…With a Grain of Salt

“Whoever first said, ‘An ounce of prevention is worth a pound of cure,’ likely wasn’t thinking of salt.”[i] However, in a current pilot program through the World Health Organization, salt is just that, a preventative measure against lymphatic filariasis (LF), a parasitic disease of tropical and subtropical areas commonly known as elephantiasis, which causes disfigurement to the lower extremities and genitals in tropical and subtropical areas. Fortification of salt is nothing new.  Switzerland and the US first began fortifying salt with iodine in the 1920s after they discovered that people who lived inland, where salt did not come from the ocean, were more likely to develop goiter, a condition resulting in an enlarged thyroid, and sometimes more serious conditions such as cretinism, a physical and mental stunting due to maternal iodine deficiency during pregnancy. Fortification continued with fluoride in the 1950s. Then later cloroquine, an anti-malarial, and diethylcarbamazine (DEC), for lymphatic filariasis were added experimentally.  The addition of medications, however, was not as well received as the addition of essential elements.[ii] Despite the success of iodized salt in lowering world iodine deficiency by 70% since it was made global fifteen years ago, people are more hesitant to fortify salt with DEC to combat LF even though it affects about 120 million people worldwide and puts about one billion at risk.[iii][iv]

In the case of DEC the problem seems to be lack of force and noncompliance of the salt industry.  China launched a test program in the 1970s after the WHO Bulletin in 1967 published a paper confirming the efficacy of DEC-fortified salt even in cooking and established that it had fewer side effects than the tablets usually administered.  China was thorough and created programs province by province as it had the greatest number of people infected and at risk. Since DEC salt only works as a preventative measure for transmission rather than a treatment, China’s program included both salt and the tablet treatment regimen where needed. All in all, about 194 million people used DEC salt, and, despite the fact that there had been about 31 million infected at the start of the program, China had no transmission by 1994 and was declared LF free in 2006.[v][vi]

After seeing the success in China, the International Task Force for Disease Eradication in 1993 listed LF as an eradicable disease.  This designation was based on the fact that transmission can be stopped by one dose of medication annually for about seven years or the use of DEC salt.  Since the parasite lives in the lymph nodes and produces a smaller form (microfilariae) in the blood, DEC significantly reduces the transmission of the disease since it makes uptake by the mosquito vector impossible by killing the microfilarial load. Thus, once transmission has stopped, only the adult worms residing in the lymph nodes must be killed by the regular drug method to stop the life cycle.

After designating LF as an eradicable disease, the WHO made a goal for its eradication in the Americas 2015 and decided to make Guyana into a test case. Guyana has been the first test of DEC salt in an open market.[vii] The Chinese program was much more controlled, so it was easy to achieve high coverage of a large population. Distribution and preference were both problems in Guyana. The program began in 2003, but was plagued by problems. First, people usually didn’t buy individually wrapped salt. Instead, stores would parcel it out as needed to make it cheaper. DEC salt was packaged separately and more expensive.  Another problem was that the label said it contained potassium ferrocyanide, an anti-caking agent that had been in salt for years, but which scared people away since they only knew what cyanide was from the Jim Jones cult that had committed suicide in Guyana in 1978.  The third problem was that the batch of salt originally sent was blue. This did not affect the taste or efficacy, but put people off of buying it. Finally, in 2004, the supply of DEC salt, which all came from one plant in Jamaica was disrupted by hurricane Ivan, leading to a supply disruption and loss in consumer confidence in 2005.  By then, only a third of the population used DEC salt and only half of stores carried it.

Now, in 2010, coverage of DEC salt in Guyana is still relatively low.   Unfortunately, the fact that the Guyana test case was not nearly as successful as China’s program will make other countries more cautious in starting their own LF eradication programs using DEC salt. The scientists who recommended it originally hope that people will eventually recognize the efficacy of the treatment and follow suit but question the choice of Guyana, which didn’t even have a successful iodization program in place, as a forerunner for another program in salt fortification.[viii][ix] Hopefully, other countries will have more success in open market distribution of DEC salt and accompanying LF treatments and bring an end to this disfiguring but eradicable disease.


References
[i] Cassandra Willyard. “Salt of the Earth.” GeoTimes, June 2008, http://www.agiweb.org/geotimes/june08/article.html?id=feature_salt.html (accessed February 21, 2010).
[ii] Ibid.
[iii] Patrick Lammie, Trevor Milner, Robin Houston. “Unfulfilled Potential: using diethylcarbamazine-fortified salt to eliminate lymphatic filariasis.” WHO Bulletin 85, 7 (July 2007), http://www.who.int/bulletin/volumes/85/7/06-034108/en/ (accessed February 21, 2010).
[iv] “Filariasis.” http://en.wikipedia.org/wiki/Filariasis#cite_note-ITFDE-10 (accessed Feb 21, 2010).
[v] Patrick Lammie, Trevor Milner, Robin Houston. “Unfulfilled Potential: using diethylcarbamazine-fortified salt to eliminate lymphatic filariasis.” WHO Bulletin 85, 7 (July 2007), http://www.who.int/bulletin/volumes/85/7/06-034108/en/ (accessed February 21, 2010).
[vi] Cassandra Willyard. “Salt of the Earth.” GeoTimes, June 2008, http://www.agiweb.org/geotimes/june08/article.html?id=feature_salt.html (accessed February 21, 2010).
[vii] GINA.“New DEC Salt to help eliminate Filariasis by 2015—Guyanese urged to take responsibility for their own.” GINA, Georgetown (July 24, 2003), http://www.gina.gov.gy/archive/researchp/statements/st030724.html (accessed February 21, 2010).
[viii] R. Houston. “Salt fortified with diethylcarbamazine (DEC) as an effective intervention for lymphatic filariasis, with lessons learned from salt iodization programmes.” Parasitology (2000), Cambridge Journals, Cambridge University Press, 2001. http://journals.cambridge.org/action/displayAbstract;jsessionid=529BF6E9089953FF6C191DB044296D4C.tomcat1?fromPage=online&aid=74637 (accessed February 21, 2010)
[ix] Cassandra Willyard. “Salt of the Earth.” GeoTimes, June 2008,
http://www.agiweb.org/geotimes/june08/article.html?id=feature_salt.html (accessed February 21, 2010).

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