Protozoa

Question 1

What is protozoa?

Answer 1

“One celled animals”

Single cell with nucleus
(Eukarytoic)

> 30,000 species.

Question 2

What are the five major groups of protozoa?

Answer 2

Flagellates
Microsporidia
Sporozoa
Amoebae
Cilliates

Question 3

Examples of flagellates protozoa?

Answer 3

Trypanosoma spp.
Leishmania spp.
Trichomonas vaginalis
Giardia lamblia

Question 4

African trypanosomiais is caused by what organisms?

Answer 4

Sleeping sickness - caused by:

• Trypanosoma brucei gambiense (West Africa) and rhodesiense (South East Africa).

Question 5

What are the symptoms of sleeping sickness?

Answer 5

Chancre
Flu like symptoms
CNS involvement
Coma & death

Question 6

How is sleeping sickness diagnosed?

Answer 6

Visualising trypomastigotes on blood film or CSF.

Question 7

Chagas disease (trypanosoma cruzi) acute phase:

Answer 7

Flu like symptoms

Question 8

Chagas disease chronic phase:

Answer 8

Cardiomyopathy
Megaoesophagus
Megacolon

Question 9

What are the vectors for African Trypanosomiasis and American Trypanosomiasis?

Answer 9

Tsetse fly and triatomine bug (kissing bug) respectively.

Question 10

Leishmaniasis is spread by what?

Answer 10

Through the bite of sandfly.

Question 11

What are the clinical pictures of Leishmaniasis?

Answer 11

Cutaneous
Mucocutaneous
Visceral

Question 12

Cutaneous and mucocutaneous Leishmaniasis result in what?

Answer 12

Ulceration and destruction. Often superadded infection.

Question 13

How is cutaneous and mucocutaneous L. diagnosed?

Answer 13

Through biopsy - amastigotes seen.

Question 14

What are the signs and symptoms of visceral L. (kala azar)?

Answer 14

Fever
Weight loss
Massive splenomegaly
Hepatomegaly
Anaemia
High fatality without treatment

Question 15

Trichomonas vaginalis

Answer 15

Sexually transmitted.

Mostly asymptomatic but dysuria and yellow frothy discharge often present (fishy smell).

Treated with Metronidazole.

Question 16

Giardiasis

Answer 16

Faeco-oral spread.

Diarrhoea, cramps, bloating, flatulence. Recent travel.

Trophozoites seen in stool.

Treated with Metronidazole.

Question 17

Amoebiasis

Answer 17

Caused by Entaemoeba histolytica.

Faeco-oral spred.

Dysentry, colitis, liver and lung abscesses.

Trophozites in stool.

Treated with metronidazole followed by a luminal amoebicide.

Question 18

Cryptosporidiosis

Answer 18

Waterborne infection caused by Cryptosporidium spp.

Watery diarrhoea, vomiting, fever, weight loss.

Oocytes seen in stool.

Self-limiting, severe disease in immunocompromised.

Question 19

Toxoplasmosis

Answer 19

Toxoplasma gondii.

Ingestion of contaminated food and water or feline faeces.

Disseminated disease, toxoplasma encephalitis, chorioretinitis.

Maternal infection can be devastating in pregnancy.

Question 20

What is the vector for malaria?

Answer 20

Female anopheles mosquito - through their bite.

Question 21

What are the 5 species that can cause human disease?

Answer 21

Plasmodium falciparum
Plasmodium ovale
Plasmodium vivax
Plasmodium malariae
Plasmodium knowlesi

Question 22

Which one of the five causative agents causes the most severe disease?

Answer 22

Falciparum.

Question 23

What are the diagnostics for malaria?

Answer 23

Blood film shows plasmodium ovale trophozite.

Question 24

What are some of the symptoms of malaria?

Answer 24

FEVER
Chills
Headache
Myalgia
Fatigue
Diarrhoea
Vomiting
Abdominal pain

Question 25

What are the signs of malaria infection?

Answer 25

Anaemia Jaundice Hepatosplenomegaly "Black water fever" = haemolysis - Hb is then passed to the urine.

Question 26

What causes the cyclical fever?

Answer 26

When trophozoite develops into a schizont, it then ruptures and re-infects another RBC.

Question 27

What is an additional quality of P. falciparum?

Answer 27

Obstructed microcirculation. RBCs ability to adhere to endothelial cells. In situe rosetting -> vascular occlusion.

Question 28

Cerebral malaria causes what?

Answer 28

Vascular occlusion causes drowsiness, raised ICP, seizures, coma and eventually death. Drowsiness can also be due to hypoglycaemia.

Question 29

What are the complications of malaria in the lung?

Answer 29

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.

Question 30

ARDS in malaria:

Answer 30

ARDS – Acute Respiratory Distress Syndrome SOB due to anaemia SOB due to lactic acidosis (compensatory) SOB due to increased vascular permeability 🡪 pulmonary oedema

Question 31

Malaria complications in the kidneys:

Answer 31

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

Question 32

Thrombocytopenia in malaria

Answer 32

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.

Question 33

What does bleeding in malaria result in?

Answer 33

Epistaxis Abnormal bleeding Worsening anaemia

Question 34

How does complicated malaria lead to shock?

Answer 34

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”.

Question 35

Complicated malaria affects which systems?

Answer 35

Cerebral ARDS/Pulmonary oedema Renal failure Sepsis Bleeding/Anaemia

Question 36

What are the treatment options for uncomplicated malaria?

Answer 36

ACTs - Artemesinin-based combination treatments such as Riamet. Others include quinine and doxycycline. PO Chloroquine.

Question 37

What are the treatment options of complicated malaria?

Answer 37

IV artesunate (IV quinine + doxycycline).

Question 38

What are the supportive measures for malaria?

Answer 38

Cerebral: antiepileptics ARDS: oxygen, diuretics, ventilation Renal failure: fluids, dialysis Sepsis: broad spectrum antibiotics Bleeding/Anaemia: blood products Exchange transfusion if huge parasite burden.

Question 39

Which species can develop hypnozoites (thus lead to relapse?)

Answer 39

P. ovale and vivax can form hypnozoites in the liver. This can lead to relapses months or years later.

Question 40

Relapses are treated with what?

Answer 40

Primiquine to eliminate hypnozoites.

Question 41

Primiquine treatment can cause what?

Answer 41

Haemolysis if the individual is G6PD deficient.