Coxsackievirus and Poliovirus

• Coxsackievirus is in the enterovirus genus of the Picornaviridae family and was first isolated in Coxsackie, New York.
• It is a naked virus with an icosahedral capsid (spherical protein shell) and a positive-sense, single-stranded RNA genome.
• Poliovirus is an enterovirus that causes poliomyelitis (polio), primarily affecting the intestines and spinal cord.
• Poliovirus is a single-stranded RNA virus with a protective capsid.

Transmission of Coxsackievirus

• Primarily transmitted via the fecal-oral route.
• Can also spread through respiratory droplets from sneezing or coughing.
• After entering the body, it replicates in the pharynx and terminal ileum.
• It then enters blood vessels and spreads to lymphatic tissue.

Coxsackievirus Symptoms

• Coxsackievirus consists of over two dozen serotypes, divided into Group A and Group B based on pathophysiology.

Group A Coxsackievirus

• Commonly affects children under five, preferring to infect the skin and mucous membranes.
• Serotype A16 causes hand, foot, and mouth disease. Symptoms include painful oval-shaped blisters on fingers, palms, soles, mouth, throat, and tonsils (herpangina).

Group B Coxsackievirus

• Prefers to infect visceral organs, leading to conditions like gastroenteritis (diarrhea and vomiting).
• It can lead to pericarditis (infection of the heart membrane) and myocarditis (infection of the heart muscle), potentially causing Coxsackievirus-induced cardiomyopathy (chest pain).
• Systemic symptoms include fever, headache, and extreme fatigue.
• Can also cause aseptic meningitis or encephalitis, leading to headache, neck stiffness, and pain.

Diagnosis of Coxsackievirus

• Primarily diagnosed clinically based on symptoms; laboratory tests are reserved for severe cases.

Treatment of Coxsackievirus

• Treatment is mainly supportive care, including hydration and fever control.
• Severe cases like meningitis and myocarditis may require intravenous immunoglobulin (IVIG).

Transmission of Poliovirus

• Fecal-oral transmission occurs through contaminated food or water.
• Respiratory droplets spread the virus when an infected person sneezes or coughs releasing virus-containing droplets.

Pathogenesis of Poliovirus

• Poliovirus binds to mucosal cells in the oropharynx and enters cells.
• The virus releases its RNA, hijacking host ribosomes to produce viral proteins.
• Viral replication lyses host cells, releasing new polioviruses.
• The virus spreads to lymph nodes and enters the bloodstream.

Targeting of Motor Neurons by Poliovirus

• Poliovirus enters the interstitial tissue of muscles.
• It invades motor neurons and travels retrograde (backward) up the axon to the anterior horn of the spinal cord.
• Immune cells cause inflammation and damage the spinal cord.
• Motor neuron death causes muscle atrophy and weakness.

Symptoms of Poliovirus

• Most people infected with poliovirus are asymptomatic. Paralytic polio occurs in only 1% of cases.
• Symptoms include high fever, muscle spasms and weakness, loss of reflexes, and flaccid paralysis (asymmetrical, primarily affecting proximal muscles, e.g., thighs).
• Acute flaccid paralysis in infants is referred to as "Sloppy Baby Syndrome" (rag-doll-like limpness).
• Respiratory failure can occur if motor neurons controlling the diaphragm are affected.

Diagnosis of Poliovirus

• Stool samples or throat swabs are used to detect poliovirus.
• Lumbar puncture (spinal tap) examines cerebrospinal fluid, looking for increased WBCs or poliovirus RNA.

Treatment of Poliovirus

• There is no specific antiviral treatment, supportive care is administered.
• Supportive care includes pain management, muscle spasm relief, bladder decompression, and respiratory support (historically using the iron lung).

Poliovirus Prevention

• Polio vaccine is highly effective.
• Humans are the only natural host of poliovirus.