Prevalence of neurocysticercosis and its characteristics among people with epileptic seizures and progressively worsening severe headaches in 60 villages in three provinces of Burkina Faso

Abstract
Purpose
Neurocysticercosis (NCC) is a common cause of epilepsy in low- and middle-income countries (LMICs). Few studies have described neuroimaging findings in individuals with headaches in addition to epilepsy. Our aim was therefore to describe the types of NCC lesions seen on cerebral computed tomography (cCT), among participants with progressively worsening severe headaches (PWSH) and epilepsy living in 60 villages in Burkina Faso, and to determine the prevalence of NCC in these groups,.

Methods
Data from a screening questionnaire for epilepsy and PWSH and subsequent neurological examination were gathered as part of a baseline cross-sectional component of a cluster randomized controlled trial conducted between February 2011 and January 2012. Those screening positive and a sub-sample of individuals screening negative were investigated by one of the two physicians in the field. Participants for whom the physician confirmed the presence of the neurological signs/symptoms of interest were invited for cCT. Participants receiving cCT were tested for the presence of circulating cysticercal antigens using the B158/B60 Ag-ELISA and of antibodies using the rT24H EITB. For all individuals undergoing cCT, observed lesions were radiology categorized as active, degenerated or inactive based on recommendations from the literature, or uncertain, when radiologists were unsure whether they met the definitions. These individuals were finally clinically categorized as definitive or probable cases of NCC according to the internationally recognized diagnostic criteria for NCC, or as uncertain cases of NCC when radiologists were unsure about the lesions.

Results
A total of 249 individuals were diagnosed with the neurological signs/symptoms of interest by the physicians. Upon further review by the neurologist, 9 were found to have no neurological signs/symptoms of interest, 109 were diagnosed with epilepsy, 116 with PWSH, and 15 with both. In total, there were 17 definitive NCC cases, 13 probable cases, and 15 cases with an uncertain NCC diagnosis. Among individuals with epilepsy and PWSH, the prevalence of NCC (based on the clinical categorization as definitive or probable NCC cases) was 16.9% (21/124, 95% CI: 10.8%-24.7%) and 7.6% (10/131, 95% CI: 3.7%-13.6%), respectively. Of the definitive or probable NCC cases, 46.7% tested positive for the rT24H EITB (14/30), and 33.3% had a positive Ag-ELISA result (10/30). Among these cases, there were a total of 19 with active lesions, of which 11 showed viable lesions with a scolex, and 6 without, and 2 with degenerating lesions), whereas 29 had inactive (calcified) lesions including 11 mixed lesions.

Discussion
This study is one of the first to provide an estimate for the prevalence of NCC in people with PWSH on the African continent. Furthermore, the findings confirm significant regional variation in the prevalence of NCC cases in people with epilepsy and underscore the need for further research into the inflammatory response to T. solium larvae. Limitations included diagnostic challenges, time delays between assessments, and potential underestimation of the prevalence of NCC due to neuroimaging constraints.

Author summary
Neurocysticercosis (NCC) is a parasitic infection of the brain caused by the larvae of Taenia solium, a zoonotic tapeworm transmitted between humans and pigs. It is a major cause of epilepsy and possibly also associated with severe headaches, particularly in low- and middle-income countries where the parasite is common. This study investigates the prevalence of NCC in people with epilepsy and those experiencing progressively worsening severe headaches (PWSH) in 60 villages in Burkina Faso. To determine how often NCC occurs in these individuals, we used brain imaging (CT neuroimaging) and blood tests to detect markers of infection. Among 124 people with epilepsy, 16.9% were diagnosed with definitive or probable NCC. In contrast, among 131 individuals with PWSH, 7.6% were found to have NCC. Most NCC cases showed calcified brain lesions, which are thought to trigger seizures and headaches through inflammation.