Cases (parasites) Flashcards
Sarah presents to your office with frequent bloody diarrhea. She is concerned because this has progressed from mild abdominal discomfort and diarrhea upon return from Jamaica 2 weeks ago and has become progressively worse.
PE reveals dehydration and evidence of intestinal abscess.
You run a stool culture and find the presence of cysts. What is the most likely organism?
Entamoeba Histolytica
Severe Complications:
Intestinal abscess, perianal fistula Extra-intestinal Amoebiasis: Liv - hepatitis Brain - encephalitis Lung - pneumonia
Cause:
Ingestion of cysts from contaminated food + water; fecal/oral
A 28 yo male comes in complaining of 2 week history of diarrhea. Your intake reveals his stools are frothy, fatty and have a very foul smell. He denies any signs of infx (fever etc) and has not noticed blood in the stool.
He mentions he went on a hunting trip last month ‘up North somewhere’ and they had no running water at the camp.
You suspect infection with…..
Giardia lamblia - flagellated protozoan
To confirm the diagnosis you run multiple stool analysis for cysts (4 nuclei and aflagelllar)
Luke needs Metronidazole.
Claire, a 19 yo college student has been experiencing vaginal itching with a foul smelling, green discharge for the past week. She admits to having ‘a one night stand’ last weekend at the bar. She can’t remember using protection. Exam shows colpitis macularis (strawberry cervix).
You suspect she has this sexually transmitted infection……
You counsel Claire on safe sexual practices and tell her you are glad she came in because this infection can cause these side effects long term…..
Trichamonas Vaginalis - flagellar protazoan
NO CYST stage.
Trophozoite is infective + Reproductive.
Diagnostics
Vaginal/Urethral Swab
Perform microscopy right after swab bc no cyst stage means they may die before you see them.
Must treat sexual partners - Metronidazole.
Linda is concerned about her son, he has had a fever for the past week. They have just returned from visiting her family in Peru.
Upon examination they boy has swollen lymph nodes (cervical, axillary and inguinal). You notice a raised, erythematous lesion on the boys cheek.
You suspect
Tympanosoma cruzi - flagellated protozoan
Transmitted via triatoma insects - Chaga’s Dx
Life cycle is similar to Malaria
Metacyclic Typomastigotes enter bite –> penetrate cells around bite wound –> inside turn to amastigotes + multiply into typomastigotes again —> cell bursts –> some go to blood some go to adjacent cells to create more infection –> the ones in blood now can infect other insects when they bite the human.
Diagnosis: blood smear
Treat: benznidazole
Jace, a farmer comes in with nausea, vomiting, abdominal discomfort and mild diarrhea. He admits that he often is hurried to get all his chores done which means meals are sometimes eaten on the go and near the livestock. You ask what type of livestock he raises, PIGS.
You suspect ….
Blantidum coli - ciliated protozoan
Especially endemic to tropical areas
Stool examination for diagnostics
Your regular patient presents with non-bloody diarrhea for the past 2 weeks. Because you know this patient is HIV+ you must include this in you ddx list……
Cryptosporidium sp - sporozoa/apicocomplexa protozoan
While this is generally asymptomatic + self limiting, worry about dissemination in HIV patients or other immunocomprimised.
Sporozoite is infective (fecal/oral - water)
Trophozoite is reproductive
All stages occur in ONE host
Diagnostic - multiple stool samples
Treatment: Paromycin
COMMUNICABLE BTWN PPL
Another regular patients comes in with exciting news, she’s pregnant! You know she has 3 cats at home so you tell her she should have the litter box well out of regular contact and that her husband should change the litter for the duration of her pregnancy. What organism are you worried about ad why?
What symptoms would present with this dx in a immunocomprimsed individual?
Toxoplasma gondii - sporozoa protozoan
This is a teratogen - one of the TORCHES of pregnancy.
Mild flu like symptoms: fever, myalgia, lymphadenopathy.
Immunocomprimised may also experience:
Encephalitis
Toxoplasma chorioretinitis
Cysts of the mycordium, skeletal mm, brain
Diagnosis: serology, immunoassays
Treatment: anti-folates
Life Cycle of Malaria
http://www.youtube.com/watch?v=VfxjJVLKWZw
Sporozoites injected by mosquito – go to liver and divide asexually – now Merizoites – the enter other liver cells and bloodstream — the ones in bloodstream enter erythrocytes — now it enlarged and becomes a ring trophozoite – divides into schizonts and they further turn into merizoites (some turn into gametocytes - these wont rupture and get extracted by mosquitoes - where they will form male and female gametes) —- now bursts and release – this is what causes the cyclical fever + chills, fatigue + nausea of malaria.
Typical Sx’s
Hepatomegaly + Splenomegaly
Anemia + Respiratory Distress (RBC’s are bursting)
Cerebral Malaria
Diagnostics
Blood Smear
Thick Film: drop of blood to determine % RBC’s inf
Drop of blood SMEARED to determine SPECIES
How does Babesia DIFFER?
Babesia microti (m/c form) From TICKS Infects ONLY erythrocyte not hepatocyte So what symptoms do you expect? Only - fever, fatigue, nausea + chills. Complications: hemolytic anemia, jaundice, disseminated intravascular coagulation
Steve and his girlfriend just got home from SouthEast Aisa. They backpacked for a few months. While away he developed Fever + Chills and the Dr there told him is lymph nodes and liver were enlarged. He felt better for a while but has noticed persistent abdominal pain and diarrhea.
You suspect while he was away he contracted this, typically acquired via exposure of skin to fresh water streams/ponds etc
Schistosomiasis - trematode (dioecious _ infective stage is the circarium - migrate to the liver to mature to adult stage)
You suspect he suffered Katayama Syndrome while away and now he has developed organ specific effects.
May also infect the GU system: dysuria, hematuria
CNS invasion is rare
Chronic Infection - egg deposition, granuloma formation, fibrosis in the affected tissue leading to long term complications:
Portal HTN
Bladder Cancer
HepatomegalySplenomegaly
Kidney Failure
May experience RASH shortly after infection.
Diagnostics: serology, urinalysis, tissue analysis
A pt presents with seizure, confusion, difficulty with balance + hydrocephalus. This can be a complication of extra-intestinal infection with what Trematode infection?
Cestodes - tapeworm
Will absorb B12 - leads to macrocytic anemia
Extraintestinal Manifestations:
Taenia Solis - cysticerosis
Cyst deposition in mm or brain
Echinococcus sp - hydatid disease
Humans are incidental/dead end hosts - comes from dogs
Cysts deposit in lung, alveoli – if rupture = anaphylactic shock.
Diagnostics:
Multiple stool samples
Alex, a 5 yo female, presents with difficult sleeping d/t itchiness of the anal region. You immediately include this on your ddx list….
E vermicularis - Pinworm - nematode
Diagnosis:
Tape Test - 3 consecutive mornings.
Stool + Fingernail analysis
A child present with diarrhea + vomiting. Labs show she also had anemia and protein deficiency, you suspect she has
N. americanus - Hookworm - nematode
Hookworm sucks blood and causes inflammation of the intestine.
Ground itch - invasion of larvae in skin at entry point causes local irritation. Looks like an insect bite.
Stool analysis
You are visiting an NDI clinical in Haiti, a patient presents with painful passage of stool and a prolapsed rectum. Labs show anemia, you test for….
T. tichuris - Whipworm - nematode
Growth retardation may present in children
Diagnostic: stool analysis
Transmission: soil, human fertilizer, contaminated fruits + veggies.
A pt comes in with wheezing, SOB and coughing. They deny asthma and you see no signs of URT infection. Pt admits to bloody stool and occasional vomiting for a few weeks. You think back to your microbiology course and wonder if this could be a rare invasive complication of…..
A. lumbricoids - Ascariasis
Primary infx is usually asxs
Transmission: contaminated soil, human fertilizer, fruits/veggies
Diagnosis: stool analysis
