Parasitology Flashcards
what is a parasite
an organism which lives in another ie host and bandits by deriving nutrients at the other expense
define these terms host symbiosis mutualism parasitism commensalism
an organism which harbours a parasite
living together, long term interaction between two different species
both species benefit from the interaction
parasite derives benefit from host but always suffers injury as a result
parasite deriving benefit without causing injury to host
what are the 3 classes of host
definitive host - either harbours in adult stage or utilises sexual method of reproduction
intermediate host - harbours lavae or asexual stage of parasite
paratenic - parasite remains viable without further development
what are the two types of parasite
(micro) protozoa: flagellates, amoeboids, sporozoans, trypanosomes
(macro) helminths: platyhelminths (flatworms), nematodes (round worms)
what are two types of helminth flat worms and round worms
flatworm - cestodes (tape worms), trematodes (flukes)
round worms - intestinal nematodes, tissue nematodes
what are the steps to approaching a parasite
distribution - where to find them (ie holidays etc)
life cycles (how they survive and breed)
clinical manifestations (affect open host)
diagnosis (how we identify them)
treatment (get rid)
control (prevent others getting infected)
what are the 4 lifecycles in parasitology
direct - only one host
indirect - more than one host
simple - one intermediate host
complex - two or more intermediate hosts
what is Ascariasis, what is the prevalence and likelihood of affliction, what is the life cycle
intestinal nematode (roundworm), affects 1/7 population, mainly in 3-8 y/o in poor areas of hygiene
acquired by ingestion of eggs - direct life cycle - ingest then get into lungs
what are the clinical manifestations of ascariasis
eosinophilia
(lung migration) Loefflers syndrome - dry cough, dyspnoea, wheeze
(intestinal migration) - mild symptoms
what is the treatment of ascariasis
albendazole - prevents glucose absorption by worm so starves
what is schistomiasis what causes it and what is the life cycle
bilharzia disease
mainy in africa - 200mil
flukes disease
chronic - can cause bladder cancer and liver cirrhosis
snails intermediate host - simple indirect cycle - penetrate skin and lay worms
what are the clinical manifestations of schistosomiasis (bilharzia disease)
swimmers itch, katayama fever
can be chronic due to eggs lain in spine and lungs
urinary - haematuria, bladder fibrosis and dysfunction
hepatic/intestinal - portal hypertension, liver cirrhosis, abdominal pain
what is the diagnosis of schistosomiasis
urinary - terminal stream microscopy, serology (doesn’t show if parasite active)
hepatic/intestinal - stool microscopy, rectal snip
what is the treatment of schistosomiasis
praziquantel
40-60mg/kg
chemical treatment to kill snails - chemoprophylaxis
what is hydatid disease
found where sheep are farmed all over world - humans are intermediate host as main is sheep and dogs
what are the clinical manifestations of hydatid disease
cysts on mainly liver, and lungs
may be asymptomatic but cysts can rupture = death
what is the diagnosis and control of hydatid
imaging and serology
regularly worm dogs to reduce eggs
what causes malaria and what is epidemiology
micro-parasite
4 species of plasmodium -eg falciparum, viva, ovale, malariae
300-500 mil every year
what i the life cycle of malaria infection
simple indirect
transmitted by anopheles mosquito as a vector
how does malaria kill RBC
mosquito injects sporozoites into RBC where is grows and kills them releasing daughter cell merozites
what is the clinical manifestation of malaria
inflammatory response
fever/rigors
confusion, headache
renal failure, pulmonary oedema, anaemia
if a returning travelling from a mosquito thriving country comes back with a fever what is the diagnosis
malaria until proven otherwise
what is the diagnosis for malaria
thick and thin microscopy, serology and detection of antigen, malarial DNA
what is the treatment or malaria
antimalarials:
non-falciparum = chloroquine and primaquine
falciparum - quinine and doxycycline, coartem, atovaquone
supportive therapy - management of seizures, pul oedema, acute renal failure
exchange of transfusion
what are the control measures for malaria
insecticide in homes, larvicidal spraying on breeding pools
chemoprophylaxis
what is crytosporidosis
caused by cryptosporidium parvum and hominis - microparasite
causes diarrhoea
what is the life cycle of cryptosporidosis
human excrete oocytes into environment - direct
what are the clinical manifestations of cryptospordosis
watery diarrhoea with mucus (no blood)
bloating, cramps, nausea
lasts up to 2 weeks
who are most at risk to cryptosporidosis
very young, old, immunocompromised
human-human spread disease, swimming pools, child care workers nursing homes
animal - human = hikers, farmers etc
what is the diagnosis of cryptosporodosis
acid fast staining and antigen detection by EIA
what is the treatment and control of cryptosporodosis
rehydration - nitazoxanide
immunocompromised - paromomycin to kill parasite and octreotide for cramps
HIV = HAART
control = isolation, hand hygiene, drinking hot water
animal - human - pasteurise milk and boil drinking water
What is trichomoniasis
trichomonas vaginalis - sexually transmitted
incubate 5-28 days
what are the symptoms and life cycle of trichomoniasis
men - asymptomatic - women smelly vagina, discharge, dysuria, lower abdominal pain, strawberry cervix
direct - sexually transmitted
what is the diagnosis and treatment of trichomoniasis
identification of organism in genital specimens
metronidazole - single or divided dose
what is giardiasis
flagellated protozon, faecal oral transmission
spectrum disease ie can be asym or severe diarrhoea
what are the symptoms of giardiasis
1-3 weeks, diarrhoea, abdominal pain, bloating nausea
what is the life cycle of giardiasis
infected adult passes cysts in faeces which contaminate water and food and ingested by another human
what is the diagnosis and treatment of giardiasis
identification of cysts or trophozoites in faeces
metronidazole/tinidazole
