Parasite

-an organism that lives on or in the body of another organism (the host) and causes damage to the other organism

Types of Parasites

Ectoparasites - live/feed on the exterior of an organism (tick)
Endoparasites - live/feed on the interior of an organism (tapeworm)

We will focus on two kingdoms:
Protist parasites and Animal Parasites

Parasitic Protists

Disease: Malaria (Phylum Sporozoa)
Protist: Plasmodium
Vector: Anopheles Mosquito
Symptoms: Chills, fever
See Life Cycle of Malaria

Disease: Cryptosporidosis (Phylum Sporozoa)
Protist: Cryptosproridium
Vector: Contaminated water
Symptoms: diarrhea, nausea, vomitting

Disease: African Sleeping Sickness (Phylum Zoomastigophora)
Protist: Trypanosoma
Vector: Tse Tse Fly
Symptoms: uncontrolled sleepiness
See Life Cycle of Trypanosoma

Disease: Hiker's Diarrhea (Phylum Zoomastigophora)
Protist: Giardia lamblia
Vector: contaminated water
Symptoms: diarrhea, vomitting, cramps

Disease: Amebic Dysentery (Phylum Rhizopoda)
Protist: Entamoeba Histolytica
Vector: Contaminated water
Symptoms: diarrhea

Most parasites are contracted from water sources, either directly ingesting contaminated water, or being infected through the skin. The best way to prevent parasitic infections is to have a clean water supply and waste treatment.


Animal Parasites

Roundworms - Phylum Nematoda

Ascaris - common roundworm, found in dogs, cats and humans; infection occurs from ingestion

Hookworm - attaches to intestine, causes bleeding, infection occurs through the skin

Pinworms - commonly infect children in all parts of the world (including US), causing itching around the anus but does not usually cause any other health problems

Guinnea Worm
--also known as fiery worm, or dracunculus
-- worms found just under skin, cause burning
Trichinella--worm embeds in muscles
--humans become infected from eating undercooked pork
--symptoms include soreness and tenderness of the muscles
--see Life Cycle of Guinnea Worm

Flatworms

Phylum Platyhelminthes

Schistosoma
--blood fluke
--intermediate host is a water snail
--humans are infected through the skin by larval form (cercariae)
-- Schistosomiasis results in approx. 1,000,000 deaths per yer
--See Life Cycle of Schistosoma

Taenia
--tapeworm found in cattle and pigs
--can infect humans
--segments called proglottids for reproduction
--head is the scolex (see slide)

Liver Fluke
--this flatworm has several species that inhabit a variety of animals
--Fasciola hepatica - common sheep liver fluke
--Fasciolopsis buski - infects humans (See Life Cycle)

 

Web Resources on Parasites

http://www.dpd.cdc.gov/DPDx/

http://www.biosci.ohio-state.edu/~parasite/home.html