Prevalence of LF Infection in Districts Not Included in LF Control Activities

Lymphatic filariasis is a neglected tropical disease earmarked for elimination as a public health problem by the year 2020. Since the year 2000, the Global Program for the Elimination of LF has together with endemic countries undertaken preventive chemotherapy in endemic districts to entire at risk populations. In Ghana, treatment of LF is based on the drugs Ivermectin and Albendazole. Remarkable achievements have been made towards the control and elimination of LF in Ghana. However, there remain programmatic and implementation challenges that need to be addressed in order to ensure that the gains made over the last 15 years are sustained. Among these challenges is the persistent transmission of LF in some districts despite more than 10 years of MDA.

Furthermore, LF cases have been identified in communities from eight districts, previously considered as non-endemic. The extent of endemicity in these new districts is unknown. In order to achieve the 2020 elimination targets, it is crucial to determine the distribution and infection prevalence of LF in these districts. Evaluating these districts for LF endemicity will help the implementation of appropriate strategies towards achieving the 2020 target.

This protocol describes the surveys to be undertaken in Ghana in 3 of these districts. The current standard mapping methodologies of LF have the potential to miss LF endemic villages, due to the focal nature of LF. As such, in order to enhance the chances to detect endemic communities, this survey will use a combination of the WHO EPI cluster survey and current LF mapping protocols. 15 communities will be selected in each district, with 100 survey participants per community. Survey participants will be screened for LF infection using immunological and parasitological methods. Study participants will also be tested for onchocerciasis infection using immunological and parasitological methods in districts where LF and oncho are co-endemic. The information from this survey will be combined with the data on the LF vectors and their infection status in the survey areas and relevant data available at the Ghana Health Service to:

1. determine whether LF intervention strategies are indicated in these three districts,
2. design, as indicated, appropriate intervention strategies to achieve LF elimination in these three districts by 2020
3. inform, if indicated, co-implementation of control, monitoring and evaluation for LF and onchocerciasis in the two onchocerciasis endemic districts
4. extract lessons learnt for the design and implementation of surveys in the other districts currently considered non-endemic but where LF cases have been reported.

New rapid diagnostic tests have been developed to assess infection Lf and onchocerciasis infection prevalence at the time of the decision to stop MDA and for surveillance for new infections once MDA has been stopped. These include Rapid Diagnostic Tests (RDT) for antibodies against the W. bancrofti antigen WB123 and the O. volvulus antigen Ov16. These tests still require large scale field validation. Provided additional funding becomes available, this survey will be used to obtain field validation data.