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Chapter 12 Laboratory Skills 227

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FIGURE 12.9 Roundworm eggs. Source: Wikimedia Commons. Used under CC BY 3.0, https://commons.m.wikimedia.org/wiki/File:Toxocara_
embryonated_eggs.jpg.

Endoparasites are encountered worldwide with many microns. They are oval shaped, have a thin cell wall, and
more common in certain areas or regions. Some of the have morula inside. There are usually 8–10 morula per
most common ones with large geographic territories are egg (Figure 12.10).
roundworms, hookworms, tapeworms, flukes, and proto-
zoans. Most are transferred from one host to another by Tapeworms
the oral–fecal route or by consuming an intermediate
host that is infected with a stage of the parasite. Tapeworms are flat worms that absorb nutrients through
their bodies so they get quite large. Their bodies are
made up of segments called proglottids that are shed
Roundworms
when gravid. The proglottids are often found around
Roundworms are very commonly found in young the anus or in bedding and look like small, white, moving
puppies and kittens because the larval stage can cross grains of rice (Figure 12.11). The flea is often an
the transplacental and transmammary barriers. Also, intermediate host to the tapeworm and so owners need
youngsters tend to defecate in their environment and so to take care of those as well as the tapeworm. Take note
by walking in the feces and then licking it from their that some types of tapeworms are zoonotic. The seg-
paws infect each other or re‐infect themselves. High ments are usually found and if an identification is
numbers of adult worms in the young can cause required they are put on a microscope slide with a drop
extremely large pot bellies that can be quite painful. The of water. Then, using applicator sticks, are broken apart
transmission of roundworms to adults is by ingesting the to spill the eggs. The eggs are usually round, with a thick
eggs found in the feces of infected animals. The round- cell wall that is striated and about half the size of round-
worm egg is seen easily under 10× and verified under worm eggs.
40× on the the microscope. It is a round egg, with a thick,
wavy cell wall (Figure 12.9). If the microscope has a Flukes
micrometer it will measure about 70–75 microns.
Roundworms are zoonotic so PPE when handling feces Flukes are more common in areas of the country that
are gloves and goggles. has lots of wetlands and lakes. They require water to
reach their intermediate hosts which are snails, crusta-
tions, or fish. If a dog or cat happens to eat an infected
Hookworms
intermediate host, the fluke larva migrates to the liver or
Hookworms can infect both animal and human by skin lungs attaches and starts to suck blood. If the adult
penetration by larva or ingestion of eggs passed in feces. population is heavy enough, the patient may show signs
This sand‐loving nematode is why many beaches ban of anemia. Otherwise, these parasites take a long time to
dogs! A heavy infection of hookworms often causes damage the lungs and liver. Eggs are picked up in the
bloody diarrhea or black tarry stools because they attach feces and are very large ovals, measuring out at 130–180
to the intestines and suck blood. The eggs are seen on microns in length and with an operculum on one end
10× and verified on 40× and should measure 75–120 (Figure 12.12).