ID Flashcards
Protozoan parasites
Hunans and Dogs as resivour, transmitted by sandflies
Most infections asymptomatic
Cutaneous: pink-colored papule, develops into a nodule or plaque-like lesion, leading to a painless ulceration ITCHY (ddx scabies)
Visceral: “black fever” slow progression of malaise, fever, weight loss, and SPLENOMEGALY +/- hepatomegaly over a period of months
Histo splenic aspirate: amastogotes - small spherical or oval bodies
Urine antigen test gold standard
What is the organism and Rx?
Leishmani
Local - Pentavalent antimonials, Paromomycin ointment
Systematic - azoles/Miltefosine
Sub-saharan Africa - blackfly/simulin fly bite, Filarial worm
Eye involvement, subcutaneous nodules, skin involvement, and systemic manifestations, including epilepsy
Skin snip biopsy: adult parasites (macrofilariae)
Slit-lamp examination: wriggling microfilariae within the anterior chamber
What is the organism and Rx?
Onchocerciasis “River blindness”
Ivermectin
Cerebral malaria
Ring-form trophozoites (rings) in normal sized RBCs
?severe malaria
Plasmodium falciparum
Impaired LOC, generalised weakness, >2 convulsions in 24hrs, acidosis, hypoglycemia, severe anaemia, renal impairment, jaundice, pulmonary oedema, bleeding, shock
high level of parasitemia
IV artesunate
Uncomplicated - artemether + lumefantrine
Oval shaped RBC with tufted ends
Plasmodium ovale
Amoeboid shaped trophozoites
Plasmodium malaria
Tropical climate - Asia 73%, Africa 12%
Most common 2-10yo
Most asymptomatic
Early phase - transient respiratory symptoms and eosinophilic pneumonitis. dry cough, dyspnea, fever, wheezing), characteristic radiographic findings (migratory bilateral round infiltrates),
Late phase - abdominal discomfort, anorexia, nausea, vomiting, and diarrhea, obstruction of the intestine, biliary, and/or pancreatic duct
?Rx
Ascariasis lumbricoides
“round worm”
Resp - supportive care
Intestinal - albendazole 400mg (<10kg 200mg) once
Thin white strands in stool
Itchy bum
Microscopy - Bean shaped eggs.
? Rx
Enterobius vermicularis “pinworm/threadworm”
Albendazole once
Tropics, poor hygiene
Loose stool with mucous
Rectal prolapse
Microscopy - barrel shaped worms
Rx?
Trichuris “whipworm”
Albendazole 3 days
Anaemia and poor growth
Eosinophilia
1) Mediterranean, Iran, India, far east?
2) Africa, America’s, south pacific islands, Indonesia?
Rx?
Chronic hookworm infection
1) acylostoma duosenale
2) necator Americans
Albendazole once
Tropical and subtropical areas - northern Australia,refugees
Upper abdominal pain, skin itch, ‘larva currens’ (serpiginous raised rash commonly on the buttocks) or transient pulmonary symptoms
Full blood examination (FBE) commonly shows eosinophilia.
Ix?
Rx?
Chronic strongyloides
Pulm SX (as worms are coughed up).
ELISA(for IgG to filariform larvae) -positive serology represents active infection.
Faecal PCR for Strongyloides is specific, but less sensitive.
Ivermectin 200 mcg/kg orally on day 1 and day 14 (2 doses total)
Albendazole in <15kg for 7 days
Immunosuppressed patient
Sub tropical/tropical soil
fever, vomiting, diarrhoea, abdominal pain and respiratory symptoms (cough, wheezing, shortness of breath and haemoptysis).
CXR - pulmonary infiltrates
Ix?
Rx?
Strongyloides hyperinfection
Disseminated disease consists of hyperinfection with spread of larvae to organs and tissues outside those in the autoinfection cycle
extraintestinal bacterial infection such as pneumonia, meningitis, or sepsis.
60% mortality
Screening is by serology - ELISA(for IgG to filariform larvae) -positive serology represents active infection.
Stool PCR less sensitive
ivermectin(adult and child 15 kg or more) 200 micrograms/kg orally or enterally with fatty food, daily until symptoms resolve and stool or sputum microscopy demonstrates clearance of larvae
FOLLOWED BY TWO FURTHER DOSES:
ivermectin(adult and child 15 kg or more) 200 micrograms/kg orally or enterally with fatty food, daily on days 7 and 8 after completion of daily therapy.
Prophylaxis for endemic areas (remote indigenous communities)
ivermectin(adult and child 15 kg or more) 200 micrograms/kg orally with fatty food, once every 3 months
Complications of congenital Zika
Microcephaly and intracranial calcifications are classical for Zika.
Congenital zika can affect the developing brain. The child can present with abnormal neurology including seizures and spasticity (anthrogryposis). Feeding difficulties and developmental delay may be present.
Due to abnormal neurology within the uterus, contractures and limb abnormalities are seen.
Visual abnormalities have been described including macular changes.
Most common travellers diarrhoea
ETEC (enterotoxigenic e. coli)
ETEC is the most common cause of traveller’s diarrhoea in both adults and children worldwide, and is thus the most likely causative organism in this instance. A notable exception is South East Asia, where campylobacter is now more common.
ETEC commonly causes watery diarrhoea and abdominal cramping, sometimes with associated vomiting. It occasionally causes fever.
High fever or bloody diarrhoea should raise the possibility of more invasive organisms, such as Campylobacter jejuni or S. typhi.
Empiric antibiotics for peritonitis in patient on peritoneal dialysis
Intraperitoneal cephazolin
Most common cause of occult bacteremia in children
E coli, Staph aureus
