Microbiology & infectious diseases
Parasites-eye
Dirofilaria repens
Author: Nat Pernick, M.D.
Last author update: 1 October 2018
Last staff update: 11 August 2022
Copyright: 2018-2024, PathologyOutlines.com, Inc.
PubMed Search: Dirofilaria repens[TI] free full text[sb]
Table of Contents
Definition / general | Epidemiology | Diagrams / tables | Clinical features | Diagnosis | Case reports | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Peripheral smear description | Peripheral smear images | Differential diagnosisCite this page: Pernick N. Dirofilaria repens. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/parasitologydirofilariarepens.html. Accessed April 25th, 2024.
Definition / general
- Dirofilariasis is an emerging roundworm infection caused by Dirofilaria sp. (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 509 [Accessed 19 October 2018])
- Should be considered whenever a patient presents with a macroscopic worm moving across the cornea
Epidemiology
- Widely distributed throughout parts of Africa, Asia and Europe, including temperate climates (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 509 [Accessed 19 October 2018])
Diagrams / tables
Images hosted on other servers:
Life cycle of D. repens
Clinical features
Diagnosis
- Clinical presentation, geographic exposure and morphology of the microfilariae in blood; Note: Dirofilaria only rarely produce microfilaria in humans (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 509 [Accessed 19 October 2018])
- Biopsy or worm extraction (CDC: Dirofilaria repens Nematode Infection with Microfilaremia in Traveler Returning to Belgium from Senegal [Accessed 19 October 2018])
- Length of the adult worm (males: 5 - 7 cm; females: 10 - 17 cm) and its cuticle (longitudinal ridges) (CDC: Biology - Life Cycle of D. repens [Accessed 19 October 2018], Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 509 [Accessed 19 October 2018])
Case reports
- 76 year old European man with recent travel to Senegal presented with right conjunctivitis (Pritt: Creepy Dreadful Wonderful Parasites Blog - Case of the Week 509 [Accessed 19 October 2018], CDC: Dirofilaria repens Nematode Infection with Microfilaremia in Traveler Returning to Belgium from Senegal [Accessed 19 October 2018])
Gross description
- Adult females are usually 10 - 17 cm long by 460 - 650 μm wide; males are usually 5 - 7 cm long by 370 - 450 μm wide (CDC: Biology - Life Cycle of D. repens [Accessed 19 October 2018])
Gross images
Contributed by Bobbi Pritt, M.D.
10 cm long D. repens removed from conjunctiva
Microscopic (histologic) description
- Cuticle: Dirofilaria has longitudinal ridges, resembling tree bark (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 509 [Accessed 19 October 2018])
Microscopic (histologic) images
Contributed by Bobbi Pritt, M.D.
470 μm in diameter
Dirofilaria has longitudinal cuticular ridges
Loa loa has irregularly spaced cuticular bosses
Contributed by Bone Moe Win, M.B.B.S.
"Third testes" in infant
Peripheral smear description
- Microfilariae are rarely seen in blood in human Dirofilaria infections (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 509 [Accessed 19 October 2018]):
- D. repens microfilariae do not have a sheath and the nuclei do not go all the way to the tip of the tail
Peripheral smear images
Contributed by Bobbi Pritt, M.D.
Knott concentration performed on blood revealed 6 larvae per mm, each ~375 μm long by ~10 μm wide
D. repens versus L. loa
Differential diagnosis
- Loa loa (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 509 [Accessed 19 October 2018]):
- Dirofilaria can be easily differentiated from L. loa by examining its cuticle:
- Dirofilaria has longitudinal ridges, while L. loa does not
- L. loa has irregularly spaced cuticular bosses or bumps that are located along along the long axis of the worm
- Microfilariae are only rarely seen in human Dirofilaria infections; unlike L. loa, the microfilariae of D. repens do not have a sheath and the nuclei do not go all the way to the tip of the tail
- L. loa can reach a maximum length of ~7 cm, while D. repens can grow to ~17 cm long (CDC: Dirofilaria repens Nematode Infection with Microfilaremia in Traveler Returning to Belgium from Senegal [Accessed 19 October 2018], CDC: Biology - Life Cycle of D. repens [Accessed 19 October 2018])
- D. repens is widely distributed throughout parts of Africa, Asia and Europe, while L. loa has a limited geographic distribution (West and Central Africa) (Trans R Soc Trop Med Hyg 2013;107:273)
- Dirofilaria can be easily differentiated from L. loa by examining its cuticle:
