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From snails to dogs: How do heartworms take advantage of their hosts?
In recent years, research on the heartworm Angiostrongylus vasorum has gained increasing attention, particularly regarding its effects on dogs. Heartworm is a parasitic nematode that flexibly uses hosts in the ecosystem, and its life cycle from snails to dogs shows its adaptability and survival strategy. In this article, we will explore the biology of heartworms, their life cycle, and the effects they have on their hosts.
Biology of Heartworms
Heartworm, commonly known as the French heartworm, is a small, pink parasitic nematode that ranges from 14.0 to 20.5 mm in length and about 0.170 to 0.306 mm in width. Female heartworms have a characteristic appearance similar to a hairdresser's corkscrew.
The wonders of life cycle
The heartworm life cycle begins with the ingestion of the third-stage larvae (L3) by a host, with the main hosts including foxes and dogs. They can enter the host through ingestion of infected snails, frogs or infected food.
After entering the host, the L3 larvae will migrate to the mesenteric lymph nodes and undergo metamorphosis, eventually parasitizing the host's pulmonary artery and right side of the heart as adult nematodes.
Pathological effects on the host
Heartworm infection can cause a variety of symptoms, the most common of which are cardiopulmonary effects. Infected dogs may develop symptoms such as persistent coughing, decreased exercise tolerance and breathing difficulties. The main reason for these symptoms is that nematodes and their eggs and larvae block blood vessels, causing obstruction of blood circulation.
In addition, heartworms can cause abnormal blood coagulation, leading to problems such as thrombocytopenia, hematoma, and prolonged bleeding.
These pathological effects significantly reduce the dog's quality of life and may even lead to death in severe cases.
Challenges of Diagnostic Procedures
Diagnosis of heartworm infection requires a combination of clinical symptoms and examination results. Although imaging tests can show lung lesions, the accuracy of stool tests is affected by different factors.
For example, although the Balmain technique stool test is more sensitive than a standard stool smear, it can produce false-negative results because the parasite's egg laying is unstable.
Host diversity
Natural intermediate hosts of heartworm include land snails and other freshwater snails, while the most common definitive hosts are dogs and certain carnivorous animals. Different animals may also act as transmitters of this parasite.
The parasite's ability to flexibly adapt to a variety of ecological environments further complicates its spread.
Geographical distribution and diffusion
According to research, heartworms are mainly distributed in several countries in Western Europe, including the United Kingdom, France and Spain. In these areas, there was a clear shift in infection rates between foxes and dogs, suggesting that foxes may be an important wild reservoir for this parasite.
Treatment and prevention methods
In Europe, the main method of treating heartworm disease is to use a combination of imidacloprid and moxidectin. This medication can be used to treat dogs that are already infected and to follow up with them after they have improved.
ConclusionIn endemic areas, regular monthly administration of this drug is recommended to effectively prevent heartworm infection and its complications.
The ecological adaptability of heartworms and the impacts they have on their hosts make them an important public health problem. Faced with the challenge of this parasite, we should remain vigilant and take reasonable measures to protect ourselves. So, have you checked your pet’s health to prevent possible future infections?
