You may have read the horrific headlines about the Colombian man who was infected by tapeworms that caused a cancer-like syndrome in his body. What you may not have read though is that the man was HIV positive and immune suppressed. The cells that acted just like cancer cells, proliferating and causing similar life-threatening consequences were not the cells of the man himself (like other forms of human cancer), but instead the cells actually originated inside the parasite. This is a new phenomenon and it has pet owners everywhere looking at their pets (and the pets’ potential parasites) in a whole new light.
CDC experts were amazed that the cancer cells came from the tapeworms but had transmitted to the human patient and then spread, eventually contributing to the man’s demise.1 This case seems to be one of the first such documented cases.
This patient’s case was a “perfect storm”. He was immune suppressed and living in an environment in which sanitation likely encouraged his infection with tapeworms. The species of tapeworm is one that lives in human beings and completes its entire life cycle inside its host.
His disease and eventual death are terrifying. There are thousands of species of tapeworms on the planet. Veterinarians see and treat tapeworms every day, but fortunately the tapeworms found in our pets are not the variety that killed this poor man.
If you have a dog or cat, here is what you must know to protect yourself and your pets:
There are three main tapeworm species seen in vet clinics (and pet beds) throughout North America: Taenia spp, Dipylidium spp and Echinococcus. These species typically require an intermediate host, the flea, to complete their life cycle and if the pet owner can control the flea, he is much more likely to control these tapeworms. There is a small zoonotic (contagious to humans) potential in these animal tapeworms, but the risk of human infection is extremely low.2
The eggs shed in the feces of infected dogs and cats are immediately infective to humans that ingest them, so proper hand washing and disposal of feces is essential. People that eat the eggs are at risk of developing cysts that could require surgery or long term treatment, but have not been found to cause cancer.
The good news that that tapeworms are not likely to give your dog cancer or even make him very sick at all. Sure, they are gross since the tiny proglottids crawl alive from your dog’s anus and can be seen wiggling on his hair or bedding. Their small potential to make humans sick combined with the “yuck factor” make treatment mandatory.
All dogs in North America should be maintained on a routine deworming program designed by their own veterinarian and a careful regional flea prevention protocol followed.
Although the fate of the Colombian man was grim and his battle against tapeworm cancer was a frightening headline, in this country, we are blessed with excellent hygiene, medical and veterinary care. Always include your veterinarian in parasite control decisions on behalf of your pets. We are here to defend you and your pets from the threat of zoonotic disease.
For more information about this and other animal topics, please look me up on Facebook.
- Malignant Transformation of Hymenolepis nanain a Human Host
Atis Muehlenbachs, M.D., Ph.D., Julu Bhatnagar, Ph.D., Carlos A. Agudelo, M.D., Alicia Hidron, M.D., Mark L. Eberhard, Ph.D., Blaine A. Mathison, B.S.M.(A.S.C.P.), Michael A. Frace, Ph.D., Akira Ito, Ph.D., Maureen G. Metcalfe, M.S., Dominique C. Rollin, M.D., Govinda S. Visvesvara, Ph.D., Cau D. Pham, Ph.D., Tara L. Jones, Ph.D., Patricia W. Greer, M.T., Alejandro Vélez Hoyos, M.D., Peter D. Olson, Ph.D., Lucy R. Diazgranados, M.D., and Sherif R. Zaki, M.D., Ph.D.N Engl J Med 2015; 373:1845-1852November 5, 2015DOI: 10.1056/NEJMoa1505892
- Conboy G. Cestodes of dogs and cats in North America. Vet Clin North Am Small Anim Pract39:1075-1090, 2012.
