Parasites Pt 1: Plasmodium + Giardia

Eukaryotic, protozoa, worms, tissue

Parasites are __ organisms

• __ are single cells, from kingdom Protista

• Multicellular animals include __ from kingdom animalia

• __ injury is frequent underlying cause of pathology → due to RBC destruction

Definitive Host

Host in which pathogen/parasite completes sexual reproduction

Intermediate Host

Host in which pathogen/parasite does NOT reproduce or does so asexually

Chronic, dose, number, extra, ingestion, insect, skin

General pathogenicity of parasites

• Parasitic infections are often __ and last months-years

• Pathogenicity - related to infecting __ and the __ of parasites acquired over time

• Most parasites are __cellular in human host

• Common routes of infection = __, __ bite, penetration of the __

Malaria

Parasite infection via protozoan and involving mosquitos (vector)

Africa, endemic, temperature, humidity, intra, protozoan

Plasmodium species

• Highest prevalence of global malaria in __

• Malaria transmitted to US via individuals traveling to where malaria is an __

  • Environment - __, __, use of insecticides affecting mosquito biome

• Obligate __cellular parasite - single-celled organism = __

Anopheles mosquito, human

• Plasmodium complex life cycle involves both sexual and asexual reproduction of protozoan

  • Sexual reproduction - In __ __ (definitive host)

  • Asexual reproduction - In __ (intermediate host)

Infects humans, liver, asexual, merozoites

Sporozoite (Plasmodium)

• Transmitted to humans by mosquito bite → Stage that __ __

• Invade __ cells and undergo __ reproduction

• Form __

Hepatocytes, trophozoites, asexual, schizont, gametocytes

Merozoite (Plasmodium)

• Released into blood by rupturing __ → Invade RBCs

• Mature into __ (refer to parasite in RBCs) via __ reproduction

• Can form into __ within RBC and give rise to more merozoites (released by rupture) → Invade more RBCs

• OR can become __

Gametocytes

Parasitic cells capable of sexual reproduction AND some can hitch a ride to mosquito biting human host

Asexual, nucleus, cytoplasm, sporozoites

Schizont (Plasmodium)

• __ reproduction in liver cells or RBCs

• __ divides many times → __ separates and encloses each nucleus

• Develop into new __

Dormant, immune, relapses

Different species of plasmodium can be __ in hepatocytes

• Evade __ response → Lead to __ in plasmodium infection

Sickle cell, thalassemias, G6pD

Genetic polymorphisms in human population can buffer against malaria parasites

• __ __ trait, __, __deficiency

Merozoites, fever, anemia, circulatory, cytokine, immune

Malaria Dx and General Sx

• Dx - Blood smear for observing malaria __ in RBC

• Sx of Malaria - __, __ (blood), __ changes, __ storm, heightened __ response

Long, liver, re-infection

Malaria Sx

• Some species have __-term infection in __ cells → Relapses over course of years

• Recovery after fairly long period of illness, susceptible to __-__

Cyclic, RBC, paroxysmal

Malaria Fever

• Linked to __ rupture of __s to release new merozoites

  • Parasite replication synchronized resulting in __ fevers at defined intervals

Lysis, vasodilation, clotting

Malaria Anemia + Circulatory

• From loss of RBC due to __ by parasite and immune-mediated mechanisms

• __ (result of fever) - Drop in blood pressure

• Potential impairment of circulation in intense parasitemia- __-adhesion of infected RBC

Malaria Attacks

6-10 hour sequence of fever, headache, vomiting, diaphoresis, then return to normal

Relapsing fever, wanes

Host Immune Response to Malaria

• Most individuals recover after fairly long period of illness __ __)

  • Immunity to malaria __ - one year away from exposure to pathogen sufficient to reduce immunity

Circumsporozoite Protein (CSP)

Initial player in malaria infection to humans used in vaccine development

RTS, Subunit Vaccine

Fusion protein containing part of plasmodium CSP and T cell recognition CSP

Plasmodium falciparum

WHO recommends use of malaria vaccines to prevent __ __ (species) malaria in children in endemic areas

RBC schizonts, hepatic schizonts, gametocytes

Tx Goals + Prophylaxis for Malaria (killing plasmodium)

• (1) Elimination of __ __

• (2) Elimination of __ __

• (3) Elimination of __ being produced in RBC

Chloroquine

Drug kills RBC schizonts and gametocytes

• inhibits replication of malaria Plasmodium

Artemisinin

Drug affects parasite membranes of plasmodium

Bed nets, repellent, travelers, gametocyte

Prevention of malaria

• Insecticide treated __ __ (furniture), insect __

• Chemoprophylaxis for __

• Early dx protects against source of __ development

Zoonotic, water, protozoan

Giardia duodenalis

• __ parasite affecting many animals as well as humans

  • Environmental transmission from wildlife contaminating __ sources

• __ parasite with flagella

2, flagella, small, GI, asexual

Trophozoite Form (Giardia)

• Has _ nuclei and several __ (motile)

• Attaches to mucosa of __ intestine → Causes pathology in __ tract

• Multiplies via __ reproduction

Non-motile, stable, trophozoites, water

Cyst Form (Giardia)

• __ (motile/non-motile), environmentally __ structures

• __ develop into cysts in colon

• Resistant to some __ treatment

Cyst, ingest, mucosa, cyst

Giardia Pathogenesis

• Infective stage in __ form

  • Human hosts __ cyst FIRST!

• Lives on GI __ in trophozoite form → Transforms back to __ form at end of GI tract (feces)

Lakes, streams, cysts

Giardiasis Epidemiology

• High risk to infants, children, travels, drinking from __ and __

• Half of infections asymptomatic via asymptomatic shedding of __

Giardia Sx

Sudden onset diarrhea, “greasy” stool, cramps

Stool, bodies of water

Giardia Dx and Prevention

• Dx - Detect cysts or trophozoites in __ samples

• Prevention - Good hygiene, handwashing, avoid drinking untreated __ of __