INF2 - A. MALARIA-COVERED Flashcards
where is malaria mainly found
tropical regions
- Africa and Asia
- central and south America
- Haiti and Dominican Republic
- Middle East
- some pacific islands
not found in UK (only returning travellers)
what factors affect travellers’ exposure to malaria
- high humidity and 20-30 degrees Celsius
- transmission doesn’t occur where temp is below 16 degrees Celsius isotherm
- parasite maturation in mosquito can’t take place >2000m above sea level
- seasonal rainfall increases mosquito breeding (monsoons)
- rural location (swampy)
- backpackers: cheap accommodation, open windows
- outdoors between dusk and dawn when Anopheles mosquitos bite
prophylaxis of malaria
ABCD
- Awareness of risk: are you at risk: where, what, how long
- Bite prevention: insect repellent, cover arms and legs, insecticide-treated mosquito net, inside between dusk and dawn
- Check if need malaria prevention tablets
- Diagnosis: immediate medical advice if develop malaria symptoms, up to a year after travelling
Consult a HC professional if going somewhere where malaria is a risk
how to prevent getting bitten
- air conditioning and screening on doors and windows
- close windows and doors
- sleep under an intact mosquito net treated with insecticide
- long lasting impregnated nets
- insect repellent on skin and when sleeping. Need at least 50% DEET
- loose-fitting trousers and long sleeves: esp at night when they prefer to feed
- homeopathic remedies don’t offer any protection
what are the 2 types of chemoprophylaxis
- casual prophylaxis
- targets liver stage
- takes 7 days to develop (liver stage)
- continue for 7 days after leaving malarious zone - suppressive prophylaxis
- targets erythrocytic stage
- continue for 4 weeks after leaving malarious zone
no prophylactic drugs for hypnozoites - P. oval and P. vivax
Atovaquone plus proguanil (Malarone) chemoprophylaxis (POM)
- 1st choice
- prevents development of liver schizonts (casual)
- take 1-2 days before entering malarial zone, when there and for a week after leave
- 1 tablet every day
- works on erythrocytic stages so used for treatment aswell
- 90% efficacy against P. falciparum and also against P. vivax
- side effects: headache, GI upset, skin rash, mouth ulcers
- NOT taken by pregnant or breastfeeding women or those with severe kidney problems
- more expensive
- licensing: 12 weeks
Mefloquine (Larium) prophylaxis (POM)
- a quinoline
- suppressive?
- take a week before, when there for 4 weeks after leave
- one tablet weekly
- 90% efficacy against P. falciparum
- NOT for those with epilepsy, seizures, depression, mental health problems, if close relative has these, severe heart or liver problem
- side effects: dizziness, headache, sleep disturbances, psychiatric reactions (anxiety, depression, panic attacks, hallucinations)
- 3-week trial recommended
- licensing: 12 months
doxycycline (vibramycin-D) prophylaxis (POM)
- suppressive: prevents development of erythrocytic stages
- take a week before, when there for 4 weeks after leave
- 1 tablet every day
- NOT taken by pregnant or breastfeeding women, under 12 (risk of permanent tooth discolouration), sensitive to tetracycline antibiotics or people with liver problems, on warfarin
- side effects: sunburn due to light sensitivity, stomach upset, heartburn, thrush
- take with food, standing or sitting
chloroquine and proguanil prophylaxis (P)
- 2 separate tablets
- chloroquine: once weekly, proguanil: everyday
- suppressive
- take a week before, when there for 4 weeks after leave
- rarely used as largely ineffective against P. falciparum
- india and Sri Lanka: P. falciparum less common
- same side effects as mefloquine
what is the most common cause of malaria
P. falciparum, where chloroquine-resistant P. falciparum is endemic
what is the incubation period for P. falciparum, vivax, oval
8-12 days
what is the incubation period for P. malariae
18 days - 6 weeks
prodromal symptoms
headache
muscular aches and pains
malaise
nausea
vomiting
- 2nd week after exposure
- incubation period can be delayed for months
what can confirm diagnosis
- history of travel to an endemic area
- typical paroxysmal episode of chills and fever
- thrombocytopenia
- jaundice
- +ve identification of parasites in blood (blood film)
what are the 3 stages of malarial febrile paroxysms
- cold stage: marked vasoconstriction
- lasts 30-60 minutes
- intensely cold and shivering
- temp rises rapidly - 41 degrees Celsius
- can have seizures - hot stage:
- lasts for 2-6 hours
- intensely hot
- delirium esp if dehydrated - sweating stage:
- bedclothes drenched
- fatigued and exhausted
- sleeps
*fever every other day with P vivax and ovale
*P. falciparum - develops in RBCs, RBCs develop knobs and stick to endothelium - organ damage to kidneys, liver, brain, GI tract
*severe fever and prodrome has no pattern
need to be in intensive care
paracetamol
fluids
oxygen
treatment
how does cerebral malaria and blackwater fever occur
- not treated promptly enough
- > 2% RBCs infected
symptoms of cerebral malaria
- increase in body temp
- rapid deterioration in consciousness
- convulsions
- coma and death
symptoms of blackwater fever
- dark brown urine from intravascular haemolysis
- only P. falciparum
- acute renal failure so dialysis needed
- splenic rupture
- jaundice
- diarrhoea
- severe anaemia
- hypoglycaemia
- acidosis
- pulmonary oedema
- if pregnant: high maternal mortality and and increased risk of LBW and infant mortality
what is tropical splenomegaly syndrome
- inflamed spleen
- where malaria is hyper endemic
treatment for severe falciparum malaria (IV)
- UK, artesunate or quinine dihydrochloride infusion
IV artesunate not licensed in UK, so has to be given on a named-patient basis but quinine is 2nd choice as not as well-tolerated or effective
use unlicensed artesunate if quinine unsuccessful, quinine resistance (for named patient and specially imported)
- haemodialysis, response support, glucose, blood transfusions, BZDs in children
treatment for uncomplicated falciparum malaria (ORAL)
- artemisinin combo therapy: artemether-lumefantrin or dihydroartemisinin-piperaquine for 3 days
- oral atovaquone-proguanil for 3 days
- oral quinine plus doxycycline for 7 days
treatment for non-falciparum malaria (vivax/ovale)
oral chloroquine or artemether-lumefantrin 3 days then primaquine 14 days
what are the emergency treatments
Malarone
artemether with lumefantrine = Riamet
quinine with doxycycline
determinants of malaria
- host: SCD, no Duffy blood factor - more resistant to malaria
- parasite: falciparum is more virulent and resistant
- tropical warms areas, heavy rainfall, high humidity, still water
- swamp draining, air conditioning etc
