Malaria Flashcards
1
Q
Define malaria
A
- systemic
- tropical parasitic infection
- of RBCs
2
Q
Cause of malaria
A
Plasmodium spp
3
Q
Transmission of malaria
A
- Female anopheles mosquitoes bite
- congenital
- blood transfusion
4
Q
5 protozoal species of genus plasmodium
A
- plasmodium falciparum (commenst, complicated)
- P vivax (uncomplicated relapsing)
- Ovale (uncomp, relapsing)
- Malariae (uncomp, doesn’t relapse)
- Knowlesi (only in certain parts of SE Asia)
5
Q
Incubation period
A
7-30 days
- shorter in falciparum
- longer in malariae
6
Q
Stable Transmission Features
A
- populations continuously exposed
- high background immunity
- young children suffer acutely
- epidemics unlikely
- Sub-Saharan Africa and Oceania
7
Q
Unstable Transmission
A
- fluctuating rates
- low background immunity
- adults and children suffer acutely
- epidemics likely
- Asia and Latin America
8
Q
Sub-Sharan Africa organism
A
P. vivax 10%
More cases than Asia
9
Q
Asia organism
A
P. vivax 45%
10
Q
Main risk for acquiring malaria in tropical travellers
A
Failure to take effective prophylaxis
11
Q
Airport Malaria
A
Stowed away in aircrafts or luggage
Infect people who haven’t been abroad
12
Q
Malaria Life in Liver
A
- sporozoites enter hepatocytes
- develop into schizonts which contain daughter merozoite cells
- only for vivax and ovale
13
Q
Hypnozoites
A
Some sporazoites enter dormancy stage
- cause relapses weeks-years later
14
Q
Pathogenesis
A
- infected erythrocytes adhere to host endothelium
= microvascular occlusion
= metabolic derangement and acidosis
= intravascular haemolysis - schizont rupture evokes cytokine response
15
Q
Falciparum malaria
A
infects all ages of RBCs
- leads to greater parasitaemias
- sequestrates
- majority of deaths caused by it
16
Q
Which plasmodiums don’t sequestrate
A
Vivax
Malariae
Ovale
17
Q
Which are mild malaria organsims
A
Vivax
Knowlesi
18
Q
Diagnosis
A
Light microscopy gold standard
Giemsa stain
Thick and thin blood smears
19
Q
Thick blood film
A
- sensitive
- allows examination of greater volume of RBCs
- concentrates parasites as RBCs lysed
20
Q
Thin blood film
A
- for species identification
- determines level of parasitaemia
- less sensitive than thick
21
Q
P falciparum on film
A
- numerous fine rings
- double chromatin dots
- cell multiple parasitisation
- schizonts rare
- red cells not enlarged
22
Q
P vivax on film
A
- thick signet ring forms
- trophozoites ameboid appearance
- enlarged red cells
23
Q
P ovale on film
A
- oval shaped trophozoite
- comet like red cells
- enlarged red cells
24
Q
P. malariae on film
A
- broad band
- red cells not enlarged
25
P. knowlesi on film
- ring stages resembling P. falciparum
- mature stages indistinguishable from P. malariae
- molecule methods needed for diagnosis confirmation
26
Antigen Detection
- histidine rich protein 2 (HRP-2) associated with P. falciparum
- plasmodium associated LDH (pLDH)
27
Clinical Presentation
- fever
- headache
- muscle aches
- diarrhoea
- vomiting
28
History questions
- 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?)
29
Examination
```
Vital signs A to G
E = exposure
F = fluids
G = glucose
- give oxygen
- position patient
- establish fluids
- look for signs of severity
```
30
Signs of severe malaria
- 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%
31
Renal impairment diagnosis
Oliguria >0.4ml/kg bodyweight per hour
OR
creatinine >265mmol/l
32
Management of malaria
- 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
33
Uncomplicated P. falciparum treatment
- oral therapy
- malarone
- riamet
- quinine & doxy or clinda
34
Non-falciparum treatment
chloroquine followed by primaquine
| - check G6PD status
35
Riamet
ACT (artemisinin combination therapy)
| Artemether-lumefantrine
36
Malarone
Atovaquone-Proguanil
37
Severe complicated P. falciparum treatment
IV artesunate (preferred)
OR
IV Quinine (cardiac & blood glucose monitoring)
Oral therapy as for uncomplicated once improved
Check blood film daily
38
Indications for IV therapy
Severe complicated P. falciparum
parasitaemia >2% or presence of shizonts
Vomiting
Pregnancy
39
Prevention of malaria
Awareness of risk
Bite prevention
Chemoprophylaxis
Prompt diagnosis and treatment
40
Public Awareness
National Travel Health Network and Centre
NHS: GPs, infection specialists
Public Health bodies, PH England
Media
41
Bite Prevention
DEET based insect repellants
Bed nets, insecticide treated
Clothing
42
Chemoprophylaxis
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
43
Vector control
Insecticide treated nets
Indoor residual spray
Genetically modified mosquitoies
44
Immunisation
On going development
