The 31st Meeting of the Mectizan Expert Committee/Albendazole Coordination (page 2)

Onchocerciasis

TDR reported that the rapid assessment technique for community prevalence of L. loa (RAPLOA) is now valid for use in Cameroon and Nigeria. Validation in other countries will be completed by February 2004. It is hoped that the technique will then be available for widespread use to identify areas at high risk for L. loa associated Serious Adverse Events, which involve disturbances of the Central Nervous System (CNS) following Mectizan treatment. It was also reported that work on the search for macrofilaricidal drugs for onchocerciasis and LF is proceeding.

The need for revisions to the existing MEC/Technical Consultative Committee guidelines for treatment with Mectizan in L. loa endemic areas was discussed based on information provided by an informal working group that had reviewed the guidelines at Merck headquarters the day before the MEC/AC meeting. After further review and discussion of the guidelines and the report by the informal working group, the MEC endorsed the conclusions and recommendations of the working group, which stated that the guidelines should be revised to:

1) Emphasize the need to use the most up-to-date L. loa endemicity map, based on remote sensing and prevalence data, in decision-making for mass treatment with Mectizan.

2) Discontinue community-by-community rapid epidemiological assessment (REA) used to exclude communities hypo-endemic for onchocerciasis in loiasis-endemic areas from mass treatment with Mectizan because the benefit of treatment was deemed insufficient to outweigh the risk of post-treatment L. loa associated CNS disturbances. Instead, decisions about mass treatment strategies should be based upon the risk of high L. loa endemicity as determined by the L. loa endemicity map mentioned above.

3) Include guidelines on clinical management of encephalopathy as an appendix.

Another major topic discussed during the meeting was the decision-making process surrounding when to stop Mectizan mass treatment for onchocerciasis control in Africa. Operational epidemiologic, parasitologic, and entomologic parameters for defining the achievement and maintenance of the elimination of onchocerciasis as a public health problem (in the presence of possible ongoing low-level transmission of the parasite) are still unknown and need urgent investigation. An opportunity exists to continue follow-up on the impact of once- and twice-annual treatment with Mectizan for at least 10 years within the former Onchocerciasis Control Program in West Africa (OCP), but funding is not yet available. The MEC recognized the importance of this work and agreed to assist TDR in finding the necessary funding for this vital research in collaboration with other parties.

Finally, it was noted that all endemic countries in Latin America are treating every six months with Mectizan and achieved greater than 85% coverage in all six of them in the first treatment cycle of 2003. Operational research is planned in Latin America to determine whether treating onchocerciasis every 3 months with Mectizan can decrease the duration of mass treatment needed to eliminate transmission in the Americas.

The next meeting of the MEC/AC will be held in April 2004 in Atlanta, Georgia, USA.

©2004 Mectizan Donation Program