- 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 with clear case definitions
- Primary outcome
- Pooled proportion with neurocysticercosis on neuroimaging, biopsy or autopsy
- Effect
- 25.2% (95% Bayesian credible interval 19.5–32.2), τ = 1.0 (0.8–1.3)
Seventy-seven studies published between 1990 and 2023 reported neurocysticercosis among people presenting with epileptic seizures, diagnosed by neuroimaging, biopsy or autopsy. The authors based their main estimate on the 35 studies that covered both sexes, all age groups, and used clear case definitions for both conditions.
The pooled proportion was 25.2% (95% Bayesian credible interval 19.5–32.2), with high heterogeneity (τ = 1.0, 95% BCI 0.8–1.3) and no variation by sex or age. Studies with loose case definitions reported markedly lower proportions — misclassification diluting a real signal, not a genuinely different population.
The proportion fell between 1990–2008 and 2008–2023 across Africa, the Americas and Southeast Asia. Whether transmission has genuinely declined or the apparent fall reflects better imaging, different referral patterns or a change in what else causes seizures is left open by the authors, and they are right to leave it open. What is not in doubt is the order of magnitude: in an endemic area, roughly one new seizure presentation in four has a visible, treatable parasitic cause.
- Image every patient with new-onset seizures in an endemic area before settling on idiopathic epilepsy — non-contrast CT will show most calcified and cystic lesions.
- Where CT is equivocal and the clinical suspicion is high, MRI is better for cysts in the posterior fossa and for scolex identification.
- Control the seizures first; antiparasitic treatment has its own indications, needs corticosteroid cover, and is not urgent.
- Ask about household pork consumption and sanitation, and consider screening household contacts for taeniasis — the tapeworm carrier, not the pig, is the source of human infection.
- India remains high burden, and neurocysticercosis is among the commonest identifiable causes of adult-onset seizures in Indian series.
Why it matters
Whether a new seizure has a treatable cause depends heavily on geography, and this puts a number on it.
Don't overread it
The 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 means the true proportion genuinely differs a great deal between settings, so 25.2% is an average across heterogeneous populations rather than a figure to apply to any particular clinic. The credible interval, 19.5% to 32.2%, describes uncertainty about that average; the spread across actual regions is wider. The authors state explicitly that the pooled estimate is not universally generalisable.
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