Extrapulmonary Dirofilaria immitis-like infections in the Western Hemisphere

Area of Science:

• Veterinary Parasitology
• Human Pathology

Background:

• Dirofilaria infections in humans are increasingly recognized, posing diagnostic challenges.
• Morphological identification is crucial for understanding parasite-host relationships and transmission dynamics.

Observation:

• Three immature Dirofilaria worms were recovered from two elderly male patients in the United States (Indiana and California).
• The worms exhibited a smooth cuticle without longitudinal ridges, a characteristic shared with Dirofilaria immitis.

Findings:

• The observed morphological features, particularly the smooth cuticle, are similar to Dirofilaria immitis.
• However, the possibility of infection by other dirofilariids with similar cuticular characteristics found in animals in the Western Hemisphere could not be excluded.

Implications:

• A diagnosis of "D. immitis-like organism" is proposed for these nematodes.
• Accurate identification of Dirofilaria species is critical for practicing pathologists to manage human infections.
• Understanding the relationship between animal and human Dirofilaria in the Americas is essential for public health and veterinary medicine.