Coxsackievirus A6 (CVA6) is a member of the Enterovirus genus, a group of small RNA viruses that frequently cause infection in humans. CVA6 has become a globally recognized pathogen since its first major appearance in Finland in 2008. While other strains traditionally caused Hand, Foot, and Mouth Disease (HFMD), CVA6 has emerged as a predominant cause of outbreaks worldwide. This virus typically causes a common, self-limiting viral illness, but its clinical presentation is often more pronounced than that of older HFMD strains.
Clinical Manifestations
CVA6 infection causes atypical Hand, Foot, and Mouth Disease (HFMD), differing from the classic presentation caused by Coxsackievirus A16. Following an incubation period of approximately three to six days, the acute phase begins with general symptoms like fever and malaise. The fever is often followed by the rapid onset of a painful enanthem, or sores inside the mouth, sometimes referred to as herpangina.
The characteristic rash associated with CVA6 is typically more widespread and severe than in classic HFMD. While lesions appear on the palms and soles, they often extend to the arms, legs, trunk, and face, presenting as a generalized eruption. These skin lesions can be bullous (large blisters) or present as papulovesicles over a broader area of the body. In individuals with conditions like atopic dermatitis, the rash may be concentrated in areas of inflammation, known as eczema coxsackium.
The lesions generally resolve within seven to ten days. However, the extensive rash can cause significant discomfort and potential misdiagnosis as other viral exanthems. CVA6 is notable for causing HFMD in older children and adults, populations less commonly affected by traditional strains. Although the infection is usually mild and resolves without intervention, the severity of the rash and mouth pain can be substantial during the acute phase.
Transmission and Prevention
CVA6 is highly contagious and spreads primarily through person-to-person contact. The virus is present in respiratory secretions (saliva and nasal discharge) and in the fluid from skin blisters. A major route of transmission is the fecal-oral route, involving contact with stool from an infected person.
Infectivity begins even before the onset of symptoms, making containment challenging. The virus can persist in the stool for several weeks after the acute illness has resolved, though CVA6 shedding is often shorter compared to other enterovirus serotypes. This prolonged shedding means infected individuals can continue to transmit the virus long after they feel well.
Preventive efforts must focus on meticulous hygiene to limit viral spread. Regular hand washing with soap and water is recommended, particularly after using the restroom or changing diapers. Disinfection of contaminated surfaces, including shared toys and common areas, can reduce the viral load. Isolation from school or childcare settings is usually recommended during the acute phase until the fever has resolved and the oral lesions have begun to heal.
Supportive Care and Symptom Management
Treatment for CVA6 infection is supportive, as no specific antiviral medication is available for routine use. The primary goal is to manage pain and prevent the most common complication, which is dehydration. Pain and fever can be managed using over-the-counter oral analgesics, such as acetaminophen or ibuprofen, to improve comfort.
The painful mouth sores (herpangina) can significantly interfere with eating and drinking, especially in young children. Encouraging fluid intake is essential; cool liquids, ice pops, or soft, bland foods are often better tolerated than hot, spicy, or acidic items. Topical anesthetic sprays or rinses may be used to provide temporary relief for severe oral pain.
Monitoring for signs of dehydration, such as decreased urination, lethargy, or lack of tears, is important. Medical attention should be sought immediately if a patient shows signs of significant dehydration, if fever persists for more than three days, or if the individual exhibits unusual symptoms. These symptoms include severe headache, neck stiffness, or confusion. Hospitalization may be necessary for intravenous hydration if oral intake is impossible due to severe mouth pain.
Post-Infectious Recovery Phenomena
Weeks to months after acute symptoms resolve, some individuals experience unique post-infectious effects. The most commonly reported phenomenon is onychomadesis: the painless shedding or detachment of the nail plate from the nail bed. This can affect fingernails, toenails, or both, typically starting at the base of the nail.
This nail loss is not caused by an active infection when it occurs. It is believed to be a temporary result of systemic stress or inflammatory disruption to the nail matrix during the peak of the acute viral illness. Onychomadesis is a benign condition, and the nails are expected to regrow normally over the following months without specific treatment.
Another late-stage effect is desquamation, or peeling, of the skin on the palms and soles. This peeling is temporary and reflects the healing of the rash, particularly where the lesions were most extensive. While these delayed effects can be alarming to the patient or caregiver, they are recognized consequences of CVA6 infection and do not indicate a severe or ongoing complication.