40 Questions
Where are the promastigotes released from during a fly bite?
Proboscis
What is the form that the promastigotes transform into once inside the human host?
Amastigote
What is the result of the amastigotes replicating in the macrophage cell?
The cell breaks down due to pressure
How do the daughter cells protozoans migrate to find new hosts?
Through the bloodstream
What is a major risk factor for Leishmaniasis?
Poverty
What is the type of leishmaniasis caused by L.tropica, L.major, and L.aethiopica?
Cutaneous Leishmaniasis
What is the primary location of the parasite in infantum (infantile visceral leishmaniasis)?
Reticuloendothelial cells of the liver, spleen, bone marrow, and lymph nodes
What is the most common cause of death in visceral leishmaniasis?
Secondary infections
What is the characteristic of Post Kala-azar Dermal Leishmaniasis (PKDL)?
Small, measles-like skin lesions on the face
Which of the following is not a diagnostic test for Visceral leishmaniasis?
ELISA test for antibodies
What is the primary difference between L.donovani and L.infantum infection?
L.donovani causes PKDL, while L.infantum does not
What is the term for the reversal of Leishmania donovani from viscerotropic to dermatotropic?
Post Kala-azar Dermal Leishmaniasis
Which insect is responsible for transmitting the parasite that causes African Trypanosomiasis?
Tsetse fly (Glossina)
What is the form of the trypomastigotes when they first enter the mammalian host?
Short and stumpy
What is the site of multiplication of the trypomastigotes in the mammalian host?
Bloodstream
What is the role of wild animals in the transmission of African Trypanosomiasis?
They act as reservoirs for the parasite
In which part of the tsetse fly do the trypomastigotes transform into epimastigotes?
Midgut
What is the final form of the trypomastigotes in the tsetse fly before transmission to the mammalian host?
Short and stumpy
What is the term for the localized swelling and erythema at the site of the insect bite?
Chagoma
What is the consequence of cardiac involvement in chronic infection?
Fibrosis within the heart muscle
What is the purpose of documenting a history of potential exposure to T.cruzi?
For diagnosis and treatment planning
What is the result of regional lymphadenopathy?
Activation and proliferation of cells
What is the technique that uses the arthropod host as an indicator of infection?
Xenodiagnosis
What is the outcome of chronic infection in the gastrointestinal tract?
Massive dilatation of the esophagus and/or colon
What is the limitation of the application of conventional antibodies for the treatment of the haemolymphatic stage of Chagas Disease?
They cannot penetrate into the VSG coat
In which stage does the parasite reproduce through binary fission in the triatomine bug?
Epimastigote stage
What is the type of reaction that is often reported as a severe side effect?
Anaphylactic shock
Where do the infectious T.cruzi reside in the triatomine bug?
On the rectal cell wall
What is the stage of the parasite when it is ingested by the triatomine bug during a blood meal?
Trypomastigote stage
What is the typical behavior of the triatomine bug during the day?
It rests and hides
Where are the developmental stages of the parasite found in the vector during xenodiagnosis?
Hindgut
What is the purpose of feeding uninfected rats with muscle tissue from a patient suspected of having trichinosis?
To diagnose trichinosis
What is the function of the midgut in the mosquito/insect gut?
Storage and digestion of the bloodmeal
What is the effectiveness of nifurtimox and benznidazole in curing Chagas' disease if given early in the acute phase?
60-80%
What is the site of multiplication of the parasite in the tsetse fly during xenodiagnosis?
Hindgut
What is the purpose of xenodiagnosis in the diagnosis of Chagas' disease?
To detect the presence of parasites in the gut of the vector
What is the type of procedure used in xenodiagnosis for the diagnosis of Chagas' disease?
Entomological test
What is the role of the uninfected reduviid bugs in xenodiagnosis?
To feed on the blood of the patient
What is the time frame during which the feces from the bugs are examined for the presence of developmental stages of the parasite?
20-25 days
What is the primary use of xenodiagnosis?
In field work, primarily in South America
Study Notes
Trypanosomiasis and Leishmaniasis
- Parasitic diseases caused by protozoa of the genera Trypanosoma and Leishmania.
Acute Infection
- Characterized by localized swelling and erythema at the site of the insect bite (chagoma).
- Result of local replication of parasites and influx of fluid and inflammatory cells.
Chronic Infection
- Tissue parasites are difficult to detect.
- Significant interstitial fibrosis occurs.
- Cardiac involvement leads to fibrosis in the heart muscle, damaging the tissue.
Diagnosis
- History of potential exposure to T.cruzi is important to document.
- Methods:
- Microscopic examination of a blood film.
- PCR.
- Culture of blood on NNN media.
- Immunoassay.
- Xenodiagnosis.
Visceral Leishmaniasis (Kala-Azar)
- Caused by L.infantum.
- Habitat: Reticuloendothelial cells, especially in the liver, spleen, bone marrow, and lymph nodes of humans and dogs.
- Pathogenesis: Parasite spreads from the site of inoculation to multiply in reticuloendothelial cells.
- Symptoms:
- Fever
- Enlargement of spleen, liver, and lymph nodes
- Anemia
- Leukopenia
- Skin changes
- Death is due to secondary infections.
Post Kala-Azar Dermal Leishmaniasis (PKDL)
- Secondary form of the disease that may set in after successful treatment.
- Caused by the reversal of L.donovani from viscerotropic to dermatotropic.
- Manifests as small, measles-like skin lesions on the face, which gradually increase in size and spread over the body.
African Trypanosomiasis (Sleeping Sickness)
- Caused by T.brucei.
- Life cycle: Between tsetse fly (Glossina) and mammalian hosts, including humans, cattle, horses, and wild animals.
- In mammalian host:
- Infection occurs when a vector tsetse fly bites a mammalian host.
- Trypomastigotes enter the lymphatic system and bloodstream.
- They multiply by binary fission and penetrate the blood vessel endothelium and invade extravascular tissues, including the CNS.
American Trypanosomiasis (Chagas Disease)
- Caused by T.cruzi.
- Life cycle:
- In animal reservoir, usually mammals, wild or domestic, including humans.
- Triatomine bug serves as the vector.
- In triatomine bug, parasite goes into epimastigote stage, making it possible to reproduce.
Treatment
- African Trypanosomiasis: Suramine, pentamidine, and melarsoprol.
- American Trypanosomiasis: Nifurtimox and benznidazole.
This quiz covers the life cycle of Leishmania parasites, from transmission through the bite of an infected sandfly to the transformation into amastigotes and replication within macrophages.
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