Returning traveller - malaria Flashcards
Suspect malaria in patient with fever, and travel history
Incubation is usually 6 days - 3 months. But 10% can present up to 1 year after exposure.
Prophylaxis provides 95% protection.
What are initial tests required?
FBC/U+E/LFT/CRP/Coag
Blood culture
Urinalysis
CXR
Malaria specific -
Malaria Ag
Blood film - thick/ thin with parasite count
ABG - acidosis/ hypoglycaemia
If positive for malaria, presume it is falciparum until proven otherwise
If patient presenting as outpatient for assessment, blood film needs to be done before discharging home
How many cases of malaria per year in UK?
What is case fatality rate?
2000/ year
1.2% case fatality
What are issues with malaria rapid antigen test?
Lower sensitivity
Detects antigen rather than live parasite, so can remain positive for weeks after treatment
Patient seen in A&E, plasmodium falciparum seen on blood film.
Patient well, no severe markers
What is management?
Admit for at least 24 hours of treatment
falciparum can deteriorate rapidly
if on chemoprophylaxis, stop. As clearly not working, and can reduce parasitaemia to make diagnosis more difficult
What are markers of severe malaria?
Any of these indicators means should be admitted, and given IV treatment
Escalate to ITU early
Parasitaemia >2%
Reduced GCS/ seizures
AKI - Cr >265
Pulmonary oedema
Hypoglycaemia
Anaemia - Hb <8 may need transfusion
Metabolic acidosis
Hypovoloaemia/ shock
jaundice - bilirubin >50
prostration
Why does hypoglycaemia occur in malaria?
increased glucose use in unwell patient
quinine stimulates insulin release
What is drug treatment of severe falciparum malaria?
This is a medical emergency
Artesunate
If artesunate no rapidly available, give IV quinine loading dose
Artesunate better than quinine, and has fewer side effects, and does not cause hypoglycaemia
What is dosage of artesunate?
When switch to oral?
2.4mg/kg IV bolus
Given at 0/ 12/ 24 hours, then daily afterwards
continue IV until can tolerate oral, patient improving, parasite count improving
After artesunate given for severe malaria, oral step down options preferred is coartem/ riamet
What is dosage?
What is duration of therapy?
Coartem/Riamet - artmether 20mg/ lumefantrine 120mg
4 tablets taken at 8 /24/ 36/ 48/ 60 hours
give with milk/ fatty foods as aids absorption
normally 48 hours IV artesunate, and 3 days oral is sufficient for cure
If co-artem/riamet oral options are not available, what other oral options are available for malaria?
Which option is suitable for pregnancy?
Atovaquone-proguanil OD 3 days
Doxycycline 200mg OD 7 days
Clindamicin 450mg TDS 7 days - suitable for pregnancy
These options are particularly helpful if artesunate/ coartem/ riamet not available.
IV quinine until stable - then oral quinine or the options above. Particularly helpful if has side effects to quinine
Patient with severe falciparum malaria. No artesunate available.
What is dose of quinine?
What is duration of therapy?
- 20mg/kg loading dose, given over 4 hours
- unless received mefloquine the previous day, when 10mg/kg should be used
- maintenance 10mg/ kg TDS
- switch IV to oral quinine once improving/ able to tolerate oral, for total of 7 days
What are side effects of quinine?
What tests need to be done before starting treatment?
Cinchonism is pathological condition caused by excess quinine or its natural source, cinchona bark
tinnitus - this is reversible, and not an indication for stopping quinine
QT prolongation - class 1 anti-arrhythmic. Can lead to Torsades de Pointes. Needs ECG before starting treatment
hypoglycaemia - promotes insulin secretion. Requires BM every 2-4 hours
Patient successfully treated for falciparum malaria with artesunate/ coartem/ riamet, and discharged home.
What follow up is required?
Increasing evidence of haemolytic anaemia, occurring 2-4 weeks after artesunate treatment
recommend weekly FBC for all patients who have received IV artesunate
Why are pregnant patients more likely to have severe malaria?
parasite count can be higher than suggested in peripheral blood film, due to placental sequestration
What are treatment options for malaria in pregnancy?
Artesunate/ quinine both safe pregnancy
quinine and pregnancy can both cause hypoglycaemia, so requires close monitoring
clindamicin is another oral step-down options
Uncomplicated falciparum malaria treatment
What are options?
- All falciparum cases, even if well, should be admitted for 24 hours
- do not use any drugs for treatment, if patient was previously using for prophylaxis e.g atovaquone-proguanil
Co-artem/ riamet 8/ 24/ 36/ 48/ 60
Quinine plus doxycyline 7 days
Quinine plus clindamicin 7 days
Atovaquone/ proguanil 3 days
Non-falciparum malaria - vivax/ ovale/ malariae
What are treatment options?
Admit if unwell, but can often be managed as outpatient
Riamet/ coartem
Chloroquine
Patient with vivax/ ovale malaria is initially treated with riamet/ coartem/ chloroquine, and improves.
What can be given to prevent relapse prevention?
Check G6PD level as risk haemolysis
Primaquine 15mg OD 14 days
Pregnant patient with vivax/ ovale improves on initial treatment.
What can be given to prevent relapse from hypnozoites?
primaquine contraindicated in pregnancy
chloroquine once a week for duration pregnancy/ breast feeding
once stops breast feeding, give primaquine 15mg OD 14 days
Patient treated for malaria, being discharged home.
What advice should you give about further travel?
Does not provide immunity
Bed nets/ insect spray
Chemoprophylaxis
be alert for symptoms in other family members who may be incubating
Plasmodium transmitted by female anopheles mosquito
Which species can cause severe malaria?
Falciparum
Vivax
Knowlesi
What is mechanism of action of artesunate?
Artesunate has endoperoxide bridge, with reacts with heme iron in malarial pigment
This generates free radicals, which inhibits protein synthesis or plasmodium parasite
