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Poor Americans in the United States suffer hidden burden of parasitic and other neglected diseases

December 26, 2007

Large numbers of the poorest Americans living in the United States are suffering from some of the same parasitic infections that affect the poor in Africa, Asia, and Latin America, says the Editor-in-Chief of PLoS Neglected Tropical Diseases.

In an article entitled "Poverty and Neglected Diseases in the 'Other' America," Professor Peter Hotez (George Washington University and the Sabin Vaccine Institute) says that there is evidence that the parasitic diseases toxocariasis, cysticercosis and toxoplasmosis as well as other neglected infections are very common in the United States, especially among poor and underrepresented minority populations living in inner cities and poor rural areas. Such infections are known as neglected tropical diseases (NTDs) because they afflict mostly poor people and are often ignored by public health officials and political leaders despite their enormous medical importance.

Toxocariasis, caused by the roundworm Toxocara canis, is now a common parasitic infection among inner city African-American and Hispanic children. Possibly as many as 23% of Americans living in poverty are exposed to this parasitic worm, in whom it causes a lung disease that resembles asthma, as well as liver and brain disease. Cysticercosis, caused by the tapeworm Taenia solium, is emerging as the leading cause of epilepsy among Hispanic populations in the US, and toxoplasmosis is an important cause of congenital birth defects among Mexican Americans and African Americans.

"Because these parasitic infections only occur among impoverished people and mostly underrepresented minorities in the US," he says, "I believe that there has been a lack of political will to study the problem. It is easier to allow these diseases of poverty to simply remain neglected."

In addition to the neglected diseases above, significant numbers of American schoolchildren living in poor areas may also be infected with other parasites, including Ascaris roundworms in the South, Strongyloides threadworms in Appalachia, Leishmania protozoan parasites in Texas, and the bacteria that cause leptospirosis.

"That reliable numbers on the actual prevalence of these neglected tropical diseases in the United States are simply not available is reflective of their neglected status, and their disproportionate impact on minorities and poor people," says Professor Hotez. "There is an urgent need to support studies that assess the disease burden resulting from these diseases in the United States, identify the minority populations at greatest risk, and identify simple and cost-effective public health solutions."

A related study in this week's journal, by Thomas Nutman (National Institutes of Health, Bethesda, Maryland, USA ) and colleagues, documents a sizeable number of imported cases to the US of parasitic worm infections (filarial infections) that are predominantly found in the developing world.

Dr. Nutman and colleagues examined data from The GeoSentinel Surveillance Network, a global network of medical and travel clinics established in 1995 to detect trends in illnesses among US travelers. Filarial infections, such as river blindness, elephantiasis, and African eyeworm comprised 0.62% (271) of the 43,722 medical conditions reported to the GeoSentinel Network between 1995 and 2004. Immigrants from filarial-endemic regions comprised the group most likely to have acquired a filarial infection; sub-Saharan Africa was the region of the world where the majority of filarial infections were acquired.

Public Library of Science