What causes hand foot and mouth disease

What is Hand, Foot, and Mouth Disease (HFMD)?

Hand, foot, and mouth disease (HFMD) is a common viral illness that usually affects infants and children younger than 5 years old, though it can occur in older children and adults. It is characterized by fever, sore throat, and a rash of small blisters on the hands, feet, and in the mouth. While generally mild and self-limiting, understanding its causes is crucial for prevention and management.

Primary Causes of HFMD

The main culprits behind HFMD are a group of viruses known as enteroviruses. These viruses are prevalent worldwide and are responsible for a range of illnesses, with HFMD being one of the most common manifestations.

Coxsackievirus A16

The most frequent cause of HFMD is the coxsackievirus A16. This particular strain typically results in a milder form of the disease, with symptoms that are less severe and resolve relatively quickly.

Enterovirus 71 (EV-71)

Another significant cause of HFMD is enterovirus 71 (EV-71). While less common than coxsackievirus A16, EV-71 can lead to more severe complications. These can include neurological issues such as encephalitis (inflammation of the brain), meningitis (inflammation of the membranes surrounding the brain and spinal cord), and even respiratory or heart problems. Outbreaks caused by EV-71 have historically been associated with a higher risk of severe outcomes.

Other Enteroviruses

Although coxsackievirus A16 and EV-71 are the most common, other types of enteroviruses can also cause HFMD. These include other strains of coxsackievirus (like coxsackievirus A6) and other enteroviruses. The specific virus involved can influence the severity and presentation of the illness.

How Does HFMD Spread?

HFMD is highly contagious and spreads easily from person to person. The viruses are shed in the bodily fluids of an infected individual, making transmission common in settings where people are in close contact.

Modes of Transmission

• Direct Contact: This includes touching an infected person's saliva, nasal mucus, or blister fluid.
• Respiratory Droplets: Coughing and sneezing can release virus-containing droplets into the air, which can be inhaled by others.
• Fecal-Oral Route: The virus is present in the stool of infected individuals and can spread through contaminated hands, objects, or surfaces, especially if hygiene practices are poor (e.g., after using the toilet or changing diapers).
• Contaminated Objects: Touching surfaces or objects contaminated with the virus and then touching one's mouth, nose, or eyes can lead to infection.

Risk Factors and Transmission Settings

Children are more susceptible to HFMD due to their developing immune systems and their tendency to put objects in their mouths and have close contact with others. Daycare centers, preschools, and schools are common places for outbreaks because of the close proximity of children and shared toys and surfaces.

Incubation Period

The incubation period for HFMD, which is the time from initial exposure to the virus until the onset of symptoms, typically ranges from 3 to 6 days. During this period, an individual may not show any signs of illness but can still be contagious.

Symptoms of HFMD

Once symptoms appear, they usually begin with a fever, sore throat, and sometimes a general feeling of being unwell (malaise). This is often followed by the characteristic rash:

• Mouth Sores: Painful red spots that develop into blisters, usually starting in the front of the mouth and spreading to the tongue and gums.
• Skin Rash: A non-itchy rash, typically on the palms of the hands and soles of the feet. It can also appear on the buttocks, legs, and arms. The rash may start as red spots and can develop into blisters.

When to Seek Medical Advice

Most cases of HFMD are mild and resolve on their own within 7 to 10 days without specific treatment. However, it is important to seek medical attention if:

• Symptoms are severe.
• The child appears dehydrated.
• Symptoms do not improve after 10 days.
• There are signs of complications, such as high fever, stiff neck, severe headache, or difficulty breathing, which could indicate a more serious enterovirus infection like EV-71.

Prevention Strategies

Preventing the spread of HFMD relies heavily on good hygiene practices:

• Frequent and thorough handwashing with soap and water, especially after using the toilet, changing diapers, and before preparing food.
• Avoiding close contact (kissing, hugging, sharing utensils) with people who have HFMD.
• Disinfecting frequently touched surfaces and toys.
• Teaching children good hygiene habits.

By understanding the viral causes and modes of transmission, individuals can take effective steps to protect themselves and their families from this common childhood illness.