These Worms Are Definitely Not For Fishing (Part 2)

The following are the answers to the questions:

1. What is the identification of the worm(s) expelled from this young woman?

This young woman, and most likely the other two women, were infected with Ascaris lumbricoides otherwise known as the Human Roundworm. The infection is called ascariasis. It is a Helminth (general term meaning worm) belonging to one of three groups, the Nematodes or roundworm group. The Helminths include the Nematodes (roundworms); Trematodes (flatworms or flukes); and the Cestodes (tapeworms). 

2. What might precipitate the outward migration of these worms?

Heavy infestations can cause worms to migrate outward through the mouth/nostrils or rectum. Heavy infestations can result in an intestinal blockage that may require surgical intervention. When worms are expelled they should be sent to the laboratory for identification by a Microbiologist or Parasitologist. 

3. The image of the egg can be described as how?

The egg in the photograph can be described as a fertile and decorticated. The eggs will many times have an albuminous coating around the cell wall that can make the egg difficult to identify by the inexperienced Microbiologist or Parasitologist. The images below are images of a corticated and a decorticated egg (left to right). The fertility of the eggs can also be determined by the shape of the eggs. Fertile eggs tend to be more elongated than the unfertile eggs.

4. How is this parasitic infection acquired?

Infections are acquired by the ingestion of eggs that are on hands or fingers that have contaminated dirt on them and are put in the mouth. Or by eating vegetables or fruits that have not been carefully peeled, washed, or cooked. Or the ingestion of water contaminated with Ascaris eggs. 

5. Considering the assumed heavy worm burden, what complications can you worry about?

Complications due to heavy infestations can be intestinal blockage requiring emergency surgical intervention. The worms can also cause biliary obstruction with cholangitis and/or pancreatic necrosis. The larval migration from the lungs up the throat to be swallowed as part of the life cycle can cause coughing which is persistent resulting in wheezing and shortness of breath. This eosinophilic cough is given the name Loeffler’s syndrome but it is important to note that the name is a broad descriptive name given to a syndrome that may be due to other parasites that can cause the syndrome as well as hypersensitivity to a variety of drugs. 

6. The eggs of this worm are very resistant to?

The eggs are extremely resistant to the commonly applied doses of chlorination treatments used for water. The eggs are one of the most resistant of water-related pathogens. They are resistant not just to chlorination but to various other methods of inactivation (strong bases, strong acids, reductants, protein-disrupting agents, etc.). UV resistance is also seen due to the protective three layers of the egg, particularly the albuminous outer layer that gives the egg it’s corticated appearance. Ascaris eggs have been described as one of the most UV-resistant water-related pathogen identified to date.

This case is an example of the importance of having a Microbiologist/Parasitologist available to make an identification in a timely manner resulting in the initiation of proper treatment. In the case of this patient it was important to begin treatment as soon as possible to minimize the chance of any complications which are likely to occur in heavy infestations with Ascaris lumbricoides. Unfortunately in many of todays healthcare facilities the ova & parasite examination has become a referral test rather than an onsite test. This can result in unavoidable delays that can have detrimental consequences to patients such as further testing that can be invasive and costly or avoidable complications. Most laboratories have adopted PCR or EIA testing methods that provide a limited detection menu, albeit detecting the most common parasites causing infections (Giardia-Cryptosporidium-Cyclospora-Entamoeba histolytica). This oversimplification of parasitology testing can however produce a false sense of parasite exclusion of the causative pathogen in patients presenting with symptoms. And for that reason the limitations of the test should be known by the ordering physician. There are times when a consultation with the laboratory or an Infectious Disease Physician is important in deciding whether a complete ova & parasite examination is warranted, or what type of specimen is needed given the parasitic infection suspected.