John Ehrenberg was named chief of the Pan American Health Organization's Communicable Diseases Unit in August. He has worked at PAHO since 1998, focusing on tropical diseases and spearheading a multicountry effort to fight lymphatic filariasis. Before joining PAHO, he managed a $6 million Carter Center project to eliminate river blindness from six Latin American countries. He has been a faculty member at the Autonomous University of Yucatán in Mexico and has taught and carried out research in Ethiopia and Liberia. He holds a doctorate from the Johns Hopkins School of Public Health, a master's from the London School of Hygiene and Tropical Medicine, a diploma from the Bernhard-Nocht Tropical Diseases Institute in Germany, and a medical degree from the National Autonomous University of Mexico.
Why do they call the diseases you work on "forgotten diseases"?
These are diseases that don't cause epidemiological emergencies and therefore aren't usually perceived as public health problems. This translates into less demand on the part of countries for important technical cooperation. It means they don't attract the attention of ministries of health or get on the agenda of important public health problems; that agenda is taken up by tuberculosis, dengue, malaria or HIV. Also, they particularly affect forgotten populations: indigenous people, people who live in difficult-to-reach rural areas, where interventions become more complicated. For example, the nomadic Yanomami population of the northern Amazon, where onchocerciasis [river blindness] is endemic, or in indigenous communities in Chiapas, Mexico. All the communities affected by these diseases share high levels of poverty. So it's also difficult to develop medications and diagnostic tools for a market that pharmaceutical companies do not see as profitable, and which is of little interest even to academics.
Yet these are important diseases?
Oh, yes. Take the case of geohelminth infections, which are caused by parasitic worms in the soil. Some 20 to 30 percent of the population in Latin America may be carriers of these parasites. In the case of lymphatic filariasis, there are nearly 9 million Latin Americans at risk of contracting it and 3.2 million already infected. It is the second-leading cause of disability worldwide. When not treated, it can cause chronic swelling in the legs, arms, breasts and genitals. These are stigmatizing effects. Then there are 2,673 communities in our region that live at risk of onchocerciasis, known as river blindness. The common denominator of all these diseases is that they affect communities with limited resources. In some cases, the highest risk groups are preschool and school-age children; in others, they are indigenous people or African Americans, women of childbearing age or people like fishermen, small farmers, or coffee pickers, whose occupations expose them to infection by larvae in the water or soil, or through an insect bite.
What is their impact on public health?
They contribute to poverty, and they lower the life expectancy of those who suffer them. Onchocerciasis and lymphatic filariasis, if not treated, can cause chronic disabilities. Geohelminth infections affect psychomotor development in childhood and therefore limit educational opportunities. They make children miss school, and they affect children's nutritional status, because the parasites consume nutrients. The problem cannot be solved exclusively from a public health standpoint; you need to coordinate with other sectors, especially the educational sector. There are socioeconomic and environmental aspects that go beyond medicine.
As diseases of poverty, do they increase in times of crises?
Yes, when the economic situation deteriorates, as in the case of Uruguay or Argentina, these parasites reemerge or become a more critical problem where they already existed. It's a vicious cycle because they are diseases of poverty that also exacerbate poverty. They are always with us, feeding chronic poverty, contributing to the global burden of disease. And in one way or another, they affect all the Millennium Development Goals.
Why haven't they spread even more throughout the region?
Unlike other diseases that have always been in the Americas, some of these forgotten diseases—like onchocerciasis and lymphatic filariasis—were introduced into the region during colonization as a result of the slave trade. Coming to a new continent, the parasites had to adapt to new vectors and new ecological environments and to biological hosts with different genes and resistance mechanisms from those they were originally adapted to. This combination of factors probably explains why they did not spread rapidly but remained localized. And this localized pattern is precisely what makes onchocerciasis and lymphatic filariasis eliminable.
What are the goals of the elimination efforts?
In the case of geohelminth infections, the goal is for no less than 75 percent of the region's school-age population to have access to antiparasitic medicines and to be under treatment by 2010. But while medicines reduce the parasitic burden, these programs are not sustainable without a political commitment to carrying out educational campaigns alongside and coordinated with other community development projects. As for onchocerciasis, the goal is that, by 2007, it be eliminated as a public health problem in the seven countries where it is endemic: Mexico, Guatemala, Ecuador, Colombia, Venezuela and Brazil. The program is based on two rounds of treatment with Ivermectin [a drug that is effective against the parasite's larval stage] for no less than 85 percent of the population at risk during 12 to 14 consecutive years. In the case of lymphatic filariasis, all indications are that it may already have been eliminated in Costa Rica, Suriname, and Trinidad and Tobago. We expect it to be eliminated in Guyana in 2005 and in Haiti and the Dominican Republic by 2010. Brazil has already eliminated eight of its 11 areas of transmission.
How do you make sure they don't remain forgotten diseases?
There is a consensus within PAHO about the need to break with the traditional scheme of vertical programs and centralization, whereby policies were defined centrally and then imposed on the countries. I think the fact that these diseases were forgotten was in part a consequence of centralization. Most countries do not have any legal agreements even though there are resolutions that countries adopted during the world health assemblies, which call for concrete actions to control or eliminate one or other of these diseases. We are currently promoting small-scale interventions to determine the feasibility of integrated, intersectoral and multi-illness approaches to controlling some of these diseases. There are initiatives under way in Haiti, the Dominican Republic, Brazil, Honduras, Nicaragua, Ecuador, Bolivia, Belize and Suriname. We are working together with UNICEF, the World Bank, the World Food Program, nongovernmental organizations, community groups, and pharmaceutical companies, some of which donate medicines that are essential to the elimination programs. We urge states and provinces to carry out these interventions with strong community participation, through local community associations, town committees and/or health promoters. In planning actions, you need to make use of existing infrastructure and trained personnel, for example, like those from leprosy programs, to manage disabilities caused by lymphatic filariasis.
Are the affected communities receptive to these efforts?
There is a growing demand in the region for help in these areas. In the case of geohelminth infections, imagine a child getting medication and shortly afterward expelling the worm. His mother is going to be impressed to see the immediate effects of the treatment. This has an impact on the mother, sensitizing her about the benefits of health actions. In the end, these programs are useful not only for controlling intestinal parasites but also for health work in general. The Regional Program for the Elimination of Onchocerciasis has practically eliminated blindness due to this disease. It has also reduced other ocular manifestations of the disease to a minimum, even in several of the Yanomami populations in the Amazon. To maintain these achievements and reach others, we have to work in ways that go beyond classical public health measures. We have to work with the private sector, the agricultural sector, and with others who favor and promote sustainable development. We have to work keeping the Millennium Development Goals in view. These diseases will be eliminated or cease to be a public health problem when we solve the problems of poverty, among them, problems of environmental sanitation and lack of access to education. This is a big job that requires interprogrammatic and intersectoral participation. This is part of our unfinished agenda with sectors of the population that have been left behind.
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