Untitled Quiz

Parasites, People, and Pets

• This topic covers parasites, their impact on humans and animals, and approaches to treatment.
• The date of the presentation is November 4, 2024.
• The presenter is Rick Maizels
• Defining Parasitism: A parasite is an organism living in or on another organism, obtaining some or all organic nutrition, often with structural adaptations potentially causing harm.
• Distinguishing parasites from symbionts and commensals: Parasitism involves harm while symbiosis and commensalism involve a different relationship.
• Prevalence, Incidence, & Intensity of Infection:
  • Prevalence: The proportion of a population infected, or the overall number infected in a specific region.
  • Incidence: The frequency of new infections within a specific timeframe.
  • Intensity: The number or density of parasites per host.
• Mortality, Morbidity, and DALYs
  • Mortality: Number or percentage of deaths resulting from infection.
  • Morbidity: The level of ill-health (including disability) directly caused by infection.
  • DALYs (Disability Adjusted Life Years): A measure of the overall disease burden: healthy years lost due to disease, disability, or premature death.
• Ecto- and Endoparasites & Zoonosis: Different types of parasites have specific locations and some can be passed from animal hosts to humans.
• Parasite Life Cycles: Detailed descriptions of the life cycle of specific parasites were presented.
• Parasite Pathology/Infection: Detailed descriptions of specific parasite infections and symptoms.
• Approaches to Treat Parasitic Infections: Methods of treatment for parasitic conditions.

Definition of Parasites

• A parasite lives in or on another organism, deriving nourishment.

Commensalism, Mutualism, Parasitism

• Commensalism: One organism benefits, the other is unaffected.
• Mutualism: Both organisms benefit.
• Parasitism: One organism benefits, the other is harmed.

Defining Prevalence, Incidence and Intensity of Infection

• Prevalence: The proportion of a population infected (e.g., 3%).
• Incidence: The frequency of new infections in a given time period (e.g., 3% per week).
• Intensity: The number or density of parasites per host.

Defining Disease - Mortality, Morbidity and DALYs

• Mortality: The number of deaths in a given time or the percentage of deaths from a specific infection.
• Morbidity: The level of ill health or disability due to infection or a disease.
• DALYs (Disability Adjusted Life Years): A measure of overall disease burden, representing the healthy years lost to disease, disability, or early death.

Prevalence, Mortality, and DALYs - Data

• A table was presented with data on prevalence, mortality, and DALYs for various parasites (e.g., Ascaris, Schistosomiasis, Malaria, Sleeping sickness).

Unicellular and Multicellular Parasites

• Protozoa: Unicellular parasites (intracellular or extracellular).
• Helminths: Multicellular parasites.
• Arthropods: Ectoparasites (e.g., ticks, lice, fleas).

Parasitic Protozoa

• Simple classification based on cellular organization (amoeboid, kinetoplastid, apicomplexa).
• Specific examples like Entamoeba histolytica, Trypanosoma, Leishmania, Plasmodium, and Toxoplasma gondii featured in the classification

Helminths

• Multicellular roundworms and flatworms, including Nematodes, Platyhelminthes.
• Specific examples of parasites included in presentations, such as intestinal nematodes and schistosomes.

Ectoparasites

• Parasitic arthropods (insects and arachnids).
• Subcategories include lice, fleas, and ticks.

Polyparasitism

• Polyparasitism is frequent.
• Example: Wood mouse (Apodemus sylvaticus) can host 12 nematodes, 7 cestodes, 4 trematodes, 10 protozoa simultaneously.

Zoonosis

• Zoonoses are infections/diseases transmissible from animals to humans.
• Specific examples including Toxocara canis, Echinococcus granulosus, and Toxoplasma gondii.

Toxocara canis

• Predominant intestinal roundworm in dogs and foxes.
• Infection occurs through ingesting eggs, which can affect humans if they ingest the eggs.
• Larval stages migrate in tissues (visceral larva migrans, ocular larva migrans).

Echinococcus granulosus

• Hydatid disease: Adult tapeworm in the small intestine of definitive hosts (dogs).
• Intermediate hosts (sheep, humans): Parasites encyst in tissues.

Toxoplasma gondii

• Zoonotic protozoan parasite (cosmopolitan).
• Definitive host: Cats.
• Life cycle involves oocysts development, infection of intermediate hosts (mice, humans) and re-activation in definitive hosts.
• Infection route: Cat feces, unwashed food, raw meat.
• Risk is higher for pregnant individuals and people with compromised immune systems.
• Symptoms: Acute, chronic or congenital toxoplasmosis.

Lyme Disease

• Lyme disease transmitted by the Ixodes ricinus tick.
• Caused by the Borrelia burgdorferi bacterium.
• The disease can manifest with a bullseye rash called erythema, and myalgia, arthralgia and malaise.
• The disease can lead to chronic arthritis and neuropathy.
• With early antibiotic treatment, it is treatable.

Ectoparasites - lice, fleas, ticks

• Species important to humans are listed including their characteristics.