Parasites

parasites are (prokaryotic/eukaryotic) organisms and often have…

eukaryotic, complicated life cycles with intermediate and reservoir hosts

t/f parasites are commonly found in the microbiome so parasitic infections are always endogenous

false- not commonly found so they are always exogenous

t/f all parasites are medically relevant and the are found all over the world

false- not all are medically relevant and the ones that are have a specific geographic distribution based on climate, presence of required vectors, and economics

certain parasitic diseases cause significant ____ and _____ in ______ countries

morbidity, mortality, resource- poor

t/f parasitic infections may also be called neglected tropical disease

true

protozoa

single-celled organisms, replicate during infection of humans usually by binary fission (asexual reproduction)

metazoan

multi-cellular organisms, do not replicate during human infection and their life cycles include stages that must occur in the environment (like soil) or other non-human hosts (lay eggs and undergo sexual reproduction)

what are the two forms of protozoa?

cyst and trophozoite

cyst form of protozoa

infective form that is acquired by ingestion, can survive in moist environments for prolonged periods, including cold water (streams and lakes)

trophozoite form of protozoa

active, replicating form that causes disease, also referred as vegetative form

what are the cellular structures of metazoans organized into?

tissues and organs systems

fast facts about trichomonas tenax

flagellated (motile), aerotolerant protozoan, can be found in human oral cavity and is distributed between the teeth/gums/tongue/tonsillar crypts/saliva, only has vegetative/trophozoite form, is transmitted thru close contact (not really on fomites), presence is considerably high in persons with more dental calculus/coated tongue/poorly cleaned periodontal tissue

dental calculus

aka tartar, buildup of plaque and bacteria on teeth, difficult to remove and can lead to gum disease, tooth decay, and bad breath

coated tongue

buildup of dead skin cells on the papillae on the surface of the tongue, papillae become enlarged and there is an increase in the number of bacteria in the mouth, produce colored pigments

how is trichomonas tenax transmitted?

saliva, droplet spray, kissing, use of contaminated dishes or drinking water

what is the clinical manifestation of trichomonas tenax?

may be involved in the degradation of periodontal tissue through the secretion of alkaline phosphatases and fibronectin cathepsin

how is trichomonas tenax diagnosed?

microscopic examination of tonsillar crypts and tartar between the teeth and the gingival margin of gums for trophozoites

how is trichomonas tenax treated?

metronidazole and tinidazole, usually recommended for oral trichomoniasis caused by t. vaginalis

how can trichomonas tenax infection be prevented?

maintaining good oral hygiene or deep cleaning with scaling and root planning

fast facts about entamoeba gingivalis

non-pathogenic amoeba, inhabits the human oral cavity and if often found in conjunction with periodontal disease, no known cyst stage, trophozoites live in the oral cavity of humans

how are entamoeba gingivalis transmitted?

trophozoites are transmitted person-to-person orally by kissing or fomites (eating utensils)

fast facts about giardia lamblia

flagellate, exists as cysts and trophozoites, causes giardiasis

how is giardia lamblia spread?

infectious cysts via fecal-oral route (contaminated food or water including swallowing water during recreational activities like swimming), soiled diapers (daycare centers), oral-anal sexual contact, or via zoonotic sources (infected beavers serve as source of cysts in streams and ponds)

what is the infection/life cycle and pathogenesis of giardia lamblia?

cysts are ingested along with fecally contaminated water or food

trophozoites emerge in small intestine

trophozoites live on surface of villi

villi become flattened and trophozoites encyst in the small intestine

cysts pass with feces

what are the clinical manifestations of giardia lamblia?

sudden, foul-smelling, watery, non-bloody diarrhea, greasy stool

other common symptoms include malaise, abdominal cramps, bloating, flatulence, nausea, and weight loss

how is giardia lamblia infection diagnosed?

stool samples are examined microscopically for the presence of trophozoites and cysts

what is the treatment for giardia lamblia?

not usually recommended for asymptomatic individuals or people with mild symptoms

drugs available that kill both cysts and trophozoites (metronidazole and tinidazole)

spontaneous recovery usually occurs in 10-14 days

supportive care is important in severe cases- oral rehydration and electrolytes may be needed

how can giardia lamblia infection be prevented?

hand-washing and good hygiene, adequate water treatment, no vaccine available

what species of plasmodium cause malaria?

plasmodium vivax, plasmodium ovale, plasmodium malariae, plasmodium falciparum, plasmodium knowlesi

what species of plasmodium is the most severe?

plasmodium falciparum

what are the 2 stages of the plasmodium species of life cycle?

schizogony- asexual reproduction, occur during human infections

sexual reproduction- can only occur within mosquitos (female anopheles mosquito), is necessary for the maintenance of malaria

how does plasmodium infect?

infects RBC- parasite digests proteins (especially hemoglobin), creates toxic product (hemozoin)

immune response- destruction of erythrocytes by rupture or phagocytosis of parasitized cells leads to anemia

how can plasmodium be diagnosed?

microscopic examination of blood specimens (smears) for ring forms of parasite in RBC

some rapid diagnostic tests available

how is plasmodium treated?

combination of supportive and chemotherapeutic measures (chloroquine treatment is a common chemotherapy)

how can plasmodium infection be prevented?

protection form mosquitos- clothing, netting, repellents

control of mosquito breeding

first vaccine recommended for use by WHO in 2021 (RTS, S) to prevent malaria in children 6 months to 5 years (contains a recombinant fusion protein consisting of antigen from surface of p. falciparum and HBsAg (from HBV))

Which one of the following statements about Giardia lamblia is TRUE?

A. It invades and persists in the large intestine.

B. It can result in malabsorption due to flattening of the intestinal villi.

C. Its presence is always associated with clinical symptoms.

D. It is treated by prescribing a gluten-free diet.

E. It is transmitted by ingesting trophozoites.

B. It can result in malabsorption due to flattening of the intestinal villi.