Comparing the effect of medications for treating Ascaris infection

What was the aim of this review?

We aimed to compare the effect of different medications for treating people with Ascaris infection. Albendazole and mebendazole are most commonly used to treat ascariasis. Ivermectin can also be used. We wanted to know if there was anything to choose between these drugs for eradicating the worms and their eggs in stool samples. We included 30 relevant studies.

Key messages

Mebendazole, albendazole, and ivermectin single dose were effective against Ascaris lumbricoides infection, yielding high parasitological cure without any differences detected between them. There were no serious side effects reported.

What was studied in the review?

Ascaris lumbricoides, also known as roundworm, is a soil-transmitted worm that can infect people. Ascariasis is common worldwide and mainly affects children living in low-income areas. Interventions against ascariasis include water and sanitation improvement, health education, and medicine treatment for infected individuals. Treatment with medications removes adult worms from the gastrointestinal tract reducing morbidity (illness) and infection transmission. Although many medicines exist to treat people who have worms (anthelmintic drugs), the most effective regimen and the optimal doses are not well known. We assessed studies that compared the use of anthelmintic medications in adults and children, as a single or a combined therapy, and in single or multiple dose regimens.

What were the main results of the review?

We included 30 randomized controlled trials (clinical studies where people are randomly put into one of two or more treatment groups), enrolling 6442 children and adults aged from 28 days to 82 years, with Ascaris infection. Twenty studies were funded or co-funded by manufacturers (which may introduce bias), while 10 were independent of manufacturer funding.

Parasitological cure is probably six-fold more frequent in people receiving anthelmintic medicines when compared to people receiving placebo (treatment with no active ingredient) (moderate-certainty evidence).

No difference in ascariasis cure was found in comparisons between single dose albendazole with single doses of either mebendazole or ivermectin; and no difference was found between single dose albendazole compared with giving multiple doses.

Severe side effects were not reported. The occurrence of other side effects (feeling sick, being sick, diarrhoea, abdominal discomfort, headache, fever) may be uncommon among the compared anthelmintic medicines (moderate- to low-certainty evidence).

How up-to-date is this review?

We searched for studies published up to 4 July 2019.

Authors' conclusions: 

Single-dose of albendazole, mebendazole, and ivermectin all appeared effective against Ascaris lumbricoides infection, yielding high parasitological cure and large reductions in eggs excreted, with no differences detected between them. The drugs appear to be safe to treat children and adults with confirmed Ascaris infection. There is little to choose between drugs and regimens in terms of cure or adverse events.

Read the full abstract...
Background: 

Ascaris lumbricoides is a common infection, and mainly affects children living in low-income areas. Water and sanitation improvement, health education, and drug treatment may help break the cycle of transmission, and effective drugs will reduce morbidity.

Objectives: 

To compare the efficacy and safety of anthelmintic drugs (albendazole, mebendazole, ivermectin) for treating people with Ascaris infection.

Search strategy: 

We searched the Cochrane Infectious Disease Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, three other databases, and reference lists of included studies, without language restrictions, up to 4 July 2019.

Selection criteria: 

Randomized controlled trials (RCT) that compared albendazole, mebendazole, and ivermectin in children and adults with confirmed Ascaris infection.

Data collection and analysis: 

Two review authors independently assessed studies for inclusion, assessed risk of bias, and extracted data from the included trials. A third review author checked the quality of data extraction. We used the Cochrane 'Risk of bias' assessment tool to determine the risk of bias in included trials. We used risk ratios (RRs) with 95% confidence intervals (CIs) to compare dichotomous outcomes in treatment and control groups. We used the fixed-effect model for studies with low heterogeneity and the random-effects model for studies with moderate to high heterogeneity. We assessed the certainty of the evidence using the GRADE approach. We used the control rate average to provide illustrative cure rates in the comparison groups.

Main results: 

We included 30 parallel-group RCTs, which enrolled 6442 participants from 17 countries across Africa, Asia, Central America and the Caribbean, and South America. Participants were from 28 days to 82 years of age, recruited from school, communities, and health facilities. Twenty studies were funded or co-funded by manufacturers, while 10 studies were independent of manufacturer funding. Twenty-two trials had a high risk of bias for one or two domains (blinding, incomplete outcome data, selective reporting).

Single dose of albendazole (four trials), mebendazole (three trials) or ivermectin (one trial) was compared to placebo. Parasitological cure at 14 to 60 days was high in all the studies (illustrative cure of 93.0% in the anthelmintic group and 16.1% in the placebo group; RR 6.29, 95% CI 3.91 to 10.12; 8 trials, 1578 participants; moderate-certainty evidence). Single dose of albendazole is as effective as multiple doses of albendazole (illustrative cure of 93.2% with single dose, 94.3% with multiple doses; RR 0.98, 95% CI 0.92 to 1.05; 3 trials, 307 participants; high-certainty evidence); or as single dose of mebendazole (illustrative cure of 98.0% with albendazole, 96.9% with mebendazole; RR 1.01, 95% CI 1.00 to 1.02; 6 trials, 2131 participants; high-certainty evidence). Studies did not detect a difference between a single dose of albendazole and a single dose of ivermectin (cure rates of 87.8% with albendazole, 90.2% with ivermectin; RR 0.99, 95% CI 0.91 to 1.08; 3 trials, 519 participants; moderate-certainty evidence).

Across all the studies, failure after single dose of albendazole ranged from 0.0% to 30.3%, mebendazole from 0.0% to 22.2%, and ivermectin from 0.0% to 21.6%.

The egg reduction rate (ERR) measured up to 60 days after the treatment was high in all treated groups, regardless of the anthelmintic used (range 96% to 100%). It was not possible to evaluate parasitological cure by classes of infection intensity.

No included trials reported complication or serious adverse events. Other adverse events were apparently similar among the compared anthelmintic groups (moderate- to low-certainty evidence). The most commonly reported other adverse events were nausea, vomiting, abdominal pain, diarrhoea, headache, and fever.

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