Introduction To Clinical Parasitology PDF

1/31/25 2 T SM Introduction to Clinical Parasitology |B 5...

1/31/25 2 T SM Introduction to Clinical Parasitology |B 5 2 02 4- 02 Intended Learning Outcomes.2 Define common Discuss the types terms related to of host. Parasitology Y S. Explain the different Explain the modes of pathophysiology of EU transmission of parasitic parasites infection/disease C 1  1/31/25 2 Outline T I. Nomenclature SM II. Exposure & Infection A. Terms III. Parasite-Host Relationship A. Type of Parasite B. Type of Host |B C. Types of Vectors D. Parasite-Host Relationship Terms E. Effect of Parasites on the Host F. Effects of the Host on the Parasite 5 IV. Parasitic Life-cycle 2 02 4- 02 Outline.2 V. Parasite Source of Infection VI. Parasitic Mode of Transmission VII. Epidemiology Y A. Terms B. Populations at Risk for Contracting Parasites S. VIII. Disease Processes & Symptoms IX. Parasitic Treatment Options A. Deworming B. Preventive Chemotherapy EU C. Other Treatment Options X. Prevention & Control Strategies C 2  1/31/25 2 T SM I Nomenclature |B International Code of Zoological Nomenclature 5 2 02 4- 02 International Code of Zoological Nomenclature Nomenclature.2 Domain o Kingdom Y § Phylum Classes S. o Orders § Families - adding -idae to the stem of the genus type § Genera § Species (suborder, superfamily, and subspecies) EU C 3  1/31/25 2 International Code of Zoological Nomenclature Nomenclature T SM |B 5 2 02 4- 02 International Code of Zoological Nomenclature Nomenclature.2 Generic names - consist of a single word written in initial capital letter Y Specific names - always begins with a small letter Italicized or underlined when written S. eg. Entamoeba coli Entamoeba coli EU C 4  1/31/25 2 T SM II Exposure & Infection |B Terms 5 2 02 4- 02 A. Terms Exposure & Infection.2 Carrier - harbors a particular pathogen without manifesting any signs and symptoms o Entamoeba histolytica (in food handlers) Y Exposure - process of inoculating an infective agent S. Infection - establishment of the infective agent in the host Incubation period - period between infection and evidence of symptoms EU Pre-patent period - also known as biological incubation period, period between infection or acquisition of the parasite and evidence or demonstration of infection C 5  1/31/25 2 A. Terms Exposure & Infection T SM Autoinfection - results when an individual becomes his own direct source of infection o Capillaria philippinensis o Enterobius vermicularis o Hymenolepis nana |B o Strongyloides stercoralis Superinfection or hyperinfection - already infected individual is further infected with the same species leading to a massive infection 5 2 02 4- 02 Y.2 III Parasite-Host Relationship S. Type of Parasite Type of Host Types of Vectors Parasite-Host Relationship Terms EU Effect of Parasites on the Host Effects of the Host on the Parasite C 6  1/31/25 2 A. Types of Parasite Parasite-Host Relationship T SM 1. Obligatory parasite - parasite that cannot survive outside of a host 2. Facultative parasite - parasite that is capable of existing independently of a host 3. Endoparasite - parasite that is established inside of a host (disease |B is called an infection) 4. Ectoparasite - parasite that is established in or on the exterior surface of a host (disease is called an infestation) 5. Erratic - found in an organ which is not its usual habitat 5 2 02 4- 02 A. Types of Parasite Parasite-Host Relationship.2 6. Accidental or incidental parasite - establishes itself in a host where it does not ordinarily live Y 7. Permanent parasite - remains on or in the body of the host for its entire life S. 8. Temporary parasite - lives on the host for a short period of time 9. Spurious parasite – free-living organism that passes through the digestive tract without infecting the host EU C 7  1/31/25 2 B. Type of Host Parasite-Host Relationship T SM 1. Accidental or incidental host - host other than the normal one that is harboring a parasite 2. Definitive or final host - host in which the adult sexual phase of parasite development occurs |B 3. Intermediate host - host in which the larval asexual phase of parasite development occurs (classified as first and secondary intermediate host if there’s more) 4. Paratenic host - parasite does not develop further to later stages but is only alive and able to infect another susceptible host (widen the 5 parasite distribution and bridge the ecological gap between the definitive and intermediate hosts) 2 02 4- 02 B. Type of Host Parasite-Host Relationship.2 5. Reservoir host - host harboring parasites that are parasitic for humans and from which humans may become infected Y 6. Carrier - parasite- harboring host that is not exhibiting any clinical symptoms but can infect others S. EU C 8  1/31/25 2 C. Types of Vectors Parasite-Host Relationship T SM 1. Biologic vector - transmits the parasite only after the latter has completed its development within the host, involved in the pathogen's life cycle 2. Mechanical or phoretic vector - only transports the parasite, it is not involved in the pathogen's life cycle |B 5 2 02 4- 02 D. Parasite-Host Relationship Terms Parasite-Host Relationship.2 1. Symbiosis - living together; the association of two living organisms, each of a different species 2. Commensalism - association of two different species of organisms that is Y beneficial to one and neutral to the other 3. Mutualism - association of two different species of organisms that is S. beneficial to both 4. Parasitism - association of two different species of organisms that is beneficial to one at the other's expense EU qPathogenic - parasite that has demonstrated the ability to cause disease C 9  1/31/25 2 E. Effect of Parasites on the Host Parasite-Host Relationship T SM 1. Interference with the vital processes of the host through parasitic enzymes Secretory and excretory products of parasites allow them to metabolize nutrients obtained from the host and store these for energy production. |B Entamoeba histolytica trophozoites - secrete cysteine proteinases, which do not only digest cellular materials but also degrade epithelial basement membrane facilitating tissue invasion. 5 2 02 4- 02 E. Effect of Parasites on the Host Parasite-Host Relationship.2 2. Invasion and destruction of host tissue Plasmodium - after multiplication, the host’s red blood cells rupture Y resulting in the release of merozoites Schistosoma japonicum - cumulative deposition of eggs in the liver → S. immune response mechanism → granuloma formation → fibrosis → portal hypertension and massive hemorrhage in the venules. Hookworms - cutting plates that attach to the intestinal mucosa and destroy the villi EU C 10  1/31/25 2 E. Effect of Parasites on the Host Parasite-Host Relationship T SM 3. Deprivation the host of essential nutrients and substances Heavy hookworm - massive intestinal bleeding → chronic blood loss and iron deficiency anemia. Diphyllobothrium latum - competes with its host for the available |B supply of Vitamin B12 → megaloblastic anemia 5 2 02 4- 02 F. Effects of the Host on the Parasite Parasite-Host Relationship.2 1. Genetic makeup of the host Sickle-cell trait (SCT) - protection in falciparum malaria Y Duffy blood factor [Fy(a-b-)] - susceptibility to Plasmodium vivax S. EU C 11  1/31/25 2 F. Effects of the Host on the Parasite Parasite-Host Relationship T SM 2. Nutritional status of the host Rich-protein diet - not suitable for intestinal protozoans Low-protein diet - amebiasis High-carbohydrate diet - tapeworms |B 5 2 02 4- 02 F. Effects of the Host on the Parasite Parasite-Host Relationship.2 3. Immune processes Absolute immunity to reinfection - occurs rarely in protozoan Y infections S. EU C 12  1/31/25 2 T SM IV Parasitic Life Cycle |B 5 02 2 4- 02 Y.2 S. Parasitic Life Cycle EU C 13  1/31/25 2 T SM V Parasite Source of Infection |B 5 2 02 4- 02 Source Parasites.2 Soil Ascaris lumbricoides Trichuris trichiura Strongyloides stercoralis Hookworm Y Water Cysts of amebae or flagellates Cercariae of Schistosoma Food Trematodes S. Source Cestodes Undercooked or Intestinal flukes Parasite Source of Infection raw freshwater Liver flukes fish EU Raw crab Paragonimus Bullastra Snails Artyfechinostomum malayanum Cats Toxoplasma Rats Hymenolepis nana C 14  1/31/25 2 Vectors and Parasites Insects T Mosquitoes Malaria, Wuchereria bancrofti, B. Anopheles malayi Culex Wuchereria bancrofti SM Mansonia B. malayi Flies Simuliidae Onchocerca volvulus (black fly) Chrysops fly Loa loa Sandfly Leishmania |B Tse tse fly Trypanosoma gambiense Vectors and Insects Trypanosoma rhodesiense Fleas Dipylidium caninum Parasite Source of Infection Dog flea Rat flea Hymenolepis diminuta Copepod Diphyllobothrium latum (water flea) 5 Ticks Babesia Deer tick Bugs 02 Triatoma bugs 2 Trypanosoma cruzi 4- 02 Y.2 VI Parasitic Mode of Transmission S. EU C 15  1/31/25 2 Ingestion Parasitic Mode of Transmission T SM Taenia solium, Taenia saginata, and Diphyllobothrium latum - eating food harboring the infective larval stages Entamoeba histolytica and Giardia lamblia - drinking water contaminated with cysts |B Clonorchis, Opistorchis, and Haplorchis - through ingesting raw or improperly cooked freshwater fish containing infective larvae Ascaris Paragonimus 5 Trichinella Giardia 2 02 4- 02 Skin penetration Parasitic Mode of Transmission.2 Hookworms and Strongyloides - soil Schistosoma - water Y S. EU C 16  1/31/25 2 Vectors Parasitic Mode of Transmission T SM Mosquito: Plasmodium, Brugia, Wuchereria Tse Tse Fly: Trypanosoma Tick: Babesia |B 5 2 02 4- 02 Congenital Parasitic Mode of Transmission.2 Toxoplasma gondii trophozoites - cross the placental barrier during pregnancy Y Ancylostoma and Strongyloides - mother’s milk S. EU C 17  1/31/25 2 Sexual Intercourse Parasitic Mode of Transmission T SM Trichomonas vaginalis |B 5 2 02 4- 02 Blood Transfusion Parasitic Mode of Transmission.2 Trypanosoma Plasmodium Y Babesia S. EU C 18  1/31/25 2 T SM VII Epidemiology |B Terms Populations at Risk for Contracting Parasites 5 2 02 4- 02 A. Terms Epidemiology.2 Prevalence - number of individuals in a population estimated to be infected with a particular parasite species at a given time. Cumulative prevalence - percentage of individuals in a population Y infected with at least one parasite Intensity of infection - burden of infection (number of worms per S. infected person expressed as eggs per gram or epg) Morbidity - clinical consequences of infections or diseases Eradication - permanent reduction to zero of the worldwide EU incidence of infection Elimination - reduction to zero of incidence of a specified disease in a defined geographic area C 19  1/31/25 2 B. Populations at Risk for Contracting Parasites Epidemiology T 1. Individuals in underdeveloped areas and countries SM 2. Refugees 3. Immigrants 4. Visitors from foreign countries |B 5. Individuals who are immunocompromised 6. Individuals living in close quarters (e.g., prisons) 7. Children who attend day care centers 5 2 02 4- 02 Y.2 VIII Disease Processes & Symptoms S. Symptoms Associated with Parasitic Disease Processes EU C 20  1/31/25 2 Symptoms Associated with Parasitic Disease Processes Disease Processes & Symptoms T 1. Diarrhea 8. Vitamin deficiency SM 2. Fever 9. Bowel obstruction 3. Chills 10. Edema 4. Abdominal pain 11. Enlargement of major organs |B 5. Abdominal cramping 12. Skin lesions 6. Elephantiasis 13. Blindness 7. Anemia 5 2 02 4- 02 Y.2 IX Parasitic Treatment Options S. Deworming Preventive Chemotherapy Other Treatment Options EU C 21  1/31/25 2 A. Deworming Parasitic Treatment Options T SM Use of anthelminthic drugs Cure rate - number of previously positive subjects found to be egg negative Egg reduction rate (ERR) - percentage fall in egg counts after |B deworming Selective treatment - individual-level deworming with selection for treatment Targeted treatment - group-level deworming where the (risk) group to be treated (without prior diagnosis) may be defined by age, sex, or 5 other social characteristics irrespective of infection status 02 Universal treatment - population-level 2 4- 02 B. Preventive Chemotherapy Parasitic Treatment Options.2 Regular, systematic, large-scale intervention involving the administration of one or more drugs to selected population groups with the aim of reducing morbidity and transmission of selected helminth infections. Y Coverage - proportion of the target population reached by an intervention Efficacy - effect of drug S. Effectiveness - measure of the effect of the drug Cure rate and egg reduction rate - measure of prevalence and reduction of intensity of infection EU Drug resistance - loss of susceptibility to a drug in a parasite population C 22  1/31/25 2 C. Other Treatment Options Parasitic Treatment Options T SM 1. Antiparasitic medications 2. Change in diet 3. Vitamin supplements 4. Fluid replacement |B 5. Blood transfusion 6. Bed rest 5 2 02 4- 02 Y.2 X Prevention & Control Strategies S. EU C 23  1/31/25 2 Prevention & Control Strategies T SM Morbidity control - avoidance of illness caused by infections Information-education-communication (IEC) - health education strategy Environmental management - planning, organization, performance, |B and monitoring of activities for the modification and/or manipulation of environmental factors or their interaction with human beings Environmental sanitation - involves interventions to reduce environmental health risks 5 2 02 4- 02 Prevention & Control Strategies Other Strategies.2 Development and implementation of parasite awareness education programs Use of insecticides and other chemicals Y Use of protective clothing S. Use of protective netting Proper water treatment Good personal hygiene EU Proper sanitation practices Proper handling, cooking, and protection of food Avoidance of unprotected sexual relations C 24