Polio

Polio

Disease-a-Month 59 (2013) 445–447 Contents lists available at ScienceDirect Disease-a-Month journal homepage: www.elsevier.com/locate/disamonth Pol...

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Disease-a-Month 59 (2013) 445–447

Contents lists available at ScienceDirect

Disease-a-Month journal homepage: www.elsevier.com/locate/disamonth

Polio Robin B. McFee, DO, MPH, FACPM, FAACT

Polio was once epidemic in the United States. By the 1950s, an inactivated polio vaccine was introduced, and it was followed by live attenuated oral polio vaccine. These preventive strategies dramatically reduced the incidence of polio, until it was considered eradicated in the US.1,2 There are several clinical syndromes of polio infection ranging from asymptomatic illness, aseptic meningitis, abortive poliomyelitis, bulbar polio, polioencephalitis, paralytic polio, the most feared version, occurring in less than one out of 1000 cases, and post-polio syndrome, it is estimated that 300,000 polio survivors of the 1950s have this, as well as vaccine-related paralytic polio, of which approximately 8–10 cases occur in the US annually, caused by the oral polio vaccine.1–3 The primary vaccine recommending the US is the inactivated poliovirus vaccine (IPV), while oral poliovirus vaccine (OPV) may still be used for travelers to endemic areas.1,2 In spite of significant global eradication efforts, polio remains a human pathogen capable of causing outbreaks.1–14 While the last known case of polio in Egypt was in 2004, as of January 2013, the WHO discovered polio from sewage water samples taken in the greater Cairo area.4 Cases of infection were not associated with the finding. As of June 2013, traces of poliovirus were discovered in sewage in the south Israel area of the Negev, Beersheba, Rahat, Kiryat Gat, and Ashdod.5,6 Although Israel has vaccinated 95% of its people against polio, a region-wide inoculation effort is being considered to provide vaccination to 150,000 children.6 As of this writing, no cases of polio have been identified in Egypt or Israel. Poliomyelitis outbreaks in Africa and Asia pose a significant risk for importation of infection, especially in polio-free nations that have low or dwindling vaccine coverage.8–15 On May 9, 2013, the Somali Ministry of Health and WHO confirmed a wild poliovirus type 1 (WPV1) case in a 32-month-old female from Mogadishu, who developed acute flaccid paralysis in April 2013.11 Subsequently, the Kenya Ministry of Public Health and WHO reported a WPV1 case from the Dadaab refugee camps near the Somalia border. Four additional cases were confirmed in the camps. A WPV 1 case was detected from Tahoua in Niger as of November 2012, which is the first case in that country since December 2011, and related to the virus circulating in Kaduna, Nigeria. Among European nations, the Ukraine is considered at risk, although it would be prudent to recognize the risk to any polio-free country that has low vaccination coverage.7 Since viruses do not respect borders, keeping current with vaccines is critically important. These events confirm the risk of ongoing international spread of poliovirus. The poliovirus is a single-stranded RNA virus and a member of the Picornaviridae family of Enteroviruses that causes the clinical infection poliomyelitis, which is a disease of the nervous system.1–3 There are three serotypes, 1–3, of polioviruses. These viruses attach to the anterior 0011-5029/$ - see front matter & 2013 Mosby, Inc. All rights reserved. http://dx.doi.org/10.1016/j.disamonth.2013.10.010

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horn cells of the spinal cord gray matter, motor neurons, and dorsal root ganglia using cellular adhesion molecules. It is a highly infectious viral illness and can cause paralysis in hours. The hosts are humans. The route of entre is oral; the virus enters the body via the mouth and multiplies in the intestines. Initial symptoms include fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the extremities. Clinically, one of the most common presenting features is weakness of an arm or leg. Asymmetric flaccid paralysis (AFP) is a key clue distinguishing polio from other neurological illnesses such as Guillain–Barre (symmetric), ALS (ascending paralysis), or botulinum toxicity (descending symmetric paralysis starting with bulbar involvement). Polio is usually purely motor in most cases. The degree of muscle involvement ranges from minimal to profound, even involving respiratory muscles. A loss of sensation should call into question the diagnosis of polio. The majority of cases are asymptomatic or minimally symptomatic. Approximately 4–8% have minor symptoms including fever, fatigue, nausea, headache, flu-like symptoms, stiff neck and back, and pain in the limbs. Polio mainly affects young children, usually under 5 years of age. Most cases are asymptomatic or minimally symptomatic, however according to WHO, one out of 200 cases will suffer from likely irreversible paralysis that can occur within hours of infection. Among those paralyzed, 5–10% will die from respiratory muscle paralysis. The death rate increases with age. There is no cure, only prevention by vaccination or aggressive symptomatic and supportive care for those who demonstrate AFP. In 1988, there were 125 countries where polio was endemic, resulting in over 300,000 cases. In 2010, there were four countries with indigenous transmission of WPV—Afghanistan, Pakistan, India, and Nigeria. By 2012, less than 250 cases were confirmed, with three countries endemic for polio—Afghanistan, Nigeria, and Pakistan, where vaccine rates remain low. Of concern are recent outbreaks. The failure to eradicate polio from these countries could result in outbreaks of 200,000 new cases annually within 10 years, according to the WHO. Also worrisome are the continued attacks on health care workers who try to implement vaccination programs for children in Pakistan and Nigeria.3 Poliovirus is spread person to person via fecal–oral contact, which includes contaminated water. Of concern, WHO estimates that for every polio case involving paralysis, there are 200 asymptomatic infected persons who are shedding the virus. WHO has therefore initiated a supplemental immunization activity (SIA) for Somalia, Kenya, as well as Ethiopia and Yemen. Of note, the Centers for Disease Control (CDC) recommend all international travelers complete their polio vaccination before travel.1,2 Those planning to visit countries with a designated polio risk, such as Ethiopia, Kenya, and Somalia, the CDC recommends an additional booster polio vaccine. Health care workers and laboratorians should make certain that vaccine status is up to date. References 1. Polio and Polio Vaccine; Epidemiology and Prevention of Vaccine-Preventable Diseases National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention. 〈http://www.cdc.gov/vaccines〉; 2012. 2. Polio Disease In-Short Centers for Disease Control. 〈http://www.cdc.gov/vaccines/vpd-vac/polio/in-short-both〉; accessed 07.16.13. 3. Poliomyelitis Fact Sheet No 114 World Health Organization. 〈http://www.who.int/mediacentre/factsheets/fs114/en/〉; 2013 accessed 07.16.13. 4. Sanchez L. Polio virus discovered in Cairo Jan 22, 2013. Daily News Egypt. 〈http://www.dailynewsegypt.com/2013/ 01/22/polio-virus-discovered-in-cairo/〉; accessed 07.16.13. 5. Sterman A. More polio virus traces detected in Israel June 12, 2013. Times of Israel. 〈http://www.timesofisrael.com/ more-polio-virus-traces-detected-in-israel/〉; accessed 07.16.13. 6. Siegel-Itzkovich J. Health Ministry to give oral polio vaccine to 150,000 children. July 16, 2013 The Jerusalem Post. 〈http://www.jpost.com/landedpages/print.article.aspx?id=317835〉; accessed 07.16.13. 7. Holt E. Ukraine at risk of polio outbreak. Lancet. 2013;381(9885):2244. 8. Hovi T. Poliomyelitis outbreaks in Africa and Asia: importation of infections—a serious risk for polio-free countries with low vaccine coverage. Euro Surveill. 2006;11(3):E060309.2.

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9. Burns CC, Shaw J, Jorba J, et al. Multiple independent emergences of type 2 vaccine-derived polioviruses during a large outbreak in Northern Nigeria. J Virol. 2013;87(9):4907–4922. 10. Polio in Niger Global Alert and Response (GAR) World Health Organization. 〈http://www.who.iint/cse/don/ 2013_02_12/en/〉; accessed 07.16.13. 11. Ehrhardt E. Outbreak of Poliomyelitis—Somalia and Kenya May 2013. MMWR Morb Mortal Wkly Rep. 2013;62(23): 484. Erratum in: MMWR Morb Mortal Wkly Rep. 2013 Jun 21;62(24):508. 12. Arie S. Murder of nine polio workers in Nigeria threatens eradication efforts. Br Med J. 2013;346: f954. 〈http://www.bmj.com/content/346/bmj.f954〉; accessed 07.16.13. 13. Cameroon on the brink of re-infection with wild poliovirus from Nigeria 11 March 2004. Br Med J. 〈http://www.bmj. com/rapid-response2011/10/30/cameroon-brink-re-infection-wild poliovirus〉; accessed 07.16.13. 14. Gulland A. More polio workers are killed in Pakistan. Br Med J. 2013;346:f15. 〈http://www.bmj.com/ content/346/bmj.f15〉; accessed 07.16.13. 15. Shimizu H. The lost decade of global polio eradication and moving forward. Virus. 2010;60(1):49–58.