Microbiology Exam 4

C (ingestion of Taenia solium cysticerci in undercooked or raw pork will cause the adult tapeworm to mature in the intestine, making the human the definitive host - if the eggs from the adult tapeworm are ingested, then the cysticerci will develop in the human causing cysticercosis and making the human the accidental intermediate host)

In infections with Taenia solium, humans can serve as the A. Definitive host B. Intermediate host C. Both of the above D. None of the above

C (these are whipworms, Trichuris trichiura, which are geohelminths, meaning environmentally exposed, and the infective stage is the embryonated egg, which has a characteristic bipolar plug appearance) (the prevalence of this worm is very high, and is more common in warm and moist soil) (E; whip it. whip it good)

A patient with intestinal worms has developed an iron-deficiency anemia due to blood loss as well as a deficiency in vitamin A. Microscopic examination of the pathogen is as shown. She was most likely infected by which of the following? A. Rhabditiform larva from contaminated water B. Filariform larva from the soil C. Embryonated eggs from the soil D. Unembryonated eggs from pet-to-human transmission E. The rhythm

E (oh yeah, now we gettin' INTEGRATIVE) (the intestinal diagnosis is giardiasis, which is an adherence [NOT INVASION] to the intestinal lumen - if you know that mucosal attachment by pathogens is inhibited by IgA, recognize the presence of sinusitis to support this conclusion, and the lack of viral or fungal infections to rule out the other choices, then you've found your answer)

A 5 year-old-boy with a history of severe allergies and recurrent sinusitis presents with foul-smelling, fatty diarrhea. He is at the 50th percentile for height and weight. The boy's mother reports that he has had several such episodes of diarrhea over the years. He does not have any known history of fungal infections or severe viral infections. Which of the following is the most likely underlying cause of this boy's presentation? A. Thymic aplasia B. Hyper IgE syndrome C. Severe combined immune deficiency D. Wiskott-Aldrich syndrome E. IgA deficiency

A (these guys are cute - he looks like he has a goofy moustache and big worried eyes!)

A child who lives in a rural community, presents with abdominal pain, anorexia, and watery diarrhea. Fecal smear reveals an abundance of protozoan organisms like the one pictured. The microbe most likely responsible is A. Giardia B. Entamoeba C. Cyclospora D. Cryptosporidium E. Balantidium

B (all groups of trematodes/flukes use a snail as a host, most often as an intermediate host)

A freshwater snail is always a part of the life cycle in which of the following groups? A. Cestodes B. Trematodes C. Filarial worms D. Intestinal nematodes

A (the diagnosis is leishmaniasis, vectored by the sandfly - this particular diagnosis is cutaneous leishmaniasis, since the same parasite can cause mucocutaneous, and visceral infections) (B; this is for Cyclospora spp) (C; this is for Plasmodium spp) (D; this is for amoebas and trichomonads) (E; this is for tapeworms and flukes)

A patient enters your clinic with complaint of a large and unsightly sore on her ankle. She has recently returned from a trip to Ethiopia. She recalls being very bothered by many biting flies, particularly about the legs. The lesion is as pictured. Which of the following is the best course of treatment? A. Antimony-containing compounds like sodium stibogluconate B. Folic acid inhibitors like trimethoprim C. Quinine D. Metronidazole E. Praziquantel

C (A, B, and C are all the 'barefoot walking worms' [or geohelminths] but Strongyloides deposits its eggs in the mucosa, so that larvae appear in the stool, while Necator lays eggs directly into the lumen) (Ancylostoma will not lay eggs in people as the definitive host for that species is dog - this guy will cause the cutaneous larva migrans, or creeping eruption)

A patient, who was walking around barefoot on a beach, presents with diarrhea. His fecal smear shows parasitic helminth larvae, but no eggs. Your initial suspicion is infection by A. Ancylostoma B. Necator C. Strongyloides D. Anisakis

D (Trichruis trichiura, to be precise - the image is showing Charcot-Leyden crystals) (whipworm is the only parasite we know of that can cause rectal prolapse, but the anemia is also a decent hint to rule out other possibilities - eosinophilia is not terribly specific where parasitic infections are concerned) (Trichuriasis is caused by ingesting the eggs found in the soil - these are NOT the 'piercing and ascending' worms, you must EAT them to get the disease)

A woman presents with a prolapse of her rectum, anemia, and eosinophilia. Her fecal smear reveals the pictured finding. She has an infection of A. Tapeworm B. Hookworm C. Pinworm D. Whipworm E. Ringworm

B (the diagnosis is most likely Giardia, which is transmitted fecal-orally through contaminated water - the infective stage is the cyst) (A; dogs do have Giardia - they just don't transmit it to people) (C, D, E; this is a whole bunch of other stuff - Giardia isn't one of them) (Giardia is considered a traveler's disease and is more prevalent in children - the diarrhea is also notable in that it's fatty, because the Giardia adheres to the small intestine and prevents fat absorption - this causes the stool to float) (treatments are azoles - usually albendazole for children, metronidazole, or tinidazole)

An 8-year old child presents abdominal distension, and a watery diarrhea that floats in the toilet bowl. Assuming all of the following are true, which is the most likely to have caused this child's infection? A. The family dog licking his face B. Drinking unfiltered water in the family's trip to Mexico one week ago C. A bite from a mosquito D. A bite from a tick E. A bite from a fly

A (Strongyloides stercoralis penetrates the skin, such as the bare soles of feet, in its filariform stage, and ascends via the circulation, typically ending up in the lungs - the host then coughs up and swallows the larvae, which is how they end up in the GI system and become symptomatic)

An immunocompromised patient has diarrhea and abdominal cramps. A blood panel revealed marked eosinophilia and stool samples showed numerous filariform and rhabditiform larvae under microscopy. Which of the following is false regarding this patient's pathogen? A. When the infective stage of this patient penetrated the patient, it went directly to the intestines. B. This pathogen is capable of auto-infecting the patient as part of its life cycle. C. The pathogen is a facultative parasite, and is capable of living freely in soil. D. The pathogen is implicated as the causative agent in some cases of childhood asthma. E. This pathogen can be consistently and safely treated with ivermectin.

F (any of the listed organisms can be host to a life cycle stage of a trematode species) (snails are the first intermediate hosts, and crustaceans, often crayfish and crab, are the second intermediate hosts - underwater vegetation is where the metacercariae encyst to be consumed by the definitive hosts)

At a seafood restaurant, Tamzid suddenly has crippling flashbacks to Dr. Jensen's intestinal fluke lectures. Which of the foods available are not a part of the trematode life cycle? A. Water chestnuts B. Crayfish C. Freshwater snail D. Watercress E. Crab F. None of the above

B (the eggs of both Ascaris lumbricoides and Trichuris trichiura must mature in soil before they are infectious, and infection occurs when the human ingests these eggs from the soil - since both nematodes are endemic in the same areas of the world, they are often seen as a mixed infection)

Because mature infectious eggs are ingested from the soil, which of the following parasites might be seen in the same patient at the same time? A. Hookworm and Ascaris lumbricoides B. Ascaris lumbricoides and Trichuris trichiura C. Trichuris trichiura and Schistosoma japonicum D. Schistosoma japonicum and hookworm

B (even if you don't know the typical history and presentation of Clonorchis sinensis, it should be reasonable to deduce that the passing of abnormal gallstones indicates something residing in the gallbladder, with cholangiocarcinoma therefore being the most likely cancer consequence)

Bernard presents with liver dysfunctions, the most notable of which is the passing of pigmented gallstones. He admits to eating raw fish recently. The parasite currently infecting him predisposes to what kind of cancer? A. Hepatic angiosarcoma B. Cholangiocarcinoma C. Pancreatic adenoma D. Duodenal adenocarcinoma

D (the patient does have Giardia lamblia, as the cysts are present in his stool, but he is not symptomatic nor immunocompromised, so there is no reason to treat him - only symptomatic cases should get treatment) (B; cryptosporidium looks different from this - look for acid fast staining of spherical [not ovoid] cysts)

Bryce recently returned home from a camping trip. He is planning on heading back to college but is worried that he may have a parasitic infection after drinking unfiltered stream water on his trip. He sets up an appointment with his primary care physician. He denies any diarrhea, constipation, bloating, or flatulence. He is adamant about having a fecal exam, so the primary care physician obliges. The fecal exam reveals the image. What is the most appropriate next step in Bryce's care? A. Treatment with metronidazole to prevent future symptoms, as he is infected with Giardia lamblia B. Treatment with azithromycin because he is infected with cryptosporidium C. No treatment, as he is not currently infected D. No treatment because is not symptomatic E. No treatment because there is no effective treatment

D (the diagnosis is neurocysticercosis, which is caused by ingestion of tapeworm eggs from human feces [humans are the definitive host], NOT from ingesting the infected pork that contains the cysticerci [pigs are the intermediate host]) (the pathogen is Taenia solium)

Carey is admitted to the hospital with recurring seizures and neurologic episodes. During his seizures, he is unable to talk, suffers visual disturbances, and loses consciousness. He has lingering neurological symptoms, including hemiparesis. The MRI revealed several cystic masses in the brain as shown. Carey was most likely infected by A. Ingesting undercooked beef B. Ingesting undercooked pork C. Ingesting raw fish D. Ingesting human fecal material E. Watching the pilot episode of House, M.D.

C (the diagnosis is cryptosporidiosis, from Cryptosporidium hominis, which causes mild diarrhea unless you don't have an immune system - then you're the patient) (treatment is supportive with rehydration and nitazoxanide or paromomycin)

Ignatius presents with severe watery diarrhea and gives a stool sample to be examined in the lab, which appears as shown under acid-fast staining. Which of the following is most likely true about Ignatius? A. Swims in freshwater streams B. Routinely eats undercooked meat C. Is HIV positive D. Works on a farm E. Owns a dog

A (the diagnosis is amebiasis from Entamoeba histolytica - a key feature is bloody diarrhea, as opposed to watery and fatty diarrhea as with giardiasis or cryptosporidiosis) (B; this is a trait of tapeworm infection, not amoeba) (C; a stool sample is a good idea, but the E. disbar cysts are not pathogenic nor diagnostic) (D; too many organisms are spread by contaminated water in underdeveloped countries for this to be a useful avenue of investigation - asking about symptoms is usually better than asking about etiology) (E; immune compromise is a good question to ask if suspecting cryptosporidiosis, but the MRI gives you no reason to suspect that, as the liver abscess is more characteristic of Entamoeba)

Jen, a medical student recently on mission to Colombia, comes in with complaints of right upper quadrant abdominal pain, but the history didn't match a true appendicitis. Suspicious, you popped her into the MRI, and found a large liver abscess in the right lobe of the liver. Which of the following should you do to determine the presence of a key symptom/sign? A. Ask about bloody diarrhea B. Check for a low level of vitamin B12 C. Acquire a stool sample and look for Entamoeba disbar cysts D. Ask if the patient drank the water in Colombia E. Whether the patient is immune-compromised

C (this guy has a cestode/tapeworm, most likely Diphyllobothrium latum based on the diet - tapeworms are long and flat, and in fact D. latum is one of the longest; adults can reach up to 10 meters long) (A; this describes ascarids/roundworms) (B; this describes trichuris/whipworm) (D; this describes trematodes/flukes) (E; Giardia or entamoeba, but those would cause diarrhea)

Kelsey comes in for tests due to a concern over his stool: he says that his stool is riddled with semitransparent white spheres, and he's worried he has a parasite. He has no diarrhea or symptoms of any kind that he knows of, nor has he felt ill. When asked about recent travel, he replies that he was in Japan a couple months ago, where he ate sushi as fresh (meaning raw) as he has ever had. Blood tests revealed pernicious anemia. Which of the following is the most likely morphology of Kelsey's parasite? A. Pencil-thick and about 30 cm long B. A thread-like anterior end and a tightly coiled posterior end C. Flat and several meters long D. Flat and leaf-shaped with two suckers E. Amoeboid

B (Crypto can cause watery diarrhea in immunocompromised or immunocompetent patients, but is obviously more severe in the former - don't let immune status or age or food poisoning possibilities confuse you, acid-fast cysts are almost definitely crypto!) (the treatment is nitazoxanide)

Mike returns from vacation in Eastern Europe. He reports he had been eating new, strange foods, and had been swimming daily in a local river for exercise. He reports that since returning home, he has had daily watery diarrhea. He denies having any blood in his stools. You order a particular stool test, and the results are shown above. What is the cause of Mike's diarrhea? A. Giardia B. Cryptosporidium C. E. coli D. S. aureus E. B. cereus

B (tapeworms/cestodes often do not produce any symptoms, with the exception of a potential B12 deficiency - the other statements are false) (A; this is true for trematodes/flukes - tapeworms are acquired by eating raw or undercooked meat infested with the procercoid) (C; praziquantel or albendazole for everybody!) (D; tapeworms are a global disease, but they are more common in some places than others) (E; humans, and many other mammals, are definitive hosts for tapeworms)

Most tapeworm infections A. Can be caused by swimming in contaminated water B. Are asymptomatic C. Have unique treatments for each species D. Occur only in underdeveloped nations E. Use the human as an accidental host

C (this is the classic 'flask shaped' lesion in the colon that indicates infection by Entamoeba histolytica, which can progress to the liver if left untreated - under microscopy, these amoeba will have ingested red blood cells in their cytoplasm, so they are distinct there as well)

Shamim traveled to Latin America presents with abdominal pain and bloody diarrhea. A biopsy of the colon revealed the histological finding shown. If treatment is withheld, Shamim is in danger of developing which of the following conditions? A. Aplastic anemia B. Neurocysticercosis C. Hepatic amoebiasis D. Bladder cancer E. Cholangiocarcinoma

D (Cryptosporidium is fecal-oral and transmitted by contaminated water - it will cause mild watery diarrhea in the immunocompetent, and is markedly more severe in the immunocompromised)

The CDC investigates a series of outbreaks of cryptosporidiosis. The cluster of cases occurs in separate upscale suburban communities. Which of the following is the most plausible source of transmission for these outbreaks? A. Fecal-oral person-to-person route B. Parasite-infected meat C. Bird-mosquito-human route D. Manure-recontaminated drinking water E. Inhalation of bird droppings

C (the hydatid cysts are found in sheep or humans, which are accidental intermediate hosts, but the adults are found in the intestines of dogs)

The adult tapeworm of Echinococcus granulosus is found in the intestine of A. Humans B. Sheep C. Dogs D. Cattle

A (cutaneous larva migrans, or "creeping eruption" is indicative of a pathogen that has infected its non-definitive host - Ancylostoma is a dog hookworm, and is unable to do anything to a human host other than aimlessly wander through the skin - aww, poor baby is lost...)

The causative agent of this particular lesion is most likely of the genus A. Ancylostoma B. Ascarida C. Dermacentor D. Strongyloides E. Diphyllobothrium

C (which is insane)

The fever generated by Plasmodium vivax malaria consumes ____ calories a day. A. 1,000 B. 3,000 C. 5,000 D. 10,000 E. 2

D (the giant intestinal fluke is commonly found in Southern and Eastern Asia but considerably rarer in the US)

The following organisms are linked with specific relevant information. The incorrect combination is A. Strongyloides stercoralis ::: internal autoinfection B. Echinococcus granulosus ::: hydatid disease C. Taenia solium ::: humans can serve as definitive and intermediate hosts D. Fasciolopsis buski ::: common within the United States

A (this is a tapeworm, and the anterior structure is a scolex - the scolex is NOT used to feed, but to attach to the intestine - nutrients are absorbed directly through the tapeworm's surface, as it does not have or need a digestive system)

The image shows the anterior end of a cestode. The structure at the tip of the organism is used for A. Attachment B. Reproduction C. Feeding D. Looking scary

D (normally, the filariform larva penetrates the body and the rhabditiform larva leaves it - but Strongyloides stercoralis is able to make the switch from one to the other within the same host, and reinfect and multiply to absurd numbers) (A; hyperparasitism is when a parasite is a host to another parasite, like a tapeworm inside a flea) (E; man, I wish)

The nematode Strongyloides stercoralis is one of the only parasites known to be capable of A. Hyperparasitism B. Hyperinfection C. Autoparasitism D. Autoinfection E. Megahypersuperultrarareparasitinfectionism

D (Ascarid worm eggs are remarkably resilient, lasting viable for up to 10 years, and a lipid layer surrounding the egg protects it from destruction)

The only way to destroy Ascaris lumbricoides eggs is to A. Freeze them B. Dessicate them C. Bathe them in formaldehyde D. You can't

B (notable features - large kidney-shaped nucleus [macronucleus] and cilia) (symptoms are similar to entamoebiasis, but the buzzword is pigs - look out for farmers and such) (treatment is tetracycline or metronidazole)

The pictured organism is from the genus A. Ascarida B. Balantidia C. Cyclospora D. Diphyllobothria E. Entamoeba

C (this is Entamoeba histolytica, as evidenced by the endocytosed red blood cells, which colonizes the large intestine, often the cecum) (D; E. histolytica does eventually get to the liver via the portal system to create abscesses, but that is not the initial site)

The pictured pathogen initially infects the A. Duodenum B. Ilium C. Cecum D. Liver

C (rule of thumb; protozoans are transmitted either fecal-orally, or by arthropod vectors - and the tsetse fly vectors something much scarier than cyclosporiasis)

Transmission of cyclosporiasis occurs by what method? A. Person-to-person B. Through the bite of the tsetse fly C. Fecal-oral route D. Respiratory route E. Sexual transmission

A (the fish tapeworm egg resembles the liver fluke egg - both are operculated [meaning they have little caps] - you need a specialist to distinguish them - D latum is the ONLY cestode that infects humans and lays operculated eggs)

Two helminth eggs that may resemble one another are A. Diphyllobothrium latum and Fasciola hepatica B. Opisthorchis sinensis and Taenia solium C. Taenia saginata and Hymenolepis nana D. Ascaris lumbricoides and Trichostrongylus

A (this reaction to medication and the morphology of the worm suggests ascariasis, for which the ascaricide albendazole is the best drug of choice - pyrantel pamoate is also good, but may cause intestinal obstruction if the worm load is high - it's also contraindicated in pregnant women and young children) (B; use this for Giardia and Entamoeba) (C; use this for cryptosporidiosis) (D; this could treat the symptoms of ascariasis, but it does not kill or expel the worms) (E; who wants chowdah?)

Upon giving a patient some medication for a suspected parasitic worm infection, the patient vomited up a large bolus of dozens of thick live worms. An even larger amount were found in his stool. The drug most likely administered was A. Albendazole B. Metronidazole C. Nitazoxanide D. Corticosteroids E. Ipecac

A (the true intermediate host is sheep, humans get Echinococcus by accident - the definitive host is dogs)

When humans have cystic hydatid disease, the causative agent and host classification are A. Echinococcus granulosus - accidental intermediate host B. Echinococcus granulosus - definitive host C. Taenia solium - accidental intermediate host D. Taenia solium - definitive host

D (the shedding of cysts is intermittent and inconsistent, making wet mounts and samples equally unreliable - the lateral flow immunoassay has a 100% sensitivity and specificity, can be read in 15 minutes, eliminates the need for a trained miscroscopist, and doesn't rely on the presence of cysts in the stool)

Which laboratory test is superior for diagnosing giardiasis? A. Wet mount examination of stool B. Trichrome stained stool sample C. DNA analysis by PCR D. Lateral flow immunoassay E. Immunofluorescence assay

C, E (the sequence is egg, miracidium, sporocyst, redia, cercaria, metacercaria, adult) (egg passed in feces into water, miracidium swims to infect first intermediate host, the snail, and becomes sporocyst, which asexually divides to become the redia, which produces the cercaria that swims to the 2nd intermediate host, where it becomes the metacercaria and encysts - the adult forms in the definitive host after the metacercaria is eaten)

Which of the following fluke life stages is adapted for free-swimming? (Select all that apply) A. Egg B. Metacercaria C. Cercaria D. Redia E. Miracidium F. Adult G. Sporocyst

E (but this is still a global disease that can and does affect any age group or nation)

Which of the following groups has the highest rate of helminth infections? A. Adults in industrialized countries B. Children in rural America C. Teenage males D. Young girls in cold climates E. Children in rural tropical or subtropical areas

B (these are the flukes, several species of which can predispose to cancers of the liver, gallbladder, and bladder)

Which of the following helminth families is best known for promoting malignancies? A. Nematoda B. Trematoda C. Cestoda D. Annelida

C (E. granulosus causes hydatid disease, and to diagnose it, you use imaging to find the cyst and an aspirate to find the proscolices inside)

Which of the following is an incorrect pairing between the parasitic pathogen and the procedure used to diagnose it? A. Cryptosporidium ::: acid-fast stain of stool sample B. Schistosoma haematobium ::: microscopic examination of urine sample C. Echinococcus granulosus ::: routine ova screen D. Taenia solium ::: microscopic examination of stool sample

C (instead, they actually resemble the eggs of tapeworm species, namely fish tapeworms - you'll need a specialist to tell them apart, but the buzzword for the eggs is 'operculated', meaning they look like they have little caps on ONE end [as opposed to having caps on BOTH ends, which is a trait of whipworm eggs])

Which of the following is false about the family represented by the pictured organism? A. Infection can cause symptoms ranging from biliary fibrosis and diarrhea to nasopharyngeal obstruction B. Its standard life cycle involves the infection of at least three hosts, one definitive and two intermediate C. The eggs produced by the species of this family greatly resemble those of the threadworm species D. The drug of choice for treatment of infection is praziquantel

E (the dwarf tapeworm, Hymenolepis nana, has a direct life cycle - it only infects one host, which serves as both the definitive and intermediate host - typically rats and humans)

Which of the following is false regarding cestode reproduction? A. Cestodes can reproduce sexually or asexually B. Cestodes require a definitive host for their sexually mature stage to survive C. Cestodes are hermaphrodites D. The proglottids contain both male and female gonads, and each individual proglottid is capable of making numerous eggs E. All species of tapeworm require an intermediate host separate from their definitive host to complete their life cycle

E (this is a Giardia intestinalis cyst, which colonizes the duodenum, is not-invasive and therefore does not cause bloody diarrhea) (the symptoms are caused by the trophozoite stage of the organism, NOT the cyst)

Which of the following is false regarding the pictured organism and life cycle stage? A. It is in the infective stage B. It is in the sexually mature stage C. It is in the environmentally resistant stage D. It is transmitted fecal-orally E. It causes bloody diarrhea as a chief symptom

A (E. granulosus forms a cyst with a capsule that settles in the liver and is treatable - E. multilocularis forms cysts with no capsules in multiple locations, and is usually fatal)

Which of the following is most characteristic of Echinococcus worms? A. Hydatid cysts B. Cutaneous larva migrans C. Predisposition to hepatic and cystic cancer D. Charcot-Layden crystals E. Eggs in the urine

D (flukes are members of the phylum Platyhelminthes, all of whom are unsegmented flatworms)

Which of the following is not a morphological feature of an intestinal fluke? A. Leaf-shaped B. Dorsoventrally flattened C. Oral and ventral suckers D. Segmented E. Unbranched digestive system

A (diarrhea is a pathologic effect of protozoans, bacteria, and viruses - things that alter the biochemistry of the GI tract with toxins and virulence factors to cause nutrient or water loss - helminths just attach and suck, or migrate, until they can reproduce and pass out eggs)

Which of the following is not a pathological effect of helminth infections? A. Diarrhea B. Hemorrhage C. Enlargement and swelling of organs D. Anemia E. Weight loss

D (you see ascariasis, you should think viscera larva migrans - Ascaris doesn't hang out in the skin, ever - the egg is ingested, hatches, migrates to the liver, migrates to the lung, gets coughed up and reswallowed) (this is a big worm, and one of the most prevalent global parasites - can be easily fatal by causing intestinal obstruction by sheer volume of worm bolus - the female lays 200,000 eggs a day, and the eggs can remain viable in the soil for 10 years)

Which of the following is the correct path of travel for the parasite Ascaris lumbricoides upon infecting a host? A. Skin B. Skin -> Muscle C. Skin -> Intestine -> Liver -> Lung D. Intestine -> Liver -> Lung -> Intestine E. Intestine -> Liver

A (the mnemonic is EAT - for enterobus, ascaris, and trichuris) (Strongyloides penetrates the skin, ascends into the lungs, and is swallowed, to reach the intestines)

Which of the following nematodes does not cause intestinal infection by ingestion of its eggs? A. Strongyloides B. Enterobus C. Ascaris D. Trichuris

C (Ascaris eggs require a period of development in soil before they are infective - ingesting the larva or unembryonated eggs will not get you sick)

Which of the following organisms and infections can occur under normal conditions but not in a hospital setting? A. Hymenolepis nana - dwarf tapeworm disease B. Taenia solium - cysticercosis C. Ascaris lumbricoides - ascariasis D. Enterobius vermicularis - pinworm infection

E (Giardia interferes with intestinal absorption - Plasmodium causes tissue absorption by lysing red blood cells)

Which of the following parasites is paired with its LEAST correct mechanism of pathogenesis? A. Diphyllobothrium latum ::: pernicious anemia B. Ascaris lubricoides ::: intestinal obstruction C. Hookworms ::: microcytic anemia D. Echinococcus granulosus ::: increased cranial pressure E. Giardia ::: tissue destruction

D (Chlorine does NOT kill Giardia - iodine does, as does boiling) (filters are somewhat effective, depending on the filter - giardia cysts are flexible and can pass through, but this is still more effective than chlorination)

Which of the following prevention and control methods on water against Giardia is LEAST effective? A. Filters B. Boiling C. Iodination D. Chlorination

C (over 50% in the Southern states, likely linked to livestock) (A; think pinworms) (B; for sexually active people, but women more than men, think trichomonas) (D; think cryptosporidium) (E; immune compromise increases risk to all parasitic infections, not just ascarids)

Which population of the US has the highest prevalence of ascariasis? A. Infants B. Sexually active women C. Southern farmers D. Sewage workers E. HIV positive patients

E (hookworms have a skin-lung-intestine path, and form their eggs in the lungs - contrast this with the Strongyloides, which use the rhabditiform larva instead and do not lay eggs)

You suspect your patient is infected with hookworms. Which of the following is the diagnostic stage for this pathogen? A. Cyst B. Procercoid C. Trophozoite D. Rhabditiform larva E. Egg

C (Anisakis worms, also called herring worms, use fish as paratenic hosts and marine mammals like whales and porpoises as definitive hosts - the human is an accidental host)

Your patient, Miles, has complaints of severe acute abdominal pain after eating ceviche, a Latin American dish that utilizes raw fish. A gastroscopic examination revealed the presence of parasitic helminth larva. Miles is which of the following for this parasite? A. Definitive host B. Paratenic host C. Accidental host D. Vector host E. Faculty awards host