Worming Their Way Back: Forgotten and New Helminths Continue to Become More Common in the United States
Appold, Karen, Journal of Continuing Education Topics & Issues
Despite efforts to eradicate the world of parasites, such as anti-helminth drugs and control measures, parasitic worms persisted in great numbers in many parts of the world, the World Health Organization noted in 1984. Around this same time, some forgotten helminths, i.e. intestinal worms, thought to have disappeared, started to appear once again. Today, the United States continues to see more and more parasites making a comeback.
This is occurring because as a cosmopolitan society, more U.S. citizens are traveling and more people are immigrating to or seeking refuge in the United States, said (the late) "Chris" Christian, BS, MT(AMT), director emeritus, School of Medical Technology, Southwest Oklahoma State University, Sayre. People are disrupted in their homelands due to malnutrition, evacuation and war. Because of living conditions and circumstances, they are picking up parasites and bringing them to the United States. In addition to parasites found prior to the 1950s, helminths not native to the United States are now being identified.
"We've heard about bacteria that have learned to survive in an antibiotic world," Christian said. "Now we are finding that parasites, too, are having revenge by returning to us."
When people displaced from native areas, including Asia, Africa, Puerto Rico and Mexico, were transported to various sites in western Oklahoma and the Texas panhandle, state health agencies contacted the college president and asked if Sayre's program could help with physical examinations. Because Christian was a medical technologist and director of the medical technology department, he volunteered to assist in this project. Students, along with Christian, performed blood counts on these people. Some were emaciated and many were asked to provide stool specimens.
"You can't believe the parasites those people are bringing into our country," he noted. In one rare instance, a man was infested with three different types of parasites: hookworm, Trichostrongylus and Strongyloides.
Three types of helminths are nematodes (roundworms), cestodes (tapeworms) and trematodes (flukes). The former is making the greatest resurgence in the United States, Christian said.
When diagnosing parasites, Christian advised learning their distinguishing features, such as where they thrive (e.g., lungs, blood, intestine); whether their ova are floaters or sinkers so you know whether to perform a concentration or dilution test; how they invade the body and what they look like.
Christian also provided a list of rules to follow when performing testing:
* Collect samples in a clean container. Some time ago, this wasn't standard procedure. People thought it was acceptable to bring urine samples to the laboratory in fruit jars, he noted.
* Send specimens to the lab as soon as possible. Don't place stool samples in an incubator.
* Request a patient provide three specimens from three different days, since parasites shower, i.e. sometimes appear as a lot or sometimes only a few, on different days.
Nematodes Found in Humans
When diagnosing nematodes, look for distinguishing characteristics of their eggs and locations of the worms in the human body. Christian provided an overview of some of these features.
Ascaris (Ascaris lumbricoides) is one of the most cosmopolitan worms worldwide. Eggs mature in soil. These embryonated ova are eaten, the larvae hatch out of the eggs in the intestine and through a liver-lung migration time, the larvae mature in individuals and occur in the small intestine. The eggs are round or ovoidal with a thick shell, are brown or yellow-brown and are corticated. This covering is occasionally lost and decorticated eggs have a colorless shell and may be mistaken for hookworm ova. Infertile eggs are elongated and usually triangular and oftentimes the shell is thin.
Ascaris is found in humid countries and thrive in areas of poor sanitation. …