Schistosomiasis and Sleeping Sickness Quiz

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Questions and Answers

What type of flukes reside primarily in the blood vessels of various organs?

Intestinal flukes

Blood flukes (correct)

Lung flukes

Liver flukes

Which schistosome species is responsible for causing vesical (urinary) schistosomiasis?

Schistosoma haematobium (correct)

Schistosoma japonicum

Schistosoma mekongi

Schistosoma mansoni

Which of the following is a common habitat for Schistosoma mansoni?

Veins of the liver

Bladder veins

Lungs

Veins of the intestine (correct)

What age group shows peak prevalence for urinary schistosomiasis caused by Schistosoma haematobium?

10-14 years Signup and view all the answers

How many eggs does a female Schistosoma mansoni lay daily?

100-300 Signup and view all the answers

Which genus of snails is known to harbor Schistosoma mansoni?

Biomphalaria Signup and view all the answers

What geographical regions are commonly associated with Schistosoma mansoni?

Africa and South America Signup and view all the answers

Which of the following statements is true regarding the reproductive structure of male schistosomes?

They possess 6-9 testes Signup and view all the answers

What is a characteristic sign of Gambian sleeping sickness?

Winter bottom’s sign Signup and view all the answers

Which organism causes a more acute and rapidly progressive form of sleeping sickness?

T.rhodesiense Signup and view all the answers

What immune response challenge do the parasites create for the host?

Antigenic variation Signup and view all the answers

What is a typical progression symptom in the chronic stage of T.gambiense infection?

Cyclical fever spikes Signup and view all the answers

What consequences arise in the final stages of T.gambiense sleeping sickness?

Meningoencephalitis and convulsions Signup and view all the answers

What typifies the clinical manifestation of T.rhodesiense early in infection?

Lethargy and mental disturbance Signup and view all the answers

Which of the following symptoms is NOT typically associated with the chronic stage of T.gambiense infection?

Rapid kidney damage Signup and view all the answers

What results from the immune response to the parasites in sleeping sickness?

Increased level of parasitemia Signup and view all the answers

Which body fluid examination is crucial for diagnosing malaria?

Blood Signup and view all the answers

In which type of parasitic infection would eggs be found in the urine?

Schistosomiasis Signup and view all the answers

What is commonly found in the stool during an intestinal parasitic infection?

Cysts and trophozoites Signup and view all the answers

What stage of the life cycle of Giardia lamblia is primarily responsible for attaching to the intestinal wall?

Trophozoite Signup and view all the answers

Which laboratory diagnostic method is used for detecting Trichomonas vaginalis?

Urethral or vaginal discharge examination Signup and view all the answers

What is the primary method of transmission for Giardia lamblia?

Ingestion of infective cysts Signup and view all the answers

What indirect evidence might indicate tissue invasion by helminthes?

Eosinophilia Signup and view all the answers

Which of the following pairs of flagellates are classified as hemoflagellates?

Trypanosoma species and Leishmania species Signup and view all the answers

During which phase do Plasmodium spp. leave the liver and enter the bloodstream?

Erythrocytic phase Signup and view all the answers

In which case is the examination of sputum particularly useful?

Respiratory tract infections Signup and view all the answers

What type of biopsy is performed in cases of Cysticercosis?

Muscle biopsy Signup and view all the answers

What triggers the excystation of Giardia lamblia after ingestion?

Gastric acid Signup and view all the answers

What is the main requirement for mosquitoes to undergo gametocytogenesis?

Sucking male and female gametes Signup and view all the answers

Which blood condition is a feature of hookworm infestation?

Anemia Signup and view all the answers

In which part of the digestive system do trophozoites of Giardia lamblia attach?

Duodenum and jejunum Signup and view all the answers

Which of the following practices should be avoided to reduce the risk of infection from pathogenic flagellates?

Drinking raw milk Signup and view all the answers

What phase is characterized by the multiplication of merozoites in tissue schizonts?

Erythrocytic Schizogony Signup and view all the answers

In which species of malaria does the erythrocytic cycle take 48 hours to complete?

Plasmodium vivax Signup and view all the answers

Which malaria parasite is known for causing cerebral malaria?

Plasmodium falciparum Signup and view all the answers

What is a characteristic feature of Plasmodium vivax infections?

Presence of Schuffner's dots in infected RBCs Signup and view all the answers

What happens to merozoites during the blood transfusion of malaria?

They only reproduce erythrocytic cycle Signup and view all the answers

What triggers the seasonality of malaria transmission?

Weather conditions Signup and view all the answers

What invasion pattern is seen in Plasmodium vivax with respect to erythrocytes?

Selective invasion of young immature erythrocytes Signup and view all the answers

Which clinical feature is NOT associated with Plasmodium falciparum?

Long incubation period Signup and view all the answers

Which of the following describes an ectoparasite?

A parasite that lives on the outer surface of its host. Signup and view all the answers

What type of host harbors a parasite in its adult stage where sexual reproduction occurs?

Definitive host Signup and view all the answers

Which term applies to a parasite that accidentally infects an unnatural host?

Accidental parasite Signup and view all the answers

What characterizes an obligate parasite?

It depends completely on the host for part or all of its life cycle. Signup and view all the answers

Which of the following accurately describes a paratenic host?

It temporarily harbors the parasite, aiding its movement to another host. Signup and view all the answers

What type of symbiotic relationship is characterized by both partners being metabolically dependent on each other?

Mutualism Signup and view all the answers

Which category does a host fall into if it typically does not suffer from the effects of a parasite but can still transmit it?

Reservoir host Signup and view all the answers

What distinguishes a facultative parasite from other types of parasites?

It can adapt to both parasitic and free-living states. Signup and view all the answers

Study Notes

General Parasitology

A parasite is a living organism that gets its nourishment and other needs from a host.
A host is an organism that supports a parasite.
Parasites in medical parasitology include protozoa, helminthes, and some arthropods.
Hosts vary depending on the life cycle stage of the parasite.

Different Kinds of Parasites

Ectoparasite: Lives on the outer surface of the host (e.g., lice, ticks, mites).
Endoparasite: Lives inside the host's body (e.g., Entamoeba histolytica).
Obligate Parasite: Entirely dependent on the host for its life cycle (e.g., Plasmodium spp).
Facultative Parasite: Can live as a parasite or non-parasitic depending on the environment (e.g., Naegleria fowleri).
Accidental Parasite: Attacks an unnatural host and survives (e.g., Hymenolepis diminuta).
Erratic Parasite: Wanders into an organ it is not usually found in (e.g., Entamoeba histolytica in the liver or lung).

Different Kinds of Hosts

Definitive Host: Harbors the adult stage or where the parasite reproduces sexually.
Intermediate Host: Harbors larval stages or asexual reproduction.
Paratenic Host: A temporary refuge and vehicle for the parasite to reach the definitive host.
Reservoir Host: A host that keeps the parasite alive and available for transmission to another host.
Natural Host: A naturally infected host for a specific parasite.
Accidental Host: A host that is not usually infected, but can harbor a parasite.

Three Common Symbiotic Relationships

Mutualism (+,+): Both partners benefit, completely dependent on each other. (e.g., protozoa and termite)
Commensalism (+,0): One partner benefits, and the other is not harmed or benefitted. (e.g., normal floras in the human body)
Parasitism (+,-): One partner benefits (parasite) and the other is harmed (host). (e.g., worms like lumbricoides, Ascaris )

Effect of Parasites on the Host

Direct effects: Mechanical injury (pressure), blockage of vessels, production of toxic substances, and deprivation of nutrients.
Indirect effects: Immunological reaction causing tissue damage (e.g., nephritis). Excessive proliferation of tissues due to invasion.

Basic Concepts in Medical Parasitology

Morphology: Size, shape, colour, and position of organelles. Important in lab diagnosis to distinguish between pathogenic and commensal organisms (e.g., Entamoeba histolytica and Entamoeba coli).
Geographical Distribution: Depends on host, presence of vector, environmental conditions, and transmission mechanisms (e.g., food habits).

Life Cycle of Parasites

The route a parasite takes from entry to exit of the host, including time outside the host.
Can be simple (one host) or complex (multiple hosts).
This information helps understand the symptomatology and pathology of the parasite and provides information for diagnosis, treatment, epidemiology, prevention, and control.

Host-Parasite Relationship

Carrier state: Perfect balance between parasite destruction and host repair.
Disease state: Parasite dominates leading to a disease condition.
Parasite destruction: Host prevails, eliminating the parasite.

Laboratory Diagnosis

Blood: Examination for parasites in the blood (e.g., malaria, filariasis).
Stool: Examination for intestinal or biliary tract parasites (e.g., amoebiasis, giardiasis).
Urine: Examination for parasites localized to the urinary tract (e.g., schistosomiasis).
Sputum: Examination for parasites in the respiratory tract (e.g., paragonimiasis).
Biopsy: Examination of tissues (e.g., kala-azar, cysticercosis, trichinosis, Chagas disease, Onchocerciasis).
Urethral/vaginal discharge: Examination for T. vaginalis.
Indirect evidences: changes in blood, e.g., eosinophilia, indicating tissue invasion by helminthes, or reduced white blood cells.

Treatment

Chemotherapy with specific drugs is used to treat parasitic infections, often targeting rapidly proliferating parasite cells to inhibit nucleic acid or protein synthesis or specific metabolic pathways (e.g., folate).

Prevention and Control

Implementing measures to break parasite transmission cycles, reduce infection sources, control vector populations, and improve hygiene.

Classification of Medical Parasitology

Parasites belong to kingdoms Protista and Animalia.
Protista includes protozoa (microscopic single-celled eukaryotes)
Helminthes are macroscopic, multicellular worms. (medical parasitology is divided into these groups: protozoology, helminthology, entomology)

Protozoa

Single-celled, morphologically and functionally complete organisms.
Composed of cytoplasm (outer hyaline ectoplasm, inner granular endoplasm), responsible for protection, movement, ingestion, excretion, respiration, and digestion.
Nuclei function in reproduction and maintaining life.
Resistant cyst stage to survive adverse conditions.

Reproduction of Protozoa

Asexual: Simple binary fission, multiple fission (schizogony).
Sexual: Conjugation, syngamy.

Prevalence of Protozoa

Ubiquitous in moist environments (sea, soil, fresh water).
Varying survival strategies in adverse environments.

Morphology of Protozoa

Predominantly microscopic, 2 to >100µm.
Nucleus with clumped or dispersed chromatin and nucleolus (karyosome) useful for species differentiation.

Pathogenesis of Protozoa

Entry and establishment in the host.
Attachment, replication, and colonization.
Harmful effects (toxins).
Immune evasion.

Antiprotozoal Agents

Targeting rapidly proliferating parasite cells, inhibiting nucleic acid/protein synthesis, or specific metabolic pathways (e.g., folate).

Important Pathogenic Protozoa

Table detailing protozoan species, their location in the host, and common diseases.

Amoebiasis

Primitive unicellular microorganisms.
Two stages: active feeding (trophozoite), & dormant, infectious (cyst)
Binary fission, formation of numerous trophozoites within a mature cyst.
Pseudopodia for movement.

Entamoeba histolytica (Morphological Features)

Trophozoites vary in size (10-60µm), moving rapidly, progressing, and unidirectional through pseudopods.
Nucleus with evenly arranged chromatin, compact, centrally located karyosome.
Cytoplasm is finely granular, with ingested bacteria and debris.
In severe cases, RBCs might be visible—a diagnostic feature.
Cysts range from 10-20µm.
Immature cysts have inclusions (glycogen and chromatoidal bars).
Maturing cysts lose inclusions.

Life Cycle of Entamoeba histolytica

Ingestion of cysts.
Excystation and penetration of the colon wall.
Multiplication by binary fission.
Diagnosis and stool samples (trophozoites or cysts).
Pathogenesis, including ulcers, extraintestinal involvement (liver).

Other types of Non-pathogenic Protozoa

Species like Entamoeba gingivalis, Entamoeba coli, Endolimax nana, Iodamoeba buetschlii, are common commensals of the intestinal tract. Details of these vary in morphological characteristics and prevalence.

Mastigophora (Pathogenic Flagellates)

Protozoan group with whip-like appendages called flagella for motility.
Includes luminal, hemoflagellates, and genital flagellates.

Giardia lamblia

Pathogenic flagellate
Pear-shaped trophozoite with suction disc attachment; a four nucleus double walled cyst
Transmission through contaminated food and water, resistant cysts survive outside hosts/water purifying facilities.
Pathogenesis involves invasion of bowel mucosa, with mucous secretions & dehydration as a symptom
Diagnosis is with stool samples.
Treatment typically with quinacrine hydrochloride or metronidazole.

Trichomonas vaginalis

Pear-shaped trophozoite with undulating membrane and 4 flagella.
Found in urethra, vagina, and prostate.
Sexually transmitted predominantly.
Inflammation and vaginal discharge symptomatic.
Treatment with metronidazole for both partners.

Coccdia (Sporozoa)

Apicomplexa class
Spore-forming protozoa.
Intracellular parasites; common in blood, tissues, and body fluids.
Toxoplasma gondii, a member of this group, causes toxoplasmosis.

Malaria

Caused by Plasmodium sp
Two hosts: Vertebrate (humans- intermediate) and Invertebrate (mosquito- definitive).
Life cycle stages: pre-erythrocytic schizogne, erythrocytic schizogne, and gametogony.
Transmission via an Anopheles mosquito bite.

Medically Important Ciliates (Balantidiasis)

The ciliate Balantidium coli is the only pathogenic member.
Simple life cycle: Ingestion of infectious cysts → excystation → invasion of trophozoites → tissue invasion, and intestinal ulcers.
Clinical findings are similar to amebiasis—abdominal pain, bloody stools, tenderness, anorexia & low level fever.
Diagnosis is through microscopic fecal examinations.
Treatment with tetracycline, metronidazole, or iodoquinol.

Medically Important Helminths

Introduction: a general overview of parasitic helminths, noting their significance, their range of habitats, and the fact that they cause morbidity and mortality.
Sources of parasitic helminthes: the ways they cause infection.
The groupings and classification of Trematodes, Nematodes & Cestodes as different 'flat' worms.

• Trematodes (Flukes): Blood flukes (Schistosoma spp.), Intestinal flukes (Fasciola hepatica, Fasciolopsis buski), Liver flukes (Clonorchis sinensis) and Lung flukes (Paragonimus westermani). Each fluke species has specific characteristics, habitats, lifecycle, symptoms, and methods of diagnosis and treatment.

• Nematodes (Roundworms): These worms feature an unsegmented, elongated, cylindrical body. They are considered parasites of humans, plants, and animals. A description (morphology) should include specifics of the various nematodes like Ascaris lumbricoides, Hookworms, Strongyloides stercoralis Enterobius vermicularis, Trichuris trichuira, Dracunculus medinensis, Trichinella, and Larva Migrans. Each species has particular details in their life cycle, symptoms, morphology, diagnosis, and treatment methods.

• Cestodes (Tapeworms): The worms in this group are flat, ribbon-like structures without a digestive tract. The key differences for the various tapeworm species should be noted - differences in lifecycle, symptoms, morphology, diagnosis, and treatment; examples include Taenia saginata, Taenia solium, Diphyllobothrium latum.

Summary of specific helminthic diseases (e.g., Schistosomiasis, Ascariasis, Hookworm)

For each of the helminthic diseases mentioned above provide an outline of the disease, including: • Causative organism (scientific name)

• Site of infection in host (anatomy and organs affected)

• Life cycle (including stages): How the parasite spreads and infects the host (e.g., soil, intermediate vector, other mammals, transmission mechanisms).

• Morphology of parasite involved/infected host organs.

• Clinical features (symptoms)

• Diagnosis (how is the diagnosis determined)

• Treatment (common method or medications used)

• Epidemiology (prevalence and risk factors)

• Prevention (measures taken to prevent transmission/ infection).

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Description

Test your knowledge on schistosomiasis and sleeping sickness with this quiz. Covering key aspects such as species, habitats, symptoms, and immune responses, it's designed for students in parasitology or related fields. Challenge yourself and improve your understanding of these significant infections.