Is Polio contagious?
The poliovirus is contagious and transmissible from person-to-person. The most common route of transmission is through contact with the stool of an infected person; however, it can also be spread through respiratory secretions (coughing, sneezing) but this mode of transmission occurs less frequently. The poliovirus enters the body through the mouth, replicates in the pharynx and gastrointestinal system, and is excreted from the body through the stool.1 2 Vaccine-strain and vaccine-derived polio are also contagious and transmitted the same way as wild-type polio.3 4
In households with children, the transmission rate among susceptible individuals is nearly 100 percent. Transmission rates in household with adults is estimated to be over 90 percent. Approximately 95 percent of people who contract the poliovirus have no symptoms but are still contagious to others. Asymptomatic spreading of poliovirus from infected persons who have no apparent symptoms, to susceptible contacts, occurs most often.5
An infected person is most contagious to others from 7 to 10 days before and after symptoms of illness occur, but the virus can still be found in the stool for up to 6 weeks or longer.6 In some cases, shedding of the poliovirus has occurred for months and even years. This usually occurs in persons who are immunodeficient; however, this has also been reported in healthy individuals.7 8 9 10 11 Persons who are immunodeficient can shed vaccine-strain poliovirus for several years. When this occurs, the vaccine-strain usually mutates into a vaccine-derived poliovirus and can cause cases and outbreaks in communities.12
In temperate climates, poliovirus infection occurs most frequently in the summer months. No seasonal pattern has been noted in tropical climates. 13 The poliovirus can be rendered inactive with chlorine, formaldehyde, heat, and ultraviolet light.14
IMPORTANT NOTE: NVIC encourages you to become fully informed about Polio and the Polio vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.
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1 CDC Poliomyelitis – Epidemiology Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book). 13th ed. 2015.
2 CDC Global Health – What is Polio? Oct. 24, 2019
3 CDC Vaccine-derived Poliovirus - Questions and Answers May 4, 2018
4 Global Polio Eradication Initiative (GPEI) Vaccine-associated paralytic polio (VAPP) and vaccine-derived poliovirus (VDPV) Fact Sheet Feb. 2015
5 CDC Poliomyelitis – Epidemiology Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book). 13th ed. 2015.
7 Minor P Characteristics of poliovirus strains from long-term excretors with primary immunodeficiencies. Dev Biol (Basel). 2001;105:75-80.
8 Martín J Vaccine-derived poliovirus from long term excretors and the end game of polio eradication. Biologicals. 2006 Jun;34(2):117-22
9 Kew OM, Sutter RW, Nottay BK et al. Prolonged Replication of a Type 1 Vaccine-Derived Poliovirus in an Immunodeficient Patient J Clin Microbiol. 1998 Oct; 36(10): 2893–2899.
10 Martín J, Odoom K, Tuite G Long-term excretion of vaccine-derived poliovirus by a healthy child. J Virol. 2004 Dec;78(24):13839-47.
11 Hovi T, Lindholm N, Savolainen C et al. Evolution of wild-type 1 poliovirus in two healthy siblings excreting the virus over a period of 6 months. J Gen Virol. 2004 Feb;85(Pt 2):369-77.
12 Aghamohammadi A, Abolhassani H, Kutukculer N et al. Patients with Primary Immunodeficiencies Are a Reservoir of Poliovirus and a Risk to Polio Eradication. Front Immunol. 2017 Jun 13;8:685.
13 CDC Poliomyelitis – Epidemiology Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book). 13th ed. 2015.
14 CDC Poliomyelitis – Poliovirus Epidemiology and Prevention of Vaccine-Preventable Diseases (The Pink Book). 13th ed. 2015.