Parasites-LM Flashcards
What does Trypanosoma Cruzi cause
Chagas Disease/American Trypanosomiasis
What is the T cruzi vector?
Where are they found?
What is the reservoir?
“Kissing Bug” Reuviid bugs
South America mainly but also in southern US and Mexico, eggs in cracks and crevices of roofs and buildings.
mostly mammals.
T. Cruzi Transmission?
The bug bites you and craps on you, the feces then gets in the bite wound or rubbed in the eye.
Blood transfusions ad congenital is possible.
describe the life cycle of T. Cruzi?
What is this?
Where are they found?
trypomastigotes
only in blood
What is this?
Where is it found?
Amastigote
Smooth muscle, affinity for cardiac muscle.
tissue is where they divide.
What is Romana’s sign?
What else can occur in the acute stage?
• Romaña’s sign – Present in Chaga’s disease unilateral edema affecting upper and lower eyelid (often occurs with conjunctivitis) occurring at bite site or were feces accidentally entered eye
Fatigue
- Fever
- Hepatosplenomegaly (swollen spleen and liver)
- Lymphadenopathy (swollen lymph glands)
- Rash (at bite site)
- Appetite loss
- Diarrhea
- Vomiting
- Brain damage sometimes progressing to death (generally in infants and children under 5
The intermediate stage is usually asymptomatic but what does the chronic stage present with?
• cardiac problems
o enlarged heart
o arrhythmias
o heart failure
o cardiac arrest
• GI problems
o Enlargement of esophagus (Megaesophagus) - associated with difficulty swallowing
o Enlargement of large bowel (Megacolon) - associated with severe constipation
Achalasia can be an effect of chagas disease, how does this happen?
What else is it associated with?
Failure of inhibitory neurons during swallowing.
megacolon
How would you detect T cruzi?
In the blood; amastigote stage via biopsy of lymph node, etc
What is T brucei called?
What are the two variations
What does it require?
What transmits it?
African sleeping sickness
gambiense (central/western africa) and rhodesiense (southern/eastern)
two hosts
Tsetse fly
Describe the life cycle?
What protects T brucei from our immune system?
How can you tell rhodesiense and gambiense apart microscopically
glycoprotein VSG coating
you can’t under microscope
T brucei can invade the brain, how?
the CSF flows/bathes the brain surface and fills the “Virchow-Robbin space”. This space, which surrounds the vessels, ends at the level of the capillaries. Thus, whatever is in the CSF is brought deep into the brain parenchyma (such as inflammatory cells). Under normal circumstances, the BB barrier is intact throughout this system.
Virchow-Robbin space fills with neutrophils.
Because the BB barrier is altered secondary to the inflammation, the brain parenchyma is altered and edematous (note pale zone) and scattered neutrophils are entering the brain tissue. T. Brucei presumably follows them through. (slides didn’t expressly explain this though)
What can T brucei cause? several weeks to months time frame
1-3 week presents with chancre over bite
- anemia
- cardiac dysfunction
- pruritus (itching)
- fatigue
- fever
- headache
- muscle or joint pain
- skin rash
- splenomegaly (enlargement of the spleen)
- swelling of the lymph nodes (most prominently in the back of the neck and in the groin), hands and face
- thrombocytopenia (low level of platelets, thrombocytes)
- weight loss.
Final stage is when the parasite gets through BBB, present with?
- blackouts
- coma
- confusion and abnormal behaviour
- death (within months or years)
- insomnia (sleeping troubles)
- personality changes
- somnolence (extreme fatigue).
What causes malaria?
Plasmodium
falciparum, vivax, ovale or malaria
What is malarias vector
When do syptoms begin/
female Anopheles mosquito
10-15 days after bite
Describe the life cycle of plasmodium?
The life cycle of malaria parasites. A mosquito causes an infection by a bite. First, sporozoites enter the bloodstream, and migrate to the liver. They infect liver cells, where they multiply into merozoites, rupture the liver cells, and return to the bloodstream. Then, the merozoites infect red blood cells, where they develop into ring forms, trophozoites and schizonts that in turn produce further merozoites. Sexual forms are also produced, which, if taken up by a mosquito, will infect the insect and continue the life cycle.
What is this?
merozoites infected hepatocyte
wHAT are these
gametocyte in blood smear
Describe the fever pattern of malaria
How does one get mites or scabies
What is in the picture?
Contact with humans that have it. It cannot be gotten from dogs and cats.
A. chitin exoskeleton
B. internal organs
C. Eggs
So complement can kill parasites but what is the big player here
Eosinophils
What is this?
There are three types how would you tell them apart?
Female schistoma flat worm wrapped by a male.
Haematobium has a terminal spine
mansoni have lateral spines
Japonicum has (Dr Femont-Smith said a lateral spine, Dr Ambler said no spine, internet show pictures both ways, take your pick)
What is the life cycle of japonicum and mansoni?
What is it called that penetrates the skin and infects
Cercariae infect their human host by penetrating through the skin. In about a month, the cercariae have developed into mature schistosomes that have formed pairs, migrated to the blood vessels around the intestine (or bladder) and have begun to produce eggs.
There are cecaria that only penetrate the skin and go no furthur this is called swimmers itch, what is the danger with ones that go to the blood.
Clog blood vessels and cause portal hypertension (perivascular fibrosis), caput medusa, esophageal varices, splenomegaly
The chonic irritation of schistosomiasis can cause what?
Dx of schistosomiasis
Tx
Invasive squamous cell carcinoma of the bladder
•Microscopic identification of eggs in stool or urine is the most practical method for diagnosis.
Praziquantel
How would you get tenia solium
Dx
What can tenia solium cause?
Tx
Pork (undercooked)
identifying eggs and proglottids in feces is the simplest way to diagnose an infection
.
•Cysticercus is clinically pathogenic. Ingestion of T. solium eggs or proglottids which rupture within the host intestines can cause larvae to migrate into host tissue to cause cysticercosis.
•
•This is the most frequent and severe disease caused by T. solium.
•
•In symptomatic cases, a wide spectrum of symptoms may be expressed, including headaches, dizziness, and occasional seizures.
Praziquantel
What is enterobius vermicularis?
What are the risk factors?
Pinworm- most common round worm infection in the US
Parent can apply the sticky surface of scotch tape to the skin around the anus and then stick the tape onto a glass microscope slide (“cellophane test”). The doctor can then look at the slide under the microscope looking for the eggs.
•The people most likely to be infected with pinworm are children under 18, people who take care of infected children and people who are institutionalized. In these groups, the prevalence can reach 50%.
What is the epidemiology of the pinworm? Sorry
•A person is infected with pinworms by ingesting pinworm eggs either directly or indirectly. These eggs are deposited around the anus by the worm and can be carried to common surfaces such as hands, toys, bedding, clothing, and toilet seats. By putting anyone’s contaminated hands (including one’s own) around the mouth area or putting one’s mouth on common contaminated surfaces, a person can ingest pinworm eggs and become infected with the pinworm parasite. Since pinworm eggs are so small, it is possible to ingest them while breathing.
•
•Once someone has ingested pinworm eggs, there is an incubation period of 1 to 2 months or longer for the adult gravid female to mature in the small intestine. Once mature, the adult female worm migrates to the colon and lays eggs around the anus at night, when many of their hosts are asleep.
•
•People who are infected with pinworm can transfer the parasite to others for as long as there is a female pinworm depositing eggs on the perianal skin. A person can also re-infect themselves, or be re-infected by eggs from another person.
What is ascaris lumbricoides?
giant roundworm, most common parasitic worm in humans worldwide.
What is the cycle of the worm?
Remember the eggs are the second most difficult thing to kill only behind prions, they can survive 1-3 years
TX
Mebendazole
Ok this is a blow fly/green bottle fly, what can you get from the eggs
How do you get this?
Myiasis- Maggot ( fly larva infection)
Myiasis, which is the medical term for parasitic infestation of a mammal by fly larva. In Tanzania (and most of East and Central Africa), the most common fly that causes this condition is Cordylobia anthropophaga, also known as the tumbu fly or putzi fly. The fly lays its eggs on soil or damp clothes (usually clothes hung out to dry), and the larva – which hatch out in 2-3 days – will penetrate the unbroken skin of mammals (or humans) that they come into contact with, creating a boil. In the South American variant, the botfly (most commonly Dermatobia hominis) lays its eggs on an intermediate vector such as a mosquito, which transmits the subsequently hatched larva to humans or other mammals. Iron your clothes in East and Central Africa…Kills larvae!
The best form of treatment is actually not surgery (and certainly not squeezing out the boil, which crushes the larva and creates more inflammation), but application of vaseline or scotch tape over the boil. This cuts out the air supply to the larva, which causes the larva to tunnel back out to the surface. Without the larva, the boil will heal by itself fairly rapidly. One useful precaution while traveling in East and Central Africa is that one should iron one’s clothes if one hangs one’s laundry out to dry.
