Chickenpox vs. Hand, Foot, and Mouth Disease

Chickenpox and hand, foot, and mouth disease (HFMD) are both contagious viral diseases that most commonly affect children.

• Incubation period for HFMD is about 3 to 6 days and is about 10 to 21 days for chicken pox.
• Both diseases are characterized by the symptoms and signs of rash formation, malaise and fever; however, the chickenpox rash starts on the body’s torso and spreads over the next 7 to 10 days outward towards the head, arms, and legs but the HFMD rash develops mainly in the mouth and on the hands and feet. Both of these diseases have rashes that often form blisters (vesicles).
• The varicella-zoster virus (VZV) causes chickenpox, whereas the coxsackievirus A-16 causes the majority of HFMD. In contrast, VSV can remain latent in the patient’s spinal nerves and, after many years, reactivate, and cause shingles (mainly in older adults). VSV additionally may cause problems for a fetus if the mother becomes infected, especially in the last 2 weeks of pregnancy.
• Both diseases share the infrequent but serious complications of encephalitis and dehydration.
• A vaccine is available against chickenpox but there is no vaccine available in the U.S. against HMFD.
• Medical treatments for severe chickenpox are available (acyclovir and varicella zoster immunoglobulin); there is no specific treatment for HFMD except supportive care.

Chickenpox, also known as varicella, is a self-limited infection that most commonly affects children between 5-10 years of age. The disease has a worldwide distribution and is reported throughout the year in regions of temperate climate. The peak incidence is generally during the months of March through May.

Lifelong immunity for chickenpox generally follows the disease. If the patient's immune system does not totally eliminate the presence of the virus, it may retreat to a dormant stage in the skin sensory nerve cell bodies where it is protected from the patient's immune system. The disease shingles is caused by the release of these viruses down the length of the skin nerve fiber and produces a characteristic painful rash. Shingles is most commonly a disease of adults.

Hand, foot, and mouth disease is a common childhood illness caused by a virus. The illness most often occurs in the spring and fall and is most frequently seen in young children, infants, and toddlers. It is characterized by fever and a blister-like rash affecting the palms of the hands and soles of the feet along with blisters inside the mouth. (It is unrelated to foot and mouth disease, which affects livestock.)

Chickenpox Symptoms

Rash

Healthy children generally experience one to two days of fever, sore throat, and malaise approximately 2 weeks following exposure to VZV. Within 24 hours of these symptoms, a characteristic rash develops initially on the torso and then spreads over the next 7 to 10 days outward to the head, arms, and legs. Skin lesions progress through a predictable evolution from a red papule ("bug bite" appearance) to blister (vesicle) to a pustule (pus-filled blister), which then scabs over. The vesicle and pustular fluids are highly concentrated with infectious virus particles.

New lesions characteristically come in recurring "waves" over the skin surface. The patient may thus have newly formed papules, middle-aged vesicles and pustules, and crusted lesions all at the same time. At the peak of the disease, a patient may have over 300 skin lesions at one time. Once all lesions are scabbed over and no new lesions are developing, the person is no longer contagious. The lesions rarely cause permanent scarring, unless secondary infection develops (see below). Lesions may commonly be found in the mouth and may also involve the genitalia.

Complications

In healthy children, chickenpox is a mild disease. Adults are 25% more likely to have significant complications from the diseases. Common complications affecting both children and adults include the following:

• Skin infection: Secondary bacterial infections caused by either Staphylococcus or Streptococcus bacteria are well described. Rarely, an invasive form of Streptococcus can quickly spread throughout the body and may be life-threatening.
• Pneumonia: This is a relatively rare complication in healthy children but is the primary cause of hospitalization for adults (occurring in one in 400 cases) and has a mortality (death) rate of between 10%-30%.
• Neurologic complications: Children most commonly develop an inflammation of the balance center of the brain called acute cerebellar ataxia. Symptoms of abnormal eye movements and poor balance develop in about one in 4,000 children approximately one week into the skin manifestations of chickenpox. Symptoms generally last for a few days, and a complete recovery is common. Adults more commonly develop a more generalized brain inflammation (encephalitis) whose symptoms may include delirium and seizures. Some studies report a 10% mortality rate and a 15% rate of developing long-term neurologic side effects in survivors.
• Reye's syndrome: This rare childhood complication of chickenpox (and influenza) is most commonly associated with the administration of aspirin. A rapid progression of nausea, vomiting, headache, delirium, and combativeness that may progress to coma is a common pattern of deterioration. Supportive measures are the only therapy.
• Rare complications: Hepatitis, kidney disease, ulcers of the intestinal tract, and inflammation of the testes (orchitis) have all been described. Chickenpox lesions involving the eye may cause scarring and permanently affect vision.

Chickenpox and Pregnancy

The first case of pregnancy-associated complications of VZV was reported in 1947. Further studies have shown that most cases of congenital (in the womb) infection occur in infants whose mothers were infected with VZV between 8 and 20 weeks' gestation. Congenital infection occurs only in infants born to mothers who experience VZV clinical infection (chickenpox) during pregnancy. Women who are immune to VZV and are exposed to chickenpox during pregnancy do not carry the same risk profile for their infant. Studies indicate that the risk of fetal anomalies as a result of congenital VZV infection is very small (0.4%-2%).

Complications that have been documented include skin pigment abnormalities and scarring (presumably due to intrauterine skin infections), eye abnormalities, brain structural abnormalities resulting in mental retardation, and structural abnormalities of the arms and legs. Maternal shingles during any trimester of pregnancy has not been associated with congenital abnormalities. Non-VZV-immune pregnant women can be reassured that localized shingles (zoster) infection is only contagious from direct contact with open lesions.

Maternal VZV infection during the last 2 weeks of a pregnancy carries an ominous risk for the infant. Infected infants have up to a 25% mortality (death) rate, and the worse prognosis exists for those infants whose mothers develop chickenpox during the last 5 days of confinement. Overwhelming generalized sepsis (infection of the bloodstream that spreads throughout the body) and multiple organ infection and failure lead to such a dismal prognosis. Specific anti-VZV gamma globulin can be used to lessen the severity of neonatal disease

Hand, Foot, and Mouth Disease Symptoms

Hand, foot, and mouth disease usually occurs in the spring and fall seasons but may occur at any time during the year. The initial symptoms include

• fever
• general malaise (poor appetite, aches and pains, etc.)

These symptoms generally last one to two days before a blister-like rash develops on the hands, feet, and in the mouth. The rash initially appears as small red spots but then develops into vesicles (blisters). The blisters may develop on the gums, inner cheeks, and tongue, and patients may complain of mouth pain and a sore throat.

These young patients tend to drool and avoid swallowing and may refuse to drink or eat because of the discomfort. Very young infants may even become dehydrated due to the refusal to drink.

Rarely, other more serious complications occur, including viral meningitis (aseptic meningitis) and encephalitis. The symptoms associated with these complications include:

• high fever,
• headache,
• legarthy,
• irritability,
• stiff neck, and
• back pain.

If your child has any of these additional symptoms, you should seek medical attention.

Chickenpox Causes

The varicella-zoster virus (VZV) causes chickenpox. The disease is highly contagious — over 90% of nonimmune individuals will develop chickenpox following exposure.

VZV spreads by both direct skin-to-skin contact and via respiratory droplets (for example, coughing, sneezing) from the infected individual. While the average incubation period from viral exposure to onset of symptoms is 12-14 days, symptoms may appear as early as 10 days or as late as 21 days after exposure to the virus.

Hand, Foot, and Mouth Disease Causes

• Hand, foot, and mouth disease is generally caused by coxsackievirus A-16, which is a member of the enterovirus family.
• There are other types of enteroviruses that can cause the symptoms as well, but these are less common.

Children usually become infected with the virus from other children in an fecal-oral pattern; that is, infection is acquired from exposure to infected fecal material or oral secretions (nasal discharge, saliva, etc.).

The incubation period (time between exposure and symptoms) is usually 5 days.

Chickenpox Treatment

• If you have a fever, your doctor may recommend acetaminophen or ibuprofen.
• If you appear dehydrated and are unable to drink fluids, your doctor may recommend IV fluids either in an emergency room or as a hospitalized patient.
• Secondary bacterial skin infections may be treated with antibiotics. Because a virus causes chickenpox, no antibiotic can cure the disease.
• For people who have severe infections, an antiviral agent called acyclovir (Zovirax) has been shown to shorten the duration and severity of symptoms if given soon after the onset of the rash. Acyclovir may be given by mouth or by IV to help people at risk for severe infection.
• Neonatal VZV infection may be treated with VZIG (varicella zoster immune globulin) -- a form of highly concentrated anti-VZV gamma globulin. The only product manufacturer of VZIG has ceased production, but an alternative product, VariZIG, is available on a research protocol.
• Most cases of chickenpox can be managed at home. Chickenpox rash tends to be extremely itchy. Several treatments can be used at home to help a child feel better.
• Cool compresses applied to blisters may give relief, as may calamine lotion. Lotions containing diphenhydramine (Benadryl) should not be used -- erratic absorption through open skin lesions may occur and be associated with toxicity due to elevated blood levels.
• You can give cool-water baths every three to four hours, adding baking soda to the water to calm itching. You may also soak in an Aveeno oatmeal bath to soothe itching blisters.
• Trimming fingernails can help prevent infection from scratching the blisters. If you have a small infant with chickenpox, cover the child's hands with mittens to minimize scratching.
• Diphenhydramine (Benadryl), loratadine (Claritin), or cetirizine (Zyrtec) taken orally also can relieve itching. These medicines are available over the counter.
• Treat fever with acetaminophen (for example, Tylenol) or ibuprofen (Advil and Motrin are common brand names). Read the label before giving any medication. Some medicines contain many different agents. If the medicine is for a child, make sure it contains no aspirin. Never give aspirin to a child because aspirin has been associated with Reye's syndrome.
• Occasionally a child will develop blisters in the mouth, making eating or drinking painful. A person should be encouraged to drink fluids to prevent dehydration. To alleviate pain, provide cold fluids (ice pops, milk shakes, and smoothies) and soft bland foods. Avoid any foods that are spicy, hot, or acidic (for instance, orange juice).
• Keep children at home from school and day care until all blisters have crusted. A child with chickenpox is extremely contagious until the last crop of blisters has crusted.
• If you take your child to a doctor's office, call ahead to let the staff know that you think your child has chickenpox. They may usher you to a special waiting or treatment room to avoid exposing other children.

Hand, Foot, and Mouth Disease Treatment

There is no specific treatment for hand, foot, and mouth disease. Supportive care, including fever management, and prevention of dehydration are the primary goals.

Occasionally, "magic mouthwash" is prescribed by the provider. This is a mix of several oral liquid medications, generally including a topical anesthetic and diphenhydramine (Benadryl). This is then applied to the mouth ulcers to decrease the pain associated with the oral lesions, decrease the inflammatory response, and encourage the affected infant to increase oral intake.

If your child's fever remains elevated despite appropriate fever-reducing drugs, or if he/she develops any signs or symptoms of dehydration (dry skin and mucous membranes, weight loss, persistent irritability, lethargy, or decreased urine output), you should seek immediate medical attention. Obviously, when concerned or in doubt, contact your child's healthcare provider.

Chickenpox Prognosis

Prior to the introduction of a chickenpox vaccine program, approximately 4 million cases occurred annually in the United States; 10,000 patients were hospitalized annually, and an average of 100 deaths occurred. The majority of deaths occurred in those who had no identifiable risk factor (for example, cancer, HIV/AIDS). Chickenpox should not be viewed as a childhood "rite of passage" and is not merely an inconvenience.

Hand, Foot, and Mouth Disease Prognosis

Appropriate infection control practices are recommended to prevent the spread of hand, foot, and mouth disease. Good hand hygiene (washing hands) is always important. Children infected with the virus causing hand, foot, and mouth disease generally have mild illness and recover within one week of developing symptoms. There is no vaccine; however, the illness is typically mild and self-limited, and children generally cannot develop the illness twice. In addition, most adults have persistent immunity and cannot become infected either.

Any high fever in a very young infant should be evaluated by a healthcare practitioner. For older infants and children, as long as the child has adequate oral intake, this particular illness can be managed comfortably at home.