Ivermectin for Ticks

White-tailed deer are the primary hosts for adult black-legged ticks, which cause Lyme disease.

According to the World Health Organization (WHO), "Ivermectin was a revolutionary drug in the 1980s, the forerunner of a new group of anti-parasitic agents with activity against both parasitic nematodes and arthropods." It was initially marketed for veterinary use by Merck & Co. in cattle, horses, pigs and dogs. Although most consumer information on ivermectin states that it is not useful for ticks, the health research and literature contradicts this claim.

General Information

Ivermectin is effective against most common intestinal worms (except tapeworms), mites and lice in animals. In humans, it is used to treat strongyloidiasis (threadworm), to control onchocerciasis (river blindness) and to treat scabies. According to the American Academy of Family Physicians (AAFP), "An estimated six million people worldwide have taken ivermectin for various parasitic infections. ... Side effects ... are thought to result from the death of parasites rather than as a reaction to the drug."

Dogs

The most common uses of ivermectin for small animals, such as dogs, is as a heartworm preventive, as well as for the treatment of ear mites and mange. In addition, a 2000 study by the Department of Parasitology at Ain Shams University in Cairo, Egypt, proved ivermectin (Ivomec) "to be effective in controlling R. sanguineus (brown dog ticks)." A similar 2005 study by London's Pathogen Molecular Biology Unit found ivermectin treatment to be "highly effective in eliminating the ticks" on dogs in an infested dog kennel.

Side Effects

Side effects may be one reason why ivermectin is not commonly used for ticks. Doses for heartworm prevention are 50 times lower than doses needed for the prevention of other parasites. Low or no side effects occur at these low doses, but problems may arise with higher doses. According to Washington State University's College of Veterinary Medicine, "Some dog breeds are more sensitive to certain drugs than other breeds. Collies and related breeds, for instance, can have adverse reactions to drugs such as ivermectin."

Llamas and Alpacas

Ivermectin is an effective tick removal treatment for llamas and alpacas in the reduction of tick paralysis disease. This uncommon but potentially fatal disease affects all warm-blooded land animals, including humans, and is caused when one of 60 species of ticks injects its toxin into the host. According to Washington State University, "Most people are not aware of the extraordinary role ticks play in disease transmission worldwide. ... Llama and alpaca owners working with their veterinarians will find the drug ivermectin to be very effective in the proper dosage."

Lyme Disease

Ivermectin-medicated whole kernel corn controlled ticks feeding on white-tailed deer.

The U.S. Department of Agriculture (USDA) states that white-tailed deer are the "primary large wild animal hosts for the parasitic stages of the lone star tick." They are also the primary hosts for adult black-legged ticks, which cause Lyme disease. A 2003 USDA study using ivermectin-medicated whole kernel corn "demonstrated the importance of white-tailed deer as major hosts for maintenance of lone star tick populations, but more importantly, they determined that employing (ivermectin) to control parasitic ticks feeding on white-tailed deer also could significantly reduce populations of free-living ticks in the treatment area."

References

• World Health Organization: Mass treatment with Ivermectin-An Underutilized Public Health Strategy
• U.S. National Library of Medicine, National Institutes of Health: Effect of Ivermectin on the Brown Dog Tick, Rhipicephalus
• U.S. National Library of Medicine, National Institutes of Health: Ticks, Ivermectin, and Experimental Chagas Disease
• WSU Veterinary College: WSU Veterinary College Warns Llama and Alpaca Owners of Tick Paralysis

Resources

• U.S. National Library of Medicine: Ivermectin
• Marvistavet: Ivermectin
• Washington State University College of Veterinary Medicine: Multidrug Sensitivity in Dogs