Parasites Flashcards
Ascaris lumbricoides
MULTICELLULAR
HELMINTHS
NEMATODES
- Found in contaminated water and food
- Goes into the gut, leaves the gut, goes into the lungs, then back to the gut
- Lives for 10 months to 2 years
- Eggs have to mature in the environment for several days
- Almost 1 billion infected worldwide
Classification of Parasites
- Multicellular
Helminths, most of the worms
Further broken down into
- Cestodes (flatworms)
- Trematodes (Flukes)
- Nematodes (round worms)
Classification of Parasites
- Single Celled
Further broken down into
- Intestinal (eg Giardia)
- Blood and tissue (Eg Malaria)
When discovering that it’s single-celled, the next question is “where does it go?” eg gut or blood/tissues
Classification of Parasites
- Two broad categories
Single Celled (Protozoa)
Multicellular (Helminths)
Clinical Detection of Malaria
Plasmodium Falciparum
- Used to observe blood samples on slides
- Now, mostly PCR is used
Some hospitals will have an antigen-based test that shows
- Presence of acute infection
- If it’s faliciparum
Clonorchis Spp.
MULTICELLULAR
HELMINTHS
TREMATODES
- Can cause liver abscess
- Like shisto, found in contaminated waters, has a complex life cycle (>1 host), and includes intermediate stage host
- Result of ingestion of contaminated or infected fish
Definition of Parasite
+ Acquired as a result of…
- Organism(s) that live ON or IN another organism (host) and derives a benefit and/or nutrients at the expense of the host
Acquired as a result of
- bites (ticks, mosquitos)
- contaminated water
- contaminated food
- contaminated environment (bed bugs etc)
Diphyllobothrium latum
MULTICELLULAR
HELMINTHS
CESTODES
Found in FISH
- Can grow up to 40 feet in the intestinal tract
- Found in raw fish
- Why all raw fish is flash frozen in Ontario, kills the eggs
Direct Life Cycle Parasites + Example
- Completed in one host, which is typically a human
- Parasite starts with a human and completes its lifecycle in a human
- Much easier to control
- Eggs are often only viable for a short time in the environment
Eg. Ascaris lumbricoides
Enterobius vermacularis
MULTICELLULAR
HELMINTHS
NEMATODES
- Most common worm infection in NA
- Often seen in PRIMARY SCHOOLS and DAYCARES
- Females live in the anus, emerge at night and travel to the perianal area, lay eggs that produce dermatitis
- Tape on the booty thing
- Indians
Exoparasites
- Examples
Scabies
- Female mite burrows into skin and lays eggs which cause an inflammatory response
Body Louse
- Lice
- Pubic lice differ from body lice.
- Body lice can live in the genital area but pubic lice cannot live on the body due to the spacing of their legs (more even due to the closer spacing of pubic hair)
Four other examples of Intestinal Protozoa
SINGLE CELLED
- Entamoeba histolytica
- Major pathogen associated with poor sanitation - Cyclospora cayetanensis
- Contaminated water and produce (eg strawberries, lettuce) - Dientamoeba fragils
- Ubiquitous and found in children worldwide
- Transmitted person to person - Cryptosporidium parvum
- Major outbreaks
- Carried in cattle and other zoonosis
- Can transmit from human-human and cattle-human
Indirect/Complex Life Cycle Parasites + Example
- Involve multiple host species, much more difficult to control
Eg. Malaria, Lyme disease
Lyme
- Starts in another animal, usually white-footed mice
- Tick bites mouse, gets Lyme (verillia)
- Tick then falls off, has one more blood meal, if on human it will transfer Lyme to human
Toxoplasmogondii
Laboratory Detection of Parasites
- Intestinal vs Blood/Tissue parasites
Intestinal
- Stool specimen in preservatives to maintain parasite structure
Tissue/Blood
- Antibody detection and biopsy
Now, it’s all gone to PCR which is faster and more sensitive
Most Clinically Significant Intestinal Protozoa
Giardia lamblia
- Found in beavers (natural host), often called “Beaver Fever”
- Leads to significant diarrhea (rice water stool) where up to 3-4L of water are lost daily
- Important to replace fluids/lytes
Plasmodium Spp.
SINGLE CELLED
BLOOD/TISSUE PROTOZOA
- Agent that leads to clinical infection in MALARIA
- FIVE TYPES
- Most clinically significant is PLASMODIUM FALICIFARUM
- Over three million infections per year, almost a million deaths per year
- Transmitted by anopheles mosquito (dusk to dawn)
- Sexually mature in mosquito and asexual states in humans
Shistosoma spp.
MULTICELLUAR
HELMINTHS
TREMATODES
Swimmer’s itch
-Also UTI and blood infection
-Risk factors include swimming in CONTAMINATED OPEN WATER
- SNAILS
- Complex life cycle with >1 host
- Has environmental stage with an intermediate host
- Found in TROPICAL to SEMITROPICAL WATERS
Single Celled - Protozoa
- Life cycle
- Route of transmission
- Virulence factors
- All have direct life cycle
- Route of transmission is typically contaminated water or soil (indirect contact) and zoonosis (direct contact)
Virulence factors
- either production of toxins (watery diarrhea)
- ability to invade GI epithelia (bloody diarrhea)
Strongyloides stercoralaris
MULTICELLULAR
HELMINTHS
NEMATODES
- Simple life cycle with ONE host
- Symptoms of infection include dermatitis, swelling, itching, larva currens
- Lives in fecal matter, soil, sand
- Risk factors include WALKING ON SAND IN TROPICAL AREAS BAREFOOT
Does 2 things
1. Can continuously auto-infect, and/or stay dormant. Screen welfare recipients and give antiparasitics
- In immunocompromised, can disseminate and produce hyper-infective syndrome producing 90% mortality rate.
Three Blood/Tissue Protozoa
SINGLE CELLED
- Trichomonas Vaginalis
- Plasmodium Spp.
- Toxoplasma Gondii
Three Types of Cestodes
(Tapeworms)
MULTICELLUAR
HELMINTHS
- Diphyllobothrium latum (fish)
- Tinea solium (pork)
- Tinea saginata (beef)
Three Types of Helminths
- Cestodes (flat worms)
- Trematodes (Flukes)
- Nematodes (Round worms)
Three Types of Nematodes
MULTICELLULAR
HELMINTHS (round worms)
- Ascaris lumbricoides
- Enterobius vermacularis
- Strongyloides stercoralaris
Tinea saginata
MULTICELLULAR
HELMINTHS
CESTODES
- Eggs found in RAW BEEF
- TISSUE PHASE parasite
- Can grow and move into muscle tissue
