PARA 410 Lecture Notes - Lecture 14: Wuchereria Bancrofti, Brugia Timori, Brugia Malayi
12 Jun 2018
School
Department
Course
Professor
Parasitology – lecture 14 (February 6th, 2018)
Slide 1 – Tissue nematodes
Slide 2 – Tissue nematodes
- Nematodes transmitted by arthropods (insects):
o Wuchereria banceofti (Elephantiasis)
o Onchocerca volvulus (River blindness)
- Nematodes transmitted by copepods (upon ingestion):
o Drancunculus medinensis (Guinea worm disease)
Slide 3 – Wuchereria bancrofti & Elephantiasis
- Swollen areas on the body caused by Wuchereria bancrofti
find more resources at oneclass.com
find more resources at oneclass.com
Slide 4 – Wuchereria – general notes
- Parasite name: Wuchereria bancrofti
- It is one of the three parasites that cause lymphatic filariasis, an infection of the lymphatic system by filarial
worms
o Wuchereria bancrofti
o Brugia malayi
o Brugia timori
- If the infection is left untreated it can (not everyone) develop into a chronic disease called elephantiasis
Slide 5 – Wuchereria – general notes
- It affects over 120 million people, primarily in Africa, South America, and other tropical and sub-tropical
countries
- Wuchereria bancrofti is spread by mosquito vectors, most if which feed during the night
- Some of these mosquito vectors have a preference for human blood
- For the nocturnal forms, microfilariae appear in the peripheral circulation during the night and disappear
during the day and go to the tissues
Slide 6 – Wuchereria – adult worms
- The worms are threadlike nematodes and the adults are located in the
lumen of lymphatic vessels
- Have been found at all sires within the lymphatic circulation and
presumable the adjacent subcutaneous tissues
- Female worms are usually 4-10 cm long and thicker than the males
- Males usually 2-4 cm long
Slide 7 – Wuchereria – adult worms
- The worms are ovoviviparous and their larvae are called microfilariae
o Ovoviviparous: mode of replication in which embryos develop inside eggs that are retained within the
mother’s body until they are ready to hatch; may hatch inside and are born as larvae or are hatched
immediately after eggs are laid
- Females can release more than 10,000 microfilariae per day
- The worms most commonly live in the lymphatics of the lower and upper extremities and male genitalia
find more resources at oneclass.com
find more resources at oneclass.com
Slide 8 – Wuchereria – larvae
- The microfilariae measure about 270µm
- Microfilariae are encased in a sheath of chitin – possibly a remnant of an egg shell
Slide 9 – Wuchereria – larvae
- The microfilariae migrate from the lymphatic circulation into the
bloodstream, typically present in large numbers between 10pm
and 6am
- During the day, the microfilariae aggregate in the capillaries of
the lungs
- Microfilariae live for about 1.5 years and must be ingested by a
mosquito
Slide 10 – Wuchereria – larvae
- The ingested microfilariae penetrate the mosquito’s stomach wall and locate the thoracic flight muscles
- Microfilariae undergo two molts and develop into the infective larvae
- Infective larvae locate the mosquito’s biting mouth parts and are deposited onto the skin adjacent to the bite
wound
- The larvae mature to adults and can live 5-8 years in the host – if you are not being treated (average)
- Infections lasting 40 years have been reported
Slide 11 – Wuchereria – life cycle
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Nematodes transmitted by arthropods (insects): wuchereria banceofti (elephantiasis, onchocerca volvulus (river blindness) Nematodes transmitted by copepods (upon ingestion): drancunculus medinensis (guinea worm disease) Swollen areas on the body caused by wuchereria bancrofti. It is one of the three parasites that cause lymphatic filariasis, an infection of the lymphatic system by filarial worms: wuchereria bancrofti, brugia malayi, brugia timori. If the infection is left untreated it can (not everyone) develop into a chronic disease called elephantiasis. It affects over 120 million people, primarily in africa, south america, and other tropical and sub-tropical countries. Wuchereria bancrofti is spread by mosquito vectors, most if which feed during the night. Some of these mosquito vectors have a preference for human blood. For the nocturnal forms, microfilariae appear in the peripheral circulation during the night and disappear during the day and go to the tissues. The worms are threadlike nematodes and the adults are located in the lumen of lymphatic vessels.
