Malaria

Question 1

Define malaria

Answer 1

• systemic
• tropical parasitic infection
• of RBCs

Question 2

Cause of malaria

Answer 2

Plasmodium spp

Question 3

Transmission of malaria

Answer 3

• Female anopheles mosquitoes bite
• congenital
• blood transfusion

Question 4

5 protozoal species of genus plasmodium

Answer 4

• plasmodium falciparum (commenst, complicated)
• P vivax (uncomplicated relapsing)
• Ovale (uncomp, relapsing)
• Malariae (uncomp, doesn’t relapse)
• Knowlesi (only in certain parts of SE Asia)

Question 5

Incubation period

Answer 5

7-30 days

• shorter in falciparum
• longer in malariae

Question 6

Stable Transmission Features

Answer 6

• populations continuously exposed
• high background immunity
• young children suffer acutely
• epidemics unlikely
• Sub-Saharan Africa and Oceania

Question 7

Unstable Transmission

Answer 7

• fluctuating rates
• low background immunity
• adults and children suffer acutely
• epidemics likely
• Asia and Latin America

Question 8

Sub-Sharan Africa organism

Answer 8

P. vivax 10%

More cases than Asia

Question 9

Asia organism

Answer 9

P. vivax 45%

Question 10

Main risk for acquiring malaria in tropical travellers

Answer 10

Failure to take effective prophylaxis

Question 11

Airport Malaria

Answer 11

Stowed away in aircrafts or luggage

Infect people who haven’t been abroad

Question 12

Malaria Life in Liver

Answer 12

• sporozoites enter hepatocytes
• develop into schizonts which contain daughter merozoite cells
• only for vivax and ovale

Question 13

Hypnozoites

Answer 13

Some sporazoites enter dormancy stage

- cause relapses weeks-years later

Question 14

Pathogenesis

Answer 14

• infected erythrocytes adhere to host endothelium
  = microvascular occlusion
  = metabolic derangement and acidosis
  = intravascular haemolysis
• schizont rupture evokes cytokine response

Question 15

Falciparum malaria

Answer 15

infects all ages of RBCs

• leads to greater parasitaemias
• sequestrates
• majority of deaths caused by it

Question 16

Which plasmodiums don’t sequestrate

Answer 16

Vivax
Malariae
Ovale

Question 17

Which are mild malaria organsims

Answer 17

Vivax

Knowlesi

Question 18

Diagnosis

Answer 18

Light microscopy gold standard
Giemsa stain
Thick and thin blood smears

Question 19

Thick blood film

Answer 19

• sensitive
• allows examination of greater volume of RBCs
• concentrates parasites as RBCs lysed

Question 20

Thin blood film

Answer 20

• for species identification
• determines level of parasitaemia
• less sensitive than thick

Question 21

P falciparum on film

Answer 21

• numerous fine rings
• double chromatin dots
• cell multiple parasitisation
• schizonts rare
• red cells not enlarged

Question 22

P vivax on film

Answer 22

• thick signet ring forms
• trophozoites ameboid appearance
• enlarged red cells

Question 23

P ovale on film

Answer 23

• oval shaped trophozoite
• comet like red cells
• enlarged red cells

Question 24

P. malariae on film

Answer 24

• broad band

- red cells not enlarged

Question 25

P. knowlesi on film

Answer 25

- ring stages resembling P. falciparum - mature stages indistinguishable from P. malariae - molecule methods needed for diagnosis confirmation

Question 26

Antigen Detection

Answer 26

- histidine rich protein 2 (HRP-2) associated with P. falciparum - plasmodium associated LDH (pLDH)

Question 27

Clinical Presentation

Answer 27

- fever - headache - muscle aches - diarrhoea - vomiting

Question 28

History questions

Answer 28

- presenting symptoms - foreign travel = when, where, prophylaxis, compliance, duration, drug type - pregnant? (complication risk) - immunocomptence status (HIV, cancer, transplant recipients) - drug history (previous prophylaxis, allergies, drug-drug interactions?)

Question 29

Examination

Answer 29

``` Vital signs A to G E = exposure F = fluids G = glucose - give oxygen - position patient - establish fluids - look for signs of severity ```

Question 30

Signs of severe malaria

Answer 30

- impaired consciousness or seizures - renal impairment - acidosis <7.3 - hypoglycaemia <2.2mmol - ARDS or pulmonary oedema - Hb 80g/L - spontaneous bleeding/disseminated intravasc. coagulation - shock - haemoglobunuria (w/o G6PD deficiency) - parasitaemia >10%

Question 31

Renal impairment diagnosis

Answer 31

Oliguria >0.4ml/kg bodyweight per hour OR creatinine >265mmol/l

Question 32

Management of malaria

Answer 32

- seek expert advice - anti-pyretic therapy - rehydration carefully if indicated as risk of pulmonary oedema - other supportive measures - nursing on HDU/ITU ward - non falciparum perhaps OP management - notify local PH team

Question 33

Uncomplicated P. falciparum treatment

Answer 33

- oral therapy - malarone - riamet - quinine & doxy or clinda

Question 34

Non-falciparum treatment

Answer 34

chloroquine followed by primaquine | - check G6PD status

Question 35

Riamet

Answer 35

ACT (artemisinin combination therapy) | Artemether-lumefantrine

Question 36

Malarone

Answer 36

Atovaquone-Proguanil

Question 37

Severe complicated P. falciparum treatment

Answer 37

IV artesunate (preferred) OR IV Quinine (cardiac & blood glucose monitoring) Oral therapy as for uncomplicated once improved Check blood film daily

Question 38

Indications for IV therapy

Answer 38

Severe complicated P. falciparum parasitaemia >2% or presence of shizonts Vomiting Pregnancy

Question 39

Prevention of malaria

Answer 39

Awareness of risk Bite prevention Chemoprophylaxis Prompt diagnosis and treatment

Question 40

Public Awareness

Answer 40

National Travel Health Network and Centre NHS: GPs, infection specialists Public Health bodies, PH England Media

Question 41

Bite Prevention

Answer 41

DEET based insect repellants Bed nets, insecticide treated Clothing

Question 42

Chemoprophylaxis

Answer 42

Travel clinics Evidence based guidelines Regimes vary for diff countries depending on malaria species and anti-malarial resistance patterns No regime is 100% protective so need to use combination of protective measures

Question 43

Vector control

Answer 43

Insecticide treated nets Indoor residual spray Genetically modified mosquitoies

Question 44

Immunisation

Answer 44

On going development