Poliomielite

90–95% assintomáticos. Forma abortiva (4–8%): febre, mal-estar, cefaleias, 2–5 dias. Meningite asséptica (1–2%): rigidez da nuca, dor lombar. Forma paralítica (<1%): PFA assimétrica, predominando nos membros inferiores. Forma bulbar (2%): paralisia de nervos cranianos, insuficiência respiratória — alta mortalidade. Síndrome pós-pólio: 25–40% dos sobreviventes, 15–40 anos depois.

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

PFA permanente (~2/3 dos casos paralíticos). Insuficiência respiratória (forma bulbar: mortalidade 25–75%). Deformidades osteoarticulares. Síndrome pós-pólio (25–40%). Mortalidade: espinal 5–10%, bulbar 25–75%.