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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



-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



-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


Cysticercosis symptoms

Cysts in the brain or spinal cord:
- cause the most serious form of the disease NEUROCYSTICERCOSIS
-seizures and/or headaches (most common)
-confusion, difficulty with balance, brain swelling, and excess fluid around the brain (less common)
-stroke or death

Cysts in the muscles
-Generally do not cause symptoms
-may cause lumps under the skin which can become tender



-preventable parasitic infection caused by the larval form of the dog or cat worms Toxocara canis and Toxocara cati
-considered Neglected Parasitic Infection
-Toxo cara eggs are found in dog or cat feces
-after someone accidentally ingests Toxocara eggs, the larvae hatch and travel through the bloodstream into organs and other tissues. This often causes fever and coughing, and sometimes leads to severe illness, including inflammation of the liver or blindness
-Two forms of toxocariasis- Ocular Toxocariasis and Visceral Toxocariasis


Ocular Toxocariasis

-results from the movement of the parasite into the eye
-causes visual impairment that can be permanent including blindness


Visceral Toxocariasis

results from the movement of the parasite through the organs or tissues
-can lead to severe damage to the liver and other organs


How do people get toxocariasis?

-accidentally ingest dirt containing Toxocara eggs
-once inside the body the roundworm larvae can hatch from the eggs and find their way to various parts of the body through the bloodstream
-rare but people can also become infected by eating undercooked or raw meat from an infected animal


Toxocariasis prevention

-Controlling Toxocara infection in dogs and cats through deworming
-Reduce risk of contact by disposing of dog and cat feces in a place away from where people work or play
-Hand washing before handling food
-Hand washing after playing with pets, picking up dog feces, or handling cat litter


Who's at higher risk for acquiring toxocariasis

-Greatest risk is children
-Dog owners
-people under the age of 20- younger people have more frequent contact with soil
-live in hot, humid regions where the roundworm eggs remain alive in the soil for long periods of time



-preventable disease caused by the parasite Toxoplasma gondii
-infection during pregnancy can lead to miscarriage or severe disease in the newborn including developmental delays, blindness, and epilepsy. Can also become infected through mothers milk
-Infected for life results in a weakened immune system can experience disease reactivation
-people with advanced HIV disease, inflammation of the brain (encephalitis) due to toxoplasmosis is common unless long-term preventative med is taken
-cats are the only host that can shed an environmentally resistant form of the organism in their feces


Symptoms of Toxoplasmosis

-usually asymptomatic

Fever, malaise, swollen lymph nodes, but can also be asymptomatic
-small number of people may experience eye disease
-infected for life


How can humans become infected by Toxoplasmosis

1) eating raw or undercooked meat containing the parasite in tissue cysts (usually pork, lamb, goat, or wild game meat, although beef and field raised chicken have been implemented in studies)
2) Ingesting food, soil, or water contaminated by cat feces
3) when pregnant woman is newly infected during or just prior to her pregnancy and transmits the infection to her child
4)organ transplant or blood transfusion


Where is Toxoplasmosis gondii present?

United state- worldwide


Who is at most risk for Toxoplasmosis

-individuals who eat undercooked meat
-drink untreated water
-exposed to contaminated cat feces or soil

-young, old, sick, and pregnant


Who is at most risk for serious complications from toxoplasmosis?

Pregnant women who can transmit the parasite to their child and those with severely weakened immune systems



-most common curable STD in the United States
-caused by an infection with a parasite Trichomonas vaginalis
-women and men who have trichomoniasis are at a higher risk for getting or spreading other STDS including HIV


Is trichomoniasis treatable and if so with what?

- prescription antimicrobial medication
without treatment infection can last for months even years