Parasite (S-T) Flashcards
which causes sarcosystosis?
intracellular coccidian protozoan parasites;
genus Sarcocystis;
which species cause intestinal sarcocystosis?
how is it transmitted?
S. heydorni
S. hominis
S. suihominis
eating undercooked beef or pork
which species cause muscular sarcocystosis?
S. nesbitti
food, water, or soil contaminated with the feces from a reptilian sporocyst-shedding definitive host, likely snakes
which areas is sarcocystosis most reported?
tropics and subtropics, particularly in SE Asia;
recent outbreaks of muscular sarcocystosis in Malaysia
what are the symptoms of sarcocystosis?
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)
how to dianose sarcocystosis?
oocysts or sporocysts in stool confirmed by light or fluorescence microscopy;
how to treat sarcocystosis?
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.
what causes scabies?
human itch mite, Sarcoptes scabiei var. hominis
how are scabies transmited?
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.
what are the symptoms of scabies?
intense itching, especially at night;
papular itchy rash;
how to treat scabies?
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
how to treat crusted scabies?
permethrin + ivermectin;
daily full-body application for 7 days;
7 or less doses of oral ivermectin
what causes schistosomiasis (bilharzia and snail fever)?
helminth parasites of the genus Schistosoma;
how do you get schistosomiasis?
larval cercariae, found in contaminated bodies of freshwater, penetrate the skin
what is the intermediate host of schistosomiasis?
snail
where are schistosomiasis cases found?
85% Africa; prevalence rates can exceed 50% in local population
which schistosomiasis species are found in Africa?
Schistosoma mansoni
S. haematobium
what schistosoma species found in Brazil, Suriname and Venezuela?
S. mansoni
what schistosoma species found in the middle east?
S. haematobium
which schistosoma specis found in the Caribbean (Guadeloupe, Martinique, Saitn Lucia, Dominican Republic)?
S. mansoni
which schistosoma species found in China, Indonesia, Philippines?
S. japonicum
what are two other species of schistosoma in Cambodia and Laos and in parts of Central and West Africa?
S. mekongi
S. intercalatum
what are some African transmission sites frequently visited by travelers that can cause schistosomiasis?
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
what is the incubation period of schistosomiasis?
incuation 14-84 days for acute schistosomiasis, and chronic asymptomatic infection can persist for years;
what is acute schistosomiasis called? symptoms?
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
what is the cause of chronic schistosomiasis?
result of host immune responses to schistosome eggs;
eggs lodged in the capillaries of organs and cause granulomatous reactions;
where do S. japonicum and S. mansoni eggs most commonly lodge in the body?
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
where do S. haematobium eggs typically lodge in?
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
what is the rare consequence of schistosomiasis?
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
how to diagnose schistosomiasis?
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.
how to treat schistosomiasis?
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
how to prevent schistosomiasis?
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)
what causes strongyloidiasis?
intestinal nematode, Strongyloides stercoralis
how do you get strongyloidiasis?
contaminated soil, filariform larva can penetrate human skin;
person-to-person is rare
what is global prevalence of strongyloidiasis?
30-100 million
where is strongyloidiasis endemic to?
tropics and subtropic;
Appalachia and the SE United States
what are the acute symptoms of strongyloidiasis?
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
what are the chronic symptoms of strongyloidiasis?
migrating larvae in the skin can cause larva currens, a serpiginous urticarial rash on the perineum or upper thighs
who is at risk for hyperinfection or disseminated disease of strongyloidiasis?
what are the symptoms?
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
how to diagnose strongyloidiasis?
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
how to treat strongyloidiasis?
ivermectin;
albendazole (lower cure rates)
which cause human taeniasis?
Taenia spp -
T. asiatica;
T. saginata (beef tapeworm);
T. solium (pork tapeworm)
where is the Taeniasis prevalence greatest?
Africa, Latin America, South and Southeast Asia;
lower rates - Eastern Europe, Iberian Peninsula (Portugal and Spain)
what are the symptoms of taeniasis?
abdominal discomfort, anorexia, diarrhea, insomnia, nausea, nervousness, perianal pruritus, weakness, weight loss
how to diagnose taeniasis?
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
how to treat taeniasis?
praziquantel (except for symptomatic neurocysticercosis);
Niclosamide is an alternative
what causes toxoplasmosis?
Toxoplasma gondii - intracellular coccidian protozoan parasites
how do you get toxoplasmosis?
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
where is toxoplasmosis endemic to?
worldwide - greater risk in developing and tropical countries
what is the incubation period of toxoplasmosis?
5-23 days
what are the symptoms of toxoplasmosis?
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
what is the risk of toxoplasmosis through congenital toxoplasmosis?
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.
what is the treatment of toxoplasmosis?
pyrimethamine, sulfadiazine, leucovorin (folinic acid)
pyrimethamine, atovaquone, azithromycin or clindamycin
what is the prevention of toxoplasmosis?
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
what are the species and 2 subspecies that cause African trypanosomiasis?
Trypanosoma brucei - T. brucei rhodesiense and T. brucei gambiense
how do you get African trypanosomiasis?
bite of an infected tsetse fly (Glossina spp.)
where is African trypanosomiasis endemic to?
rural sub-Saharan Africa
where is T. brucei rhodesiense reported in?
eastern and southeastern Africa - malawi, Tanzania, Uganda, Zambia, Zimbabwe
where is T. brucei gambiense reported in?
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
In 2018, WHO received 4,977 reports of sleeping sickness cases from African countries; —- accounted for 98% of cases.
T. brucei gambiense
where do Tsetse flies inhabit ?
Tsetse flies inhabit rural areas, including forests and savannah areas, and areas of thick vegetation along rivers and waterholes, depending on the fly species.
when dose Tsetse flies bite?
during the day
who is at risk of getting bitten by tsetse flies?
hunters and villagers with infected cattle herds. Tourists and other people working in or visiting game parks are at risk for contracting African trypanosomiasis
clinical symptoms from T. brucei rhodesiense?
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.
clinical symptoms from T. brucei gambiense?
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.
how to treat African trypanosomiasis?
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
what causes Chagas disease?
Trypanosoma cruzi - protozoan parasite
waht is the other name of Chagas disease?
American trypanosomiasis
how do you get Chagas disease?
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
T. cruzi is endemic to ?
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
acute symptoms of Chagas disease?
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.
chronic symptoms of Chagas disease?
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.
how to diagnose Chagas disease?
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.
how to treat Chagas disease?
benznidazole (ok to use in kids 2-12 yrs);
nifurtimox (ok to use from birth>2.5kg to <18 years old)
