Emerging Zoonotic 

Risks of Dirofilaria repens

Dirofilaria repens is a filaroid helminth primarily associated with canids, with domestic dogs serving as the principal reservoirs for this parasite. The life cycle of D. repens includes five larval stages and has a prepatent period that typically lasts between 6 to 9 months.

The development of the parasite is contingent upon the presence of suitable mosquito species, appropriate hosts, and both male and female adult D. repens. Additionally, the bacterial endosymbiont Wolbachia sp. plays a crucial role, as it is necessary for the successful molting and embryogenesis of the helminths.

Image Credit: https://en.wikipedia.org/wiki/...

Humans can become infected with D. repens in a manner similar to dogs, following the bite of an infected mosquito from the Culicidae family. In most situations, the human immune system detects the infective larvae, resulting in the elimination of the parasite before any infestation symptoms can be recognized. However, there are instances where a single larva may survive long enough to develop into a preadult and eventually an adult worm.

D. repens infestation typically presents with localized inflammation, often affecting subcutaneous and ocular tissues. The symptoms are generally mild and tend to resolve quickly following the surgical removal of the worm. Notably, the development of D. repens into a sexually mature stage in humans is rare, as both the parasite and its endosymbiont, Wolbachia sp., can trigger specific immunological responses that inhibit the full maturation of the helminth. Consequently, humans are often regarded as dead-end hosts for D. repens, although there are uncommon instances where the parasite can evade host defenses and reach sexual maturity.

Despite dirofilariasis being an increasingly significant parasitic disease affecting both humans and dogs in Europe, it remains underappreciated and infrequently recognized as a potential cause of ocular and dermatological issues. Recent research suggests a more pronounced role for humans as definitive hosts for D. repens. From a diagnostic standpoint, it is recommended that the modified Knott's test be regularly employed in both human and canine cases when evaluating clinical symptoms that may indicate filariasis.

For purchase inquiries, reach out to us at- [email protected]