Protozoa Flashcards
What is protozoa?
“One celled animals”
Single cell with nucleus
(Eukarytoic)
> 30,000 species.
What are the five major groups of protozoa?
Flagellates
Microsporidia
Sporozoa
Amoebae
Cilliates
Examples of flagellates protozoa?
Trypanosoma spp.
Leishmania spp.
Trichomonas vaginalis
Giardia lamblia
African trypanosomiais is caused by what organisms?
Sleeping sickness - caused by:
- Trypanosoma brucei gambiense (West Africa) and rhodesiense (South East Africa).
What are the symptoms of sleeping sickness?
Chancre
Flu like symptoms
CNS involvement
Coma & death
How is sleeping sickness diagnosed?
Visualising trypomastigotes on blood film or CSF.
Chagas disease (trypanosoma cruzi) acute phase:
Flu like symptoms
Chagas disease chronic phase:
Cardiomyopathy
Megaoesophagus
Megacolon
What are the vectors for African Trypanosomiasis and American Trypanosomiasis?
Tsetse fly and triatomine bug (kissing bug) respectively.
Leishmaniasis is spread by what?
Through the bite of sandfly.
What are the clinical pictures of Leishmaniasis?
Cutaneous
Mucocutaneous
Visceral
Cutaneous and mucocutaneous Leishmaniasis result in what?
Ulceration and destruction. Often superadded infection.
How is cutaneous and mucocutaneous L. diagnosed?
Through biopsy - amastigotes seen.
What are the signs and symptoms of visceral L. (kala azar)?
Fever
Weight loss
Massive splenomegaly
Hepatomegaly
Anaemia
High fatality without treatment
Trichomonas vaginalis
Sexually transmitted.
Mostly asymptomatic but dysuria and yellow frothy discharge often present (fishy smell).
Treated with Metronidazole.
Giardiasis
Faeco-oral spread.
Diarrhoea, cramps, bloating, flatulence. Recent travel.
Trophozoites seen in stool.
Treated with Metronidazole.
Amoebiasis
Caused by Entaemoeba histolytica.
Faeco-oral spred.
Dysentry, colitis, liver and lung abscesses.
Trophozites in stool.
Treated with metronidazole followed by a luminal amoebicide.
Cryptosporidiosis
Waterborne infection caused by Cryptosporidium spp.
Watery diarrhoea, vomiting, fever, weight loss.
Oocytes seen in stool.
Self-limiting, severe disease in immunocompromised.
Toxoplasmosis
Toxoplasma gondii.
Ingestion of contaminated food and water or feline faeces.
Disseminated disease, toxoplasma encephalitis, chorioretinitis.
Maternal infection can be devastating in pregnancy.
What is the vector for malaria?
Female anopheles mosquito - through their bite.
What are the 5 species that can cause human disease?
Plasmodium falciparum
Plasmodium ovale
Plasmodium vivax
Plasmodium malariae
Plasmodium knowlesi
Which one of the five causative agents causes the most severe disease?
Falciparum.
What are the diagnostics for malaria?
Blood film shows plasmodium ovale trophozite.
What are some of the symptoms of malaria?
FEVER
Chills
Headache
Myalgia
Fatigue
Diarrhoea
Vomiting
Abdominal pain
What are the signs of malaria infection?
Anaemia
Jaundice
Hepatosplenomegaly
“Black water fever” = haemolysis - Hb is then passed to the urine.
What causes the cyclical fever?
When trophozoite develops into a schizont, it then ruptures and re-infects another RBC.
What is an additional quality of P. falciparum?
Obstructed microcirculation. RBCs ability to adhere to endothelial cells.
In situe rosetting -> vascular occlusion.
Cerebral malaria causes what?
Vascular occlusion causes drowsiness, raised ICP, seizures, coma and eventually death.
Drowsiness can also be due to hypoglycaemia.
What are the complications of malaria in the lung?
The lungs can be directly affected through vascular occlusion.
Anaemia and lactic acidosis can cause a fast respiratory rate (tachypnoea) through compensatory mechanisms.
Increased vascular permeability causes fluid to leak directly into the lungs causing pulmonary oedema.
ARDS in malaria:
ARDS – Acute Respiratory Distress Syndrome
SOB due to anaemia
SOB due to lactic acidosis (compensatory)
SOB due to increased vascular permeability 🡪 pulmonary oedema
Malaria complications in the kidneys:
Vascular occlusion
Dehydration
Hypotension
Heamolysis
Heamoglobulinuria
Renal failure can occur due to…
A direct effect through vascular occlusion
Hypoperfusion secondary to dehydration (fever) or hypotension
Haemolysis creating products that can be nephrotoxic
Proteinuria
Fatigue
Haematuria
Thrombocytopenia in malaria
Thrombocytopenia occurs through platelet aggregation and therefore reduced circulating platelets
Generalised inflammation activates the coagulation cascade, causing clotting factors to be used up.
This then causes DIC (disseminated intravascular coagulation) – lots of micro clots have formed in the blood, but a lack of circulating clotting factors causes bleeding.
What does bleeding in malaria result in?
Epistaxis
Abnormal bleeding
Worsening anaemia
How does complicated malaria lead to shock?
Hypotension
Tachycardia
Drowsy
Pale
People with complicated malaria often go into shock
Pro-inflammatory cascade causing vasodilation.
Anaemia (if bad enough) can cause cardiogenic shock.
Gram negative sepsis can occur from increased vascular permeability in the bowel 🡪 so gram negative bacteria colonising the bowel can enter the bloodstream.
Bleeding causes a hypovolaemic shock.
Increased vascular permeability means that intravascular fluid can leak out into the “third space”.
Complicated malaria affects which systems?
Cerebral
ARDS/Pulmonary oedema
Renal failure
Sepsis
Bleeding/Anaemia
What are the treatment options for uncomplicated malaria?
ACTs - Artemesinin-based combination treatments such as Riamet.
Others include quinine and doxycycline.
PO Chloroquine.
What are the treatment options of complicated malaria?
IV artesunate (IV quinine + doxycycline).
What are the supportive measures for malaria?
Cerebral: antiepileptics
ARDS: oxygen, diuretics, ventilation
Renal failure: fluids, dialysis
Sepsis: broad spectrum antibiotics
Bleeding/Anaemia: blood products
Exchange transfusion if huge parasite burden.
Which species can develop hypnozoites (thus lead to relapse?)
P. ovale and vivax can form hypnozoites in the liver. This can lead to relapses months or years later.
Relapses are treated with what?
Primiquine to eliminate hypnozoites.
Primiquine treatment can cause what?
Haemolysis if the individual is G6PD deficient.
