A paper by Dr. Thomas Nutman, a scientist with the National Institute of Allergy and Infectious Diseases, and colleagues of his reviewed data collected from 1997 to 2004 to determine demographic and travel characteristics of travelers diagnosed with parasitic worm -- filarial -- infections.

The researchers found that filarial infections responsible for such diseases as onchocerciasis, or river blindness; lymphatic filariasis, or elephantiasis; and loiasis, or African eyeworm illness, made up 271, or 0.62 percent, of the 43,722 medical conditions reported during that time period.

Additionally, the data showed immigrants from filarial-endemic regions were most likely to come to the travel/tropical diseases clinics, and that long-term travel of more than one month was more likely to be associated with filarial infection than shorter trips.

The paper, published in the PLoS Neglected Tropical Diseases, said the most commonly acquired filarial infection -- 37 percent -- was Onchocerca volvulus, the worm that causes river blindness.