A Study of Frequency and Secular Trends of Seropositivity for Cysticercosis in Peru Over 20 Years

Neurocysticercosis is a leading cause of acquired epilepsy in endemic regions. Scarce longitudinal data sets exist to allow assessment of secular trends in prevalence. This study analysed temporal trends of cysticercosis seropositivity among suspected patients across Peru over two decades.

An ecological study was conducted using anonymized serological data from patients who underwent enzyme-linked immunoelectrotransfer blot (EITB) testing for the first time at a neurological referral centre in Lima, Peru. Seropositivity was defined as antibody reactivity to ≥ 1 glycoprotein band, and higher thresholds (≥ 3, ≥ 4 bands) were also assessed considering their association with active disease. Temporal trends were analysed using generalised linear models with Poisson regression.

Among 39,481 individuals, seropositivity was 31.3% (12,350/39,481). The prevalence of seropositivity increased from 27.3% in the initial 5-year period (2000-2004) to 37.4% in the last (2014-2019), while the numbers of requested tests decreased from 15,074 to 5130 and the overall numbers of new seropositive individuals decreased from 4109 cases to 1918. High-reactivity cases also increased in proportion but decreased in number (≥ 3 bands: 18.1% to 27.1% and 2734 to 1392; ≥ 4 bands: 7.9% to 17.5% and 1194 to 897), suggesting a greater proportion of active or clinically relevant infections.

Over 20 years, the demand for cysticercosis serology and the numbers of seropositive cases by 5-year periods decreased while the proportion of seropositive cases rose significantly within a single specialised referral centre. While data from suspected clinical cases do not necessarily represent disease burden at the population level, the reduction in case numbers may represent reduced disease prevalence. At the same time, the persistence of significant numbers of cases in this single centre study through the last examined period and the increased proportion of strong seropositive cases demonstrate that cysticercosis is still endemic in Peru.