|Egg of Trichuris sp.|
Several, see text
Trichuris, often referred to as whipworms (which typically refers to T. trichiura only in medicine, and to any other species in veterinary medicine), is a genus of parasite worms from the roundworm family Trichuridae, which is a type of helminth. The name whipworm refers to the shape of the worm; they look like whips with wider "handles" at the posterior end. The name Trichocephalus is sometimes used for this genus.
The genus Trichuris includes over 20 species which infect the large intestine of their host including:
- Trichuris trichiura (sometimes Trichocephalus trichiuris) - causes trichuriasis in humans]
- Trichuris campanula (cat whipworm)
- Trichuris serrata (cat whipworm)
- Trichuris suis (pig whipworm)
- Trichuris muris (mouse whipworm)
- Trichuris vulpis (dog whipworm)
Other species in this genus include Trichuris cynocephalus, Trichuris discolor, Trichuris laevitestis,Trichuris pardinasi, Trichuris navonae,Trichuris ovis, Trichuris rhinopithecus, Trichuris thrichomysi and Trichuris travassosi.
Researchers are currently facing difficulties completely differentiating the numerous species under the genus Trichuris. When different whipworm species were discovered, the main factor used to differentiate species was the length of the spicule sheath. However, it was eventually discovered that many species had similar spicule sheath lengths. Therefore, researchers began to compare other morphologies, such as the structure or orientation surrounding female sex organs of species suspected to be similar but different. Relatively recently, studies have been conducted to differentiate similar Trichuris species based on mitochondrial DNA differences, a much more accurate method of distinction. However, there is currently a paucity of research devoted to encoding the DNA of each and every species. As a result, Trichuris species distinction is still largely based on morphological differences.
Currently, the general life cycle of the whipworm is not completely understood. However, all whipworm species have a similar general life cycle. Whipworm eggs are first ingested by the host. They eventually reach the duodenum of the small intestine, where the eggs ultimately hatch. The larva from these eggs travel into the large intestine’s cecum. For approximately four weeks, the whipworms feed on blood vessels located within the cecum. Eventually, the whipworms leave the cecum and begin to lay thousands of eggs. These unembryonated eggs are then released out of the host through feces. The process from egg ingestion to release takes approximately twelve weeks. The released eggs become embryonated in approximately nine to twenty-one days and are eventually ingested by another host.
Whipworm eggs have thick, lemon-shaped, light yellow shells. Located on opposite ends of the shells are plugs that protect the eggs in unfavorable conditions such as rugged dirt and the acidic environment of the small intestine. The actual egg is covered by a vitelline membrane. When the egg first exits the uterus of their mother, they are composed solely of yolk granules. Over a period of 72 hours, the egg undergoes mitotic division into two blastomeres that are separated by a transverse cleavage. Two additional cleavages occur within at least 96 hours so that the egg is now composed of four cells. Cellular division continues in this manner and the morula stage is reached within the next week. After a total of 21–22 days, the larva becomes fully developed and will not hatch until ingested by a host. The larva can be alive for a total of 6 months without the assistance of a host. The timeline of egg development can vary depending on the species.
In domestic animals
Whipworms develop when a dog swallows whipworm eggs, passed from an infected dog. Symptoms may include diarrhea, anemia, and dehydration. The dog whipworm (Trichuris vulpis) is commonly found in the U.S. It is hard to detect at times, because the numbers of eggs shed are low, and they are shed in waves. Centrifugation is the preferred method. There are several preventives available by prescription from a veterinarian to prevent dogs from getting whipworm.
The cat whipworm is a rare parasite. In Europe it is mostly represented by Trichuris campanula, and in North America it is more often Trichuris serrata more often. Whipworm eggs found in cats in North America must be differentiated from lungworms, and from mouse whipworm eggs that are just passing through.
Trichuris campanula can be found in cats throughout the United States, having a whip like shape, living in the large intestine and cecum of cats. T. campanula is closely related to T. vulpis which is a dog whipworm. They are both roundworms of the genus Trichuris, also known as whipworms. The cat gets infected with T. campanula by ingesting food or water that is contaminated with the whipworm eggs. Once the cat ingests the infected eggs, they hatch and the larvae mature as adults in the large intestine where they feed on the blood from the intestinal wall. The T. campanula lays eggs that are passed in the feces of the infected cat, remaining alive in soil for years. The infection can be found by examining the feces of the infected cat. Also, blood can be found in the feces that can help in diagnosing of the infected cat. For prevention, cats should visit the veterinarian to get worming, having the feces inspected. Pet owners should be more aware of what their pets consume, and pick up the cat feces to prevent future infections from occurring. Also, litter boxes need to be cleaned to remove any contaminated feces. Currently, there are no drugs to help infected cats remove all of the worms. The best way to avoid a cat being infected is by practicing good prevention techniques.
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