Table 7 Research priorities in the estimation of the current burden of OAE

1

More fundamental research is required to investigate the biological mechanisms of a potential relationship between onchocerciasis and epilepsy. Fundamental evidence of causality could assist in the establishment of burden estimates as well as the potential development of diagnostic algorithm to identify an OAE cases.

2

Repeat the previous performed meta–analysis by Pion et al. [4] including recently performed epilepsy surveys in onchocerciasis-endemic regions to incorporate new information. Sources of bias of included studies should be tracked and a meta-analysis should preferably adjust for potential confounders (age, sex, residence, certain parasitic infections (e.g. NCC)). A correction should be made to exclude epilepsy potentially initiated by other causes.

3

Perform epilepsy incidence or prevalence surveys in onchocerciasis-endemic areas where no data is yet available, using standardised tools for O. volvulus and epilepsy diagnosis. Information should be collected on the age and sex distribution of OAE cases (including age of onset of the epilepsy) and the co-prevalence of other sequelae including onchocerciasis associated skin disease (including itching) and ocular disease. Such studies should tempt to include diagnosis of various other parasitic infections, including NCC, malaria, and toxoplasmosis. Muslim or Orthodox Ethiopian-Christian areas where pigs are not raised but endemic for onchocerciasis could be included in such surveys.

4

Design, implement and evaluate a simple tool for ubiquitous use in limited resource settings to identify suspected epilepsy cases, which can be used by community distributors of ivermectin and local primary healthcare workers so that these cases are timely referred to local health facilities.

5

Conduct prospective, longitudinal community intervention trials on the impact of MDA on the incidence of OAE in ivermectin-naïve areas with high onchocerciasis transmission with individual-level follow-up recording O. volvulus infection status, epilepsy onset, and ivermectin usage. Compare alternative onchocerciasis control strategies on reducing OAE incidence, e.g. different frequencies of distribution of ivermectin, use of new macrofilaricidal drugs in development, and vector control where feasible.

6

Determine the direct and indirect health-related costs, and intangible costs due to OAE by disease stage, country, sex, and age through a cost-of-illness analysis for a more precise economic burden estimate for OAE.