Echoviruses (Enteric Cytopathogenic Human Orphan Viruses): Pathology, Clinical Presentations, Diagnosis And Treatment
Aseptic Meningitis As A Manifestation Of Echovirus Infection
Clinical Manifestations Of Echoviruses
These are RNA viruses ranging in size from 20 to 30 nm which produce a spectrum of diseases ranging from mild upper respiratory infection, fever with rash, aseptic meningitis to acute hemorrhagic conjunctivitis. Over 30 serotypes have been identified by using virus neutralization tests.
Pathogenesis: The virus gets in by ingestion and the mode of spread is fecal-oral. After an initial period of virus multiplication in the epithelium of the intestines and respiratory tract, they enter the blood stream to produce viremia. The organisms reach the various target organs from the blood stream.
The incubation period is generally 2 to 5 days but for hemorrhagic conjunctivitis, it is shorter (12 to 72 hours). The clinical manifestations include non-specific fever, upper respiratory tract infections, exanthemas, diarrheas, pneumonia, myopericarditis and serious neurological involvement. Enterovirus 70 (EV 70) is the causative agent of acute hemorrhagic conjunctivitis.
Aseptic Meningitis: Aspetic meningitis may occur as a result of infection by several strains of ECHO viruses. Signs of meningeal irritation or rise in intracranial tension may be evident. The acute phase may last for 4 to 7 days.
The CSF shows lymphocytic pleocytosis usually less than 500/cmm. Mixed pleocytosis may occur in some cases. Complete recovery is the rule, but rarely complications such as transverse myelitis, bulbar paralysis, Guillaine-Barre syndrome, cerebella lesions and coma may develop.
Hemorrhagic conjunctivitis: An important cause of hemorrhagic conjunctivitis which has occurred in pandemics is EV 70. It is characterized by peri-orbital edema, pain, photophobia, blurred vision and conjunctival suffusion. Though the vast majority clear up completely in a week, neurological complications develop in a few cases. These include multiple cranial nerve palsies, paralysis of lower limbs, bladder disturbances etc.
Hemorrhagic Conjunctivitis As A Physical Manifestation Of Echoviral Infection
Diagnosis And Treatment Of Echoviruses
Diagnosis: Clinical diagnosis is suggested by the acute onset and the meningeal manifestations. Laboratory diagnosis can be made by isolating the virus from the spinal fluid, throat swabs and rectal swabs in the early part of the illness. Rising antibody titers can be demonstrated in sera and the CSF. In EV 70 infection of the eyes, the virus can be isolated from conjunctival swabs.
Treatment: There is no specific treatment and therefore treatment is symptomatic and supportive. Prophylactic measures include improvement of environmental sanitation, provision of protected water supply and elimination of flies. Vaccines are not available for general use.
© 2014 Funom Theophilus Makama