parasitic infections - dr mcquaid

what is a parasite?

organism that lives on or in another organism and harms it

-parasite benefits from relationship

-host is harmed/injured

the extent of host harm in a host-parasite relationship depends on _________

parasitic load

host’s nutritional status

host’s immunologic function

parasite replicates within the host

a. definitive host

b. intermediate host

c. reservoir host

d. vectors

a.

larva and other asexual stages of parasite life cycle occur within the host

a. definitive host

b. intermediate host

c. reservoir host

d. vectors

b.

carry or harbor parasites that may cause diseasse to a secondary host

a. definitive host

b. intermediate host

c. reservoir host

d. vectors

c.

can be a definitive or intermediate host, aid in transmission of parasite to secondary host

a. definitive host

b. intermediate host

c. reservoir host

d. vectors

d.

list the protozoa

giardia

entamoeba

babesia species

trypanosoma cruzi

plasmodium species

list the helminths

hookworms

ascaris lumbricoides “round worm”

enterobius vernicularis “pin worm”

taenia solium “tape worm”

list the ectoparasites

sarcoptes scabei “scabies”

pediculus humanus capitis “lice”

what is the most common cause of parasitic diarrhea?

giardia lamblia

what are high-risk groups for giardia lamblia?

< 10 y.o.

travelers

international adoptees

immunocompromised

CF

how is giardia lamblia transmitted? (SATA)

a. waterborne

b. airborne

c. foodborne

d. person-person

a. —major

c.

d.

what are common signs/symptoms of giardia lamblia?

diarrhea

malaise

fever

N/V

weight loss

flatulence

abdominal cramping

bloating

what are symptoms of chronic giardiasis?

profound weight loss: 10-20% body weight

stunted growth (children)

depression

loose stools

steatorrhea

flatulence

when can you suspect giardiasis?

foul-smelling, fatty diarrhea > 1 week

sx of chronic giardiasis with risk factors

what is the preferred treatment for giardia lamblia?

tinidazole

what are tx options for giardia lamblia in pregnant women in the first trimester?

paramomycin

what are the tx options for giardia lamblia in pregnant women in the 2nd or 3rd trimester?

metronidazole (flagyl)

tinidazole (alternative if flagyl is CI)

T/F you should wait to treat giardia lamblia until diagnosis is confirmed

TRUE

list counseling points for giardia lamblia tx

avoid natural water and swimming pools ≥ 2 weeks

admin with food

list risk factors for entamoeba hystolytica

tropical and subtropical low income countries

-migrants/travelers

genetic susceptibility

age

immune status

how is entamoeba hystolytica transmitted? (SATA)

a. waterborne

b. airborne

c. foodborne

d. person-person

a.

c.

d.

what is the more common presentation for entamoeba hystolytica?

a. asymptomatic

b. symptomatic

a. asymptomatic

90% of infections

what are the symptoms of entamoeba hystolytica (amebiasis)?

hallmark symptom?

bloody diarrhea: hallmark

abdominal cramps

flatulence

stomach ulcers

weight loss

what is the preferred testing for entamoeba hystolytica (amebiasis)?

a. PCR

b. ELISA

c. antigen

d. serologic

c.

tx of entamoeba hystolytica (amebiasis) is based on severity of symptoms

when do we treat with luminal amebicides vs tissue amebicides?

asymptomatic or mild GI symptoms: luminal amebicides

severe GI symptoms: tissue amebicides

list luminal amebicides tx options for amebiasis

remember: you use luminal amebicides for asymptomatic or mild GI sx

paramomycin (preferred for all and pregnancy)

iodoquinol

diloxanide furoate

list tissue amebicides tx options for amebiasis

remember: you use tissue amebicides for severe GI sx

metronidazole (preferred)

tinidazole

DO NOT TREAT IN PREGNANCY

what babesia species is most common in the US?

how is it transmitted?

babesia microti

transmission vectors: black-legged or deer ticks

how do you treat mild-moderate babesia microti?

severe illness?

mild-moderate: PO azithromycin or atovaquone

severe: IV azithromycin + atovaquone

how do you treat asymptomatic babesia microti?

pregnant pts?

asymptomatic: no tx

pregnant: IV clindamycin + quinine

what is the cause of Chagas disease?

how is it transmitted?

trypanosoma cruzi

transmission: triatomine bug

how can trypanosoma cruzi (Chagas disease) manifest?

cardiomyopathy

GI disease

list the antitrypanosomal drugs (trypanosoma cruzi)

benznidazole

nifurtimox

what is the vector of transmission for plasmodium causing malaria?

what is the most common species?

what species exhibits the highest mortality rates?

vector: anopheles mosquito

common: p. vivax

highest mortality: p. falciparum

list the phases of malaria and what symptoms they are associated with

prodromal phase: HA, anorexia, malaise, farigue, myalgia, fever, chills, rigor

cold phase: cyanosis of lips, severe pallor

hot phase: severe fever

sweating phase: 2-6 hours after hot phase, fatigue, tachycardia, delirium, N/V/D

what is the gold standard for diagnosing malaria?

microscopy

T/F the preferred first-line agent for malaria prophylaxis is doxycycline

FALSE

no preferred first-line agent

who needs to have a weekly regimen for malaria prophylaxis?

pregnant women

list DAILY malaria prophylaxis options

atovaquone/proguanil

doxycycline

primaquine

who is atovaquone/proguanil CI in?

pregnancy

< 30 mL/min

primaquine is most effective against ________ and CI in ________

effective: P. vivax

CI: pregnancy, G6PD-deficiency

list WEEKLY malaria prophylaxis options

mefloquine

chloroquine

who is mefloquine CI in?

administer with _________

CI: psychiatric disorders or seizure disorders

admin with food and 240 mL water

what does choice of tx for malaria infections depend on?

species

location and local resistance rates

severity

list treatment options for malaria (mild-moderate)

atovaquone/proguanil

quinine sulfate + doxy or tetra or clinda

mefloquine

chloroquine

hydroxychloroquine

what is the preferred treatment for malaria (severe)?

what is used outside of the US if it’s not available?

preferred: artesunate IV

outside US: artemether IM or quinine IV

what tx for malaria (severe) is used if we know there is p. falciparum artemisinin resistance?

artesunate IV + quinine IV

how are hookworms and ascaris lumbricoides diagnosed?

microscopy: visualization of organisms in stool sample

what is the biggest risk factor for hookworm transmission?

walking barefoot in soil

compare symptoms from hookworms vs ascaris lumbricoides

hookworms: itching, localized irritation, abdominal pain, diarrhea, anemia, protein deficiency

ascaris lumbricoides (usually asymptomatic): intestinal blockage, impaired growth in children, migrates to lungs: pneumonitis, cough

how do you treat hookworms and ascaris lumbricoides?

mebendazole (emverm)

how do you treat hookworms and ascaris lumbricoides in pregnancy?

postpone tx until 3rd trimester

mebendazole

list counseling points for mebendazole

without regard to food

tablets may be swallowed whole, chewed, crushed, or mixed with food

ADRs: GI upset

what helminth is highly contagious, especially within households?

enterobius vermicularis

“pinworms”

how do you diagnose enterobius vermicularis (pinworms)?

tape test

-apply to perianal region for 3 consecutive nights

-visualize under microscope

list tx options for enterobius vermicularis (pinworms)

pyrantel pamoate: OTC

mebendazole

albendazole

when can enterobius vermicularis (pinworm) tx be given in pregnancy?

2nd and 3rd trimester if benefit outweighs risk

albendazole should be given with _______ to increase absorption

high-fat meal

if Larry’s son, Michaelangelo, has pinworms, who needs to be treated?

a. just Michaelangelo

b. no one

c. the whole school

d. all members of the household

d.

what should you counsel pts on with enterobius vermicularis (pinworms)?

hand hygiene

fingenail care

clean bedding, underwear in HOTTEST water possible

shower often

sanitize toys

self tx: if symptoms persist, seek medical care

how do you diagnose tapeworms?

microscopy

-3 stool samples collected from 3 different days

list tx options for taenia solium (tapeworms)

praziquantel (preferred)

albendazole

list counseling points for praziquantel

do NOT chew tablets

admin with water, 30 minutes prior to OR 2 hours after a meal

how is pediculus humanus captitis (head lice) transmitted?

direct contact with the head of infected persons

what is pruritus caused by when a pt has head lice (pediculus humanus captitis)?

allergic reaction to lice saliva

how do you diagnose head lice (pediculus humanus captitis)?

wet or dry combing

wet combing is preferred

what are treatment options for lice (pediculus humanus captitis)?

permethrin 1% (Nix, Elimite) RX

malathion (ovide)

spinosad (natroba)

ivermectin (soolantra) RX
sklice OTC

how do you use lice treatment?

apply to dry hair and massage thoroughly

leave on for 10 minutes, then rinse

allow to dry naturally

may repeat in 7 days if live lice are seen

how is sarcoptes scabei (scabies) transmitted?

person-person through skin contact

how do you diagnose scabies (sarcoptes scabei)?

microscopy

skin scrapings to identify mites, eggs, or mite fecal matter

what are tx options for scabies (sarcoptes scabei)?

permethrin (preferred)

crotamiton (only if intolerance to permethrin)

how do you apply permethrin cream for scabies?

massage into skin from hairline to soles of feet

wash off 8-14 hours after application

repeat in 2 weeks, if needed

how do you apply crotamiton cream for scabies?

massage into skin from hairline to soles of feet

adults: wash off 24 hours after application, repeat in 2-4 weeks PRN

children: apply once daily x 3 days, do NOT rinse between applications, rinse 48 hours after final application, repeat in 1 week PRN

list counseling points for permethrin and crotamiton

avoid contact with eyes and mucous membranes

wear gloves while applying

clean or dispose of bedding and personal hygiene products