Protozoa Flashcards
what are Protozoa
Single-celled eukaryotic organisms (with nucleus)
can be free-living or parasitic
what are the 5 major groups of protozoa
Flagellates
Amoebae
Sporozoans
Ciliates
Microsporidia
What are flagellates
locomotory organelles that reproduce by binary fission
often intestinal
what are the 5 main examples of flagellates
sleeping sickness
american trypanosomiasis
leishmaniasis
trichomonas vaginalis
giardiasis
what flagellate causes sleeping sickness ?
sleeping sickness = human african trypanosomiasis
Trypanosoma spp
Trypanosoma brucei gambiense = west African milder version
Trypanosoma brucei rhodesiense = S.E African
how is human african trypanosomiasis transmitted?
the bite of an infected tsetse fly
causes a chancre at site (red large sore)
what are the symptoms of human African trypanosomiasis?
initially flu like symptoms
CNS symptoms - personality change, body clock alteration, confusion, seizures
untreated leads to coma and death
can human African trypanosomiasis be diagnosed and treated?
Diagnosed by seeing protozoa on microscopy of blood or CSF
Can be treated by drugs
what other trypanosoma species (a flagellate) causes a major disease, this time in central/South America?
american trypanosomiasis, aka chagas disease
Caused by trypanosoma cruzi
how is American trypanosomiasis spread ?
Spread by triatomine bug faeces, blood, contaminated food
what are the symptoms of American trypanosomiasis (chagas disease)
acute and chronic
acute – flu like and romana sign
chronic – dilated cardiomyopathy, failure , malnutrition, swallowing problems and weight loss as a result of Megaesophagus + Megacolon
what does the romana sign look like
swollen eyelid from faeces in eye
can you treat chagas disease?
Effective treatment for acute phase, but once in the chronic phase can only treat supportively eg pacemakers, antiarrhythmics
example 3 of a flagellate
leishmaniasis
how is it spread?
leishmaniasis is spread by infected sand fly
infected sad fly bite
leishmaniasis has 3 clinical pictures:
Cutaneous and Mucocutaneous, and visceral
describe Cutaneous and Mucocutaneous
Both have ulceration and destruction
Ulcers on face,arms,legs
Mucocutaneous lesions can lead to partial or total destruction of the mucous membranes of the nose, mouth and throat cavities and surrounding tissues. → lead to recurrent bacterial pneumonia + sepsis
no treatment
why does having leishmaniasis lead to social prejudice?
When the ulcers heal, they invariably leave permanent scars, which are often the cause of serious social prejudice.
leishmaniasis has 3 clinical pictures:
Cutaneous and Mucocutaneous, and visceral
describe visceral
Affects internal organs
Aka. black fever
Characterised by irregular bouts of fever, substantial weight loss, swelling of the spleen and liver, and anaemia secondary (which may be serious).
high fatality without treatment
Example 4 of flagellates → trichomonas vaginalis
how is it spread?
Sexually transmitted
Example 4 of flagellates → trichomonas vaginalis
symptoms
Can be asymptomatic, have dysuria and yellow frothy discharge
Example 4 of flagellates → trichomonas vaginalis
treatment
Metronidazole
Example 5 of flagellates → giardiasis
spread
Giardia lamblia
Faeco-oral spread
Example 5 of flagellates → giardiasis
symptoms
diarrhoea, cramps, bloating, flatulence,
Example 5 of flagellates → giardiasis
risk factors
recent travel and childcare workers
Example 5 of flagellates → giardiasis
treatment
metronidazole
what are amoeba ?
class of protozoa
Move by means of flowing cytoplasm and production of pseudopodia
what is the key example of an amoebiasis?
amoebic dysentery
amoebic dysentery
- how is it spread?
Faeco-oral
amoebic dysentery
- epidemiology
Common in poor sanitary conditions/ tropical countries
amoebic dysentery
- symptoms
dysentery, colitis, lung and liver abscesses
or asymptomatic
amoebic dysentery
- treatment
metronidazole
what are sporozoans?
class of protozoa
No locomotory extensions
All species parasitic
what does cryptosporidiosis ( a sporozoan) cause?
Causes diarrhoea (watery, no blood), vomiting, fever, weight loss
Symptoms last 1-2 weeks, usually self-limiting
but severe in immunocompromised
how does cryptosporidiosis spread and who is at risk ?
Waterborne
At risk: children, swimmers (recreational water contaminated)
what does toxoplasma gondii (a sporozoan) cause?
Toxoplasmosis
can cause :
Toxoplasma encephalitis (inflammation of the brain)
Glandular fever type symptoms
Chorioretinitis (inflammation of choroid around retina)
how is Toxoplasmosis spread?
Ingestion of oocytes or bradyzoite (tissue cyst) through:
contaminated food eg. rare beef
Contaminated water
feline faeces eg. pet cat
toxoplasmosis can be deveststaing in pregnancy
therefore what foods/activities should a pregnant women avoid?
avoid raw meat, unpasteurised goats milk, avoid gardening or cleaning cat litter trays
what type of protozoa is malaria?
a sporozoan
name the different species of sporozoan that can cause malaria in humans
Plasmodium falciparum/ovale/vivax/malariae/knowlesi
which of the 5 types of sporozoan species that cause malaria in humans causes the highest mortality?
Plasmodium falciparum
which of the 5 types of sporozoan species that cause malaria in humans takes the longest to present?
Vivax and ovale
Presents after a year!
Don’t tend to cause death
how is malaria transmitted?
By bite of infected female Anopheles mosquitoes
what are the 2 factors that if a patient with them you should suspect and test for malaria
- fever
- recent travel history
so crucial you test for malaria when a patient has these 2 things because early identification of malaria is key
what are the clinical features of malaria
FEVER
possible:
- headache
- myalgia
- fatigue
- nausea and vomiting
- diarrhoea
what are possible signs of malaria in a patient?
Anaemia
Jaundice (look yellow)
Hepatosplenomegaly (big spleen and liver)
Black water fever that occurs from haemolysis à haemoglobin then passes into the urine
what 2 tests can be used to diagnose malaria ?
- Diagnose using light microscopy (see the trophozoite)
Three blood films are done on consecutive days, as this is the length of the life cycle
- can also use rapid diagnostic tests, that work like pregnancy tests, and detect plasmodium antigens in the blood
how to treat complicated malaria
IV artesunate - newer drug
IV quinine + doxycycline
what is ‘complicated malaria’ ? what happens to the RBCs
obstructed microcirculation in organs causing failure
Infected RBCs in the human blood stages of life cycle have a greater ability to adhere to endothelial cells (they get sticky) leading to occlusion of vessels
which species of malaria tends to cause complicated malaria?
plasmodium falciparum
what impact can plasmodium falciparum have on major organs during complicated malaria ?
- the brain
cerebral malaria
Vascular occlusion + hyperglycemia that occurs in maleria
Leads to droesiness, increase in pressure, seizures and coma
Support with Antiepileptics
what impact can plasmodium falciparum have on major organs during complicated malaria ?
- the lungs
In the lungs, there is acute respiratory distress syndrome
lead to ARDS?pulmonary oedema
Support with oxygen, diuretics, ventilation
what impact can plasmodium falciparum have on major organs during complicated malaria ?
- kidneys
Causes fatigue, proteinuria, haematuria
This is from the vascular conclusion, dehydration, hypotension, haemolysis
renal failure
Support with fluids, dialysis
what impact can plasmodium falciparum have on major organs during complicated malaria ?
- blood
sepsis - Support with broad spectrum antibiotics
abnormal bleeding or anaemia
- Support with blood products
Anaemia can cause cardiogenic shock
Bleeding causes hypovolemic shock
Signs: drowsy, pale, tachycardia, hypotension
when and how do malaria relapses happen?
hypnozoites can lie dormant in liver and reactivate months later
not eradicated by conventional anti malaria treatment
prevent by using broad spectrum antibiotics as well as conventional treatment
what are the 3 main cycles in the malaria life cycle ? how long is the cycle?
Erythrocytic cycle
Exo-erythrocytic cycle
Sporogonic cycle
^ life cycle = 4 week
malaria life cycle:
- Mosquito bites an infected human,
what does it ingest? how long is the mosquito now infected for?
- Mosquito bites an infected human
ingests plasmodium gametocytes
It is Infected for life!
malaria life cycle:
- sporogonic cycle
what happens in this cycle (after mosquito has bitten infected human) ?
Within the mosquito:
the gametocytes ingested are within the midgut, and undergo development,
they end up as sporozoites in the salivary glands of the mosquito
malaria life cycle:
- what happens In the life cycle after the mosquito has bitten an infected human and the sporozoites have formed in the mosquitos salivary glands?
step 3 = Mosquito bites another human
When taking its next blood meal it injects the sporozoites into the human
malaria life cycle
- human liver stages
the human has been bitten by an infected mosquito. what happens next, in the humans liver?
Hepatocytes in liver get infected by proliferating sporozoites (that were injected by the mosquito)
SYMPTOM; abdominal pain in human
malaria life cycle
- Exo-erythrocytic cycle
what happens to the liver cells infected with sporozoites?
Infected liver cell develops into a schizont,
This then bursts and infects red blood cells
malaria life cycle
- after the Exo-erythrocytic cycle , what happens to the infected RBCs in the human ?
step 6 = human blood stages
Within the red blood cell, plasmodium becomes a trophozoite
This is one of the forms we can see on a blood film to diagnose malaria
malaria life cycle
- erythrocytic cycle
what happens to the trophozoites in the RBCs on bitten human?
The trophozoite develops into a schizont,
which then ruptures
It re-infects another RBC
This blood stage cycle lasts 48 hours in most of the plasmodium species
what symptoms present during the erythrocytic cycle (in the malaria life cycle) ?
Cyclical fever when RBCs rupture
Haemolysis leads to -
Anaemia
Jaundice from bilirubinemia
Haemoglobinuria
malaria life cycle
- during the erythrocytic cycle, some of the trophozoites dont develop into schizonts, some develop into something else…what?
Some of the trophozoites develop into gametocytes instead of schizont
malaria life cycle
- the human now has plasmodium gametocytes, how is the life cycle repeated?
Another mosquito bites this human
This bug takes up the infected gametocytes in its blood meal
It is now infected
and can carry on the cycle by biting a human and infecting them
what are ciliates? why ar they called ciliates?
another type of protozoa
have Cilia that beat rhythmically
name a ciliate
Balantidium coli
what are Microsporidia?
5th types of protozoa
what is unique about microsporidia ?
produce spores
have a Unique polar filament; coiled inside spore
what is the main treatment for infections caused by many protozoa?
Metronidazole
what antibody is triggered by malaria ?
IgE response
