شلل الأطفال

90–95% بدون أعراض. الشكل الشللي (<1%): شلل رخو حاد غير متماثل يسيطر على الأطراف السفلية. الشكل البصلي: شلل أعصاب قحفية وفشل تنفسي. متلازمة ما بعد شلل الأطفال: 25–40% من الناجين بعد 15–40 سنة.

Host factors increasing risk of paralytic disease:

• Age: Risk of paralysis increases with age at infection. Adults develop paralytic polio more frequently and with greater severity than children.

• Immunodeficiency: Primary immunodeficiency (especially B-cell defects such as agammaglobulinemia) dramatically increases risk of paralytic disease and chronic infection. These individuals can excrete vaccine-derived poliovirus for years (immunodeficiency-associated VDPV, iVDPV).

• Pregnancy: Pregnant women have a higher incidence of paralytic polio and higher case-fatality rates.

• Tonsillectomy: Prior tonsillectomy increases risk of bulbar polio.

• Intramuscular injections: Injections in the weeks before or during infection increase risk of paralysis in the injected limb ("provocation polio").

• Strenuous physical exercise: Physical exertion during the incubation period or early illness is associated with increased severity of paralysis.

Environmental and geographic risk factors:

• Lack of vaccination: Unvaccinated or under-vaccinated individuals in any country are at risk. Immunity gaps from missed routine immunization are the primary driver of cVDPV outbreaks.

• Poor sanitation: Fecal contamination of water supplies facilitates transmission.

• Conflict and displacement: Disruption of immunization programs in conflict zones (Afghanistan, Pakistan, parts of Africa) sustains transmission.

• Overcrowding: Close living conditions in camps or urban slums increase exposure risk.

Travel-related risk factors:

• Travel to endemic countries (Afghanistan, Pakistan) or countries with active cVDPV outbreaks

• Extended stays in rural areas with poor sanitation infrastructure

• Visiting friends and relatives (VFR) travelers may underestimate risk and delay vaccination

شلل رخو دائم. فشل تنفسي (الشكل البصلي: وفيات 25–75%). تشوهات عظمية مفصلية. متلازمة ما بعد شلل الأطفال.