Picornaviridae: Family Groups, Causes and Diagnosis

Picornaviridae are the smallest among the RNA virus family. These viruses cause a wider range of illnesses and can cause clinical diseases like aseptic meningitis, encephalitis, and rash illnesses like hand-foot and mouth disease. The Picornavirus family includes one of the most important viruses that is polio and poliomyelitis is one of the first recorded infections.

Picornaviridae Family Groups

1. Enterovirus- This group of the picornavirus family is mainly transmitted by fecal-oral route. The types of viruses are polio, Coxsackievirus, and echovirus.
2. Rhinovirus- this group of virus is mainly transmitted by inhalation.

Enterovirus

The diseases caused by enterovirus are acute hemorrhagic conjunctivitis, hand-foot-mouth disease, and hepatitis A virus.

Poliovirus

• It has three antigenic types- type 1, type 2, and type 3.
• The incubation period is one to two weeks.
• Mainly transmitted by fecal-oral route.
• The infective period Is one week before and two to three after the onset of signs and symptoms.
• After ingestion, the virus is present in the GIT, and then from the git, it reaches lymphatics. It spreads into the blood (Viremia) from the lymphatics. At this stage symptoms like fever, headache, malaise, and vomiting occur. After this CNS can get affected which leads to meningitis and if this situation becomes severe the patient can present with paralytic polio.
• The earliest change is Nissl’s body degeneration and the motor neurons are the final site.
• There is asymmetric descending flaccid paralysis in which the proximal muscles are more involved than the distal muscles. There can be respiratory failure and meningoencephalitis.

Diagnosis

• Throat or rectal swabs are used as a sample.
• Antibody detection can be done.
• Molecular methods like RT-PCR can be used.

Also Read: Intravenous Fluid: Uses and Types

Coxsackie Virus

• The mode of infection is the fecal-oral route.
• The viruses are of two types: Coxsackie A and Coxsackie B.
• Coxsackie A virus can cause Flaccid paralysis and Coxsackie B virus can lead to Spastic paralysis.
• Coxsackie-A virus has 1- 24 serotypes and can cause diseases like herpangina, acute hemorrhagic conjunctivitis, and hand-foot-mouth disease.
• Coxsackie B virus has 1-6 serotypes and can lead to dilated cardiomyopathy, pleurodynia, and hand-foot-mouth disease.

                                     Hand-foot-mouth Disease

Also Read: Tetanus: Causes, Symptoms, Prevention

Echovirus

It is an Enteric cytopathogenic human orphan virus.

Causes

• Aseptic meningitis
• Encephalitis
• Common cold
• Rashes

Also Read: Myasthenia Gravis: Causes, Antibodies, Manifestation, Diagnosis, Treatment

Rhinovirus

• It is an acid labile virus which is spread by inhalation.
• The incubation period is 2 to 4 days and the optimal temperature required for its growth is 33°.
• ICAM1 Receptors act as a site of attachment of rhinovirus.
• Nasal IgA antibodies give immunity against this virus.
• Clinical features are of the common cold.

Also Read: Listeriosis : Causes, Symptoms, Risk Factors, Diagnosis, Treatment, Prevention

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