Clinical Course of Common Picorna Virus Diseases

Poliomyelitis (for more information see the  March of Dimes Home Page )

Incubation period: 3-4 days
Seasonality: Summer

Before the introduction of the polio vaccine, polio was a common childhood disease.  It was most know for infantile paralysis and mostly affected young children although it can affect young adults and older people.   In developed countries where standards of hygeine and sanitation the incidence of infection overall  has decreased.  However, it has prevented  most people from acquiring immunity as a child when it is less likely to cause paralysis.

Most polio infection manifest in a mild form of illness ( ~90% ) : fever, malaise, sore throat, headache, vomitting, aseptic meningitis.

10% of cases are more severe:

The virus enters the blood through the stomach and travels through the blood to the CNS (brain and spinal cord) : high fever, meningitis, severe neck and back pain.

1% of cases cause paralysis:

The virus attacks the nerves inside the spine which can cause partial or complete paralysis.  In the most severe cases this can affect the muscles involved in breathing and other important functions which can lead to death.
 Common Cold (Rhinoviruses)

Incubation period : 1-3 days

Duration:  3 days to 2 weeks

Symptoms:  malaise, low fever, watery nasal discharge (rhinorrhea), nasal congestion, headache, sneezing, cough, sore    throat -- mild severity with no real consequences after recovery; mainly an infection of the upper respiratory tract

Seasonality:  year round with peaks in fall and spring (Some enteroviruses are associated with summer colds)

At risk groups:  Children and infants are much more susceptible to the common cold than adults.

Hand Foot and Mouth Disease (most commonly caused by Coxsackie A16 )
Incubation period: 3-5 days

Duration: 7-10days

Symptoms: cold like symptoms and rash ( ulcer on inside of mouth, cheeks, tongue, gums; blisters and bumps on palms of hands and fingers, soles of feet and other parts on skin)

Seasonality: summer, early fall
At risk groups: Young children are most often affected although adults can also get infected.

Hepatitis A

Incubation period: 2-6 weeks

Duration: ~ 4 weeks although there can be a relapse resulting from physiologic stress like drinking or heavy exercise

Symptoms: early symptoms: abrupt onset,malaise, nausea, fever, anorexia, lethargy;
later symptoms : hepatomegaly: may cause pain in upper right abdominal quadrant, bilirubinuria, pale feces, jaundice. 

Most infected children are asymptomatic.  Severity increases with age.

Nonlethal infections recover fully with no permanent liver damage.

At risk groups: Children tend to be more often affected although adults experience more severe cases.
Additional Information:  lifelong immunity after infection, no chronic infection