Podcast
Questions and Answers
Why is the diagnosis of Wuchereria bancrofti typically performed using blood samples collected at night?
Why is the diagnosis of Wuchereria bancrofti typically performed using blood samples collected at night?
- Microfilariae exhibit nocturnal periodicity, increasing their concentration in the peripheral blood. (correct)
- Mosquitoes are more likely to transmit the parasite during the day, so the parasite can be detected at night.
- The lymphatic system is more active at night, releasing more microfilariae into the bloodstream.
- The parasite's metabolic activity peaks at night, making it easier to detect.
What is the primary mechanism by which adult Wuchereria bancrofti worms cause elephantiasis?
What is the primary mechanism by which adult Wuchereria bancrofti worms cause elephantiasis?
- Directly damaging the skin and subcutaneous tissues, leading to inflammation and thickening.
- Triggering an autoimmune response that attacks the lymphatic vessels.
- Obstructing lymphatic vessels, impairing drainage and causing chronic lymphedema. (correct)
- Secreting toxins that cause fluid accumulation and enlargement of affected body parts.
Why is there no drug available to directly target and eliminate adult Wuchereria bancrofti worms?
Why is there no drug available to directly target and eliminate adult Wuchereria bancrofti worms?
- Adult worms develop a resistance to all known anthelmintic drugs.
- The adult worms are located in immunologically privileged sites, preventing drug access.
- The physical size, location within the lymphatic system, and unique physiology of adult worms pose significant drug development challenges. (correct)
- The metabolism of adult worms is too similar to humans, so any drug will also harm the host.
How does the life cycle of Wuchereria bancrofti within the mosquito vector ensure efficient transmission to a human host?
How does the life cycle of Wuchereria bancrofti within the mosquito vector ensure efficient transmission to a human host?
What is the primary reason that diethylcarbamazine (DEC) is effective against microfilariae but not adult Wuchereria bancrofti worms?
What is the primary reason that diethylcarbamazine (DEC) is effective against microfilariae but not adult Wuchereria bancrofti worms?
Predict the most significant impact on Wuchereria bancrofti transmission if a new mosquito control program drastically reduced the lifespan of Culex mosquitoes without eliminating them entirely.
Predict the most significant impact on Wuchereria bancrofti transmission if a new mosquito control program drastically reduced the lifespan of Culex mosquitoes without eliminating them entirely.
What evolutionary advantage might nocturnal periodicity confer to Wuchereria bancrofti microfilariae?
What evolutionary advantage might nocturnal periodicity confer to Wuchereria bancrofti microfilariae?
In a scenario where a patient is diagnosed with lymphatic filariasis but shows no visible signs of elephantiasis or hydrocele, what is the most likely explanation?
In a scenario where a patient is diagnosed with lymphatic filariasis but shows no visible signs of elephantiasis or hydrocele, what is the most likely explanation?
How might climate change indirectly impact the prevalence and distribution of Wuchereria bancrofti infections?
How might climate change indirectly impact the prevalence and distribution of Wuchereria bancrofti infections?
If a vaccine were developed to prevent Wuchereria bancrofti infection, what would be the most effective target of the vaccine, considering the parasite's life cycle and the goal of preventing disease?
If a vaccine were developed to prevent Wuchereria bancrofti infection, what would be the most effective target of the vaccine, considering the parasite's life cycle and the goal of preventing disease?
Flashcards
Definitive host of Wuchereria bancrofti
Definitive host of Wuchereria bancrofti
Humans
Vector of Wuchereria bancrofti
Vector of Wuchereria bancrofti
Culex mosquitoes
Where are the two forms of Wuchereria bancrofti found?
Where are the two forms of Wuchereria bancrofti found?
Adult worms in the lymphatic system and microfilariae in the blood
How is Wuchereria bancrofti transmitted?
How is Wuchereria bancrofti transmitted?
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What causes elephantiasis?
What causes elephantiasis?
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What is hydrocele?
What is hydrocele?
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How is Wuchereria bancrofti diagnosed?
How is Wuchereria bancrofti diagnosed?
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Treatment for Wuchereria bancrofti
Treatment for Wuchereria bancrofti
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Characteristics of W. bancrofti microfilariae
Characteristics of W. bancrofti microfilariae
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Study Notes
- Wuchereria bancrofti is a parasitic nematode which causes lymphatic filariasis (elephantiasis) in humans.
- Humans are the definitive host for W. bancrofti.
- Culex mosquitoes serve as the intermediate host, acting as vectors for transmission.
Forms of Wuchereria bancrofti
- Adult worms reside in the human lymphatic system causing lymphatic blockage.
- Microfilariae are present in the blood, specifically exhibiting nocturnal periodicity.
Transmission
- The filariform larvae of W. bancrofti are transmitted to humans through the bite of infected Culex mosquitoes.
Clinical Symptoms
- Elephantiasis (Lymphatic Filariasis) results from the blockage of lymphatic vessels by adult worms.
- Hydrocele, the accumulation of fluid in the scrotum, is a symptom.
- Swelling of the limbs is a characteristic sign of elephantiasis.
Diagnosis
- Microfilarial larvae can be directly observed in thick blood smears collected at night due to their nocturnal periodicity.
- Skin biopsy specimens also may reveal the presence of microfilariae.
Treatment
- Diethylcarbamazine (DEC) is used to eliminate microfilarial larvae from the bloodstream.
- Currently, there is no drug available to kill the adult worms.
Life Cycle
- An infected mosquito introduces filariform larvae onto the skin during a blood meal.
- The larvae enter the bite wound and travel to the lymphatic system, where they mature into adult worms.
- Adult worms produce microfilariae, which are microscopic, sheathed, and exhibit nocturnal periodicity.
- Blood samples are collected at night to observe microfilariae due to their activity patterns.
- Microfilariae migrate through the lymphatic and blood vessels.
- A mosquito ingests microfilariae during a blood meal, where the microfilariae lose their sheath.
- Inside the mosquito, the larvae develop into third-stage infective larvae.
- The infective larvae migrate to the mosquito's proboscis.
- Infective larvae are transmitted when the mosquito feeds on another human.
Physical Characteristics of Adult Worms
- Female worms range from 80 to 200 mm in length.
- Male worms measure approximately 40 mm × 1 mm.
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