110 - Eukaryotic Parasites Flashcards
Parenteric hiost
Host in which the parasite enters the body, doesn’t undergo development but remains infective
Intermediate host
Host in which development occurs but the parasite doesn’t reach sexual maturity
Definitive host
Host in which parasite reaches sexual maturity
Body louse
Pediculus humanis
Head louse
Pediculus capitis
Crabs
Pediculus pubis
Name for infection with lice
Pediculosis
What in a lice infection causes itching?
Itching caused by louse saliva when lice are attaching eggs to hair shaft
Distribution of louse infections
Worldwide
Symptoms of lice
1
2
3
1) Itch.
2) Macules.
3) Secondary infection.
What can lice be a vector for?
Rickettsia, spirochetes
Scabies Latin name
Sarcoptes scabiei (Arachnids, not insects)
Where do scabies live?
Live in tunnels in the epidermis.
Lay eggs as they burrow (moulting pouch).
Size of scabes
Less than 0.5mm in size
Where do scabies prefer to live?
Favours fingerwebs, elbows, axillae, genitals.
Scabies treatment
Single dose of Ivermectin.
Sterilise clothes and bedding
Diagnosis of scabies
Detection of mite in scrapings or biopsy
What are ticks important vectors for?
Viral
Rickettsial
Protozoal
Are humans the definitive host of ticks?
Often not.
What can ticks sometimes cause in humans?
Ascending paralysis
Type of contact that ticks have with humans
Brief contact. Take a blood meal and then drop off host
Distribution of ticks in Australia
Eastern Australia
Latin name for ticks
Ixodes holocyclus
Diagnosis and treatment of ticks
Detect, remove tick
Ticks responsible for paralysis
Females. Males don’t take a blood meal
Examples of pathogenic protozoal diseases
Malaria, amoebiasis, giardiasis, toxoplasmosis, trypanosomiasis
Protozoa
Unicellular, complex, eukaryotic
Most-common disease-causing protozoan in humans
Entamoeba histolytica
Where does E histolytica invade?
Invades tissues in the colon (faecal-oral transmission)
Symptoms of amoebiasis
Prolonged watery diarrhoea, liver abscess
Diagnosis of amoebiasis
Faecal cysts, serology (particularly after the diarrhoeal phase)
Amoebiasis treatment
Metronidazole + paromomycin, drainage of abscess
Immunity to amoebiasis
Poor. Reinfections common
Giardia intestinalis
1
2
3
1) Flagellate, primitive eukaryote.
2) Long-lived cysts, so can survive in environment for a long time.
3) Zoonotic
Giardia distribution
Worldwide
Symptoms of giardiasis
Diarrhoea, might be acute or chronic, with malabsorption.
Diagnosis of Giardia
Cysts in faeces
Treatment of Giardia
Tinidazole
Immunity to Giardia
Poor. Re-infeciton common
Toxoplasma gondii features
1
2
3
1) Obligate intracellular parasite
2) Infects all mammals, many birds
3) Most infections from undercooked meat
Length of Toxoplasma infection
Lifelong.
Usually asymptomatic in the immunocompetent
When can Toxoplasma be dangerous?
Immunocompromised (EG: HIV)
Congenital infection can be serious
How does Toxoplasma exist in host?
Circulates in blood, can infect almost any organ (forms cysts in tissues (EG: muscle)
Symptoms of Toxoplasma
Asymptomatic.
Sometimes CNS lesions, ocular disease in HIV
Treatment of Toxoplasmosis
Often nothing. Bactrim antibiotics if serious
Diagnosis of Toxoplasmosis
Serology
