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Presentation of Quiz #48

A patient is a 22 year-old female, living within the United States, who had been complaining of intermittent abdominal pain for several weeks. She assumed the symptoms were related to work stress. After taking antacids, she experienced some relief of her symptoms. However, she denied eating spicy foods and drinking excessive caffeinated beverages. She had never traveled outside of the United States and had been living in Florida for the last two years. Due to continued symptoms, she made an appointment to see her physician.

Images from an upper GI series revealed the presence of intraluminal worms, measuring about 5 to 7 inches in length. After a routine stool examination for parasites, the following structure was seen in the concentration sediment.

  • This helminth egg represents which group of helminths?
  • What is the genus and species name of this parasite?
  • Should the patient be treated?

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Answer and Discussion of Quiz #48

The image presented in Diagnostic Quiz #48 represents an Ascaris lumbricoides fertilized egg (note the bumpy shell).

Answers to Questions:

This particular helminth belongs to the nematode (roundworm) group. It can be identified as an Ascaris lumbricoides fertilized egg. Since this is considered a pathogen, the patient should be treated.

Comments on the Patient:

Other laboratory findings were all within normal range. After therapy, the patient passed several adult worms, and both fertilized and unfertilized eggs were seen in the concentration sediment wet preparations.

      

(Left): Adult male Ascaris with coiled posterior end; (Middle): fertilized egg; (Right): unfertilized egg (note the very bumpy shell on the more elongated unfertilized egg)

Comments on Diagnostic Methods:

Although the finding of "worms" in the upper GI films strongly suggested the presence of adult Ascaris lumbricoides, additional stool specimens were submitted for examination for parasites. Both fertilized and unfertilized eggs were recovered from the stool sedimentation concentration procedure. Due to the large number of eggs produced each day by the female worm, the presence of eggs can almost always be detected with a single stool examination. The presence of unfertilized eggs only would indicate the presence of female worm(s) only.

Remember that the unfertilized Ascaris eggs will not float with the use of the zinc sulfate flotation concentration method (the eggs are too heavy). Also, if too much iodine is added to the wet mount preparations, the eggs may look like darkly stained debris. Eggs may be very difficult to identify on a permanent stained smear because of stain retention and asymmetric shape.

Intestinal disease can often be diagnosed from radiographic studies of the gastrointestinal tract.

Comments on the Infection:

Other involved body sites may present specific symptoms indicative of bowel obstruction, biliary or pancreatic duct blockage, appendicitis, or peritonitis. The presence of the adult worms in the intestine usually caused no difficulties unless the worm burden is very heavy; however, because of the tendency of the adult worms to migrate, even a single worm can cause serious sequelae. Worm migration may occur as a result of stimuli such as fever, the use of general anesthesia, or other abnormal conditions. This migration may result in intestinal blockage; entry into the bile duct, pancreatic duct, or other small spaces; or entry into the liver or peritoneal cavity. They can also migrate out of the anus or come out the mouth or nose.

There can also be signs of pneumonitis if the number of larvae migrating through the liver and lungs is quite large. The picture of transient pulmonary infiltrates that clear within a couple of weeks and are associated with peripheral eosinophilia is frequently called Loeffler's syndrome. Larvae can be recovered from sputum or pulmonary aspirates; however, this is not a common finding.

The transmission of ascariasis depends on fecal contamination of the soil and the ingestion of soil contaminated with infective eggs. There are apparently no practical means of killing the eggs while they are in the soil. The adult worms will survive from 1 to 2 years.

References:

  1. Garcia, LS, 2016. Diagnostic Medical Parasitology, 6th Ed., ASM Press, Washington, DC.
  2. Garcia, L.S.2009. Practical Guide to Diagnostic Parasitology, 2nd Ed., ASM Press, Washington, D.C.
  3. Garcia, L.S. (ed.). 2010. Clinical Microbiology Procedures Handbook, 3rd Ed., vol. 1, 2, and 3. ASM Press, Washington, D.C.
  4. Isenberg, H. D. (ed.). 2004. Clinical Microbiology Procedures Handbook, 2nd Ed, vol. 1, 2 and 3. ASM Press, Washington, D.C.
  5. Isenberg, H. D. (ed.). 1995. Essential Procedures for Clinical Microbiology, ASM Press, Washington, D.C.