Protozoa Flashcards
What defines a protozoa
Eukaryotic (single cell with nucleus)
What are there 5 major groups of protozoa
- Flagellates
- Amoebae
- Sporozoa
- Ciliates
- Microsporidia
What endemic is currently effecting Africa
Human African Trypanosomiasis
How is the trypanosomes transmitted
Bite of an infected Tsetse fly
Symptoms of Human African Trypanosomiasis
Fly-like symptoms
Alteration of the biological clock
Seizures
How is American Trypanosomiasis spread
Faeces of triatomine bug
Blood and food
What are two phases of American Trypanosomiasis
Asymptomatic (most go asymptomatic)
Life-threatening
Why can American Trypanosomiasis be life-threatening
- Chronic inflammation -> Fibrosis
- Dilated cardiomyopathy -> Heart failure, arrhythmias, cardiac arrest
- Colon -> Malnutrition
How is Leishmaniasis spread
Bite of the sandfly
How is Leishmaniasis diagnosed
Through biopsy
Serology combined with clinical signs
What can act as a reservoir for Leishmaniasis
Animals
What is the most common variation of Leishmaniasis
Cutaneous Leishmaniasis
How long does it take for cutaneous leishmaniasis to appear
- Week to months
- Ulcers on the exposed parts of the body
- Lesions
Do the ulcers disappear in the cutaneous leishmaniasis
No, they invariably leave permanent scars
What is the consequence of lesions from mucocutaneous leishmaniasis
Lesions can lead to partial or total destruction of mucous membranes of nose, mouth and throat
What three issues can people face with Leishmaniasis
- Social Rejection
- Scarring
- Superadded Infection
Long-term effects of mucocutaneous Leishmaniasis
Recurrent bacterial pneumonias
Die from sepsis due to the destruction caused to their nose and palate
What does Visceral Leishmaniasis cause
Black Fever
Weight loss
Anaemia
How is Visceral Leishmaniasis diagnosed
Biopsy
How long until Visceral Leishmaniasis killed a person
2 years
How is Trichomonas Vaginalis spread
STD
Symptoms of Trichomonas Vaginalis
Asymptomatic
Dysuria
Yellow frothy discharge
How is Trichomonas Vaginalis
Metronidazole
What is Metronidazole
Antibiotic
How is Giardiasis (flagellate) spread
Faecal-oral spread
Symptoms of Giardiasis
Diarrhoea
Cramps
Bloating
Cysts in stool
How is Giardiasis treated
Metronidazole
How is Amoebiasis spread
Faeco-Oral spread
What does Amoebiasis cause
Dysentry
Colitis
Liver + Lung abscesses
Cysts seen in stool
What is Amoebiasis treated by
Metronidazole
Symptoms of Amoebiasis
Invade colon and consume red blood cells
Begins asymptomatically
Symptoms of Cryptosporidiosis (Sporozoa)
- Diarrhoea
- Vomiting
- Oocytes in stool
When is cryptosporidiosis severe
Immunocompromised
How long does infection by cryptosporidiosis last
1-2 weeks
How is toxoplasmosis (protozoa) caught
Ingestion of oocytes in contaminated food and water /faeces
What three things can Toxoplasmosis cause
- Disseminated disease
- Toxoplasma Encephalitis
- Chorioretinitis
What women are particularly susceptible to toxoplasmosis
Pregnancy
What species tend to be most effected by toxoplasmosis
Cats
Why are humans and other mammals intermediate hosts for toxoplasmosis
They can only get it from ingestion
Pathology of toxoplasmosis
- Ingest oocyte
- Haematogenous spread
- Invasion of tissues and tissue cysts develop
- Primarily in muscles and neurons
Symptoms of acute toxoplasmosis
Asymptomatic (90%)
Glandular fever (10%)
How do we reduce effects of toxoplasmosis
Prevention:
- Avoid raw meats
- Avoid unpasteurised goats milk
- Wear gloves or wash hands
Define myalgia
Muscle pains
How is malaria transmitted
Bite of female anopheles mosquitos
5 Species of Malaria-causing toxoplasmodium
- Plasmodium falciparum
- Plasmodium ovale
- Plasmodium Vivax
- Plasmodium malariae
- Plasmodium Knowlesi
How long does it take for malaria to show
1 year
Which Plasmodium causes the most severe disease of malaria
Falciparum
When do symptoms for falciparum infection show
In a month
How do we diagnose malaria
Light microscopy
Blood sample in thick and thin films
Properties of thick film
Sensitive but low resolution (does this person have malaria)
Properties of thin film
Allows identification of species of malaria (high resolution)
How many blood films are done
Three (as this is the length of the lifecycle)
Symptoms of malaria
Fever Headache Myalgia Fatigue Diarrhoea Jaundice Hepatosplenomegaly
What is Hepatosplenomegaly
Enlargement of the liver and spleen
How does the plasmodium infect a human
- Mosquito bites an infected human
2. Ingests plasmodium gametocytes
Lifecycle for a mosquito
4 weeks
Development of gametocytes
- In the midgut of the mosquito undergo development and form sporozoites in salivary glands of mosquito
- Mosquito takes blood meal and injects sporozoites into human
Where are sporozoites often injected in the human
Hepatocytes of the liver
What do the sporozoites develop into
Schizont which bursts and infects red blood cells
What symptom is associated with Schizont development
ABDO PAIN
What happens to the plasmodium that infect the red blood cells
Becomes a trophozoite
What form of the plasmodium do we see on a blood film to diagnose the malaria
Trophozoites
What happens after the trophozoite develops
Forms into another Schizont which ruptures and re-infects another RBC
OR
Develop back into gametocytes
Blood stage
What symptoms are associated with the blood stage of malaria
Haemolysis -> anaemia -> Jaundice -> Haemoglobinurea
FEVER
What happens to the trophozoites -> gametocytes
Taken up by another mosquito during a blood meal
Why are plasmodium falciparum more dangerous
Infected RBCs have knobs on surface which bind to endothelial cells
OBSTRUCTURED CIRCULATION - HYPOXIA
What is cerebral Malaria caused by
Infection by P. falciparum
How does P. falciparum cause cerebral malaria
- Vascular occlusion
- Hypoglycaemia
Drowsiness
Seizures
Coma
How does P. falciparum cause ARDS (Acute respiratory Distress Syndrome)
Vascular occlusion, anaemia, lactic acidosis and increased vascular permeability leads to hypoxia, pulmonary oedema
How does P. Falciparum cause renal failure
Proteinuria
Fatigue
Haematuria
Due to..
Vascular occlusion
Dehydration
Hypotension
Haemolysis
How does thrombocytopenia occur
Platelet aggregation and reduced circulating platelets
How does P. falciparum cause bleeding
DIC and Thrombocytopenia leads to abnormal bleeding and epistaxis
Define epistaxis
Nose bleeds
What causes DIC
Generalised inflammation activates coagulation cascade causing clotting factors to be used up - micro clots form
Why do people with malaria go into shock
- Pro-inflammatory cascade causes vasodilation
- Anaemia causes cariogenic shock
- Bleeding causes hypovolaemic shock
- Increased vascular permeability causes leaked fluid into space
Describe the pro-inflammatory cascade associated with malaria
- Alters endothelial cell wall function -> leaky vessels -> ARDA , sepsis
- Switches cells to anaerobic metabolism -> hypoxia and lactate increases
- Reduces gluconeogenesis -> hypoglucaemia
How is malaria treated
- IV Quinine = Doxycycline
2. IV artesunate
What is the problem with artesunate
Some are becoming resistant
Why do we have releases in malaria
P. ovale and vivat form hypnozoites in the liver which re-activate after being dormant
How do we eliminate the hypnozoites
Use primiquine
Chloroquine to treat acute infection
What do we need to look out for when using Primaquine
Can cause haemolysis if deficient in G6PD
