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Worms infect more poor Americans than thought
Tue Dec 25, 2007 8:13pm EST Email | Print | Share| Reprints | Single Page | Recommend (3) [-] Text [+]


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WASHINGTON (Reuters) - Roundworms may infect close to a quarter of inner city black children, tapeworms are the leading cause of seizures among U.S. Hispanics and other parasitic diseases associated with poor countries are also affecting Americans, a U.S. expert said on Tuesday.

Recent studies show many of the poorest Americans living in the United States carry some of the same parasitic infections that affect the poor in Africa, Asia, and Latin America, said Dr. Peter Hotez, a tropical disease expert at George Washington University and editor-in-chief of the Public Library of Science journal PLoS Neglected Tropical Diseases.

Writing in the journal, Hotez said these parasitic infections had been ignored by most health experts in the United States.

"I feel strongly that this is such an important health issue and yet because it only affects the poor it has been ignored," Hotez said via e-mail.

He said the United States spent hundreds of millions of dollars to defend against bio-terrorism threats like anthrax or smallpox or avian flu, which were more a theoretical concern than a real threat at present.

"And yet we have a devastating parasitic disease burden among the American poor, right under our nose," Hotez said.

He noted a recent study by the Centers for Disease Control and Prevention, presented in November, found that almost 14 percent of the U.S. population is infected with Toxocara roundworms, which dogs and cats can pass to people.

"Urban playgrounds in the United States have recently been shown to be a particularly rich source of Toxocara eggs and inner-city children are at high risk of acquiring the infection," Hotez wrote, adding that this might be partly behind the rise in asthma cases in the country. Up to 23 percent of urban black children may be infected, he said. "Because of its possible links to asthma, it would be important to determine whether covert toxocariasis is a basis for the rise of asthma among inner-city children in the northeastern United States," he added.

"Cysticercosis is another very serious parasitic worm infection ... caused by the tapeworm Taenia solium, that results in seizures and other neurological manifestations," Hotez wrote.

He said up to 2,000 new cases of neurological disease caused by tapeworms are diagnosed every year in the United States. More than 2 percent of adult Latinos may be infected, and with 35 million Hispanics in the United States, this could add up to tens of thousands of cases, Hotez said.

"In the hospitals of Los Angeles, California, neurocysticercosis currently accounts for 10 percent of all seizures presenting to some emergency departments," he wrote.

"We need to begin erasing these horrific health disparities," Hotez wrote in the paper, available online at www.plosntds.org/article/info:doi/10.13 ... td.0000149. (dead link)

(Mod Edit)

http://www.dpd.cdc.gov/dpdx/HTML/Taeniasis.htm
Life cycle of Taenia saginata and Taenia solium
Taeniasis is the infection of humans with the adult tapeworm of Taenia saginata or Taenia solium. Humans are the only definitive hosts for T. saginata and T. solium. Eggs or gravid proglottids are passed with feces ; the eggs can survive for days to months in the environment. Cattle (T. saginata) and pigs (T. solium) become infected by ingesting vegetation contaminated with eggs or gravid proglottids . In the animal's intestine, the oncospheres hatch , invade the intestinal wall, and migrate to the striated muscles, where they develop into cysticerci. A cysticercus can survive for several years in the animal. [size=]Humans become infected by ingesting raw or undercooked infected meat . [/size]
In the human intestine, the cysticercus develops over 2 months into an adult tapeworm, which can survive for years. The adult tapeworms attach to the small intestine by their scolex and reside in the small intestine . Length of adult worms is usually 5 m or less for T. saginata (however it may reach up to 25 m) and 2 to 7 m for T. solium. The adults produce proglottids which mature, become gravid, detach from the tapeworm, and migrate to the anus or are passed in the stool (approximately 6 per day). T. saginata adults usually have 1,000 to 2,000 proglottids, while T. solium adults have an average of 1,000 proglottids. The eggs contained in the gravid proglottids are released after the proglottids are passed with the feces. T. saginata may produce up to 100,000 and T. solium may produce 50,000 eggs per proglottid respectively.

Geographic Distribution:
Both species are worldwide in distribution. Taenia solium is more prevalent in poorer communities where humans live in close contact with pigs and eat undercooked pork
and is very rare in Muslim countries. Clinical Features:
Taenia saginata taeniasis produces only mild abdominal symptoms. The most striking feature consists of the passage (active and passive) of proglottids. Occasionally, appendicitis or cholangitis can result from migrating proglottids. Taenia solium taeniasis is less frequently symptomatic than Taenia saginata taeniasis. The main symptom is often the passage (passive) of proglottids. The most important feature of Taenia solium taeniasis is the risk of development of cysticercosis.

Laboratory Diagnosis:
Microscopic identification of eggs and proglottids in feces is diagnostic for taeniasis, but is not possible during the first 3 months following infection, prior to development of adult tapeworms. Repeated examination and concentration techniques will increase the likelihood of detecting light infections. Nevertheless, speciation of Taenia is impossible if solely based on microscopic examination of eggs, because all Taenia species produce eggs that are morphologically identical. Eggs of Taenia sp. are also indistinguishable from those produced by cestodes of the genus Echinococcus (tapeworms of dogs and other canid hosts). Microscopic identification of gravid proglottids (or, more rarely, examination of the scolex) allows species determination.

TAKE EXTREME CARE IN PROCESSING THE SAMPLES! INGESTION OF EGGS CAN RESULT IN CYSTICERCOSIS!

Diagnostic findings

Microscopy
Antibody detection may prove useful especially in the early invasive stages, when the eggs and proglottids are not yet apparent in the stools.
Morphologic comparison with other intestinal parasites
Treatment:
Treatment is simple and very effective. Praziquantel* is the drug of choice. For additional information, see the recommendations in The Medical Letter (Drugs for Parasitic Infections).