Coxsackie viruses and Echoviruses

Dr. Hala Al Daghistani

EPIDEMIOLOGY

The coxsackieviruses and echoviruses are widespread throughout the world. Their epidemiology and pathogenesis are much the same as those of the polioviruses.

The consequences of infection with these agents are highly variable and related only in part to virus subgroup and serotype.

Up to 60% of infections are subclinical.

 Inapparent infection is common. Illness manifestations vary from mild to lethal

Coxsackieviruses

  • Coxsackieviruses, a large subgroup of the enteroviruses, weredivided into two groups, A and B, having different pathogenicpotentials for mice.
  • They produce a variety of illnesses inhumans, including aseptic meningitis and respiratory andundifferentiated febrile illnesses.
  • Coxsackie type A is typically associated with exanthems, whereas both types A and B can lead to myocarditis.
  • If untreated, infection may result in aseptic meningitis involving headache and fever, stiff neck, and malaise.
  • Coxsackie type A can cause painful mouth ulcers of the tongue and hand-foot-mouth disease, exhibited by blisters on the hands and feet.
  • A number of group A and B serotypes can give rise to meningoencephalitis and paralysis.

Pathogenesis and Pathology

-Virus has been recovered from the blood in the early stages ofnatural infection in humans.

-Virus is also found in the throatfor a few days early in the infection and in the stools for up to5–6 weeks.

-The entry of coxsackie virus into cells, especially endothelial cells, is mediated byCoxsackie virus receptor.

Clinical Findings

  • The incubation period of coxsackievirus infection rangesfrom 2 to 9 days. The clinical manifestations of infection withvarious coxsackieviruses are diverse and may present as distinctdisease entities
  • They range from mildfebrile illness to CNS, skin, cardiac, and respiratory diseases.

Aseptic meningitisis caused by all types of group B coxsackievirusesand by many group A coxsackieviruses, mostcommonly A7 and A9.

-Fever, malaise, headache, nausea, andabdominal pain are common early symptoms.

-The diseasesometimes progresses to mild muscle weakness suggestive ofparalytic poliomyelitis.

Laboratory Diagnosis

A. Recovery of Virus

In cases of aseptic meningitis,strains have been recovered from the CSF aswell as from the alimentary tract.

In tissue culture, a cytopathic effect appearswithin 5–14 days.

B. Nucleic Acid Detection

Reversetranscription PCR tests can be broadly reactive (detect manyserotypes) or more specific. Such assays have advantages overcell culture methods because many enterovirus clinical isolateshave poor growth characteristics.

C. Serology

Neutralizingantibodies appear early duringthe courseof infection, tend to be specific for the infecting virus, andpersist for years. Serum antibodies can also be detected byother methods such as immunofluorescence.

Epidemiology

Viruses of the coxsackie group have been encountered aroundthe globe. Isolations have been made mainly from humanfeces, pharyngeal swabbings, and sewage. Antibodies to variouscoxsackieviruses are found in serum collected from persons

all over the world .

Echoviruses

  • Echoviruses (enteric cytopathogenic human orphan viruses),based on historical terminology, were grouped togetherbecause they infect the human enteric tract and because theycan be recovered from humans only by inoculation of certaintissue cultures.
  • More than 30 serotypes are known butnot all have been associated with human illness.
  • Asepticmeningitis, encephalitis, febrile illnesses with or withoutrash, common colds, and ocular disease are among the diseasescaused by echoviruses

Clinical Findings

-Many echoviruses have been associated with asepticmeningitis. Rashes are most common in young children.

-For many echoviruses, nodisease entities have been defined.

Laboratory Diagnosis

It is impossible in an individual case to diagnose an echovirusinfection on clinical grounds. However, in the following epidemicsituations, echoviruses must be considered:

(1)summeroutbreaks of aseptic meningitis

(2)summer epidemicsespecially in young children of a febrile illness with rash.

The diagnosis depends on laboratory tests. Nucleic aciddetection assays, such as PCR, are more rapid than virus isolation for diagnosis.