What is Poliomyelitis?
Poliomyelitis is a highly infectious disease of the nervous system caused by poliovirus (types 1, 2, and 3). The disease mainly affects young children under 5 years of age. The incubation period is usually 7 – 10 days, with a range of 4 – 35 days. Most cases are asymptomatic or only have mild symptoms such as fever, tiredness, headache, vomiting, stiffness in the neck, and pain in the limbs. In rare cases (less than 1%), it may result in permanent limbs paralyses. Breathing and swallowing functions may also be affected and can be life-threatening.
How does it spread?
Poliovirus is spread from person-to-person mainly through the faecal-oral route or less frequently, by a common vehicle (for example, contaminated water or food).
How can you prevent it?
Vaccination is the most effective way of preventing the disease. There are two types of polio vaccine: Oral Polio Vaccine (OPV) to be taken by mouth and Inactivated Polio Vaccine (IPV) to be given by injection. As OPV is known to be associated with a rare complication “vaccine-associated paralytic poliomyelitis”, IPV has been used in the Hong Kong Childhood Immunisation Programme since 2007. OPV is no longer used in Hong Kong.
The World Health Organization (WHO) recommends that before travelling to polio-affected areas (i.e. those with active transmission of a wild or vaccine derived poliovirus [VDPV]), travellers from polio-free countries should ensure that they have completed the age-appropriate polio vaccine series, according to their respective national immunisation schedule. Travellers to polio-affected areas who have not received any polio vaccine previously should complete a primary schedule of polio vaccination before departure.
Travellers are also advised to maintain good personal and food hygiene. They should always wash hands before eating or handling food, and after going to toilet to avoid exposure to any potentially contaminated food or drinks.
How is it treated?
There is currently no curative treatment for the disease and the goal of clinical management is to control symptoms. Lifesaving measures such as assistance with breathing may be required in severe cases.
Temporary Recommendations by the WHO
On 5 May 2014, the WHO Director-General declared the international spread of poliovirus to be a Public Health Emergency of International Concern (PHEIC) and issued Temporary Recommendations to reduce the international spread of poliovirus.
Countries infected with wild poliovirus or circulating VDPV (cVDPV) with potential risk of international spread should ensure/encourage that all residents and long-term visitors (i.e. > four weeks) of all ages, receive a dose of polio vaccine between four weeks and 12 months prior to international travel. Those undertaking urgent travel (i.e. within four weeks), should receive a dose of polio vaccine at least by the time of departure. Countries infected with wild poliovirus type 1, cVDPV type 1 or type 3 with potential risk of international spread should ensure such travellers to be provided with an International Certificate of Vaccination or Prophylaxis to record their polio vaccination and serve as proof of vaccination.
Further information on the latest Temporary Recommendations of the WHO and the updated list of affected countries of polioviruses is available on the following website (English only): http://polioeradication.org/polio-today/polio-now/public-health-emergency-status./