The role of entomology in onchocerciasis elimination

Onchocerciasis is a disease caused by the filarial nematode Onchocerca volvulus transmitted through bites of female blackflies. Historical control of onchocerciasis solely used vector control. In Uganda, treatment with ivermectin and vector control were strategies adopted for elimination. However, despite the contributions of vector control in onchocerciasis elimination, its role remained downplayed. This PhD research was conducted in the context of Uganda Onchocerciasis elimination programme. Eight studies were conducted to investigate the role of entomology in onchocerciasis elimination. The first study was in Mpamba-Nkusi focus, located in Mid-western Uganda. In 2003, entomological and epidemiological surveys were conducted in the focus.  We observed that information on blackfly dynamics and physiochemical parameters were vital for blackfly elimination. A second study was performed in Pader district in Madi Mid-North focus, northern Uganda. In this area, onchocerciasis is endemic including epilepsy and nodding syndrome. Our study reported for the first time onchocerciasis related “blindness” in northern Uganda. The third, fourth and fifth studies were performed in Itwara, Mpamba-Nkusi and Kashoya-Kitomi foci. In the three foci, onchocerciasis was hyper endemic.   In 2011, 2012 and 2013 entomological, epidemiological and serological surveys were conducted to assess the impact of interventions. We concluded that ivermectin treatment and vector control interrupted onchocerciasis transmission. A sixth study was conducted in Obongi focus in North Western Uganda. In 2014-2015 we assessed the feasibility of combining chemotherapy of onchocerciasis and Lymphatic Filariasis. We observed that integrated chemotherapy interrupted the transmission of the two diseases.  Success was based on effective mass treatment for both diseases. The seventh study was conducted in Ituri focus, eastern Democratic Republic of Congo where onchocerciasis is endemic. In 2009, we conducted entomological and epidemiological surveys. The study identified political commitment as one of the key factors for the success of cross-border collaboration. The eighth study was conducted in Maridi County in South Sudan where onchocerciasis is hyperendemic including, epilepsy and nodding syndrome. Maridi dam was confirmed to be responsible for rising cases of epilepsy and nodding syndrome. Community-based removal of vegetation from blackfly breeding habitat was shown to be effective in decreasing blackfly biting rates. Limited entomological work force, underfunding for vector control, cross-border transmission and refugee crisis were the key challenges. Policies related to vector control and cross-border collaborations are recommended.

Jaar van publicatie:2023

Trefwoorden:Doctoral thesis

Toegankelijkheid:Open