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Fact check: What are the most common parasitic infections treated with ivermectin in the US?

Checked on October 12, 2025

Executive Summary

Ivermectin is presented in the supplied analyses primarily as a veterinary anthelmintic effective against intestinal nematodes and certain ectoparasites in dogs, with efficacy depending on formulation and concentration; a 2015 comparative study found the 0.5% pour-on formulation more effective than 0.2% against several parasites, and a 2022 clinic audit identified ivermectin as a widely used anthelmintic in veterinary practice [1] [2] [3]. The provided materials do not include US-specific human-treatment data, so any claim about the most common parasitic infections treated with ivermectin in the US cannot be directly supported by these sources.

1. Why the 2015 dog study demands attention: dosage and parasite-specific results

A 2015 study comparing two pour-on ivermectin formulations in naturally infected stray dogs reports that 0.5% ivermectin achieved 100% efficacy against ascarids and 79% against Ancylostoma caninum, while 0.2% removed 90.2% of ascarids and 50.4% of A. caninum, demonstrating a clear dose-dependent efficacy profile for gastrointestinal nematodes in canines [1]. The paper’s data highlight that formulation concentration materially affects outcomes, and that performance varies by parasite species, signaling that broad statements about ivermectin’s effectiveness must be qualified by parasite identity and dose. The study context—stray dogs—also shapes infection dynamics and treatment response.

2. The 2015 abstract confirms broader antiparasitic reach in dogs

The study’s abstract reiterates that both ivermectin concentrations were effective against intestinal parasites, fleas, and lice in dogs, with the 0.5% formulation outperforming 0.2% in reducing parasite burdens and ectoparasite loads, and both achieving 100% efficacy against lice [2]. This reinforces the earlier point that ivermectin’s antiparasitic spectrum in the study extended beyond helminths to include ectoparasites, and that formulation strength correlated with measured reductions in egg counts and adult parasites. The abstract’s summary format emphasizes practical outcomes—parasite clearance metrics—rather than mechanistic explanations.

3. A 2022 veterinary clinic audit shows ivermectin is commonly used, but context matters

An anthelmintic-utilization study from 2022 found that ivermectin was the second most commonly used anthelmintic in a university veterinary clinic, accounting for 214 of 557 anthelmintic uses, underscoring its central place in veterinary parasite control programs [3]. This frequency suggests ivermectin is a standard tool for treating animals in clinic settings, but the audit does not specify which species or clinical indications predominated, nor does it indicate geographic or human-health applications. The study demonstrates widespread veterinary reliance on ivermectin while leaving gaps about infection types treated.

4. Synthesis: what the supplied evidence allows us to conclude—and what it does not

From these three provided analyses, the defensible conclusion is that ivermectin is commonly used in veterinary medicine to treat intestinal nematodes and some ectoparasites in dogs, and that higher-concentration topical formulations showed greater efficacy in the sampled population [1] [2] [3]. The materials do not supply data about human use patterns, US-specific treatment indications, or epidemiologic frequency of parasitic infections in people. Therefore, any statement about the “most common parasitic infections treated with ivermectin in the US” is not supported by these sources and would require additional, country- and human-focused evidence.

5. Missing pieces and potential biases readers should note

The supplied studies have clear scope limitations: one is a 2015 efficacy trial in stray dogs comparing topical concentrations, and another is a 2022 veterinary clinic utilization audit without detail on species or diagnoses [1] [2] [3]. These contexts introduce biases toward animal health settings and toward institutions that may favor particular anthelmintics. The absence of US human-public-health data, randomized controlled trials in humans, or national prescribing statistics means that extrapolation to human or US practice would risk misstatement. Users should therefore treat these findings as veterinary-focused, not human-focused.

6. How to get a definitive answer for US human treatments

To determine the most common parasitic infections treated with ivermectin in the United States, one would need up-to-date, US-specific clinical and public-health sources—for example CDC treatment guidelines, FDA drug usage records, and large clinical prescribing databases—none of which are present in the supplied analyses [1] [2] [3]. The current materials show ivermectin’s veterinary dominance and species-specific efficacy but cannot fill the geographic and human-health evidence gaps. Any subsequent inquiry should request those targeted US human-health sources for a definitive, evidence-based list.

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