Hand, Foot, and Mouth Disease
Hand, Foot, and Mouth Disease
Disease History, Characteristics, and Transmission
Introduction
Hand, foot, and mouth disease (HFMD) is a mild, self-limiting disease caused by the enterovirus family of viruses. HFMD usually affects infants and children under the age of ten. It is endemic around the world, with periodic outbreaks. Symptoms include fever, nausea, ulcers in the mouth, and sores on the hands and feet. Infected individuals generally recover within two weeks; complications are rare. The disease is considered contagious and spreads through contact with fluids from infected persons.
Although there is no treatment for the disease and there are no formal preventative measures, the majority of persons with HFMD recover without any complications. However, more severe strains of enteroviruses have emerged, causing potentially fatal diseases, high-lighting the need to monitor HFMD.
HFMD is not to be confused with foot-and-mouth disease, which is an unrelated disease that only affects cattle, sheep, and swine.
Disease History, Characteristics, and Transmission
Hand, foot, and mouth disease was first diagnosed during an outbreak in Canada in 1957, but the name was not assigned until 1960 when Birmingham, England, suffered a similar outbreak. Individual cases of HFMD occur worldwide with a peak occurrence in late summer and early fall.
The disease, most common in children, results from infection by a group of enteroviruses, namely coxsackievirus A16. More severe forms of infection have appeared due to human enterovirus-71, causing epidemics with associated fatalities from HFMD-associated meningitis or encephalitis in countries such as Japan, Taiwan, Singapore, Malaysia, and Indonesia.
The onset of disease symptoms is usually three to seven days, after which children will suffer from a mild fever, loss of appetite, nausea, abdominal cramping, and a sore throat. After one to two days, the fever will heighten. In addition, painful sores will develop on the tongue, gums, and cheeks; these begin as small dots but quickly blister and ulcerate. At this point, patients will usually also display a rash affecting the palms of hands, soles of feet, and often the buttocks.
HFMD is considered moderately to highly contagious during the first week of infection and can be transmitted through contact with nose and throat discharge, blister fluids, and stools of those affected. There is no evidence of transmission from mother to infant during pregnancy, but mothers infected just prior to delivery may pass the virus on to the newborn baby. The risk of severe infection among babies is highest during the first two weeks of life.
Scope and Distribution
The people most commonly infected with HFMD are infants and children below the age of ten, although some cases may occur in adults. Children are the most susceptible to the disease due to their lack of previous exposure to the antigens and therefore lack of inbuilt immune defense.
The development of outbreaks and epidemics of this infection is rapid among cohorted children attending childcare facilities and schools, due to the high degree of physical contact and child interaction aiding transmission. The ratio of boys affected to girls is 1:1 and there does not appear to be a higher susceptibility to infection among certain races or ethnic groups.
Both individual cases and outbreaks of HFMD occur worldwide with no regions demonstrating a higher predisposition to the disease caused by infection with the coxsackievirus. However, HFMD presents two very different disease states depending upon the specific enterovirus causing infection and demonstrates a varied distribution.
The more severe illness, which is caused by the human enterovirus-71, presented in the first outbreak in Singapore in 1970, then occurred in Malaysia in 1997, in Taiwan in 1998, and again in Singapore in 2000. As an example of the scope of this disease, 1.5 million people were reportedly affected during the outbreak in Taiwan, including 78 child fatalities. In nearly all of the above-mentioned outbreaks, fatalities occurred as a result of infection leading to viral meningitis or encephalitis. The mortality rates and chances of complication were higher in later epidemics than those previous, which raised much concern amongst health care facilities in these countries.
Despite the fatalities occurring during outbreaks associated with this disease, HFMD caused by coxsackievirus infection is generally still considered to be a mild disease with global distribution.
WORDS TO KNOW
ENTEROVIRUS: Enteroviruses are a group of viruses that contain ribonucleic acid as their genetic material. They are members of the picornavirus family. The various types of enteroviruses that infect humans are referred to as serotypes, in recognition of their different antigenic patterns. The different immune response is important, as infection with one type of enterovirus does not necessarily confer protection to infection by a different type of enterovirus. There are 64 different enterovirus serotypes. The serotypes include polio viruses, coxsackie A and B viruses, echoviruses and a large number of what are referred to as non-polio enteroviruses.
COHORT: A cohort is a group of people (or any species) sharing a common characteristic. Cohorts are identified and grouped in cohort studies to determine the frequency of diseases or the kinds of disease outcomes over time.
Treatment and Prevention
HFMD is caused by a viral infection and there is no specific treatment for the infection. The infection is self-limiting, so patients will usually recover once the virus has run its course, usually within ten days. The most common complication of HFMD is dehydration due to the pain experienced when swallowing. As such it is important for patients to maintain adequate fluid intake during the course of the illness. Medication may also be administered to manage symptoms, such as non-steroidal anti-inflammatory medication for pain and fever.
There is no vaccination or formal prevention available for HFMD, but transmission may be minimized by hygiene practices such as cleaning contaminated surfaces and preventing the sharing of utensils. It is also important to limit exposure of those infected, so infected children should avoid group environments until sores have healed and the fever subsided.
In cases of disease with a strong potential for outbreak, prevention must be maintained at both the individual and societal levels. Health ministries in Singapore have been made aware of the possible severity of enterovirus infection and have made laws requiring childcare centers and general practitioners to report any suspected outbreaks of HFMD. This creates a heightened awareness among the community of the possibility of infection and increases the chances of preventing an epidemic.
IN CONTEXT: EFFECTIVE RULES AND REGULATIONS.
With regard to public health concerns Centers for Disease Control and Prevention (CDC) states that CDC has “no 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 persons 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.”
SOURCE: Centers for Disease Control and Prevention (CDC)
Impacts and Issues
One important feature of HFMD is the speed and ease with which it can be transmitted. In addition to the weeklong incubation period during which infected persons display no symptoms, the virus may remain present in the saliva for up to ten days and in the stool for months. This combination means that children may be contagious for months, even if symptoms have been displayed only for a short time, making implementation of successful prevention strategies difficult.
Once a person has had HFMD, they will no longer be susceptible to infection from that particular strain of enterovirus. However, the person will remain susceptible to infection from other enteroviruses, which means that previous infection does not infer complete immunity. Studies into outbreaks of HFMD involving human enterovirus-71 have suggested that previous infection by other enteroviruses, including coxsackievirus A16, may cause increased sensitivity to the disease, as well as increased severity.
Although generally HFMD enterovirus infection is mild and self-limiting, there has been an emergence of more critical forms of disease. The high numbers of fatalities among later outbreaks suggests that certain strains of infection are gaining virulence, while populations remain defenseless against them. Discrepancies exist among symptoms and presentation of persons with HFMD in epidemics involving fatalities. Some patients display the usual symptoms of HFMD before experiencing further complications, while others display no signs at all. The onset of complicating viral meningitis, encephalitis, or endocarditis following enterovirus infection is rapid, which further limits the treatment opportunities for persons affected with these strains of enterovirus.
See AlsoChildhood Infectious Diseases, Immunization Impacts; Contact Precautions; Emerging Infectious Diseases; Handwashing; Microbial Evolution; Notifiable Diseases; Polio (Poliomyelitis); Viral Disease.
BIBLIOGRAPHY
Books
Mandell, G.L., J.E. Bennett, and R. Dolin. Principles and Practice of Infectious Diseases, Vol. 2. Philadelphia, PA: Elsevier, 2005.
Mims, C., et al. Medical Microbiology. St. Louis, MO: Mosby, 2004.
Periodicals
Chan, K.P., K.T. Goh, and C.Y. Chong. “Epidemic Hand, Foot and Mouth Disease caused by Human Enterovirus 71, Singapore.” Emerging Infectious Diseases. 9, 1 (2003): 78–85.
McMinn, P.C. “An Overview of the Evolution of Enterovirus 71 and its Clinical and Public Health Significance.” FEMS Microbiology Reviews. 26, 1 (2002): 91–107.
Web Sites
Centers for Disease Control (CDC). “Hand, Foot, & Mouth Disease.” Sep. 5, 2006 <http://www.cdc.gov/ncidod/dvrd/revb/enterovirus/hfhf.htm> (accessed Feb. 23, 2007).