Malaria

Question 1

State the full name of the organism usually responsible for severe malaria (1)

Answer 1

Plasmodium falciparum

Question 2

State two (2) provinces in South Africa where seasonal malaria may occur (1)

Answer 2

Mpumulanga, Limpopo, Northern KwaZulu Natal

Question 3

State three (3) groups of people who are at particular risk for acquiring malaria (3)

Answer 3

Young children <5 years old, Pregnant women, Travellers (coming from areas with little or no malaria transmission who lack immunity)

Question 4

Define malarial hyperparasitaemia (1)

Answer 4

Parasite count of 5% or more of parasitized RBC’s

Question 5

Forty-four-year-old Ms Charmaine Phillips has recently returned from her vacation in Mozambique. A few days after her return she notices feeling malaise and feverish. She continues to go to work but later develops vomiting and dizziness. Her condition deteriorates and Charmaine decides to go to her local hospital. At the hospital Dr Luvuyo Kahla finds Charmaine to be very pale, pyrexia, dehydrated and tachycardic. With her recent travel history in mind her doctor decides to do a rapid Malaria test which is positive. He also does a finger prick haemoglobin which is 6g/dL. The doctor admits her and over the next two days the patient develops deep jaundice and hypotension.

a) Does Ms Phillips have uncomplicated or severe malaria? (½)
b) Outline reasons for your answer (2)

Answer 5

Severe malaria

She has clinical features of severe malaria: Circulatory collapse, Jaundice

Question 6

Discuss your management plan for Ms Phillips (the pregnancy test was negative) (5)

Answer 6

– Intravenous Artesunate (preferred treatment) followed by oral artemether-lumefantrine when able to tolerate oral treatment
– Alternative regimen Intravenous Quinine
- Supportive management
– Discuss all cases with an Infectious Diseases specialist
- Notify all cases

Question 7

Outline how malaria is transmitted (2)

Answer 7

Most commonly by the bite of mosquitos (Anopheles), but can also be spread by blood transfusions, sharing of needles

Question 8

Describe the measures that Mr Stephens should have taken to prevent malaria while travelling (2½)

Answer 8

Chemoprophylaxis – ideally with mefloquin or atovaquone/ proguanil (1)

Prevention of bites – bed nets, insect repellant, protective clothing (1½)

Question 9

Discuss four (4) precautions, excluding chemoprophylaxis, that travellers should take when travelling to malaria endemic areas (2)

Answer 9

Insecticide treated bed nets, protective clothing (long sleeves and pants), avoiding the outdoors during the times when mosquitos bite, topical insect repellents, spatial repellents, pregnant women should avoid travel to these areas.

Question 10

Outline four (4) measures that can be taken to prevent malaria amongst the local population in Mozambique (4)

Answer 10

Insecticide-treated bednets (ITNs), Larval control and other vector control interventions, Mass drug administration, Malaria vaccine under development, Remain indoors from dusk to dawn, Wear long sleeved clothing, Intermittent preventive treatment of malaria in pregnant women (IPTp), Intermittent preventive treatment of malaria in infancy (IPTi), Indoor residual spraying (IRS)

Question 11

Outline four (4) pieces of advice that you would have given Ms Phillips before her vacation to prevent malaria (4)

Answer 11

Remain indoors from dusk to dawn, wear long sleeved clothing, Chemoprophylaxis for travelers, Sleep under Insecticide-treated bednets (ITNs), Insect repellants (20-50% DEET most effective)

Question 12

Name four (4) symptoms of uncomplicated malaria and state what illness these symptoms may be misdiagnosed as (2)

Answer 12

Headache, fever, nausea and vomiting, body pains, misdiagnosed as influenza

Question 13

List six (6) clinical findings of severe malaria (3)

Answer 13

Cerebral: Delirium, seizures, prostration or encephalitis,

Adrenals: Circulatory collapse,

GIT: Dysenteric malaria, fulminant haemorrhage,

Kidneys: Acute tubular necrosis,

Lungs: Pulmonary oedema,

Liver: Jaundice and abnormal bleeding

Question 14

Name three complications of malaria (usually only seen with infections caused by the organism named in question 41) (1½)

Answer 14

Cerebral malaria, Acute tubular necrosis, Pulmonary oedema, Jaundice, GIT haemorrhage

Question 15

Describe the key elements in the pathogenesis of the common clinical manifestations of malaria caused by Plasmodium falciparum (5)

Answer 15

Sporozoites infect erythrocytes (½), and can either cause RBCs to lyse (½), or become sticky (½). Lysis of RBCs leads to fever (pyrogen release), anaemia, haemoglobunuria, raised liver enzymes, hypertropohy of reticuloendothelial system (2). Sticky red blood cells result in sludging and blockage of capillaries (½), reduce tissue oxygenation and leakage of fluid out of capillaries (½) – oedema and hypoxia of vital organs esp CNS (½).

Question 16

Describe the pathogenesis of cerebral malaria (4)

Answer 16

P. falciparum parasites infect red cells (½) which develop small protrusions at the cell surface (½). These “knobs” make the red cell “sticky” (½) and promote adherence to endothelial cells (½)  capillary sludging  blocked capillaries (½)  decreases 02 and glucose to tissue and in the CSF (½)  reduces capillary endothelial integrity  leakage of fluid (½)  congestion, haemorrhage and necrosis of cerebral tissue (½).

Question 17

Briefly describe how the laboratory diagnosis is made (definitive diagnosis) (1)

Answer 17

Thin and thick blood smear. PCR

Question 18

Name two (2) different types of test commonly used to diagnose malaria (1)

Answer 18

Blood smears, Antigen detection (rapid diagnostic tests)

Question 19

Discuss the gold standard technique used for the laboratory diagnosis of malaria (3)

Answer 19

Blood smear stained with the Giemsa stain (Romanovsky stain) (1)

A thick smear (½) - make a more rapid diagnosis than with thin smears (more sensitive as see more red cells in each field) (½) - cannot distinguish the different plasmodia (½)

A thin smear (½) - used to identify the different plasmodium species (½)

Question 20

Explain in detail (apart from rapid tests) how malaria is diagnosed in the laboratory (4)

Answer 20

The gold standard is microscopy. A blood smear is made with a drop of blood on a glass slide. Thin and thick blood smears are made. The blood smear is stained with the Giemsa stain.

Question 21

Outline the importance of a thick blood smear when diagnosing malaria (1)

Answer 21

One can see more red cells and with low parasite counts one is less likely to miss the diagnosis. More rapid diagnosis

Question 22

List five (5) laboratory features of severe malaria (2½)

Answer 22

Laboratory findings in severe falciparum malaria, Severe anaemia/ low Hb, Low platelets, Hypoglycaemia, Hyperlactataemia, Acidosis, Renal Impairment, Hyperparasitaemia

Question 23

Name four (4) laboratory features of severe malaria (2)

Answer 23

Severe anaemia, low platelets, hypoglycaemia, hyperlactataemia, acidosis, renal impairment, hyperparasitaemia