is a parasitic organism that feeds exclusively on the blood of its
host. In addition to its obvious interaction with its hostís such as
dogs, cats, foxes, or even humans to name a few, Dirofilaria immitis
also has close ties to the mosquito. The mosquito serves as an
intermediate host so without this important interaction, the parasite
would not be able to complete its life cycle. The interaction with the
mosquito can be classified as commensal because the microfilaria, which
eventually develop into the parasitic worm Dirofilaria immitis,
are allowed to feed and grow inside the mosquitoes gut without causing
any harm to the mosquito.
Looking closer at how Dirofilaria
immitis interacts with its host, we can see the parasitic
relationship that affects the host species. When the microfilaria
carrying mosquito bites the dog (host in this example), the microfilaria
are released into the dogs bloodstream where they grow and develop into
mature male and female worms. These mature worms reside in the heart,
blood vessels, and lungs on the host, which makes sense because this is
where the most blood is flowing.
Another important interaction that
takes place is between Dirofilaria immitisís bacterial
endosymbiont Wolbachia and the host organism. Wolbachia
play an important role in the interaction with the host organism because
they regulate the hostís immune response (Simon 2007).
In a study done on dogs in Italy, it
was found that all the dogs that were infected with Dirofilaria
immitis had significant total anti-Wolbachia surface protein
IgG (Immunoglobulin G) levels compared to those of uninfected dogs
can affect humans, but it is very unlikely due to the human immune
response to the parasite. Humans act as aberrant or dead end hosts,
meaning they may become infected from the bite of an infected mosquito,
but most often the microfilaria do not develop because they cannot reach
sexual maturity (Johnstone 2000).