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Onchocerciasis or (river blindness) is a disease caused by filarial worms which are part of the genus onchocerca. It can cause a rash, bumps under the skin, and vision problems including vision loss or blindness. Onchocerciasis was first discovered in Guatemala, where coffee plantations along the slopes of volcanoes with elevations of 500-1500 meters, are found to be the disease-endemic communities exposed to onchocerca volvulus. This disease can be transmitted by black fly bites which are present in large numbers during the coffee harvest months around the coffee trees. Coffee production areas tend to be large commercial plantations that require a lot of labor. About 40% of the labor is from migrants who travel from the highlands of Guatemala, where onchocerciasis is not transmitted. Onchocerciasis breeds in small, clean streams that run down the volcanoes where coffee grows best. Areas in the onchocerciasis central endemic zone or the (OCEZ) receive ivermectin twice per year. Ivermectin is a medication that kills developing worms but does not kill the adult worms. Treatment usually does not include the migrant workers because treatment occurs before and after the coffee harvest season. Scientists did this study so they could “assess the level of transmission of onchocerciasis to seasonal migrant workers.” (Lindblade et al. 2009) Because the migrant workers in general usually miss the semiannual ivermectin treatments, they found that although onchocerciasis is close to being eliminated due to the semiannual ivermectin treatments still “15% of migrant workers sampled on coffee farms in the OCEZ were found to have microfiliaria (a minute larval) in skin biopsies.” (Lindblade et al. 2009) Even though the OCEZ area was receiving administration of ivermectin, in one area of the country there was an annual influx of the disease. The hypothesis was that this was largely due to migrant workers during the harvest season being exposed and infected with O. volvulus. Researchers conducted two evaluations. “The first was a pilot study purposely selected to be able to complete survey and blood samples in a selected plantation in one day.” (Lindblade et al. 2009) “For the second survey, they set the criteria for deciding whether migrant populations pose a threat to the elimination of onchocerciasis in Guatemala (i.e. those persons who have worked on a plantation in a disease-endemic area at least once during the period of 1-5 years before the survey.” (Lindblade et al. 2009) Workers in the pilot study filled out a brief questionnaire of their 3 year plantation work history, how much they know about onchocerciasis, and information about their participation in the mass drug administration program. In the second survey a more precise definition of migrant worker was used. For those who qualified, they filled out a 5 year history of contract labor, knowledge of onchocerciasis ,and participation in the MDA program. “In both studies, finger prick blood samples were taken using sterile procedures and 4-5 drops were placed on a labeled square of Whatman No. 2 filter paper.” (Lindblade et al In the pilot study out of the 85 migrant workers that were surveyed and tested none were found to have the antibodies. In the second survey out of 126 migrant workers who had time for their bodies to potentially generate antibodies 1 was found positive. In the two surveys 170 migrant workers that were tested had worked on a disease-endemic area and had time to build up an immune response. 1 worker that was found positive was 45 years of age and had worked in OVEZ zones for the past five years. No further tests were done. Although it was confirmed that during the period of peak black fly biting, migrant workers were present in OCEZ plantations and strong evidence was not found that the workers were being exposed to onchocerciasis. “As long as transmission in the OCEZ continues to decrease, it is unlikely that migrant workers will pose a threat to the eventual success of the elimination effort, even when excluded from the ivermectin treatment program.” (Lindblade et al. 2009) It was concluded that migrant workers stand as protectors for the OCEZ and that the treatment program is successful in halting transmission of onchocerciasis. 1. Kim A. Lindblade, Michael Richards, Jane Richards, Rodrigo J. Gonzales, Nancy Cruz- Ortiz, Guillermo Zea-Flores, Alba Lucia Morales, Mauricio Sauerbrey, Julio Castro, Eduard Catu’, Bryon Arana, Frank O. Richars Jr, and Robert E. Klein. (2009) Exposure of Seasonal Migrant Workers to Onchocerca volvulus on Coffee Plantation in Guatemala. American Journal of Tropical Medicine and Hygiene, 81 (3) 438-442 ePortfolio site: Http://jpslcceportfolio.yolasite.com

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