Prevalence of active epilepsy in rural Tanzania: A large community-based survey in an adult population

Ewan Hunter, Jane Rogathi, Simukai Chigudu, Ahmed Jusabani, Margaret Jackson, Richard McNally, William Gray, Roger G. Whittaker, Ahmed Iqbal, Daniel Birchall, Eric Aris, Richard Walker
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Purpose: To estimate the prevalence of active epilepsy in adults in an established demographic surveillance site in rural Tanzania. To describe the clinical characteristics of epilepsy and to estimate the treatment gap in this population.

Methods: A pilot study established that a previously validated screening questionnaire was sensitive for detecting cases of epilepsy in a Kiswahili-speaking Tanzanian population. A door-to-door census of the adult population (total 103,026) used the screening questionnaire to identify possible cases of epilepsy, who were then assessed by a research doctor to establish a diagnosis of epilepsy or otherwise. The prevalence of active epilepsy in this population was estimated with age-standardisation to the WHO standard population. Seizure types and epilepsies were classified according to current recommendations of the International League Against Epilepsy. The treatment gap for epilepsy was estimated based on antiepileptic drug use as reported by cases.

Results: Two hundred and ninety-one cases of active epilepsy, all with convulsive seizures, were identified. The age-standardised prevalence was 2.91/1000 adults (95% CI 2.58–3.24); the crude prevalence adjusted for non-response was 3.84/1000 adults (95% CI 3.45–4.20). Focal-onset seizures accounted for 71.5% of all cases identified. The treatment gap was 68.4% (95% CI 63.0–73.7).

Conclusions: This is one of the largest community-based studies of the prevalence of epilepsy in adults conducted in sub-Saharan Africa to date. We identified a lower prevalence than has previously been described in this region. The high proportion of focal onset seizures points to a large burden of acquired, and possibly preventable, epilepsy in this population. A treatment gap of 68.4% confirms that interventions to raise awareness of the treatable nature of epilepsy are warranted in this and similar populations.