Introduction to Parasitology

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Questions and Answers

What is the habitat of trypanosomes?

Inside plant roots

In the blood plasma (correct)

In soil

In freshwater lakes

Which organism serves as the intermediate host for trypanosomes?

Tse tse fly (correct)

Mosquito

Housefly

Fruit fly

What is the definitive host for trypanosomes?

Bacteria

Fungi

Invertebrate

Vertebrate, including humans (correct)

What unique feature is present in the structure of trypanosomes?

A spindle-shaped body covered by a shell Signup and view all the answers

How is the body shape of trypanosomes described?

Spindle-shaped and pointed at both ends Signup and view all the answers

What is the shape of the nucleus found within the cytoplasm?

Oval Signup and view all the answers

Where is the basal granule located in relation to the flagellum?

At the base of the flagellum Signup and view all the answers

Which part of the flagellum is attached to the body?

Undulating membrane Signup and view all the answers

What is located at the back of the flagellum?

Kinetoplast Signup and view all the answers

Which component is responsible for movement in this structure?

Flagellum Signup and view all the answers

What is the consequence of damage to vital organs according to the content?

It often results in the death of the patient. Signup and view all the answers

Which organism is directly mentioned in relation to organ damage?

Plasmodium sp. Signup and view all the answers

What is the relationship between Plasmodium sp. and patient outcomes?

It can cause damage to vital organs, potentially leading to death. Signup and view all the answers

Why is the understanding of Plasmodium sp. important in medical contexts?

Its effects on vital organs can be critical and fatal. Signup and view all the answers

What possible outcome can result from organ damage caused by pathogens like Plasmodium sp.?

Patient mortality. Signup and view all the answers

What is a common characteristic of infections in normal human hosts?

Infections are usually asymptomatic. Signup and view all the answers

In which group of individuals can infections become severely problematic?

Immunocompromised individuals. Signup and view all the answers

What does recrudescence refer to in the context of infections?

Relapse of the infection. Signup and view all the answers

What are potential transmission methods for certain infections?

Blood transfusion or organ transmission. Signup and view all the answers

What is typically the outcome for normal human hosts infected with certain viruses?

They commonly remain asymptomatic. Signup and view all the answers

Where is the primary site of infection for urinary tract Schistosoma?

Veins of the urinary bladder Signup and view all the answers

What is a common symptom associated with urinary tract Schistosoma infections?

Hematuria Signup and view all the answers

Which condition is not typically associated with intestinal Schistosoma?

Fibrosis of the urinary bladder Signup and view all the answers

What complication can arise from the eggs of urinary tract Schistosoma?

Granulomas Signup and view all the answers

Which of the following symptoms is characteristic of intestinal Schistosoma?

Liver damage Signup and view all the answers

Which of the following are potential ectopic sites for larvae migration?

Subcutaneous tissue Signup and view all the answers

What is one way that larvae can reach the lungs during ectopic migration?

By penetrating through the diaphragm Signup and view all the answers

Which of the following statements accurately describes ectopic migration locations?

They involve various body regions including neural tissue. Signup and view all the answers

Which ectopic migration site is least likely for larvae based on common occurrences?

Liver tissue Signup and view all the answers

Which has been identified as an ectopic site aside from the diaphragm and lungs?

Subcutaneous tissue Signup and view all the answers

Study Notes

Parasitology

Parasitology is the study of parasites.
Medical parasitology studies parasites of medical importance that can cause disease in humans.
A parasite is an organism entirely dependent on another larger organism (host) for shelter and/or nutrition.
Symbiosis is a close and prolonged association between two organisms of different species. It can be commensalistic (one benefits, the other not affected), parasitic (one benefits, the other is harmed), or mutualistic (both benefit).
Parasites can be permanent (e.g., head lice) or temporary (e.g., bed bugs).
Ectoparasites live on the outside of the host (e.g., head lice).
Endoparasites live inside the host (e.g., Entamoeba histolytica).
Parasites can be facultative (able to live free living and as parasites), obligate (must live as a parasite), or coprozic (spurious, passing through the host's digestive tract).
A host is the organism that harbors a parasite.
Definitive host: harbors the adult, most developed stage of the parasite.
Intermediate host: harbors sexually immature or larval stages of a parasite.
Reservoir host: holds the same parasite species as a human, acting as a source of infection.
Habitat: the tissue or organ where the adult parasite exists in the definitive host.
Infective stage: The stage of parasite capable of causing infection (entering the host and continuing development).
Diagnostic stage: the stage of a parasite that can be detected in specimens (stool, blood, urine, sputum, CSF) for diagnosis.
Vectors are arthropods that transport parasites from infected to uninfected hosts.
Biological vectors: necessary to complete the life cycle of a parasite.
Mechanical vectors: passive carriers of parasites.
Infection: invasion of the body by any pathogenic organism (except arthropods).
Infestation: establishment of arthropods on or within a host.
Autoinfection: infected individuals act as a source of infection for themselves.
Zoonosis: animal diseases transmissible to humans.

Classification of Medically Important Parasites

Parasites are classified according to international code taxonomy.
Classification often includes Kingdom, Phylum, Class, Order, Family, Genus, and Species.
Some parasites have further divisions: Sub-order, Superfamily, Subspecies.
The scientific name of a parasite consists of the genus and species names (e.g., Plasmodium falciparum). The genus name is one word; the species name is two words.

Entamoeba histolytica (Amoebiasis)

Disease: Amoebiasis
Mode of locomotion: Pseudopodia (false feet)
Geographic distribution: Cosmopolitan, common in tropical and subtropical countries with poor sanitation.
Habitat: Lumen of the large intestine; pathogenic because it can invade the intestinal wall.
Reservoir: Primarily humans, also dogs, pigs, monkeys.
Morphology: 2 forms: Cysts and Trophozoites.
Infective stage: ingested in contaminated water/food.
Pathogenic stage: Trophozoite stage, causing ulcerations and possible tissue invasion.
Clinical picture: Dysentery (bloody/mucous diarrhea), severe abdominal pain, tenesmus.
Complications: Intestinal (peritonitis, appendicitis, hemorrhage), Extraintestinal (liver abscess, complications involving lung, brain, and skin).

Trypanosoma (Trypanosomiasis/Sleeping Sickness)

Disease: Trypanosomiasis
Mode of locomotion: Undulating movement of flagella and undulating membrane.
Geographic distribution: Cosmopolitan.
Habitat: Blood plasma.
Intermediate host: Tsetse fly.
Definitive host: Vertebrates, including humans.
Morphology: Spindle-shaped.
Reproduction: Asexual, longitudinal binary fission.
Transmission: Tsetse fly bite, rarely mother-to-child, accidental needle-sticking, rarely sexual contact.
Infection and symptoms: Initial stage (haemo-lymphatic stage) includes fever, headache, enlarged lymph nodes, and itching. Later (CNS involvement) includes behavior changes, confusion, sensory problems, sleep cycle disturbance.
It is usually fatal without treatment.
Other related diseases: Chagas disease/American trypanosomiasis (bite from triatomine bugs/kissing bugs).

Toxoplasma gondii (Toxoplasmosis)

Disease: Toxoplasmosis
Geographic distribution: Worldwide.
Transmission: Ingesting raw, undercooked meat from sheep/cows containing viable trophozoites; consuming water/food contaminated with cat feces; transplacental transmission; blood transfusion/organ transmission.
Infection in healthy immunologically competent people is usually asymptomatic.
Severe illness in immunocompromised individuals and congenital infections can lead to significant complications/blindness in newborns.
Symptoms may include fever, headache, splenomegally, lymphadenopathy, hydrocephalus; in severe cases this can lead to toxoplasmosis encephalitis.

Malaria (Plasmodium spp.)

Disease: Malaria
Geographic distribution: Primarily Africa, Asia, and Latin America, previously widespread.
Causative agent: Protozoan parasites of the genus Plasmodium.
Transmission: Bite from the female Anopheles mosquito.
Reproduction: Asexual & sexual reproduction
Asexual reproduction occurs in humans (sporozoites multiply to produce trophozoites/merozoites).
Sexual reproduction in mosquite
Symptoms: Episodes of chills, fever, sweating, anemia, often leading to cerebral malaria and death.

Intestinal Flukes (e.g., Heterophyes heterophyes)

Heterophyes heterophyes is a fluke that affects humans.
Definitive host: is typically humans, often ingesting undercooked fish.
Intermediate host: freshwater snails and fish. These snails and fish then act as a source of the infection.
Symptoms: inflammation, diarrhea, tissue-damage, neuro-logical disorders and often fatalities.

Ficolia Hepatica (Liver Flukes)

Disease: infection of the liver
Transmission: Occurs by ingestion of undercooked freshwater fish
Pathology: The fluke causes extensive mechanical injury to the liver tissue.
Symptoms: May involve symptoms of fever and abdominal pain; severe cases may lead to biliary obstructions.

Bilharzia/Schistosomiasis (Blood Flukes)

Disease of the venous system.
Transmission: Direct skin penetration from contaminated water.
Definitive host: Humans
Intermediate host: Snails
Symptoms: intestinal/urinary blood, and other issues.
Pathology: Eggs cause tissue damage in intestinal or urinary bladder, liver damage.

Balantidium coli (Ciliates)

Disease: Balantidiasis an intestinal parasitic infection.
Geographic distribution: Worldwide. It is found mostly in pigs and other animals, but humans can be infected by ingesting food/water contaminated with the parasite.
Habitat: Large intestine of humans, pigs, and non-human primates.
Symptoms: diarrhea, possibly dysentery, sometimes asymptomatic. This infection generally does not involve locations external to the intestines.

Trichomonas vaginalis

Disease: Trichomoniasis.
Habitat: In the vagina and cervix of females, and in the anterior urethra of males.
Transmission: Commonly sexually transmitted.
Symptoms: Mild irritation to severe inflammation, foul-smelling discharge, painful urination, dyspareunia.

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Description

This quiz covers the foundational concepts of parasitology, including the definitions and classifications of parasites. It also delves into the relationships between parasites and their hosts, the types of parasites, and their medical significance. Test your understanding of both ecto- and endoparasitic organisms.