7th Call - Dr. Dziedzom Komi de Souza

Project Title: Unraveling Persistent Patent Infection after 6 Rounds of Mass Drug Administration to Eliminate Lymphatic Filariasis in Ghana.

Principal Investigator: Dr. Dziedzom komi de Souza (Department of Parasitology,NMIMR)

Email Address: ddesouza@noguchi.ug.edu.gh

Award Amount: GHC 24,995.00

Project Status: On-going

 Summary:

Lymphatic filariasis (LF) is a debilitating mosquito-borne nematode infection that has been earmarked for elimination by 2020. It affects 120 million people in 73 countries where 1.3 billion more are at risk of acquiring the infection through infectious mosquito bites. In 2000, the World Health Organization, in collaboration with pharmaceutical companies and endemic country governments, launched the Global Programme to Eliminate LF (GPELF). It was estimated that 5-6 rounds of MDA were required to eliminate the disease. Many countries including Ghana have since undertaken more than 6 rounds of MDA in several implementation units without interrupting transmission. In Ghana, where the MDA coverage rates have been more than the required 65%, 17 sentinel sites with persistent residual infections have been identified, with microfilaria prevalence rates ranging from 2.5-18.2% after 8 rounds of MDA. Other factors responsible for effective MDA campaigns include baseline MF rates and vector parasite relationships (Kyelem et al., 2008). A micro epidemiological study is therefore required to better understand the existence of hot spots and continuing transmission of LF in Ghana after more than 6 rounds of MDA. We have demonstrated differences in the diversity of W. bancrofti in Ghana (unpublished data) that may influence the outcome of MDA on the transmission of LF. We have also shown that similar to the parasite, the Anopheles gambiae vectors of LF differ between endemic areas (de Souza et al., unpublished data), whiles their distribution is driven by environmental factors (de Souza et al., 2010). The diversity and distribution of Anopheles vectors with different vectorial capacities could partly explain the geographical variation in the outcomes of MDA campaigns in the country. We have reviewed the uniqueness of LF vectors in West Africa, differing vector parasite interactions, and the challenges to the 2020 elimination goal, based on the current MDA strategies (de Souza et al., 2012). The situation is further compounded by the recent observation in Ghana that Mansonia species, previously unrecognized vectors of LF, are involved the transmission of the disease (Ughasi et al., 2012). A closer examination of thediversity in the vector and parasite populations could help us understand the outcome of MDA campaigns in different epidemiological settings in Ghana and the reasons for persistent infections after the recommended number of MDA rounds. There are many factors that could influence the success of MDA (Kyelem et al., 2008; de Souza et al., 2012; Amuzu et al., 2010; Boakye et al., 2004; Boyd et al., 2010; alexander et al., 2001; Sunish et al., 2002). Combining multi-dimensional data with spatial modeling, disease distribution and environmental analysis will enable us better understand the transmission dynamics of LF in Ghana. Thus, the objectives of this study are to; examine entomological, parasitological and environmental factors that could influence the outcome force of LF transmission and the outcome of repeated rounds of MDA, determine the potential impacts on other surrounding communities where LF has been eradicated, and address the programmatic challenges of achieving the 2020 target.