Terminating a helminth infection

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This page addresses the termination of the four species of helminth used in helminthic therapy. The eradication of other organisms requires different species-specific drugs and dosing regimes. [1]

The efficacy of anthelminthic treatment depends on the drug used, the dosing regimen and the timing of doses in relation to food. It may also depend on the host's microbiome profile. [2] Even the most effective anthelminthic can fail to kill every last worm, but the efficacy rates for anthelminthic drugs used in developed countries are likely to be higher than those quoted below, which are taken from studies carried out in less developed areas, where mass deworming programmes have led to the development of drug resistance.

Terminating a human hookworm (NA) infection[edit]

Anthelminthic drugs compared[edit]

Albendazole was found to be the most effective of five drugs (albendazole, mebendazole, pyrantel pamoate, levamisole and thiabendazole) tested against hookworms (mostly NA) in 1993, [3], and again in 2017. [4] However, the efficacy of frequently used anthelminthic drugs such as albendazole and mebendazole has decreased over time, [5] and, while a single dose of 400 mg albendazole completely cleared infections with the hookworm, Ankylostoma duodenale in 1997, [6] a study reported in 2018 found that a single dose of albendazole (40 mg/kg) only gave a relatively low cure rate against hookworms, calculated at between 66.7% and 79.8%, [7] although this was better than a single dose of 500 mg mebendazole, which only achieved an overall cure rate of 27.6% in NA. [8]

A 2019 study found that 400 mg albendazole given daily for three consecutive days achieved a 100% cure rate against hookworms. [9]

A study comparing albendazole with mebendazole [10] found the following cure rates.

  • a triple dose of albendazole (1 dose of 400 mg taken each day for 3 consecutive days) ……........ 92%
  • a single dose of albendazole (400 mg) …………………………………………………………..................... 70%
  • a triple dose of mebendazole (1 dose of 500 mg taken each day for 3 consecutive days) ….................. 58%
  • a single dose of mebendazole (500 mg) ……………………………………………………………............... 31%

See also: Resources for Health Professionals: Hookworm

Availability of anthelminthic drugs[edit]

The availability of anthelminthic drugs varies between countries. For example, albendazole is not available on prescription in the US or UK, and, where it is prescribed "off-label", the cost can be astronomical. [11] Fortunately, albendazole can be obtained online from suppliers such as United Pharmacies and MedsMex.

Factors that may affect success[edit]

The timing of treatment in relation to meals can make a significant difference to treatment efficacy.

  • The efficacy of albendazole (and possibly other anthelminthics) against hookworms can be enhanced by taking the drug on an empty stomach.
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When a systemic pharmacological effect of albendazole is required, e.g. in echinococcosis, maximal systemic availability is desirable and may be achieved by giving albendazole together with a fatty meal. However, in conditions where low systemic availability and a high intraluminal content of the drug is desirable, as in the treatment of intestinal helminthiasis, the drug should be taken on an empty stomach in order to reduce its absorption. [12]
  • When a single dose of 400 mg of albendazole was given to subjects who had not eaten for 6 hours or more prior to treatment, the cure rate for hookworm was raised from 59% to 90%. [13]

Different brands of an anthelminthic drug may have different efficacy rates. [14]

Different forms of tablet containing an anthelminthic drug may have different success rates. For example, chewable tablets may be more effective if they are crushed. [15]

Patient experiences[edit]

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1x400 mg (albendazole) tablet per day for 3 days worked for me. A previous attempt using only 1 dose of 400 mg. 'stunned' the HW, but they recovered in 3 or 4 days. [16]
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I initially tried using combantrin (pyrantel pamoate) but it didn't kill the hookworms. Albendazole killed the worms. [17]

An NA host who is helminth-permissive (her genetic endowment gives any helminths she hosts a much easier time than they would get in most other people) was able to terminate her hookworm colony by taking 400 mg albendazole each day for four days. Even though the drug was 2 years past its expiration date, she stopped passing hookworm eggs and was unable to incubate more larvae until 12 weeks after reinoculating with 5 larvae from another source.

Alternative anthelminthics[edit]

Anything marked with an ❌ on the following page will or may kill, or cause the loss of, human helminths, including hookworms.

The timing of re-dosing with hookworms[edit]

There may be some advantage in allowing a period of time for the host’s immune system to resettle after the termination of a hookworm colony, but no specific reason to do this has been suggested and, since the biological half-life of albendazole and mebendazole is only 8-12 hours and 3-6 hours respectively, it should be safe to reinoculate 48 hours after completing the course of anthelminthic treatment.

Terminating a human whipworm (TT) infection[edit]

Single drug doses are ineffective[edit]

Single doses of anthelminthics are not very effective against Trichuris trichiura. For example, in one study, a single 500 mg dose of mebendazole only achieved a cure rate of 25.5%. [18] In another trial, a single dose of ivermectin (at 600 mcg/kg) had a cure rate of only 12.2%. [19]

Combining drugs improves efficacy[edit]

A head-to-head comparison of single doses of three different drug combinations showed the highest efficacy was achieved by the combination of albendazole and oxantel pamoate. [20]

Drug ........................................................... Cure rate
Albendazole plus oxantel pamoate ……….. 68·5%
Albendazole plus ivermectin …….….…....... 27·5%
Albendazole plus mebendazole ………....….. 8·4%
Mebendazole alone ………………………...… 8·4%

Oxantel pamoate is not universally available, and mebendazole has been found to be marginally more effective against whipworm than albendazole. [21]

Three-day courses are more effective[edit]

The US Centers for Disease Control and Prevention (CDC) state that whipworm is effectively treated using albendazole, mebendazole or ivermectin, but that each drug needs to be taken for 3 days. [22]

Drug ............................. Dosage for adults and children
Albendazole .................. 400 mg orally for 3 days
Mebendazole ................ 100 mg orally twice a day for 3 days.
Ivermectin ..................... 200 mcg/kg/day orally for 3 days

While the CDC recommend the use of albendazole and mebendazole, these drugs have been shown to have limited efficacy against T. trichiura, (e.g., albendazole: [23]) and their efficacy is continuing to diminish. [24]

400 mg albendazole, given daily for three consecutive days to children infected with T. trichiura, only achieved a 61% cure rate. [25]

Five-day courses are the most effective[edit]

100 mg mebendazole, given twice daily for 5 consecutive days, can effectively terminate a T. trichuria infection. [26]

Terminating a rat tapeworm (HD) infection[edit]

Hymenolepis diminuta (HD) is only likely to mature in adult humans who are immunocompromised. Otherwise, the worms will die naturally after approximately 2-3 weeks, so there is rarely any need to deliberately terminate an HD infection in adults.

There is a possibility of HD maturing and persisting in approximately 1% of children, potentially causing gastric pain and/or worsening of behavioural symptoms. In these cases, termination of the infection using an anthelminthic drug will bring about a cessation of symptoms within 1-3 weeks of the drug being administered.

The drugs used to terminate a Hymenolepis infection are described on the following webpage.

Terminating a pig whipworm (TS) infection[edit]

Since the porcine whipworm, trichuris suis, only survives in humans for approximately 2-3 weeks, there is little need to deliberately terminate a TS infection. If it were necessary, Wikipedia suggests that this species can be terminated with medicines such as doramectin, ivermectin and febantel.

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