There have been cases of paralytic polio in the Dominican Republican and Haiti from wild type virus for the first time in the Western Hemisphere since 1991. Polio is more common in infants and young children and occurs under conditions of poor hygiene. However, paralysis is more common and more severe when infection occurs in older individuals. Infection ranges in severity from an inapparent infection to a paralytic disease which may result in death. Symptoms include fever, malaise, headache, nausea and vomiting, excruciating muscle pain and stiffness in the neck and back.
Poliovirus is transmitted from person to person primarily by direct fecal-oral contact.
However, it can also be transmitted by indirect contact with infectious saliva or feces or by contaminated sewage or water. Patients are most infectious from seven to 10 days before and after the onset of symptoms. However, patients are potentially contagious as long as the virus is present in the throat and feces. The virus persists in the throat for approximately one week after the onset of illness and is excreted in the feces for several weeks or, occasionally, months. There are three types of polio virus.