1. Home
  2. /

  3. /

    The Impact of Greyhound Racing on the Development of an Advanced Parasitic Organism (Part 2)
The Impact of Greyhound Racing on the Development of an Advanced Parasitic Organism (Part 2)
Hookworm. Source: Midjourney

The Impact of Greyhound Racing on the Development of an Advanced Parasitic Organism (Part 2)

Challenges with parasites

The impact of drug-resistant parasites varies depending on the individuals they infect. Whilst resistant hookworms are typically not fatal for most dogs, and they will eventually die without reinfection, the risk of death increases for puppies and other vulnerable individuals as these worms spread within the population.

Moreover, A. caninum, the parasite responsible for hookworm infections, can also infect humans. In humans, these worms cause a painful condition called cutaneous larva migrans, where the larvae burrow into the skin and sometimes even the eyes, in search of the molecular signals that indicate they have found the appropriate host. There have been rare cases of A. caninum causing severe gastrointestinal symptoms in humans, known as eosinophilic enteritis, according to Hawdon. He also mentions recent, albeit unconfirmed, reports of individuals with detectable adult parasites in their bodies, a condition known as patent A. caninum infections. He points out that even if these specific cases remain unverified, it is not unlikely that such cases will occur in the future.

Since the same drug classes are used to treat hookworm infections in both dogs and humans, the emergence of drug-resistant worms will complicate the treatment of these infections for both species.

Whilst it is generally considered rare for hookworms to be transmitted from animals to humans, there is a lack of reliable data on the number of cases in the United States. Most reported infections in humans occur in individuals who have travelled to tropical areas with poor sanitation and animal care practices. However, the transmission of the disease from animals to humans may be underestimated. When Kaplan raised concerns about drug-resistant hookworms to the Centers for Disease Control and Prevention, he found little interest because they do not monitor or track a condition called cutaneous larva migrans. Nevertheless, data from Australia in 2020 indicated that a species of hookworm, which commonly infects cats and dogs in Southeast Asia, also infects humans, accounting for up to 46 per cent of hookworm infections in some areas.

Ancylostoma Caninum. Source: Midjourney
Ancylostoma Caninum. Source: Midjourney

Despite these concerning developments, Kaplan and Hawdon emphasise that we should not blame greyhounds for the situation. Hawdon expresses a concern that stigmatising them is unfair as these dogs will need homes as the last of the greyhound racing tracks close down. Resistant worms are already present among the canine population in the United States, meaning that all dogs can become infected and spread them. To put the risk into perspective, Kaplan argues that although most greyhounds have hookworms, other dog breeds are likely the main carriers when it comes to pet exposure. He points out that there are only a few thousand greyhounds adopted each year, whereas there are approximately 100 million dogs in the United States, with a parasite prevalence of about 4 per cent.

Safeguarding your animal from contacting a parasite

Veterinarian Pablo David Jimenez Castro collaborated with Kaplan during his time as a graduate student, focusing on research related to greyhounds. Currently, he serves as the co-chair of the Hookworm Task Force at the American Association of Veterinary Parasitologists. According to him, the most effective measure dog owners can take to safeguard their pets from hookworms, regardless of whether they have adopted a greyhound or not, is to have their veterinarian conduct faecal egg tests for worms four times annually. If your dog is diagnosed with worms, it is crucial to diligently follow the treatment prescribed by the vet and, most importantly, clean up after your pet. Jimenez Castro emphasises the importance of promptly removing dog faeces, stating, "Pick up the poop as soon as you can." By preventing the infected dog from becoming reinfected or transmitting the parasite to other pets in the household, the worms will naturally run their course and perish. Jimenez Castro acknowledges that dog owners may have the urge to completely sanitise their backyard and lawn due to the presence of hookworms, but he assures that disposing of faeces within 48 hours is sufficient to eliminate any eggs they may contain before they hatch and become infectious. Furthermore, he states that dog owners should not be afraid of dog parks, particularly in major cities like New York, where dog parks are often the only spaces for dogs to freely roam and socialise. However, owners must comprehend the associated risks and maintain regular check-ups with the veterinarian. Unfortunately, cities have limited options for eradicating hookworms in parks since once the larvae have infiltrated the grass and soil, they become virtually undetectable and indestructible.

Meanwhile, it is necessary for researchers to closely monitor other species in order to detect any signs of infection caused by these highly resistant parasites. Since we are incapable of treating the environment to eliminate worms, there is a potential risk that wild canids such as coyotes and foxes, which frequently inhabit urban areas, may also acquire these resistant worms. Unlike their domesticated counterparts, wild canines roam much larger territories and are not regularly subjected to parasite treatment or monitoring. Consequently, they could unknowingly act as carriers, spreading these drug-resistant worms without being detected.

Hookworm eggs. Source: Midjourney
Hookworm eggs. Source: Midjourney

The emergence of drug-resistant hookworms in dogs serves as a cautionary tale for the potential consequences in other species of roundworms that infect humans. Various severe tropical diseases, such as river blindness, lymphatic elephantiasis, and ascariasis, are caused by roundworms in humans. These worms are genetically similar to dog hookworms and are treated with the same medications, which means they can develop similar mutations that render them resistant to drugs. Over the past decade, public health officials, non-governmental organizations, and pharmaceutical companies have implemented mass drug administration programmes in communities affected by these disease-causing worms. These programmes have successfully delivered millions of doses of antiparasitic drugs primarily to children, who suffer the most from the health complications and developmental setbacks caused by heavy worm infections. As a result of these initiatives, lymphatic elephantiasis has been declared eradicated in several countries.

There have already been reports of the same benzimidazole-resistant mutations appearing in roundworms that infect humans. Gilleard, an expert in the field, warns that relying solely on drugs is insignificant to eliminate parasites. The case of greyhounds demonstrates that drug resistance can emerge in one population and easily spread to others. Therefore, comprehensive surveillance for resistance is crucial, especially considering the capabilities of modern DNA sequencing technologies. Without such surveillance, drug resistance will silently propagate before control programmes can adapt, resulting in a world with a higher prevalence of worm infections for everyone.


Get the latest news to your inbox.

Subscribe to the newsletter

We value your privacy and promise not to distribute your email to third parties.