Trichuris

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Trichuris
Parasite140080-fig3 Gastrointestinal parasites in seven primates of the Tai National Park - Helminths Figure 3i.jpg
Egg of Trichuris sp.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Nematoda
Class: Enoplea
Order: Trichocephalida
Family: Trichuridae
Genus: Trichuris
Roederer, 1761
Species

Several, see text

Trichuris, often referred to as whipworms or the silent serpent (which typically refers to T. trichiura only in medicine, and to any other species in veterinary medicine), is a genus of parasitic worms from the roundworm family Trichuridae, which are helminths. 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. [1]

Contents

Species

The genus Trichuris includes over 20 species, which infect the large intestine of their host, including:

A new species – as yet unnamed – has been identified in François’ leaf monkey ( Trachypithecus francoisi ). [2]

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 .

Trichurias is a soil-transmitted helminthiasis and belongs to the group of neglected tropical diseases, affecting about 604 million people globally. [3]

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, many species were eventually discovered to have similar spicule sheath lengths. [4] 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. [5] Relatively recently, studies have been conducted to differentiate similar Trichuris species based on mitochondrial DNA differences, a much more accurate method of distinction. [6] However, currently a paucity of research devoted to encoding the DNA of each and every species exists. As a result, Trichuris species distinction is still largely based on morphological differences.

Lifecycle

Currently, the general lifecycle of the whipworm is not completely understood. [7] However, all whipworm species have a similar general lifecycle. Whipworm eggs are first ingested by the host. They eventually reach the duodenum of the small intestine, where the eggs ultimately hatch. The larvae from these eggs travel into the large intestine’s cecum. [8] For about 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 from the host through feces. The process from egg ingestion to release takes around 12 weeks. [9] The released eggs become embryonated in approximately nine to twenty-one days and are eventually ingested by another host. [10]

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 soil and the acidic environment of the small intestine. [9] The actual egg is covered by a vitelline membrane. [11] When the eggs first exit the uterus of their mother, they are composed solely of yolk granules. Over a period of 72 hours, the eggs undergo mitotic division into two blastomeres that are separated by a transverse cleavage. Two additional cleavages occur within at least 96 hours, so that the eggs are now composed of four cells each. Cellular division continues in this manner and the morula stage is reached within the next week. After a total of 21–22 days, the larvae become fully developed and will not hatch until ingested by a host. The larvae can live for a total of six months without the assistance of a host. The timeline of egg development can vary depending on the species. [11]

In domestic animals

Whipworms develop when a dog swallows whipworm eggs, passed from an infected dog. Clinical signs may include diarrhea, anemia, and dehydration. The dog whipworm (T. 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. Several preventives are 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 T. campanula, and in North America it is more often T. serrata. [12] [13] Whipworm eggs found in cats in North America must be differentiated from lungworms, and from mouse whipworm eggs that are just passing through.

T. campanula can be found in cats throughout the United States, having a whip-like shape, living in the large intestine and cecum of cats. 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. 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. [14]

Related Research Articles

<i>Trichuris trichiura</i> Parasitic roundworm that causes intestinal infection

Trichuris trichiura, Trichocephalus trichiuris or whipworm, is a parasitic roundworm that causes trichuriasis when it infects a human large intestine. It is commonly known as the whipworm which refers to the shape of the worm; it looks like a whip with wider "handles" at the posterior end.

<span class="mw-page-title-main">Trichuriasis</span> Infection by Trichuris trichiura (whipworm)

Trichuriasis, also known as whipworm infection, is an infection by the parasitic worm Trichuris trichiura (whipworm). If infection is only with a few worms, there are often no symptoms. In those who are infected with many worms, there may be abdominal pain, fatigue and diarrhea. The diarrhea sometimes contains blood. Infections in children may cause poor intellectual and physical development. Low red blood cell levels may occur due to loss of blood.

Toxocariasis is an illness of humans caused by the dog roundworm and, less frequently, the cat roundworm. These are the most common intestinal roundworms of dogs, coyotes, wolves and foxes and domestic cats, respectively. Humans are among the many "accidental" or paratenic hosts of these roundworms.

Spirometra is a genus of pseudophyllid cestodes that reproduce in canines and felines, but can also cause pathology in humans if infected. As an adult, this tapeworm lives in the small intestine of its definitive host and produces eggs that pass with the animal's feces. When the eggs reach water, the eggs hatch into coracidia which are eaten by copepods. The copepods are eaten by a second intermediate host to continue the life cycle. Humans can become infected if they accidentally eat frog legs or fish with the plerocercoid stage encysted in the muscle. In humans, an infection of Spirometra is termed sparganosis.

Trichuris muris is a nematode parasite of mice. It is very similar to the human roundworm parasite Trichuris trichiura due to its immunological reactivity when crossed, and so is often used in related studies.

<i>Taenia pisiformis</i> Species of flatworm

Taenia pisiformis, commonly called the rabbit tapeworm, is an endoparasitic tapeworm which causes infection in lagomorphs, rodents, and carnivores. Adult T. pisiformis typically occur within the small intestines of the definitive hosts, the carnivores. Lagomorphs, the intermediate hosts, are infected by fecal contamination of grasses and other food sources by the definitive hosts. The larval stage is often referred to as Cysticercus pisiformis and is found on the livers and peritoneal cavities of the intermediate hosts. T. pisiformis can be found worldwide.

<span class="mw-page-title-main">Ancylostomiasis</span> Medical condition

Ancylostomiasis is a hookworm disease caused by infection with Ancylostoma hookworms. The name is derived from Greek ancylos αγκύλος "crooked, bent" and stoma στόμα "mouth".

Necatoriasis is the condition of infection by Necator hookworms, such as Necator americanus. This hookworm infection is a type of helminthiasis (infection) which is a type of neglected tropical disease.

<i>Toxocara canis</i> Species of roundworm

Toxocara canis is a worldwide-distributed helminth parasite that primarily infects dogs and other canids, but can also infect other animals including humans. The name is derived from the Greek word "toxon," meaning bow or quiver, and the Latin word "caro," meaning flesh. T. canis live in the small intestine of the definitive host. This parasite is very common in puppies and somewhat less common in adult dogs. In adult dogs, infection is usually asymptomatic but may be characterized by diarrhea. By contrast, untreated infection with Toxocara canis can be fatal in puppies, causing diarrhea, vomiting, pneumonia, enlarged abdomen, flatulence, poor growth rate, and other complications.

Capillaria philippinensis is a parasitic nematode which causes intestinal capillariasis. This sometimes fatal disease was first discovered in Northern Luzon, Philippines, in 1964. Cases have also been reported from China, Egypt, Indonesia, Iran, Japan, Korea, Lao PDR, Taiwan and Thailand. Cases diagnosed in Italy and Spain were believed to be acquired abroad, with one case possibly contracted in Colombia. The natural life cycle of C. philippinensis is believed to involve fish as intermediate hosts, and fish-eating birds as definitive hosts. Humans acquire C. philippinensis by eating small species of infested fish whole and raw.

<i>Trichuris suis</i> Species of roundworm

Trichuris suis is a whipworm; the variations in thickness of the anterior and posterior segments give the parasite the characteristic "whip-like" appearance. Adult females measure 6 to 8 cm and adult males 3 to 4 cm. T. suis eggs are oval and yellow-brown with bipolar plugs. T. suis is also used in helminthic therapy studies.

<i>Toxascaris leonina</i> Species of roundworm

Toxascaris leonina is a common parasitic roundworm found in dogs, cats, foxes, and related host species. T. leonina is an ascarid nematode, a worldwide distributed helminth parasite which is in a division of eukaryotic parasites that, unlike external parasites such as lice and fleas, live inside their host. The definitive hosts of T. leonina include canids and felines (cats), while the intermediate hosts are usually rodents, such as mice or rats. Infection occurs in the definitive host when the animal eats an infected rodent. While T. leonina can occur in either dogs or cats, it is far more frequent in cats.

<i>Linguatula serrata</i> Species of crustacean

Linguatula serrata is a species of cosmopolitan zoonotic parasite, belonging to the tongueworm order Pentastomida. They are wormlike parasites of the respiratory systems of vertebrates. They live in the nasopharyngeal region of mammals. Cats, dogs, foxes, and other carnivores are normal hosts of this parasite. Apparently, almost any mammal is a potential intermediate host.

Trichuris vulpis is a whipworm that lives in the large intestine of canines in its adult stages. Out of different types of worms, Trichuris vulpis is one of the smaller worms with a size ranging from 30–50 mm in length. As the name suggests, the worm has a whip-like shape with distinct features including a small, narrow anterior head, which is the digestive part of the worm, and a larger posterior tail, which is the reproductive part of the worm. Eggs from T. vulpis are oval shaped with bipolar plugs and contain a thick outer shell. Their sizes range from 72–90 μm in length and 32–40 μm in width. Because of their thick outer shell, T. vulpis eggs are very resistant to environmental extremes such as freezing or hot temperatures, thus allowing for their long viability in the outside world.

Taenia serialis, also known as a canid tapeworm, is found within canines such as foxes and dogs. Adult T. serialis are parasites of carnivores, particularly dogs, with herbivorous lagomorph mammals such as rabbits and hares, serving as intermediate hosts. In definitive hosts, T. serialis is acquired by eating tissues from a variety of intermediate hosts. Accidental infection of humans though, can occur when eggs are ingested from food or water contaminated with dog feces and the human then becomes the T. serialis intermediate host.

Trichuris serrata, commonly known as a whipworm, is a nematode of the genus Trichuris first discovered in domestic Brazilian cats by Dr. Otto Friedrich Bernhard von Linstow in 1879. Since then, there have been reports of this species in North and South America, Australia, and the Caribbean islands. Information regarding the species' general life cycle and egg development can be seen in the Trichuris page.

Trichuris ovis, commonly known as a whipworm, is a nematode belonging to the genus Trichuris. This whipworm species was first discovered in 1795 and is known to infect sheep and goats. These organisms are capable of inhabiting any region that has the aforementioned hosts, as can be attested by the numerous reports of T. ovis findings throughout North and South America, Australia, Europe, and Asia. Information regarding the species' general life cycle and egg development can be seen in the Trichuris page.

Trichuris discolor, commonly known as a whipworm, is a nematode belonging to the genus Trichuris. The species was discovered by Otto Friedrich Bernhard von Linstow in 1906 and primarily infects cows. However, they can also infect sheep and goats. Like Trichuris ovis, T. discolor is known to be located in any region that their hosts are located. There have been specific reports of this species being found in Japan, Indo-Pakistan, and North America. Information regarding the species' general life cycle and egg development can be seen in the Trichuris page.

<span class="mw-page-title-main">Cat worm infections</span> Worm infections in cats

Cat worm infections, the infection of cats (Felidae) with parasitic worms, occur frequently. Most worm species occur worldwide in both domestic and other cats, but there are regional, species and lifestyle differences in the frequency of infestation. According to the classification of the corresponding parasites in the zoological system, infections can be divided into those caused by nematode and flatworms - in the case of the latter, mainly cestoda and trematoda - while other strains are of no veterinary significance. While threadworms usually do not require an intermediate host for their reproduction, the development cycle of flatworms always proceeds via alternate hosts.

<span class="mw-page-title-main">Nematode infection in dogs</span> Threadworm infections of dogs are frequent

Nematode infection in dogs - the infection of dogs with parasitic nemamotodes - are, along with tapeworm infections and infections with protozoa, frequent parasitoses in veterinary practice. Nematodes, as so-called endoparasites, colonize various internal organs - most of them the digestive tract - and the skin. To date, about 30 different species of nematode have been identified in domestic dogs; they are essentially also found in wild dog species. However, the majority of them often cause no or only minor symptoms of disease in adult animals. The infection therefore does not necessarily have to manifest itself in a worm disease (helminthosis). For most nematodes, an infection can be detected by examining the feces for eggs or larvae. Roundworm infection in dogs and the hookworm in dogs is of particular health significance in Central Europe, as they can also be transmitted to humans (zoonosis). Regular deworming can significantly reduce the frequency of infection and thus the risk of infection for humans and dogs.

References

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