Alternative common names:
The heartworm nematode is a parasitic roundworm that is spread through the bites of mosquitoes. It causes heartworm disease in animals such asdogs, cats and, rarely, humans. Occasionally, adult heartworms migrate to the right side of theheart and even the great veins in heavy infections. Heartworm infectionmay result in serious disease for the host, with death typically the result of congestive heart failure.
Where does this species come from?
United States of America.
What is its invasive status in South Africa?
NEMBA Category 1b.
Where in South Africa is it a problem?
Gauteng, KwaZulu-Natal and Mpumalanga.
How does it spread?
Spread from host to host through the bites of mosquitoes.
Why is it a problem?
It causes heartworm disease in animals such as dogs, cats and, rarely, humans. Occasionally, adult heartworms migrate to the right side of the heart and even the great veins in heavy infections. Heartworm infection may result in serious disease for the host, with death typically the result of congestive heart failure.
What does it look like?
Description: The heartworm nematode is a cylindrical, slender, white worm. It has a cuticle with three main outer layers made of collagen and other compounds. The outer layers are non-cellular and are secreted by the epidermis. The cuticle layer protects the nematodes so they can invade the digestive tracts of animals.
Both sexes are different. The adult male, measuring 12-16cm, is smaller than the adult female, which is 25-30cm. The male has a posterior end that is spirally coiled and a tail with many alae, which are thickenings of the cuticle. The female posterior is straight. Both sexes have a mouth, a filariform esophogus, anal pore, excretory pore and a nerve ring. The male has a seminal vesicle and testis while the female bears an ovary and oviduct. They have a straight posterior end regardless of the sex and a tapered anterior end.
Habitat: Found in many tropical, subtropical and temperate regions of the world, particularly humid areas and river valleys where environmental conditions harbour the breeding of mosquito vectors.
Breeding: Females may produce a pheromone to attract males. The male coils around a female with his curved area over the female genital pore. The gubernaculum, made of cuticle tissue, guides spicules that extend through the cloaca and anus. Males use spicules to hold the female during copulation. Nematode sperm are amoeboid-like and lack flagella.