It is common for parents and caregivers to confuse Fifth Disease, also known as Erythema Infectiosum, with Hand, Foot, and Mouth Disease (HFMD) because both are common childhood viral illnesses that produce a rash. Despite the superficial similarity of causing a rash, these conditions are entirely distinct. They are caused by different pathogens, present with unique symptoms, and have different periods of contagiousness.
Causes and Causative Agents
The fundamental difference between the two conditions lies in the viruses responsible for each infection. Fifth Disease is caused exclusively by Parvovirus B19, a common human virus that often affects school-age children, typically between 5 and 15 years old. This virus is species-specific to humans and is not the same as the parvovirus that affects pets.
Hand, Foot, and Mouth Disease (HFMD), by contrast, is caused by viruses belonging to the Enterovirus genus, most commonly Coxsackievirus A16 or Enterovirus 71. Because multiple strains of enteroviruses can cause HFMD, a person can contract the illness more than once. HFMD is most frequently seen in infants and children younger than five years old, often circulating in daycare and preschool environments.
Distinctive Symptoms and Rash Presentation
The visual signs of these two illnesses are the most reliable way to tell them apart, as the rashes appear in characteristically different locations and patterns.
Fifth Disease is often preceded by mild, non-specific symptoms such as a low-grade fever, headache, and runny nose, which typically resolve before the rash appears. The rash then progresses in a two-stage pattern, starting with a bright red appearance on the cheeks, which gives the condition its common nickname, “slapped cheek” disease.
A few days after the facial rash, a second rash develops on the trunk, arms, and legs. This body rash has a classic lacy or reticular appearance, where the redness forms a net-like pattern as it fades in the center. This lacy rash may intensify or reappear for several weeks, often triggered by heat, exercise, or sun exposure. The Fifth Disease rash usually does not involve the palms or soles of the feet.
Hand, Foot, and Mouth Disease (HFMD) generally begins with a higher fever, reduced appetite, and a sore throat, leading to painful sores inside the mouth. These mouth sores, or herpangina, are small, blister-like lesions that appear on the tongue, gums, and cheeks, making eating and drinking difficult. The characteristic rash of HFMD involves small, non-itchy spots or blisters that appear predominantly on the palms of the hands and the soles of the feet. The concentration on the hands and feet is highly specific to this diagnosis.
Transmission and Contagiousness
Fifth Disease primarily spreads through respiratory secretions, such as droplets from a cough or sneeze. A person infected with Parvovirus B19 is most contagious during the initial, non-specific period when they have cold-like symptoms but before the characteristic rash appears. Once the “slapped cheek” rash develops, the person is generally no longer contagious and can safely return to school or work.
HFMD is highly contagious and spreads through multiple routes. These include respiratory droplets, direct contact with blister fluid, and contact with an infected person’s stool. The virus can be shed in the stool for several weeks after symptoms have resolved, meaning the period of contagiousness lasts much longer. This long shedding period and the fecal-oral route of transmission make diligent handwashing important in controlling HFMD outbreaks in childcare settings.
Managing the Illnesses
Since both Fifth Disease and Hand, Foot, and Mouth Disease are caused by viruses, the primary approach to care is supportive, focusing on managing symptoms until the body clears the infection. Standard recommendations include rest, hydration, and using over-the-counter medications like acetaminophen or ibuprofen to manage fever and discomfort. Antibiotics are ineffective against either illness because they target bacteria, not viruses.
Managing HFMD
The most pressing concern for HFMD is preventing dehydration, particularly in young children, due to painful mouth sores. Offering cold liquids and avoiding acidic or spicy foods can help minimize pain and encourage fluid intake. If oral discomfort prevents adequate drinking, intravenous hydration may be necessary.
Specific Risks of Fifth Disease
Fifth Disease rarely requires specific treatment in otherwise healthy children, but it poses risks for certain groups. Pregnant women exposed to Parvovirus B19 must consult their doctor, as the virus can be transmitted to the fetus, potentially leading to complications like severe anemia. Individuals with chronic blood disorders, such as sickle cell anemia, or those with weakened immune systems are also at risk for more severe illness and require immediate medical attention if exposed.