Onchocerciasis elimination challenges and co-endemic diseases

Onchocerciasis is one of the neglected tropical diseases targeted by the World Health Organization (WHO) for elimination through preventative chemotherapy, population surveillance, and post-elimination vector surveillance strategies. Several Onchocerca volvulus endemic regions suffer from co-infections that create challenges for preventative chemotherapy which ultimately hinders global elimination efforts. Though co-infection dynamics between onchocerciasis and other neglected tropical diseases are described in literature, this review demonstrates notable gaps in human immunological studies with regard to the impacts of onchocerciasis elimination in co-infected populations. In regions where multiple NTDs coexist healthcare workers are faced with diagnostic and treatment challenges that underscore the need for integrated control strategies and diagnostic tools to identify multiple diseases endemic to a particular region. Though treatment and control measures have demonstrated challenges, a positive aspect was noted in this review regarding co-infection of onchocerciasis and soil-transmitted helminths (STH), wherein Mass Drug Administration (MDA) with ivermectin for treatment of onchocerciasis had a positive impact in treating hookworm co-infections. With limited availability of comprehensive data on the immunological interactions between O. volvulus and other neglected tropical diseases there is a need for further research to determine the necessary steps required to reach onchocerciasis elimination in foci that currently face treatment challenges and complications.