Post‑Acute Infection Syndromes (PAIS)

Post‑acute infection syndromes (PAIS), also known as infection‑associated chronic conditions (IACC), are long‑term illnesses that can follow viral or bacterial infections. They are multi‑system, disabling conditions that can last for months, years, or a lifetime. Long COVID (PASC), ME/CFS, post‑Ebola, post‑SARS, post‑polio, and post‑dengue syndromes are all part of this family.

Signs and symptoms

PAIS symptoms are often non‑specific and overlap across different infections: post‑exertional malaise (PEM), severe fatigue, unrefreshing sleep, cognitive and sensory problems, flu‑like symptoms, muscle and joint pain, and cardiovascular or neurological complaints. The severity fluctuates, and for many people the impact is profound, causing loss of work, independence, and basic daily function.

Causes and mechanisms

PAIS can follow many pathogens, including SARS‑CoV‑2, EBV, influenza, dengue, polio, chikungunya, and others. The biology is complex and still under‑researched. Leading hypotheses include viral persistence or remnants, immune dysregulation and autoimmunity, chronic inflammation, reactivation of latent infections, microbiome disruption, and organ or vascular damage. The common symptom patterns across different infections point to shared mechanisms that demand urgent biomedical investigation.

Diagnosis and management

Diagnosis is often delayed because there are no definitive tests for most PAIS conditions. Patients are frequently sent from clinic to clinic, told nothing is wrong, or labeled as psychological. This is unacceptable. Lack of tests does not mean the illness is not real. Treatment remains largely symptomatic because funding and research have not matched the scale of the crisis.

The scandal of decades‑long neglect

For decades, PAIS conditions were minimized, psychologized, or ignored. This systemic neglect delayed research, denied care, and left patients to suffer in silence. It is a public‑health failure: millions harmed, families destroyed, and a medical system that too often chose stigma over science. Long COVID did not create this crisis, it exposed it.

A call to action

The suffering is extreme, and the stakes are life‑and‑death. Patient communities report high levels of despair and increased suicide risk, and some countries are seeing assisted‑dying cases linked to the unbearable burden of untreated illness and social abandonment. This must end. We demand recognition, accessible care, and a massive investment in biomedical research, now.

If you or someone you know is in immediate danger or crisis, please seek urgent local support. You are not alone.