Enteroviral infections

What are enteroviral infections?

Enteroviral infections cover a wide range of illnesses that are caused by enteroviruses (EVs). They are members of the Picornaviridae family; small, icosahedral, single-stranded, positive-sense RNA viruses.

The most well known of the enteroviruses is the poliovirus (PV) but this has mostly been eradicated. Other enteroviruses are the Coxsackie A and B viruses (CVA and CVB) and the echoviruses (ECHO: enteric cytopathic human orphan).

How are enteroviruses classified?

Enteroviruses have been classified into five groups based on their molecular properties.

1. Poliovirus: PV1–PV3
2. Human EV A (HEV-A): CVA2–CVA9, CVA10, CVA12, CVA14, CVA16 and EV71
3. Human EV B (HEV-B): CVA9, CVB1–CVB6, E1–E7, E9, E11–E21, E24–E27, E29–E33, EV69
4. Human EV C (HEV-C): CVA1, CVA11, CVA13, CVA15, CVA17–CVA22, CVA2
5. Human EV D (HEV-D): EV68, EV70, EV73–EV75, EV77–EV78

Enteroviruses are the cause of many illnesses including the common cold. Some of the coxsackieviruses, echoviruses and EV71 cause exanthems (skin rash or skin eruption as a symptom of a more general disease) or enanthems (rash on the mucous membranes). Cutaneous manifestations may be severe and atypical in some cases.

Who gets enteroviral infections?

Enteroviral infections are widespread and it is estimated that more than one billion people worldwide are affected annually. In the United States 30,000 to 50,000 hospitalisations each year are due to enteroviral infections. People at risk include:

• Infants and children
• Neonates acquiring infection from mothers
• Immunocompromised patients
• People in lower socio-economic groups.

How are enteroviral infections spread?

Enteroviral infections are highly contagious. Enteroviruses spread from person-to-person via:

• Oral–oral routes; for example viruses are carried in respiratory droplets and transmitted when someone coughs and sneezes
• Oral–faecal transmission
• Direct contact with fluid from skin lesions
• From mother to child in the peripartum period.

The incubation period for enteroviruses is usually 2–5 days. Once someone is infected, the enteroviruses implant and replicate in the alimentary tract.

If the infection remains localised there are usually no symptoms. However, if the virus passes into the lymphatic system, generalised un-wellness may develop. If the virus spreads into the bloodstream more severe symptoms are experienced.

Which enteroviral infections cause cutaneous signs?

Many enteroviruses cause diseases with associated cutaneous or mucous membrane reactions.

Herpangina

• Herpangina is caused by Coxsackie group A, Coxsackie B, enterovirus 71, and echovirus.
• Lesions develop on the mucous membranes, most often on the anterior tonsils, uvula, and soft palate of the mouth.
• Lesions are characterised by tiny grey-white papulovesicles about 1–2 mm in diameter.
• They are self-limiting and resolve over 5–10 days.
• Generalised symptoms include high fever, headache, sore throat, difficulty swallowing, vomiting and abdominal pain.

Hand, foot and mouth disease

• Hand, foot and mouth disease (enteroviral stomatitis) is caused by Coxsackievirus A16 and enterovirus 71.
• Oral lesions develop anywhere inside the mouth but most frequently appear on the hard palate, tongue, cheek and gums.
• Oral lesions begin as erythematous macules, and papules (flat, inflamed red spots) 2–8 mm in diameter and progress to form thin-walled vesicles (blisters) that burst and form painful ulcers surrounded by a red halo. These heal without treatment over 5–10 days.
• Skin lesions appear at the same time or shortly after the oral lesions. There may be a few to more than 100 lesions on the hands and the feet.
• Skin lesions begin as erythematous macules or papules which quickly turn into small, grey vesicles surrounded by a red halo. These lesions resolve spontaneously over 7–10 days without scarring.

Boston exanthem disease

• Boston exanthem disease is caused by echovirus 16.
• After a short fever, pink macules and papules suddenly erupt on the face and trunk, and less commonly the extremities.
• Small ulcers may also be found on the soft palate and tonsils.

Eruptive pseudoangiomatosis

• Eruptive pseudoangiomatosis is caused by echovirus 25 and 32, Coxsackie B, Epstein-Barr virus, and CMV.
• Up to about ten cherry red lesions develop on the face, trunk and extremities.
• The pseudoangiomas are 2–4 mm in diameter and resemble cherry angiomas.
• They resolve spontaneously within ten days.

Other cutaneous features are sometimes seen in enterovirus infections and include:

• Pustular stomatitis with erythema multiforme: caused by CVB5
• Widespread vesicular eruption (blisters): CVA4
• Papular acrodermatitis of childhood (Gianotti-Crosti): CVA16
• Rubelliform eruption (rash looks like rubella): E2
• Morbilliform eruption (rash looks like measles): E6, E11, E25
• Petechiae (tiny purple spots or purpura): E11, E19
• Punctate macular eruption: E19
• A vesicular eruption (blisters): E11
• Eczema coxsackium (a severe infection associated with atopic dermatitis).

See enteroviral images.

What are the complications of enteroviral infections?

Fewer than 1% of enteroviral infections result in symptomatic severe illness. Occasionally, enteroviruses can cause heart and nervous system complications such as myocarditis, aseptic meningitis, meningoencephalitis and paralysis.

How are enteroviral infections diagnosed?

The diagnosis of enteroviral infections is primarily based on clinical findings.

• Enteroviral PCR assays are helpful in confirming the pathogens.
• Serologic testing and culture of the virus are done in rare cases.

What is the treatment of enteroviral infections?

Treatment is limited to supportive therapy.

• Hand washing (especially after changing a nappy) and personal hygiene
• Disinfecting surfaces and objects
• Avoiding close contact
• Hydration with plenty of fluids
• Antipyretics such as paracetamol for fever
• Mouthwashes containing topical anaesthetics (lidocaine 2%) and antihistamines (eg, diphenhydramine hydrochloride) to relieve mouth pain

Intravenous immunoglobulin has been used for the treatment of enterovirus infection in symptomatic infants.

The antiviral drug pleconaril has shown to be an effective treatment in some severe enteroviral infections. Pleconaril is not available in New Zealand (December 2016).

What is the outcome of enteroviral infections?

Most enteroviral infections heal spontaneously within 7–10 days. Cutaneous lesions heal without scarring.