Travellers

Travel Health Information sheets

Poliomyelitis

Introduction

Poliomyelitis (polio) is a vaccine-preventable disease caused by the polio virus, a small RNA virus, of the genus Enterovirus within the picornavirus family. There are three serotypes of the human poliovirus (1, 2 & 3) [1]. Polio has been eradicated from most countries in the world; as of the mid 2004, only six countries remain polio endemic (Nigeria, Niger, Egypt, Pakistan, Afghanistan, India.) However, lapses in vaccine coverage in Nigeria has led to recurrence of polio in several African countries.

Epidemiology

(Data from the Travel Health Surveillance Section of the Health Protection Agency Communicable Disease Surveillance Centre)

Global Epidemiology [2]

In 1988, more than 125 countries of the world in five continents were endemic for polio, with more than 1000 children paralysed every day. In that same year, the World Health Assembly voted to launch a global initiative to eradicate polio by 2000. The Global Polio Eradication Initiative was set up by national governments, the World Health Organization (WHO), Rotary International, the US Centers for Disease Control and Prevention (CDC) and UNICEF, and is the largest public health initiative ever known. The Initiative involved collaborative efforts to improve surveillance of polio and to organise mass and 'mop-up' immunisation campaigns. These activities have interrupted transmission of polio in over 100 countries. As a result of the Initiative, by mid 2004, only six countries (Nigeria, Pakistan, India, Niger, Afghanistan and Egypt) were endemic for wild-type poliovirus, and only 784 cases of polio were reported worldwide in 2003 (compared with 1918 cases reported in 2002).

Figure 1 . Global status of polio, 2003

Global status of polio, 2003
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Map reproduced from the Global Polio Eradication Initiative website, http://www.polioeradication.org/progress.asp

The number of cases reported worldwide continues to decline. However, during 2003 and the beginning of 2004, the number of polio cases reported began to increase in Africa, especially in northern Nigeria. This was due to the cessation of polio vaccination in northern Nigeria because of local concerns about vaccine safety. The vaccination campaign was reinstated in July 2004. Nevertheless the increase in the number of cases in Nigeria had affected other African countries; in 2003 and up to 18 August 2004, ten previously polio-free countries (Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Côte D'Ivoire, Ghana, Togo, Sudan and Botswana) reported 90 cases of polio that were related to strains found in Nigeria. One country, Lebanon reported one imported case from India in 2003.

Polio in Travellers from England and Wales

Control of polio in the UK is excellent and there have been no confirmed cases of polio in over a decade. The last imported case reported was in a child who had travelled to India in 1993 [3].

Risk for Travellers

Three regions of the world (Western Hemisphere, Western Pacific and European regions) have eradicated wild type virus so travel to these regions presents a negligible risk. See Clinical Update. The risk of acquiring polio for those visiting the remaining countries at risk, in Africa and the Indian subcontinent, depends on several factors including living conditions, length of stay and standards of food and water hygiene. The risk is highest for those intending to visit areas where there may be poor sanitation [4 5].

Transmission

Polio is transmitted via the faecal-oral route by exposure to faecally contaminated food or water or by person to person contact. Pharyn geal secretions may contain virus and could play a limited role in transmission in areas where sanitation is good [6 7].

Signs and Symptoms

These can be categorised according to the severity of symptoms [1];

Asymptomatic

Accounts for up to 95% of all polio infections. Estimates of the ratio of asymptomatic to paralytic illness vary from 50:1 to 1000:1 (usually 200:1).


Minor, non-specific

Accounts for 4%-8% of infections. Three syndromes are seen and may be indistinguishable from other viral illnesses:

  • upper respiratory tract infection (sore throat and fever)
  • gastrointestinal disturbances ( nausea, vomiting, abdominal pain, constipation or rarely diarrhoea)
  • influenza-like illness

There is no central nervous system invasion and recovery is less than a week.

Non - paralytic aseptic meningitis

Occurs in 1%-2% of infections and is characterised by a non-specific prodrome followed by stiffness of the neck, back, and/or legs. Lasts from 2 to 10 days with complete recovery.

Flaccid paralysis

Occurs in less than 1% of all polio infections. Prodromal symptoms last for 1 to 10 days followed by paralytic symptoms which progress over 2 to 3 days and stabilize as the temperature returns to normal.

There may be two phases, especially in children. Minor symptoms may be followed by a 1 to 7 day interval before the onset of flaccid paralysis with diminished deep tendon reflexes.

Death rates are generally 2%-5% of cases in children and up to 15%-30% of cases in adults (depending on age), increasing to 25%-75% of cases with bulbar involvement.

About 50% of people with paralytic polio recover without paralysis. Another 25% have mild permanent disability, and 25% have permanent severe paralysis. Rarely persons, who have made a complete recovery from polio, will develop a return or worsening of muscle weakness 15 or more years after this attack of polio. This is called Post Polio Syndrome.

Treatment

There are no antiviral drugs available, so treatment is supportive . This includes bed rest and respiratory support if there is respiratory muscle paralysis. Occupational therapy, physiotherapy and occasionally surgery have important roles in patient rehabilitation [1, 6].

Prevention

Travellers should also be advised to:

  • Observe a high level of personal hygiene i.e. hand washing , especially after using the toilet and before eating.
  • Only swim in chlorinated water or that which is unlikely to be contaminated with sewage.
  • Eat food that has been thoroughly cooked and is served piping hot.
  • Do not eat salads and fresh fruit.(5 7 8)
  • See Food & Water hygiene advice

References

1. Centers for Disease Control. Chapter 8; Polio in National Immunization Program Pink Book 8 th ed. Altanta: CDC; 30 January 2004. www.cdc.gov/nip/publications/pink/polio.pdf

2.  World Health Organization. Global Polio Eradication Initiative website [online] [cited 23August 2004]. Geneva: WHO; 2004. Available at http://www.polioeradication.org/

3.  CDSC. 1999/2000 review of communicable diseases - England and Wales . London: PHLS: 2000.

4.  Department of Health Immunisation against Infectious Disease. The 'Green Book' chapters on Diphtheria, Hib, Pertussis, Polio and Tetanus. London: HMSO; 2004.

5.  World Health Organization. International Travel & Health . Geneva: WHO; 2004.www.who.int/ith/index.html

6.  Kumar P, Clark M. Clinical Medicine 5 th ed. Edinburgh; WB Saunders 2002 www.kumarandclark.com

7.  Chin J, editor. Control of Communicable Diseases Manual . 17 th ed. Washington: American Public Health Association; 2000.

8.  Lea G, Leese J, editors. Health Information for Overseas Travel. 2 nd ed. London: The Stationery Office; 2001.

 

 

Reading List

Centers for Disease Control. Poliomyelitis Prevention in the United States. Introduction of a sequential vaccination schedule of Inactivated Poliovirus vaccine followed by Oral Poliovirus vaccine; Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1997; 46 (RR-3): 1 - 25.

Centers for Disease Control. Poliomyelitis Prevention in the United States; Updated Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2000; 49(RR05): 1-22. www.cdc.gov/mmwr/preview/mmwrhtml/rr4905a1.htm

Cook G, Zumla A, editors. Manson's Tropical Diseases 21 st ed. London : WB Saunders Co Ltd; 2003.

Plotkin S, Orenstein W editors Vaccines 4 th ed. Philadelphia: WB Saunders Co Ltd; 2004

Links

Centers for Disease Control (CDC) http://wwwn.cdc.gov/travel/yellowBookCh4-Poliomyelitis.aspx

Committee to Advise on Tropical Medicine and Travel (CATMAT)

http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/03vol29/acs-dcc-10/index.html

The Merck Manual of Medical Information 2004 online www.merck.com/mrkshared/mmanual_home2/home.jsp