Salt fortified with diethylcarbamazine (DEC) as an effective intervention for lymphatic filariasis, with lessons learned from salt iodization programmes

DEC-fortified salt has been used successfully as a principal public health tool to eliminate lymphatic filariasis (LF) in China and, less extensively, in several other countries. Studies from 1967 to the present conducted in Brazil, Japan, Tanzania, India, China, and Taiwan involving administration of DEC salt for 18 days to 1 year, have shown this intervention to be effec tive for both bancroftian and brugian filariasis, as measured bq; reduction s in both microfilarial density and positivity, and in some studies through reduction in mosquito positivity rates as well. Furthermore, studies sugge st specifc advantages from using DEC salt, including lack of side effects,, particularly for bancroftian filariasis, and ability to reduce prevalence below 1% when used in conjunction with standard regimens of DEC tablets. Ho wever, use of DEC salt as a control tool suffers from a concern that health authorities might find it difficult to manage a programme involving a comm odity such as salt. Ill the past decade, the very successful global efforts to eliminate iodine deficiency through universal salt iodization have demo nstrated that partnership with the salt industry can be both successful and effective as a public health tool. Use of DEC: salt can be most successful ly implemented in areas in which (a) there is adequate governmental support for its use and for elimination of filariasis, (b) filariasis-endemic area s are clearly defined, (c) political leaders, health officials and tile sal t industry agree that DEC salt is an appropriate intervention, (d) the salt industry is well-organized and has known distribution patterns, (e) a succ essful national salt iodization effort exists, (f) a monitoring system exis ts that ensures adequacy of salt iodine content during production and that can also measure household coverage, and (g) measurement of impact on trans mission of LF with the new antigen or filarial DNA detection methods call b e established. There are advantages and disadvantages of using DEC-fortifie d salt compared with other interventions for LI: elimination programmes, bu t rather than being considered as a 'competing' intervention, DEC salt shou ld be seen as an additional option. Indeed, it is likely that many countrie s will derive maximal benefit from the synergistic effects of combining dif ferent intervention strategics in their national programmes to eliminate ly mphatic filariasis.