For many, heartworm infection has always been associated with dogs and cats. While the disease causes severe consequences in infected pets, transmission to humans has not really been highlighted or commonly known among pet owners or the general public. Heartworm infection in people is often classified as accidental, if any.
Several journals reported human dirofilariasis cases and an infective larval stage of the worm Dirofilaria immitis was identified as the culprit. The same worm affects both dogs and cats to cause heartworm infection. These larvae invade various human tissues without any evident clinical signs in the affected person during development. More common tissues affected by the larvae’s migration include connective tissues and the pulmonary arteries. The migrating larva would embed itself in the human tissues but will be unable to thrive in this environment. It eventually dies in the tissues and an inflammatory response occurs which results in a granuloma or nodule in the affected tissue. This can be seen in x-rays as a dense “coin” lesion in the chest area.
Earlier studies reported no clinical signs in affected humans, but recent data report chest pains, coughing (sometimes with blood), fever and pneumonitis as more frequently observed effects. Extrapulmonary infection was mentioned in an article where the brain, eye and testicles were affected. Extensive diagnostic tests were conducted on the infected individuals to rule out other infectious agents and cancer. And in almost all scientific research conducted on human dirofilariasis, there is mention of misdiagnosis as a common occurrence in the affected patients presented to medical doctors due to the very common signs found in these patients. As with any disease, arriving at a definitive diagnosis is a very costly, time-consuming and emotionally draining process which affects the quality of life of the infected individual as well as his loved ones. For those diagnosed with human dirofilariasis, the surgical removal of the granuloma was the most appropriate solution.
Extra precaution against health problems is oftentimes a conscious effort. And in the Philippines where mosquitoes (which are vectors of the Dirofilaria larvae) are everywhere 24/7 all year round, heartworm infection is very much an expected occurrence in dogs. Regular preventives against heartworm for our pets (and consequently for us, too) are available to keep us worry-free and disease free. Talk to your vet about it.
By: Ayn Arejola