Parasite (S-T)

Question 1

which causes sarcosystosis?

Answer 1

intracellular coccidian protozoan parasites;
genus Sarcocystis;

Question 2

which species cause intestinal sarcocystosis?
how is it transmitted?

Answer 2

S. heydorni
S. hominis
S. suihominis

eating undercooked beef or pork

Question 3

which species cause muscular sarcocystosis?

Answer 3

S. nesbitti

food, water, or soil contaminated with the feces from a reptilian sporocyst-shedding definitive host, likely snakes

Question 4

which areas is sarcocystosis most reported?

Answer 4

tropics and subtropics, particularly in SE Asia;
recent outbreaks of muscular sarcocystosis in Malaysia

Question 5

what are the symptoms of sarcocystosis?

Answer 5

most asymptomatic, or mild gastroenteritis, but severe illness has been described;
self-limited in immunocompetent hosts

symptoms: arthralgia, cough, fatigue, fever, headahe, myalgias; less frequent symptoms include diarrhea, nausea, vomiting, lymphadenopathy, rash, wheezing, cardiac involvment (palpitation)

Question 6

how to dianose sarcocystosis?

Answer 6

oocysts or sporocysts in stool confirmed by light or fluorescence microscopy;

Question 7

how to treat sarcocystosis?

Answer 7

no proven treatment;
trimethoprim-sulfamethoxazole might act against schizonts in the early phase of muscular sarcocystosis;
glucocorticoids and NSAIDS can improve the symptoms associated with myositis.

Question 8

what causes scabies?

Answer 8

human itch mite, Sarcoptes scabiei var. hominis

Question 9

how are scabies transmited?

Answer 9

Direct transmission of conventional scabies occurs after prolonged skin-to-skin contact with a person infested with the mite.

Crusted scabies, by contrast, is more contagious than conventional scabies.

Although <20 mites typically are found on a host with conventional scabies, a person with crusted scabies, formerly called Norwegian scabies, can harbor thousands of mites in just a small area of skin. The large number of mites present in crusted scabies greatly increases the chances that a person with crusted scabies will pass mites to others by both direct and indirect routes of transmission.

Question 10

what are the symptoms of scabies?

Answer 10

intense itching, especially at night;
papular itchy rash;

Question 11

how to treat scabies?

Answer 11

permethrine 5% cream;
ivermectin

permethrine - apply from neck down, left on 8-12 hours or overnight; wash off; 2nd application after 1 week
-treat household members and close contacts

ivermectin - 200 ug/kg, repeated after 1-2 weeks; oral ivermecti should not be used in children weight <15kg or in pregnant people

Question 12

how to treat crusted scabies?

Answer 12

permethrin + ivermectin;
daily full-body application for 7 days;
7 or less doses of oral ivermectin

Question 13

what causes schistosomiasis (bilharzia and snail fever)?

Answer 13

helminth parasites of the genus Schistosoma;

Question 14

how do you get schistosomiasis?

Answer 14

larval cercariae, found in contaminated bodies of freshwater, penetrate the skin

Question 15

what is the intermediate host of schistosomiasis?

Answer 15

snail

Question 16

where are schistosomiasis cases found?

Answer 16

85% Africa; prevalence rates can exceed 50% in local population

Question 17

which schistosomiasis species are found in Africa?

Answer 17

Schistosoma mansoni
S. haematobium

Question 18

what schistosoma species found in Brazil, Suriname and Venezuela?

Answer 18

S. mansoni

Question 19

what schistosoma species found in the middle east?

Answer 19

S. haematobium

Question 20

which schistosoma specis found in the Caribbean (Guadeloupe, Martinique, Saitn Lucia, Dominican Republic)?

Answer 20

S. mansoni

Question 21

which schistosoma species found in China, Indonesia, Philippines?

Answer 21

S. japonicum

Question 22

what are two other species of schistosoma in Cambodia and Laos and in parts of Central and West Africa?

Answer 22

S. mekongi
S. intercalatum

Question 23

what are some African transmission sites frequently visited by travelers that can cause schistosomiasis?

Answer 23

Banfora regions (Burkina Faso) and areas populated by the Dogon people (Mali), Lake Malawi, Lake Tanganyika, Lake Victoria, the Nile River, the Omo River (Ethiopia), and the Zambezi River

Question 24

what is the incubation period of schistosomiasis?

Answer 24

incuation 14-84 days for acute schistosomiasis, and chronic asymptomatic infection can persist for years;

Question 25

what is acute schistosomiasis called? symptoms?

Answer 25

penetration of cercariae can cause a rash that develops within hours or up to a week after contaminated water exposure; Katayama syndrome - diarrhea, fever, headache, myalgia, respiratory symptoms Eosinophilia; painful hepatomegaly or splenomegaly also can occur

Question 26

what is the cause of chronic schistosomiasis?

Answer 26

result of host immune responses to schistosome eggs; eggs lodged in the capillaries of organs and cause granulomatous reactions;

Question 27

where do S. japonicum and S. mansoni eggs most commonly lodge in the body?

Answer 27

S. japonicum and S. mansoni eggs most commonly lodge in the blood vessels of the liver or intestine - blood in the stool, constipation, diarrhea; chronic inflammation can lead to bowel wall ulceration, hyperplasia, polyposis, and with heavy infections, to periportal liver fibrosis and splenomegaly

Question 28

where do S. haematobium eggs typically lodge in?

Answer 28

Urinary tract - cause dysuria and hematuria; calcifications in the bladder might appear late int eh disease. can cause genital symptoms and has been associated with increased risk for bladder cancer; eosinophilia might be present during chronic infection with any species

Question 29

what is the rare consequence of schistosomiasis?

Answer 29

CNS manifestation - adult worms or eggs migrate and deposit in the spinal cord or brain - ectopic granulomas in the CNS and can present as transverse myelitis

Question 30

how to diagnose schistosomiasis?

Answer 30

eggs in stool or urine; serologic tests are useful in light infections - egg shedding might not be consistent in travelers and in others who have not had schistosomiasis previously.

Question 31

how to treat schistosomiasis?

Answer 31

Praziquantel - most effective against adult forms of the parasite and requires a host immune response to the adult worm to be fully effective; repeat treatment might be needed after 2-4 weeks to increase effectiveness

Question 32

how to prevent schistosomiasis?

Answer 32

untreated piped water coming directly from freshwater sources could contain cercariae - fine-mesh filters, heat bathing water to 50 degress celcius for 5 minutes, allow water to stand for 24 hours, swim in chlorinated pools, vigorous towel-drying to remomve cercariae, DEET and inset repellents can block penetrating cercariae (but short-lived)

Question 33

what causes strongyloidiasis?

Answer 33

intestinal nematode, Strongyloides stercoralis

Question 34

how do you get strongyloidiasis?

Answer 34

contaminated soil, filariform larva can penetrate human skin; person-to-person is rare

Question 35

what is global prevalence of strongyloidiasis?

Answer 35

30-100 million

Question 36

where is strongyloidiasis endemic to?

Answer 36

tropics and subtropic; Appalachia and the SE United States

Question 37

what are the acute symptoms of strongyloidiasis?

Answer 37

most asymptomatic or minimal symptoms; acute infection - localized, pruritic, erythematous papular rash at the site of skin penetration, followed by pulmonary symptoms (a Loffler-like pneumonitis), abdominal pain, diarrhea, eosinophilia

Question 38

what are the chronic symptoms of strongyloidiasis?

Answer 38

migrating larvae in the skin can cause larva currens, a serpiginous urticarial rash on the perineum or upper thighs

Question 39

who is at risk for hyperinfection or disseminated disease of strongyloidiasis? what are the symptoms?

Answer 39

immunocompromised, especially those receiving systemic corticosteroids, HIV, hematologic malignancies, hematopoietic stem cell or organ transplants; abdominal pain, diffuse pulmonary infiltrates, septicemia, meningitis from enteric bacteria

Question 40

how to diagnose strongyloidiasis?

Answer 40

blood and stool testing; peripheral blood eosinophilia is often absent in hyperinfection and disseminated strongyloidiasis; rhabditiform larvae can be visualized on microscopic examinatin of stoo

Question 41

how to treat strongyloidiasis?

Answer 41

ivermectin; albendazole (lower cure rates)

Question 42

which cause human taeniasis?

Answer 42

Taenia spp - T. asiatica; T. saginata (beef tapeworm); T. solium (pork tapeworm)

Question 43

where is the Taeniasis prevalence greatest?

Answer 43

Africa, Latin America, South and Southeast Asia; lower rates - Eastern Europe, Iberian Peninsula (Portugal and Spain)

Question 44

what are the symptoms of taeniasis?

Answer 44

abdominal discomfort, anorexia, diarrhea, insomnia, nausea, nervousness, perianal pruritus, weakness, weight loss

Question 45

how to diagnose taeniasis?

Answer 45

edetecing eggs, proglottids (segments), or tapeworm antigens in the feces or on anal swabs; differrential diagnosis of Taenina spp. is based on morphology of the scolex and gravid proglottids

Question 46

how to treat taeniasis?

Answer 46

praziquantel (except for symptomatic neurocysticercosis); Niclosamide is an alternative

Question 47

what causes toxoplasmosis?

Answer 47

Toxoplasma gondii - intracellular coccidian protozoan parasites

Question 48

how do you get toxoplasmosis?

Answer 48

cat feces - ingestion of food, soil, or water contaminaed ; eat underooked meat or shellfish; congenital transmission from a person infected during or shortly before pregnancy; blood transfusions or organ transplantation

Question 49

where is toxoplasmosis endemic to?

Answer 49

worldwide - greater risk in developing and tropical countries

Question 50

what is the incubation period of toxoplasmosis?

Answer 50

5-23 days

Question 51

what are the symptoms of toxoplasmosis?

Answer 51

influenza-like symptoms or mononucleosis syndrome with prolonged fever, elevated liver enzymes, lymphadenopathy, lymphocytosis, weakness; rarely chorioretinitis or disseminated disease can occur in immunocompetent people; severe and even fatal encephalitis, pneumonitis, and other systemic illnesses can occur in immunosupp

Question 52

what is the risk of toxoplasmosis through congenital toxoplasmosis?

Answer 52

infants with eye disease, neurologic disease, or other systemic symptoms can occur, and cognitive deficits, learning disabilities or visual impairments could develop later in life.

Question 53

what is the treatment of toxoplasmosis?

Answer 53

pyrimethamine, sulfadiazine, leucovorin (folinic acid) pyrimethamine, atovaquone, azithromycin or clindamycin

Question 54

what is the prevention of toxoplasmosis?

Answer 54

change the litter box daily; avoid changing cat litter if pregnant or immunocompromised; wash hands after gardening, after contact with sand or soil, after changing cat litter

Question 55

what are the species and 2 subspecies that cause African trypanosomiasis?

Answer 55

Trypanosoma brucei - T. brucei rhodesiense and T. brucei gambiense

Question 56

how do you get African trypanosomiasis?

Answer 56

bite of an infected tsetse fly (Glossina spp.)

Question 57

where is African trypanosomiasis endemic to?

Answer 57

rural sub-Saharan Africa

Question 58

where is T. brucei rhodesiense reported in?

Answer 58

eastern and southeastern Africa - malawi, Tanzania, Uganda, Zambia, Zimbabwe

Question 59

where is T. brucei gambiense reported in?

Answer 59

central and west Africa - Democratic Republic of the Congo, Angola, Cameroon, Central African Republic, Chad, Congo, Cote d'Ivoire, Equatorial Guinea, Gabon, Guinea, South Sudan, (norther) Uganada, and other countries

Question 60

In 2018, WHO received 4,977 reports of sleeping sickness cases from African countries; ---- accounted for 98% of cases.

Answer 60

T. brucei gambiense

Question 61

where do Tsetse flies inhabit ?

Answer 61

Tsetse flies inhabit rural areas, including forests and savannah areas, and areas of thick vegetation along rivers and waterholes, depending on the fly species.

Question 62

when dose Tsetse flies bite?

Answer 62

during the day

Question 63

who is at risk of getting bitten by tsetse flies?

Answer 63

hunters and villagers with infected cattle herds. Tourists and other people working in or visiting game parks are at risk for contracting African trypanosomiasis

Question 64

clinical symptoms from T. brucei rhodesiense?

Answer 64

1-3 weeks after bite - painful chancre at the bite site, high fever, headache, myalgia, skin rash, thrombocytopenia, less commonly cardiac dysfunction, renal failure, splenomegaly Central nervous system (CNS) involvement can occur within a few weeks of the exposure and results in sleep cycle disturbance, mental deterioration, and, if left untreated, death within months.

Question 65

clinical symptoms from T. brucei gambiense?

Answer 65

appear months to years after exposure, but the incubation period can be <1 month. Signs and symptoms are nonspecific and can include arthralgia, facial edema, intermittent fever, headache, lymphadenopathy, malaise, myalgia, pruritus, and weight loss. CNS involvement occurs after several months to years of infection and is characterized by daytime somnolence and nighttime sleep disturbance, headache, and other neurologic manifestations (e.g., behavioral changes, mood disorders, focal deficits). In residents of endemic areas, the clinical course of disease caused by T. brucei gambiense generally progresses more slowly (estimated average total duration of 3 years) than that caused by T. brucei rhodesiense, but if not treated, both forms of African trypanosomiasis typically are fatal.

Question 66

how to treat African trypanosomiasis?

Answer 66

Pentamidine, the recommended treatment for first-stage T. brucei gambiense infection Nifurtimox Other drugs used to treat African trypanosomiasis (e.g., eflornithine [used in combination with nifurtimox], melarsoprol, suramin) are not commercially available in the United States but can be obtained from CDC

Question 67

what causes Chagas disease?

Answer 67

Trypanosoma cruzi - protozoan parasite

Question 68

waht is the other name of Chagas disease?

Answer 68

American trypanosomiasis

Question 69

how do you get Chagas disease?

Answer 69

triatomine insect (reduviid bug) feces; enter through the skin at the site of a reduviid bug bite, eyes with contaminated fingers, GI by eating food or beverages; also through blood transfusions, organ transplantation, mother to infant

Question 70

T. cruzi is endemic to ?

Answer 70

parts of Mexico and Central and South America; rare locally acquired Chagas disease cases have been reported in the southern United States. not in the Caribbean islands

Question 71

acute symptoms of Chagas disease?

Answer 71

Acute illness typically develops ≥1 week and ≤60 days after exposure. A chagoma (indurated local swelling) might develop at the site of parasite entry (e.g., Romaña’s sign, edema of the eyelid and ocular tissues). Most infected people never develop symptoms, but remain infected throughout their lives. Approximately 20%–30% of infected people develop chronic manifestations after a prolonged asymptomatic period.

Question 72

chronic symptoms of Chagas disease?

Answer 72

Chronic Chagas disease usually affects the heart; clinical signs include conduction system abnormalities, ventricular arrhythmias, and, in late-stage disease, congestive cardiomyopathy. Chronic gastrointestinal problems (e.g., megaesophagus, megacolon) are less common. and can develop with or without cardiac manifestations. Reactivation disease can occur in immunocompromised patients.

Question 73

how to diagnose Chagas disease?

Answer 73

During the acute phase, parasites can be detected in fresh preparations of buffy coat or stained peripheral blood specimens; PCR testing also can help detect acute infection. After the acute phase, diagnosis requires ≥2 serologic tests to detect T. cruzi–specific antibodies, most commonly ELISA, immunoblot, and immunofluorescent antibody test.

Question 74

how to treat Chagas disease?

Answer 74

benznidazole (ok to use in kids 2-12 yrs); nifurtimox (ok to use from birth>2.5kg to <18 years old)