Podcast
Questions and Answers
Why is Loa loa infection also known as African eye worm?
Why is Loa loa infection also known as African eye worm?
- The adult worms migrate through subcutaneous tissues, causing skin discoloration that resembles traditional African tribal markings.
- The adult worms migrate across the conjunctiva, a behavior frequently observed in Western Africa where the infection is endemic. (correct)
- The infection primarily affects individuals of African descent due to genetic predispositions.
- The microfilariae are easily observed in urine samples, leading to detection through urinary analysis in Africa.
Diethylcarbamazine (DEC) is effective in treating Loiasis. What is its primary mechanism of action that leads to the resolution of the infection?
Diethylcarbamazine (DEC) is effective in treating Loiasis. What is its primary mechanism of action that leads to the resolution of the infection?
- DEC disrupts the microfilariae's surface, making them more susceptible to immune destruction. (correct)
- DEC directly paralyzes and kills adult worms, facilitating their removal from subcutaneous tissues.
- DEC enhances the host's immune response, leading to increased clearance of microfilariae.
- DEC inhibits the molting process of microfilariae, preventing their development into adult worms.
What adaptation allows Onchocerca volvulus microfilariae to thrive primarily in the skin and lymphatics rather than circulating in the peripheral blood?
What adaptation allows Onchocerca volvulus microfilariae to thrive primarily in the skin and lymphatics rather than circulating in the peripheral blood?
- Microfilariae possess specialized enzymes that degrade blood components, making the skin a more hospitable environment.
- Microfilariae have migratory patterns which result in decreased presence in peripheral blood. (correct)
- Microfilariae secrete anti-coagulant factors that prevent their aggregation and clearance in the bloodstream.
- Microfilariae exhibit a unique surface protein profile that prevents recognition and clearance by blood-borne immune cells.
Why is Suramin, although effective against adult Onchocerca volvulus worms, not the first-line treatment for onchocerciasis?
Why is Suramin, although effective against adult Onchocerca volvulus worms, not the first-line treatment for onchocerciasis?
What is the significance of diurnal periodicity in the context of Loa loa microfilariae detection?
What is the significance of diurnal periodicity in the context of Loa loa microfilariae detection?
In the life cycle of Onchocerca volvulus, what critical developmental process occurs within the thoracic muscles of the black fly following the ingestion of microfilariae?
In the life cycle of Onchocerca volvulus, what critical developmental process occurs within the thoracic muscles of the black fly following the ingestion of microfilariae?
What environmental factor most significantly contributes to the prevalence and transmission of Onchocerca volvulus by Simulium blackflies?
What environmental factor most significantly contributes to the prevalence and transmission of Onchocerca volvulus by Simulium blackflies?
How do the subcutaneous nodules (onchocercomata) formed in onchocerciasis contribute to the parasite's survival and transmission?
How do the subcutaneous nodules (onchocercomata) formed in onchocerciasis contribute to the parasite's survival and transmission?
In the context of Loa loa filariasis, what is the underlying mechanism behind the development of Calabar swellings?
In the context of Loa loa filariasis, what is the underlying mechanism behind the development of Calabar swellings?
What is the primary reason that microfilariae of Loa loa are found in higher concentrations in peripheral blood during the day compared to the night?
What is the primary reason that microfilariae of Loa loa are found in higher concentrations in peripheral blood during the day compared to the night?
Flashcards
Loa loa
Loa loa
A nematode parasite also known as the African eye worm, endemic in Western Africa.
Loa loa Transmission
Loa loa Transmission
Transmitted by the bite of infected Chrysops flies, filarial larvae penetrate the skin and develop into adult worms.
Loiasis Symptoms
Loiasis Symptoms
Migratory swellings and ocular lesions caused by adult worms moving in the eye.
Loiasis Diagnosis
Loiasis Diagnosis
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Diethylcarbamazine (DEC)
Diethylcarbamazine (DEC)
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Onchocerca volvulus
Onchocerca volvulus
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Onchocerca volvulus Vector
Onchocerca volvulus Vector
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Onchocerciasis Treatment
Onchocerciasis Treatment
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Onchocerca volvulus Transmission
Onchocerca volvulus Transmission
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Onchocerciasis Pathogenesis
Onchocerciasis Pathogenesis
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Study Notes
Loa Loa (African Eye Worm)
- Endemic to Western Africa
- The definitive host is humans
- The vector is day-biting deer flies (Chrysops species)
- Transmitted through the bite of an infected Chrysops fly
Clinical Symptoms of Loiasis
- Calabar swellings (migratory swellings)
- Ocular lesions
Diagnosis of Loiasis
- Observation of microfilarial larvae in peripheral blood
- Isolation of the adult worm from the eye
Treatment of Loiasis
- Diethylcarbamazine (DEC) is effectively used to treat it
Loa Loa Life Cycle
- Infected Chrysops flies introduce filarial larvae onto the skin during blood meals.
- Larvae penetrate the bite wound, migrate, and develop into adult worms in subcutaneous tissues.
- Adult females: 40–70 mm long (0.5 mm diameter)
- Adult males: 30–34 mm long (0.35–0.43 mm diameter)
- Adults produce microfilariae (250–300 µm long, 6–8 µm wide); they circulate in peripheral blood during the day and migrate to the lungs at night
- Microfilariae are ingested by flies during blood meals
- Inside the fly, microfilariae migrate from the midgut to the hemocoel
- Then they develop into infective third-stage larvae in the thoracic muscles
- These larvae migrate to the fly’s proboscis, allowing transmission during the next blood meal
Onchocerca Volvulus (Blinding Filaria)
- The definitive host is humans
- The vector is day-biting black flies (Simulium species), which breed in fast-flowing rivers
- Transmitted through the bite of an infected Simulium fly
Treatment for Onchocerca Volvulus
- Ivermectin kills microfilariae
- Suramin kills adult worms but is highly toxic
Onchocerca Volvulus Life Cycle
- Infected black flies introduce infective filarial larvae onto human skin during blood meals.
- Larvae penetrate the bite wound and develop into adult filariae in subcutaneous connective tissue nodules.
- Adult worms can live for 10–15 years Some nodules contain multiple worms
- Female worms continuously produce microfilariae, which live for 12–15 months
- Microfilariae migrate through skin and lymphatic tissues rather than circulating in peripheral blood.
- Black flies ingest microfilariae during blood meals
- Inside the fly, microfilariae migrate from the midgut to the hemocoel
- Then they develop into infective third-stage larvae in the thoracic muscles
- These larvae migrate to the fly’s proboscis, allowing transmission to a new human host
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