painful. A typical finding is for the rash to spread to the palms of the hands and soles of the feet. It usually spares the trunk, but the rash can be seen on the buttocks. A person with HFMD may have only the rash or only the mouth ulcers.
HFMD is caused by viruses that belong to the genus (group) Enterovirus. This group of viruses includes polioviruses, coxsackieviruses, echoviruses, and other enteroviruses. HFMD is most commonly caused by coxsackievirus A16. Sometimes, HFMD is caused by enterovirus 71 or other coxsackieviruses.
The diagnosis of HFMD is typically made based on the clinical appearance of the disease. Usually, the physician can distinguish between HFMD and other causes of mouth sores based on the age of the patient, the pattern of symptoms reported by the patient or parent, and the appearance of the skin rash and sores on examination.
A throat swab or stool specimen may be sent to a laboratory to determine which enterovirus caused the illness. Since the testing often takes 2 to 4 weeks to obtain a final answer, the physician usually does not order these tests.
HFMD is generally a mild illness, and nearly all patients recover without medical treatment in 7 to 10 days.
Specific prevention, including vaccines, for HFMD or other non-polio enterovirus infections is not available, but the risk of infection can be lowered by good hygienic practices. Preventive measures include the following:
- Frequent hand washing, especially after diaper changes.
- Cleaning of contaminated surfaces and soiled items, first with soap and water, then disinfecting them using a dilute solution of chlorine-containing bleach (made by mixing approximately ¼ cup of bleach with 1 gallon of water).
- Avoidance of close contact (kissing, hugging, sharing utensils, etc.) with children who have HFMD may also help to reduce the risk of transmission of the virus to caregivers.
HMFD in the childcare setting
HFMD outbreaks in child care facilities occur most often in the summer and fall months, and usually coincide with an increased number of cases in the community.
The Centers for Disease Control and Prevention (CDC) does not have specific recommendations regarding the exclusion of children with HFMD from child care programs, schools, or other group settings. Children are often excluded from group settings during the first few days of the illness, which may reduce the spread of infection, but will not completely interrupt it. Exclusion of ill persons may not prevent additional cases since the virus may be excreted for weeks after the symptoms have disappeared. Also, some people excreting the virus, including most adults, may have no symptoms. Some benefit may be gained, however, by excluding children who have blisters in their mouths and drool, or who have weeping lesions on their hands.
If an outbreak occurs in the child care setting:
- Make sure that all children and adults use good hand washing technique, especially after diaper changes.
- Thoroughly wash and disinfect contaminated items and surfaces using diluted solution of chlorine-containing bleach.
Chances of Developing Hand, Foot, and Mouth Disease
HFMD occurs mainly in children under 10 years of age, but may also occur in adults. Everyone is at risk of infection, but not everyone who is infected becomes ill. Infants, children, and adolescents are more likely to be susceptible to infection and illness from these viruses, because they are less likely than adults to be immune from previous exposures to them. Infection results in immunity to the specific virus, but a second episode may occur following infection with a different member of the enterovirus group.
Risks to pregnant women
Because enteroviruses, including those causing HFMD, are very common, pregnant women are frequently exposed to them, especially during summer and fall months. As with other adults, the risk of infection is higher for pregnant women who are not immune from earlier exposures to these viruses, and who are exposed to young children, the primary spreaders of enteroviruses.
Most enterovirus infections during pregnancy cause mild or no illness in the mother. Although the available information is limited, currently there is no clear evidence that maternal enteroviral infection causes adverse outcomes of pregnancy such as abortion, stillbirth, or congenital defects. However, mothers infected shortly before delivery may pass the virus to the newborn. Babies born to mothers who have symptoms of enteroviral illness around the time of delivery are more likely to be infected. Most newborns infected with an enterovirus have mild illness, but, in rare cases, they may develop an overwhelming infection of many organs, including liver and heart, and die from the infection. The risk of this severe illness in newborns is higher during the first two weeks of life. Strict adherence to generally recommended good hygienic practices by the pregnant woman may help to decrease the risk of infection during pregnancy and around the time of delivery.
How HFMD is Spread
The viruses that cause HFMD are 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. A person is most contagious during the first week of the illness and can even spread the virus before symptoms appear. HFMD is not transmitted to or from pets or other animals and is not known to be transmitted by food or water.
Complications are uncommon. Rarely, the patient with coxsackievirus A16 infection may also develop "aseptic" or viral meningitis. This illness presents with fever, headache, stiff neck, or back pain, and may require to be hospitalized for a few days. Another cause of HFMD, enterovirus 71, may also cause viral meningitis and, rarely, more serious diseases, such as encephalitis, or a poliomyelitis-like paralysis. Enterovirus 71 encephalitis may be fatal. Cases of fatal encephalitis have occurred during outbreaks of HFMD in Malaysia in 1997, Taiwan in 1998, and Japan in 2000.
Individual cases and outbreaks of HFMD occur worldwide, more frequently in summer and early autumn. In the recent past, major outbreaks of HFMD attributable to enterovirus 71 have been reported in some South East Asian countries (Malaysia 1997, Taiwan 1998, Japan 2000).
- ↑ Bendig JW, Fleming DM. Epidemiological, virological, and clinical features of an epidemic of hand, foot, and mouth disease in England and Wales. Commun Dis Rep CDR Rev. 1996 May 24;6(6):R81-6. Abstract
- ↑ Chan LG, Parashar UD, Lye MS, et al. Deaths of children during an outbreak of hand, foot, and mouth disease in Sarawak, Malaysia: clinical and pathological characteristics of the disease. For the Outbreak Study Group. Clin Infect Dis. 2000 Sep;31(3):678-83. Epub 2000 Oct 4. Abstract | Full Text | PDF
- ↑ Shieh WJ, Jung SM, Hsueh C, et al. Pathologic studies of fatal cases in outbreak of hand, foot, and mouth disease, Taiwan. Emerg Infect Dis. 2001 Jan-Feb;7(1):146-8. Abstract | Full Text
- ↑ Fujimoto T, Chikahira M, Yoshida S, et al. Outbreak of central nervous system disease associated with hand, foot, and mouth disease in Japan during the summer of 2000: detection and molecular epidemiology of enterovirus 71. Microbiol Immunol. 2002;46(9):621-7. Abstract | PDF
Centers for Disease Control and Prevention (CDC)