AskDefine | Define anthelmintic

Dictionary Definition

anthelmintic adj : capable of expelling or destroying parasitic worms [syn: anthelminthic, helminthic, parasiticidal] n : a medication capable of causing the evacuation of parasitic intestinal worms [syn: vermifuge, anthelminthic, helminthic]

User Contributed Dictionary



  1. destructive to parasitic intestinal worms
    Research is progressing well on finding native plants with anthelmintic properties.


  1. an anthelmintic agent


Extensive Definition

Anthelmintics or antihelminthics are drugs that expel parasitic worms (helminths) from the body, by either stunning or killing them. They may also be called vermifuges (stunning) or vermicides (killing).


Examples of drugs used as anthelmintics include:
Natural anthelmintics include black walnut (Juglans nigra), wormwood (Artemisia absynthium), clove (Syzygium aromaticum), tansy tea (Tanacetum vulgare), Hagenia (Hagenia abyssinica), kalonji (Nigella sativa) seeds, and the male fern (Dryopteris filix-mas). In Brazilian folk medicine, Plumeria (P. acutifolia or P. rubra) is also an anthelmintic. Peganum harmala is used as an anthelmintic. Please note that many natural vermifuges or anthelmintics are poisonous and, in improper dosages, dangerous to humans as well as parasites.

Anthelmintic resistance

The ability of worms to survive treatments that are generally effective at the recommended dose rate is considered a major threat to the current future control of worm parasites of small ruminants and horses.
The clinical definition of resistance is a 95% or less reduction in a "Fecal Egg Count" test.

Development of resistance

Treatment eliminates worms whose genotype renders them susceptible. Worms that are resistant survive and pass on their "resistance" genes. Resistant worms accumulate and finally treatment failure occurs.

Causes of resistance

  1. Treatment at frequent intervals
    • Greater than 3 treatments per year
    • Many farms apply greater than 6 treatments per year
  2. Treating all animals at same time
    • No refugia for non-resistant worms
  3. Treating and moving to clean pasture
    • No dilution
  4. Under dosing
    • Worms with low-level resistance survive. Worms can develop resistance a little at a time.



General references

  • U.S. Army Survival Manual Fm 21-76

External links

anthelmintic in Catalan: Antihelmíntic
anthelmintic in Czech: Anthelmintikum
anthelmintic in German: Anthelminthikum
anthelmintic in Spanish: Antihelmíntico
anthelmintic in Dutch: Anthelminthicum
anthelmintic in Japanese: 虫下し
anthelmintic in Polish: Leki przeciwrobacze
anthelmintic in Slovak: Antihelmintikum
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