Parasites Flashcards
Entomoeba histolytica
Protozoa
Pathogenesis: Infection occurs when the cysts are transmitted via the fecal oral route in areas of poor sanitation.
Seen in migrants, travelers, instiutionalized, MSM
Clinical presentation: Asymptomatic carriers, amoebic dysentary (bloody diarrea, foul odor, low grade fever ), amoebic abscesses (most common in liver)
Diagnostic: serology, fecal/serum antigen testing, stool exam, colon biopsy
Treatment: metronidazole
Prevention: good personal hygiene, purification of water supply
Giardia intestinalis (lamblia)
Protozoa flagellate
Infects duodenum and small intestine
More prevalent in children
Pathogenesis: major reservoir is contaminated water, cysts resistant to chlorine, person to person spread
Clinical manifestions: incubation is 1-2 weeks, chronic diarrhea, low grade fever, stool is watery and greasy and foul smelling, malabsorption of sugars, fats and fat soluble vitamins
Diagnostic: 3 stool specimens with a sensitive of >90%
Treatments: Metronidazole
Prevention: hand washing, water purification
Trypanosoma brucei
Protozoa
Transmitted via the teste fly
Animal reservoirs: impalas (East Africa), humans and cattle (West Africa)
African sleeping sickness
Primary chancre at bite site, Winterbottom’s sign (early onset)
Bloodstream invasion by trypomastigote
Eventually invades the CNS
Diagnostic: Rapid PCR
Treatment: Eflornithine, pentamidine
Prevention: wear long sleeve and neural colors so the tsete fly won’t bite
Trypanosoma cruzi
Protozoa American trypanosomiasis Vector: reduvid kissing bug, bites on face Romana's sign: swelling at bite site Symptoms: mild disease with fever. complications begin 10-20 year later. Chagas disease: cardiomegaly, megacolon, megaesophagus Diagnostic: Examine bug feces, Treatment: Benzinidozale Prevention: better construction material
Plasmodium falciparum
Protozoa
2 billion infections/ 3 million deaths
Malaria
Humans are the only reservoir
Transmission by female mosquito
Within 30 min of the bite it enters the liver, infected liver cell ruptures, enters red blood cells
Symptoms: fever, sudden onset of chills, anemia, splenomegaly, jaundice
Diagnostic: Geimsa stained smear
Treaments: Chloroquine
Prevention: mosquito control, vaccines are under development
Toxoplasma gondii
Protozoa
Cat is a definitive host
Acquired by eating undercooked meat containing cysts or ingestion of oocytes in cat feces
Parasites form dormant cysts
Mononucleosis like symptoms
Congenital infection during first trimester
Diagnostic: antibody detection
Prevention: fully cooked meat, careful cleaning of litter box
Treatment: Pyrimethamine +sulfadiazine
Leishmania donovani
Protozoa Obligate intracellular parasite Transmitted by the sand fly Tissue destruction at the bite site Kala-azar black fever 3-6 month incubation period High fever, splenomegaly, anemia Diagnostic: PCR, ELISA Treatment: Sodium stibogluconate, Amphoterasin B Prevention: insecticides
Trichomonas vaginalis
Protozoa
STI more common in women
Trophozite is the only stage present in the life cycle
Obligate parasite
Infects squamous epithelium
Presentation: vulvovaginitis, purulent discharge, strawberry cervix, urethritis
Men: non-gonococcal urethritis
Diagnostic: Elisa, Culture (gold standard), microscopy (jerky and twitching motility)
Treatment: metronidazole
Prevention: condoms
Ascaris lumbricoides
Metazoa
Roundworm (Nematode, non segmented)
One of the largest human parasites
Eggs are ingested –> larvae hatch is small intestine enter bloodstream and go to liver –> migrate to heart and lungs–> then up the trachea where they are swallow
Contaminations of fruits and veggies where human feces is used as fertilizer.
Light infections are asymptomatic
Heavy infection leads to malnutrition, bowel obstruction
Diagnostic: O & P
Treatment: Mebendazole
Prevention: proper disposal of feces
Enterobius vermicularis (pinworm)
Metazoa
Roundworm (nematode)
Common in kids, homeless, poor hygiene
Eggs are ingested –> pinworms hatch in lining of intestine–> pregnant worms migrate to the rectum –> legs eggs in the anal area at night
Major symptom is anal pruritis, vaginal salpingitis
Diagnostic: Scotch tape method
Treatment: Albendizole
Prevention: health education, treating the patients and carriers
Necator americanus
Metazoa
Hookworm (nematode)
Larvea enter bloodstream and reach heart–> enters lungs and migrate up the trachea and are swallowed–> adults mature in small intestine–> eggs passed in feces–> quest on blades of grass
Clinical disease: iron deficiency anemia, failure to thrive
Diagnostic: O & P
Treatment: mebendazole
Prevention: proper disposal of feces
Trichnella spiralis
Metazoa
Roundworm (nematode)
Ingestion of undercooked meat with cysts (pig meat and polar bears)–> larvae to small intestine–> newborn larvae to the bloodstream or lymph–> enters skeletal muscle–> larvae matures in muscle
Symptoms: diarrhea, muscle pain, headache, involvement of heart and CNS
Treatment: Albendazole, Mebendazole
Taenia saginata
Metaoza
Cestodes (segmented)
Beef Tapeworm
Definitive host: human
Intermediate host: cattle
Distribution: cosmopolitan, poor sanitation and where there is no inspection of meat
Transmission: ingestion of larval form in undercooked beef
Eggs are passed in feces–> cattle eat infected vegetation–> oncospore develops into cystercerci in muscle–> human eat meat–> adults are in small intestine
Diagnostic: O &P
Taenia solium
Metazoa Cestodes (segmented) Pork Tapeworm Def host: humans Int. host: pigs Cosmopolitan Ingestion of uncooked pork Eggs are passed in feces--> cattle eat infected vegetation--> oncospore develops into cystercerci in muscle--> human eat meat--> adults are in small intestine Larvea forms causes cystercercosis Diagnostic: O & P
Diphyllobothri um latum
Metazoa Cestodes (segmented) Broad fish Tapeworm Def host: fish eating carnivores 1st. int host: crustaceans 2nd int host: fish (trout and salmon) Transmission: The parasite is eaten Symptoms: Diphyllobothriasis , nausea diarrhe, anemia because consumption of B12 Diagnostic: O & P, CT, MRI Treatment: Przaiquantal
