Anthelmintics or antihelminthics are a group of

antiparasitic drugs Antiparasitics are a class of medications which are indicated for the treatment of parasitic diseases, such as those caused by helminths, amoeba, ectoparasites, parasitic fungi, and protozoa, among others. Antiparasitics target the parasitic agen ...

that expel parasitic worms ( helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. They may also be called vermifuges (those that stun) or vermicides (those that kill). Anthelmintics are used to treat people who are infected by helminths, a condition called

helminthiasis Helminthiasis, also known as worm infection, is any macroparasitic disease of humans and other animals in which a part of the body is infected with parasitic worms, known as helminths. There are numerous species of these parasites, which are br ...

. These drugs are also used to treat infected animals. Pills containing anthelmintics are used in mass deworming campaigns of school-aged children in many developing countries. The drugs of choice for soil-transmitted helminths are mebendazole and albendazole; for

schistosomiasis Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdominal pain, diarrhea, bloody s ...

and tapeworms it is praziquantel.

Types

Antiparasitics that specifically target worms of the genus '' Ascaris'' are called

ascaricides Ascaricides are drugs to treat ascariasis that is caused by infections with parasitic nematodes (''roundworms'') of the genus ''Ascaris'' (''giant intestinal roundworms''). The large roundworm of pigs (''Ascaris suum'') typically infects pigs whil ...

. * Benzimidazoles: ** Albendazole – effective against threadworms, roundworms,

whipworms ''Trichuris trichiura, Trichocephalus trichiuris'' or whipworm, is a parasitic roundworm (a type of helminth) that causes trichuriasis (a type of helminthiasis which is one of the neglected tropical diseases) when it infects a human large intes ...

, tapeworms,

hookworms Hookworms are intestinal, blood-feeding, parasitic roundworms that cause types of infection known as helminthiases. Hookworm infection is found in many parts of the world, and is common in areas with poor access to adequate water, sanitation, an ...

** Mebendazole – effective against various nematodes ** Thiabendazole – effective against various nematodes ** Fenbendazole – effective against various parasites ** Triclabendazole – effective against liver flukes ** Flubendazole – effective against most intestinal parasites * Avermectins (including ivermectin) - effective against most common intestinal worms, except tapeworms, for which praziquantel is commonly used in conjunction for mass dewormings * Diethylcarbamazine – effective against '' Wuchereria bancrofti'', '' Brugia malayi'', ''

Brugia timori ''Brugia timori'' is a filarial (arthropod-borne) nematode (roundworm) which causes the disease "Timor filariasis", or "Timorian filariasis". While this disease was first described in 1965, the identity of ''Brugia timori'' as the causative agen ...

'', and '' Loa loa'' * Pyrantel pamoate – effective against most nematode infections residing within the intestines * Levamisole * Salicylanilide – mitochondrial un-couplers (used only for flatworm infections): **

Niclosamide Niclosamide, sold under the brand name Niclocide among others, is an anthelmintic medication used to treat tapeworm infestations, including diphyllobothriasis, hymenolepiasis, and taeniasis. It is not effective against other worms such as flukes ...

Oxyclozanide Oxyclozanide is a salicylanilide anthelmintic. It is used in the treatment and control of fascioliasis in ruminants mainly domestic animals such as cattle, sheep, and goats. It mainly acts by uncoupling of oxidative phosphorylation in flukes. Alon ...

Nitazoxanide Nitazoxanide, sold under the brand name Alinia among others, is a broad-spectrum antiparasitic and broad-spectrum antiviral medication that is used in medicine for the treatment of various helminthic, protozoal, and viral infections. It is ind ...

– readily kills '' Ascaris lumbricoides'', and also possess antiprotozoal effects *

Oxamniquine Oxamniquine, sold under the brand name Vansil among others, is a medication used to treat schistosomiasis due to '' Schistosoma mansoni''. Praziquantel, however, is often the preferred treatment. It is given by mouth and used as a single dose. ...

– effective against flatworms (e.g., tapeworms and

schistosoma ''Schistosoma'' is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed '' schistosomiasis'', which is considered by the World Health Organ ...

) * Praziquantel – effective against flatworms (e.g., tapeworms and

) * Octadepsipeptides (e.g.

Emodepside Emodepside is an anthelmintic drug that is effective against a number of gastrointestinal nematodes, is licensed for use in cats and belongs to the class of drugs known as the ''octadepsipeptides'', a relatively new class of anthelmintic (research ...

) – effective against a variety of gastrointestinal helminths * Monepantel (aminoacetonitrile class) - effective against a variety of nematodes including those resistant to other anthelmintic classes * Spiroindoles (e.g. derquantel) - effective against a variety of nematodes including those resistant to other anthelmintic classes * Artemisinin – shows anthelmintic activity

Anthelmintic resistance

Anthelmintic resistance in parasites is now widespread. It is a major threat to the sustainability of modern ruminant livestock production, resulting in reduced productivity, compromised animal health and welfare, and increased greenhouse gas emissions through increased parasitism and farm inputs. A database of published and unpublished European AR research on gastrointestinal nematodes was collated in 2020. A total of 197 publications were available for analysis, representing 535 studies in 22 countries and spanning the period 1980–2020. Results in sheep and goats since 2010 reveal an average prevalence of resistance to benzimidazoles of 86%, macrocyclic lactones except moxidectin 52%, levamisole 48%, and moxidectin 21%. All major gastrointestinal nematodes genera survived treatment in various studies. In cattle, prevalence of anthelminthic resistance varied between anthelmintic classes from 0–100% (benzimidazoles and macrocyclic lactones), 0–17% (levamisole) and 0–73% (moxidectin), and both '' Cooperia'' and '' Ostertagia'' survived treatment. The ability of parasites to survive treatments that are generally effective at the recommended doses is a major threat to the future control of worm parasites in small ruminants and horses. This is especially true of

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

s, and has helped spur development of aminoacetonitrile derivatives for treatment against drug-resistant nematodes, as well as exploration of

doxycycline Doxycycline is a broad-spectrum tetracycline class antibiotic used in the treatment of infections caused by bacteria and certain parasites. It is used to treat bacterial pneumonia, acne, chlamydia infections, Lyme disease, cholera, typhus, an ...

to kill their endosymbiotic '' Wolbachia'' bacteria. The resistance is measured by the " fecal egg count reduction" value which varies for different types of helminths. Treatment with an antihelminthic drug kills worms whose phenotype renders them susceptible to the drug, but resistant parasites survive and pass on their "resistance" genes. Resistant varieties accumulate, and treatment failure finally occurs.

References

External links

* * Holden-Dye, L. and Walker, R.
Anthelmintic drugs
(November 2, 2007), WormBook, ed. The C. elegans Research Community, WormBook, doi/10.1895/wormbook.1.143.1 {{Authority control * Articles containing video clips

Types

Anthelmintic resistance

See also

References

External links