Midterm Flashcards
Symbiotic relationships
when an animal lives in close physical contact for a “significant portion” of their lives
Two types of symbiotic relationships
Mutualism and Commensalism
Parasitic Relationships
- Every organism has numerous parasites and those parasites also have parasites.
- parasitism comprises over 50% of symbiotic relationships
- only in parasitic relationships is harm done to one of the species involved in the relationship
List the major parasitic disease of humans from most infected to least
1) Ascaris (round worm)– 1.3 billion
2) Hookworms– 1.3 billion
3) Whipworms– 1 billion
4) Filarial worms– 657 million
5) Malaria (protozoan)– 500 million
6) Schistosomes (fluke)– 270 million
7) Amoebiasis (protozoan)– 50 million
8) Taeniad Tapeworms– 50 million
9) Clonorchis (fluke)– 20 million
10) Chagas Disease– 15 million
Malaria
- Caused by Trypanosome
- a child dies every minute from malaria
Chagas Disease
- named after the Brazilian physician Carlos Chagos
- disease discovered in 1909
- caused by the parasite Trypanosoma Cruzi which is transmitted to animals and people by insect vectors
- found in Americas, mainly in rural areas of Latin America where poverty is widespread
- also referred to as American Trypanosomiasis
How do people get Chagas Disease
1) In Chagas Disease-endemic areas–>vector borne transmission
- Insect vectors are called triatomine bugs, also known as kissing bugs
- these bugs get infected by biting an infected animal or person
- once infected, the bugs pass T. cruz parasites in their feces
- The bugs emerge at night
- after the bug bites and ingest food, they defecate on the person, the person can become infected if T. cruz enters the body through mucous membranes or breaks in the skin.
2) Congenital transmission (pregnant woman to baby)
3) blood transfusion
4) organ transplantation
5) consumption of uncooked food contaminated with feces from infected bugs
6) accidental lab exposure
Should females breastfeed if they are infected with Chagas disease? Why?
Yes, it is generally considered safe to breastfeed even if the mother has Chagas disease. BUT if the mother has cracked nipples or blood in the breast milk, she should pump and discard them milk until the nipples heal and the bleeding resolves
Where is Chagas disease found? (in the world)
Can be found anywhere
- Vector borne transmission if confined to the Americas, mainly rural areas in parts of Mexico, Central America,a nd South America
- Rare vectorborne cases of Chagas disease have been noted in Southern United States
Signs and Symptoms of Chagas disease
Two phases of Chagas disease: Acute phase or Chronic phase can be symptoms free or life threatening
1) Acute Phase
-lasts for the first few weeks or months of infection
-usually occurs unnoticed (asymptomatic) or exhibits mild symptom that are not unique to Chagas Disease
-symptoms- fever, fatigue, body aches, headache, and rash
-physical examination signs- mild enlargement of the liver or spleen, swollen glands, and local swelling where the parasite entered the body
***Most recognized sign of chugs disease is called ROMANA SIGN- includes swelling of the eyelids on the side of the face near the big wound or where the bug feces were deposited or accidentally rubbed into the eye
-symptoms usually resolved, but if untreated the infection persists
2) Chronic Phase
-infection may remain silent for decades or even life some people may develop
A) cardiac complications-enlarged heart (cardiomyopathy), heart failure, altered heart rate or rhythm, and cardiac arrests (sudden death)
B) Intestinal complications- enlarged esophagus (megaesophagus) or colon (megacolon) and can lead to difficulties with eating or passing stool
What parasite causes Chagas DIsease
Trypanosoma cruzi
Cysticercosis
- parasitic infection caused by larval cysts of the tapeworm Taenia Solium
- Larval cysts infect brain, muscle, or other tissue, and are a major cause of adult onset seizures in most low-income countries
- a person gets cysticercosis by swallowing eggs found in the feces of a person who has an intestinal tapeworm. Person living in household with someone who has a tapeworm have a much higher risk of getting cysticercosis
- People do NOT get cysticercosis by eating undercooked pork. Eating undercooked pork results in intestinal tapeworm if the pork contains larval cysts.
Life cycle of Cysticercosis
- caused by larvae of the tapeworm, Taenia Solium
1) a person with an adult tapeworm (lives in a person gut) sheds eggs in the stool
2) A pig then eats the eggs in the stool
3) the eggs develop into larvae inside the pig and form cysts (called cysticerci) in the pig’s muscles or other tissues - The infection with the cysts-cysticercosis*
4) Humans who eat undercooked or raw infected pork swallow the cycle in the meat.
5) The larvae come out of their cysts in the human gut forming the adult tapeworm, completing the lifecycle - infection w/adult tapeworm- TAENIASIS
What are the ways people can get cysticercosis?
People get cysticercosis when they swallow eggs that are excreted in the stool of people with adult tapeworms. This may happen when people
1) drink water or eat food contaminated with tapeworm eggs
2) put contaminated fingers in their mouth
**Cysticercosis is not spread by eating undercooked meat
Where is Human Cysticercosis found?
found worldwide, especially in areas where a pig is common.
-Both taeniasis and cysticercosis are most often found in rural areas of developing countries with poor sanitation, where pigs roam freely and eat human feces