A quarter of people with epileptic seizures in endemic regions have neurocysticercosis

Design

Systematic review with Bayesian meta-analysis of prevalence

Population

77 studies of people with epileptic seizures in endemic regions, 1990–2023; main estimate from 35 studies with clear case definitions

Primary outcome

Pooled proportion with neurocysticercosis diagnosed by neuroimaging, biopsy or autopsy

Effect

25.2% (95% Bayesian credible interval 19.5–32.2), τ = 1.0 (0.8–1.3)

Twenty databases and 16,202 records yielded 77 studies of neurocysticercosis among people presenting with epileptic seizures between 1990 and 2023. The authors restricted the main estimate to the 35 studies that included both sexes and all ages and used clear case definitions for both neurocysticercosis and epileptic seizures. Diagnosis had to be by neuroimaging, biopsy or autopsy.

In that subset the pooled proportion was 25.2% (95% Bayesian credible interval 19.5–32.2), with high between-study heterogeneity (τ = 1.0, 95% BCI 0.8–1.3). The proportion did not vary by sex or age. Studies that lacked clear case definitions reported substantially lower proportions, which the authors read as misclassification rather than as a real difference — a useful reminder that a loose definition attenuates towards nothing.

The proportion declined between the 1990–2008 and 2008–2023 periods across Africa, the Americas and Southeast Asia. Whether that decline is real is genuinely open: it could reflect better pig husbandry and sanitation, or changing imaging, changing case mix, or a shift in what else is causing seizures. Either way, one in four is the number to carry into a clinic in an endemic area.

• Image every adult presenting with new-onset seizures in an endemic area — CT is usually enough to see calcified or cystic lesions.
• Do not diagnose idiopathic epilepsy in an endemic setting without imaging.
• Ask about household pork consumption and sanitation, and consider screening household contacts for taeniasis.
• Treat the seizures first; antiparasitic therapy has its own indications and risks, and needs corticosteroid cover.
• India remains a high-burden setting for Taenia solium, and neurocysticercosis is among the commonest identifiable causes of adult-onset seizures here.

Why it matters

The probability that a new seizure has a treatable infectious cause depends on where the patient lives, and this quantifies it.

Don't overread it

The apparent decline since 2008 may reflect changes in imaging and case definitions rather than falling transmission.

The statistics, in plain English

A τ of 1.0 signals large real differences between studies, so 25.2% is an average across very different settings rather than a figure to apply to any one clinic. The credible interval (19.5% to 32.2%) describes uncertainty in that average, not the range you would see across regions, which is wider. The authors say explicitly that the pooled estimate should not be treated as universally generalisable.

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