Lecture I 2024_Introduction.pdf

Parasitology PMC503 Introduction Lecture 1 Yosra Nagy, PhD [email protected]  Grading Points Distribution Midterm Exam Oral Exam 15 points 10 points Practical Final...

Parasitology PMC503 Introduction Lecture 1 Yosra Nagy, PhD [email protected]  Grading Points Distribution Midterm Exam Oral Exam 15 points 10 points Practical Final Exam 25 points 50 points PMC503 2  What is Parasitology? Study of parasites, their hosts, and the relationship between them Symbiosis The association of two living organisms in direct contact with each other, each of a different species Parasitism Mutualism One is harmed Commensalism The two One benefits and the benefit other is unaffected PMC503 3  The Parasite An organism that obtains benefit “food” from another organism (the host, which shelters it) and causes harm to it in the process Pathogenic Opportunistic PMC503 4  Medically Important Parasites Ectoparasite Endoparasite Infestation Infection Obligate Periodic Facultative Zoonotic PMC503 5  The Host Final Paratenic “Definitive” “Transport” Reservoir Intermediate Accidental “Dead-end” PMC503 6  Vector Biological Mechanical Vectors are usually insects (arthropods) responsible for the transmission of the parasitic infection. Which of the 2 types can be an intermediate host? PMC503 7 The Life Cycle of a Parasite Click here 8 https://www.cdc.gov/dpdx/reference.html  The Life Cycle of a Parasite It is the sequence of morphological and environmental stages needed for the survival, growth and reproduction of parasite. Direct 19 October 2021 PMC503 9  Modes of Transmission Ingestion of Insect the Parasite a. Bite a. Contaminated Skin Penetration b. Contaminated a. Water feces Food/Water b. Soil c. Ingestion b. Undercooked meat/fish Oral-Fecal Route Sexual Direct Blood Transplacentally Contact Contact Transfusion Which is the most common? PMC503 10  Populations at Risk Individuals in underdeveloped areas Refugees, Immigrants Travelers Individuals who are immunocompromised Individuals living in close quarters (e.g., prisons) Children who attend day care centers PMC503 11 Prevention and Control of Parasites Breaking the chain! 1. Infectious agent (Parasite) – Diagnosis and treatment; and Antimicrobial stewardship 2. Reservoir – Cleaning; disinfection and sterilization – Infection prevention policies; and pest control 3. Portal of exit – Hand hygiene; PPE; Control of aerosols and splatter; – Respiratory etiquette; and waste disposal PMC503 12 Prevention and Control of Parasites 4. Mode of transmission – Hand hygiene; PPE; Food safety; cleaning; disinfection and sterilization; and isolation 5. Portal of entry – Hand hygiene; PPE; personal hygiene; and first aid 6. Susceptible host – Immunizations – Treatment of underlying conditions; and patient education PMC503 13  Parasite – Host Effect 1. Nourishment of the parasite on the host (food acquisition) 2. Mechanical effect leading to tissue destruction because of trauma, pressure, compression or obstruction, feeding on tissues or irritation of tissues leading to inflammatory or neoplastic reactions 3. Toxic effects from toxins secreted or waste products excreted by the parasite, leading to poisoning or allergic reactions 4. Secondary infection with other organisms as bacteria PMC503 14  Classification of Parasites 1. Protozoology = study of protozoa (primitive single cells) 2. Helminthology = study of helminths (worms) including multicellular parasites with organs (also known as metazoa) 3. Entomology = study of insects (arthropods) PMC503 15 Areas of Study for Each Parasite 1. Epidemiology: geographical distribution, statistics, mortality rates 2. Descriptive biology: morphology and structure 3. Ecology (habitat) and life cycle: with focus on infective and diagnostic stages 4. Pathogenesis: mechanism of disease causation 5. Clinical features: signs and symptoms 6. Diagnosis 7. Treatment, prevention and control PMC503 16 Zeibig, Elizabeth. Clinical parasitology: A practical approach. Elsevier Health Sciences, 2014. PMC503 17  Reservoir Carrier an organism (usually an animal) that an organism, typically a human, that harbors a parasite, often without being harbors a parasite but shows no affected by it, and serves as a source of symptoms of the disease. infection for other hosts, including However, carriers can still transmit the humans. parasite to others, making them a source The parasite can survive, grow, and even of infection. reproduce within the reservoir host. Carriers are particularly important in the Reservoirs maintain the parasite's spread of diseases within a population, presence in the environment and play a even when they themselves are not crucial role in the parasite's lifecycle by suffering from the disease. acting as a natural source of infection. Rodents are reservoirs for the A person infected with *Entamoeba *Leishmania* parasite. They harbor the histolytica* (causative agent of parasite and can transmit it to sandflies, amoebiasis) may not exhibit symptoms which then infect humans. but can still shed cysts in their stool, potentially infecting others. A reservoir typically refers to an animal host that maintains the parasite in nature, while a carrier refers to an asymptomatic human host that can transmit the parasite to others. 1 October 2024 PMC503 18 Enjoy the course!