Lecture 18: Protists in blood and intestines Flashcards
what is malaria caused by?
Plasmodium protist
what is malaria transmitted by?
female anopheles mosquitos
what does malaria infect?
red blood cells causing a fever
what serious diseases can arise from malaria?
anaemia and blocking of small capillaries
how many children die per day in sub-Saharan africa?
1200
what facilitates host invasion?
apical complex
what are the 4 stages of malaria development?
- skin infection
- liver stage development
- blood stage development
- mosquito stage development
what occurs in malarial skin infection?
sporozoites within the mosquito salivary gland are injected into the skin
what happens in liver stage development?
- sporozoites invade liver cells and are engulfed by host cell membrane
- divide asexually within hepatocytes forming schizonts
what can Plasmodium vivax do in the liver stage development?
form a non-replicating hypnozoite to enable long term survival
what do schizonts become?
merozoites that invade red blood cells
what do merozoites do?
bind to receptors on red blood cells and are engulfed
what happens once merozoites are engulfed?
differentiate into trophozoites and ingest cytoplasm of the red blood cell
what is malaria paroxysm?
rupture of haemocyte schizont in the blood releases malaria endotoxin that induces the host to produce high levels of pro-inflammatory cytokines TNF-a inducing a fever
what occurs in the blood stage development?
proteins are expressed on the surface of infected red blood cells enabling attachment to the endothelium and can causing rosetting and capillary obstruction
what do some trophozoites become?
gametophytes
what do the female anopheles mosquitos pick up?
gametocytes from host blood
what happens do the gametocytes once ingested?
gametocytogenesis forming a zygote and a ookinete
what does the ookinete do?
forms an oocyst that releases sporozites than migrate to the salivary gland
which malaria antigen evades immunity using antigenic variation?
PfEMP1
what is the first licensed malaria vaccine?
RTS,S
what is the newest malaria vaccine?
R21/Matrix-M vaccine
what do trypansomes cause?
chagas disease and sleeping sickness (trypanosomiasis)
what subgroup of excavata are trypanosomes from?
discoba kinetoplastids
what are 4 facts about chagas disease (cruzi)?
- transmitted by triatomine bug
- Latin america
- acute symptoms: fever, fatigue, headache, rash
- chronic symptoms: severe cardiac and intestinal lesions
what are 4 facts about sleeping sickness (brucei)?
- transmitted via the tsetse fly
- sub-saharan africa
- causes skin lesions and sleep disturbance
what occurs in the acute phase of trypanosomes life cycle?
binary fission
what occurs in the chronic phase of trypanosome life cycle?
10-30 years symptom free
what are 3 gastrointestinal symptoms of protozoa in the gut?
diarrhoea, gastroenteritis, and dysentery
what is gastroenteritis?
nausea, vomiting, and abdominal distress
what is dysentery?
blood and mucus in poo due to large intestine damage
what subgroup of the excavata is giardia part of?
metamonada
what subgroup of SAR is cryptosporidium part of?
alveolata
what are the symptoms of giardia?
NO SYMPTOMS
how does giardia live in water?
as a cyst passed in faeces
how does giardia live in humans?
in the gut as a trophozoite adhered to the intestine via an adhesive disk
how often does antigenic variation occur in giardia?
once every 10 generations
what are the 2 main pathogens of cryptosporidium?
C. hominis and C.parvum
what does cryptosporidium cause?
inflammation of intestinal epithelial cells impacting nutrient and ion absorption
how can diarrhoeal diseases be prevented?
good sanitation and access to clean water
