Parasites 2

Question 1

GI parasitic disease

Answer 1

• protozoa and helminths
• prevalent in developing countries
• protozoan more common in developed countries than helminths
• significant morbidity and mortality in endemic countries
• 90% of pops in developed countries probably have them
• enterobius vermicularia, giardia, ancyclostoma duodenale, necator americanus, entamoeba histolytica, cryptosporidium

Question 2

entamoeba species

Answer 2

• some are pseudopod forming
• e histolytica is parasitic, brother is e dispar
• e coli and polecki mean contaminated water

Question 3

e histolytica

Answer 3

• fecal oral
• poor hygiene during food prep
• night soil
• oral anal
• crowding and poor sanitation in asia, africa, latin america
• 10% worlds pop infected, 90% asymptomatic
• 50 million symptomatic, 100,000 fatal
• second leading cause of protozoan death

Question 4

life cycle of e histolytica

Answer 4

• trophozoites in hosts large intestine and cysts in feces
• can infect liver and lungs
• pseudomembranous colitis

Question 5

amebiasis and e histolytica

Answer 5

• intraluminal and disseminated
• disrupt protective layer-bloody diarrhea 2-6 weeks, malaise, weight loss, pain, fever
• trophozoites penetrate intestinal wall spread through the body via portal circulation-abscesses, they can rupture

Question 6

hepatic disease from e histolytica

Answer 6

• hematogenous spread to liver
• 5%
• visualized radiologically, sonically, or by radionuclear scan- abscess in right lobe
• rupture into pleural space

Question 7

giardia lamblia

Answer 7

• zoonosis, cross infectivity among beaver, cattle, dogs, rodents, bighorn sheep
• common cause of travelers diarrhea, world wide
• most common in world, second most common in US after pinworm

Question 8

giardia transmission

Answer 8

• in the US, very common
• direct between children or sex partners or indirectly though contaminated food or water
• cysts are hardy and can survive several months in cold water
• drinking contaminated water from beaver dam or raccoons

Question 9

clinical presentation of giardia

Answer 9

• oral ingestion
• incubation of 1-2 weeks
• diarrhea, abd cramps, bloating, flatulence
• malaise, nausea, anorexia, sulforic belching
• vomiting, fever, tenesmus less common
• stools profuse and watery and then commonly greasy and foul smelling and float

Question 10

cryptosporidium parvum

Answer 10

• worldwide
• waterborne in milwaukee in 93
• water diarrhea, dehydration, weight loss, abd pain, fever, nausea, vomiting
• in immunocompetent persons, symptoms short lived, worse in immunocompromised patients

Question 11

transmission of cryptosporidium

Answer 11

• recreational water places
• as few as 4 oocytes needed
• confusing

Question 12

cryptosporidiosis

Answer 12

• mean incubation period between infection and onset of symptoms is 7-14 days
• immunocompetent-asymptomatic shedding to severe for 3 months
• HIV is worse

Question 13

trichomonas vaginalis

Answer 13

• infection acquired through sexual intercourse
• site specific, can’t survive outside UG system
• proliferation after introduction- IF and large numbers of trophozoites

Question 14

t vaginalis infection

Answer 14

• men generally asymptomatic, 25-50% of women exhibit symptoms
• dysuria, vaginal itching and burning, foamy yellowish green discharge with a foul odor
• in many women infection becomes symptomatic and chronic with periods of relief in response to therapy
• recurrences of infection may be from asymptomatic partner or failure of metronidazole
• symptoms in men-prostatitis, urethritis, epididymitis, urethral stricture

Question 15

ascariasis

Answer 15

• most common helminthic infection of humans, >1/4 pop
• live and mate in lumen of small intestine
• each female has daily output of 200,000 ova or more
• eggs embryonate and become infective only on soil in warm humid environments
• nematode

Question 16

ascaris lifecycle

Answer 16

• eggs pass in feces and embryonate in soil in 10-14 days
• upon ingestion the egg hatches in intestine and liberated larva penetrates mucosa and passes to the liver via portal vessels and then into lungs
• larvae penetrate alveolar air sac and is coughed up and swallowed
• become sexually mature in small intestine and produce eggs in 60-75 days
• if not good cough reflex worms can come out nose
• heavy infections can cause blocking, must deworm

Question 17

trichuriasis

Answer 17

• humid tropical environments and temperate zones-SE US in warm humid monthes
• most people have less than 20 worms, some children have more than 200
• human whipworm
• nematode

Question 18

trichuria life cycle and clinical manifestations

Answer 18

• ingestion of eggs from soil
• no symptoms or peripheral blood eosinophilia
• in heavy infections, mucosa is inflamed, edematous and friable
• high worm burden in children can lead to rectal prolapse and growth retardation

Question 19

hookworm

Answer 19

• two nematodes=ancyclostoma duodenale and necator americanus
• 1/4 worlds pop
• low prevalence in pockets of SE US

Question 20

hookworm life cycle

Answer 20

• eggs are passed in stool and hatched in warm moist shade in 1-2 days
• the released rhabditiform larvae grow in the feces/soil after 5-10 days then become filariform larvae that are infective
• on contact with the human host, the larvae penetrate the skin and are carried in the veins to the heart and lungs
• they penetrate pulm alveoli and are coughed up and swallowed
• larvae reach the small intestine where they reside and mature into adults

Question 21

hookworm clinical manifestations

Answer 21

• most persons harbor light infections and are asymptomatic
• persons infected with adult hookworms may have chronic abd pain and persistant eosinophilia
• iron deficiency anemia and protein energy malnutrition
• anemia depends on intensity and duration
• blood loss is gradual and body can adapt

Question 22

enterobuis vermicularia

Answer 22

• pinworm
• common in kids
• most asymptomatic
• perianal and perineal pruritus and scratching
• perianal pruritus at night, lead to excoriations and bacterial superinfection
• invasion of female genital tract
• anorexia, irritability, abd pain

Question 23

pinworm life cycle

Answer 23

• gravid females migrate nocturnally outside the anus and oviposit while crawling on skin of perianal area
• larvae develop in 4-6 hours
• retroinfection may occur
• self infection by transferring eggs to mouth

Question 24

intestinal cestodes

Answer 24

• tapeworms
• t saginata and t solium
• humans only- contaminate soil
• cows and pigs infected after feeding in that area
• in cow and pig, cysts enter meat and cause cysticercosis
• raw or undercooked and humans become infected

Question 25

saginata and solium

Answer 25

• no symptoms or mild
• saginata have more symptoms because larger 10 m vs 3 m
• cause digestive problems including abd pain, loss of appetite, weight loss, upset stomach
• active passing of proglottids through anus and in feces
• pigs/cattle intermediate host
• humans can be intermediate for pork worms
• painful cysticeri- autoinfection
• pork in mexico, central america, south america, africa, southeast asia, india, philippines, southern europe

Question 26

cysticercosis

Answer 26

• tissue infection with larval cysts from t solium
• multiple cysts in many parts
• neurocysticercosis is CNS
• intracerebral lesions- mass effects, seizures, both
• obstruction of CSF flow or meningeal irritation
• injury of local blood vessels, cranial nerves, brain stem

Question 27

diphyllobothrium latum

Answer 27

• fish tapeworm
• uncooked freshwater fish with cysts
• 3-6 weeks after exposure, may survive for 30 years
• poop-crustacean-small fish-big fish