Parasitology Quiz: Trichomonas and Leishmaniasis

Principle of Parasitology - BIOL3061

• Course name: Principle of Parasitology
• Course code: BIOL3061
• Instructor: Saron Efekadu

Chapter One - Concepts of Parasitology

• Parasitism is a form of symbiosis where one organism (parasite) benefits at the expense of another (host).
• Symbiosis can occur between plants, animals, or protists
• Commensalism is a one-way beneficial relationship, no harm to the host
• Mutualism involves a two-way beneficial relationship
• Parasites rely on their hosts for part or all of their life cycle and metabolic requirements
• Parasites are smaller than their hosts
• Parasites outnumber their hosts
• Parasites have shorter lifespans compared to their hosts
• Parasites often have a higher reproductive potential than their hosts
• Parasitology is the study of parasites, their hosts, and the relationship between them

Classifications of Parasites

• Habitat

  • Ectoparasites live on the body surface of the host
    • Lice, ticks, fleas
  • Endoparasites live within the body of the host
    • Leishmania, Ascaris, Plasmodium

• Dependence on the host

  • Obligate parasites: parasites that require their host to survive; cannot live outside their host
    • Plasmodium species, Trichomonas vaginalis
  • Facultative parasites: parasites that can live independently but also have parasitic life stages
    • Strongyloids stercolaris, Naegleria fowleri
  • Accidental parasites: parasites that parasitize an animal other than their normal host
    • Ascaris of dogs or cats accidentally infecting humans

• Pathogenicity

  • Pathogenic parasites cause disease
    • Entamoeba histolytica
  • Non-pathogenic parasites do not cause disease; commensal parasites
    • Entamoeba coli
  • Opportunistic parasites cause mild disease in healthy hosts but severe disease in immuno-compromised hosts
    • Pneumocystis carnii, Toxoplasma gondii

Terminologies in Parasitology

• Infective stage: The stage of the parasite when it can enter and continue to develop within the host.
• Infection: Invasion of the body by a pathogenic organism (excluding arthropods) and the response of the host's tissue to the parasite.
• Infestation: Establishment of arthropods on or within a host.
• Zoonosis: Disease of animals that are transmittable to humans.
• Biological Incubation (Prepatent) Period: Time between initial infection and the detection of the parasite.
• Clinical Incubation Period: Time between exposure and the first signs of disease.
• Autoinfection (Hyperinfection): Reinfection by the same parasite in the same host.
• Retroinfection: Newly hatched larvae migrate from the perianal region to the colon.

The Hosts

• Host: An organism that harbors the parasite
• Definitive host: The host where the parasite reaches sexual maturity.
• Intermediate host: A host where the parasite reproduces asexually.
• Reservoir host: An animal that carries the parasite, becoming a source of infection to humans.
• Vector: Arthropods that transmit parasites from one host to another.
• Biological vector: Essential to the life cycle of the parasite. Often an intermediate host.
• Mechanical vector: Not essential to the life cycle of the parasite; transfers the parasite mechanically.

Host-Parasite Relationship

• Transmission: Movement of parasites from one host to another.
• Distribution and localization: Establishing distribution of the parasite within the body.
• Growth and multiplication: Increase in the numbers of parasites.
• Resistance of host to the parasite and parasite adaptation to the host: Interaction between parasite and host.

Adaptations of Parasites

• Morphological adaptations (e.g. size, shape, special organs for attachment and nutrients absorption) enable the parasite to survive within the host.
• Life cycle adaptations (e.g. alternation of hosts, host behavior modifications) enable the parasite to spread between hosts
• Examples presented include diphyllobothrium, loss of organs (CNS), high reproductive capacity of parasites.

Morphology

• Some morphological adaptations describe size, shape, loss of locomotion, and parasitic organs.

Life cycle adaptations

• Adaptations in development with alternation of hosts (increasing range, temporary host scarcity, intermediate host directly to definitive host)
• Host behavior modifications (e.g., crawling out from the anus to spread eggs)
• Life cycle synchronisation to host.

Effects of Parasites on their Hosts

• Consumption of nutritive elements
• Obstruction of passages
• Bleeding
• Destruction of tissues
• Compression of organs
• Opening pathways to secondary infections
• Allergy development
• Transmission of pathogens to humans
• Predisposition to malignancy (can develop to cancer)
• Chronic immune stimulation leading to unresponsiveness to infections

Host Susceptibility Factors

• Parasite factors (strain, load, site, metabolic processes leading to waste products/toxins
• Host factors (genetic constitution, age, sex, immunity level, nutrition, co-existing diseases, lifestyle, and occupation
• Host response

Sources of Parasitic Infections

• Contaminated soil
• Contaminated water
• Insufficiently cooked meat of pork and beef
• Blood-sucking arthropods
• Animals
• Human beings (clothing, bedding, environment, through sexual intercourse, autoinfection)

Mode of Transmission

• Direct transmission (does not require biological vectors or an intermediate host)
  • Horizontal (feco-oral route; sexual intercourse, blood transfusion,,Direct skin penetration)
  • Vertical (congenital, transplacental, transmammary).
• Indirect transmission (requires vectors or an intermediate host)

Routes of Transmission

• Ingestion of infective parasites or stages
• Skin penetration from contaminated areas
• Through insect bites
• Sexual contact
• Inhalation of contaminated air
• Transplacental
• Kissing

Taxonomy of Parasites

• Classification of parasites based on biological characteristics.
• Major taxonomic groups belong to kingdoms Protista (Protozoa) and Animalia (Metazoa).
• Different types of parasite classifications are seen.
• Amoebas, flagellates, ciliates, coccidians, sporozoans, and microspores.

Major Differences between Parasites

• Protozoa vs metazoa

Kingdom: Protista (Protozoa)

• Protozoa are single-celled eukaryotic organisms.
• Classified into several phyla, including Apicomplexa, Amoebozoa, Euglenozoa, and Metamonada.
• Examples: Plasmodium (malaria), Entamoeba histolytica (amebiasis), Trypanosoma (sleeping sickness), Giardia lamblia, Trichomonas vaginalis, Toxoplasma gondii, Cryptosporidium.

Phylum Amoebozoa

• Move and feed using pseudopodia.
• Examples: Entamoeba histolytica (intestinal disease), Acanthamoeba (eye and brain infections), Naegleria fowleri (primary amoebic meningoencephalitis).

Phylum Apicomplexa

• Intracellular parasites with apical complex for host-cell invasion.
• Examples: Plasmodium (malaria), Toxoplasma gondii (toxoplasmosis), Cryptosporidium (diarrheal disease).
• Stages described for these organisms are included in detail.

Phylum Euglenozoa

• Flagellated protozoans
• Examples: Trypanosoma (sleeping sickness, Chagas disease), Leishmania (leishmaniasis).

Phylum Metamonada

• Often inhabit the digestive tracts of animals.
• Some are flagellated

Kingdom: Animalia (Metazoa)

• Multicellular parasites.
• Example: helminths (flatworms and roundworms), ectoparasites (ticks, fleas, lice).
• They are further categorized.

Chapter Two - Medical Protozoology

• Introduction to protozoa:
• Fossil record shows protozoa were present during the Precambrian era ( 4 billion- 541 million years)
• Protozoan diversity and their world-wide distribution:
• Protozoa in different human body locations
• Brief description introduced for different human body locations and types of parasites in them

Phylum Amoebozoa - Detail on Amoebas

• Amoebas are different based on their location ( in human body).
• Intestinal tract.
• Oral cavity.
• Eyes (Acanthamoeba keratitis)
• Nervous system (Naegleria fowleri)

Species Detail: Entamoeba histolytica

• Structure, life cycle, and pathogenicity.
• Transmission modes, prevention, and control.
• Importance of hygiene and sanitation.
• Diagnostic methods
• Treatment methods
• Distribution/Prevalence

Species Detail: Entamoeba gingivalis

• Structure, habitat, and pathogenicity
• Transmission

Free-living pathogenic amoebas

• Important genera and their associated diseases.

Phylum Metamonada (Detail)

• Dientamoeba fragilis characteristics
• Life cycle
• Diagnosis
• General features
• Diagnosis descriptions
• Distribution descriptions

Species Detail: Giardia lamblia

• Description of morphology (trophozoites
• Cyst)
• Life cycle
• Major Symptoms
• Methods of transmission
• Importance of treatment and prevention.

Species Detail: Trichomonas tenax

• Description of morphology (trophozoites).
• Pathogenicity
• Transmission
• Importance of diagnosis method and prevention /control methods.

Species Detail: Trichomonas vaginalis

• Description of morphology (trophozoites).
• Life cycle and transmission.
• Distribution and habitat.
• Symptoms.
• Importance of prevention to avoid the infection.

Phylum Euglenozoa (Detail)

•Blood and tissue flagellates general life cycle

• Species characteristics (Trypanosoma/ Leishmania)
• Habitat
• Life cycle descriptions
• Pathology
• Method of diagnosis
• Prevention and control

Leishmania Species

• Geographical Distribution
• Species habitats (amastigotes and promastigotes)
• Leishmania tropica minor and major
• Leishmania aethiopica
• Diagnosis
• Prevention and Control (for different species of Leishmania).
• Pathology descriptions

Trypanosoma Species

• Geographical Distribution
• General species habitats (trypomastigotes, epimastigotes, metacyclics).
• T. gambiense and rhodesiense characteristics
• Morphology (trypomastigote forms)
• Pathology descriptions (e.g., sleeping sickness)
• Life cycle
• Diagnosis methods
• Control measures

Trypanosoma cruzi

• Species characteristics
• Morphology (trypomastigote forms)
• Life cycle and transmission
• Pathology characteristics.
• Prevention and control
• Diagnostic measures

Class Ciliata

• Balantidium coli
• Characteristics (morphology, life cycle, habitat, and distribution)
• Pathogenicity
• Methods of prevention and control
• Diagnostic measures

Plasmodium Species (Malaria)

• General features and general characteristics
• Morphology (young and mature trophozoites, schizont)
• Life cycle and transmission modes
• Major Symptoms
• Laboratory diagnosis
• Factors for malarial infection
• Prevention and control

Babesia

• Details on the parasite
• Diagnosis Methods
• Geographical distributions
• General characteristics

General Summary

• Classification of Protozoa (using a table)
• Classification of Metazoa (using a table)
• List of medically important protozoa and some common parasites.

Test your knowledge on the characteristics, transmission, and symptoms of Trichomonas vaginalis and visceral leishmaniasis. This quiz covers various aspects including reproductive methods, geographic distribution, and preventative measures related to these parasites.