GI: Malaria Flashcards
(32 cards)
What type of infection is Malaria?
Parasitic infection
How is it transmitted?
bite of infected mosquito
stats, curable??
More than 627,000 deaths worldwide in 2020
481,500 of these were children under 5, mainly in Africa
Curable if diagnosed and treated promptly
Malaria and travel from UK
Around 1,500 cases of malaria are reported annually in travellers returning to or arriving in the UK – eight or fewer deaths each year in UK since 2006
Who is at high risk of malaria?
migrants
pregnant women
those with no spleen
children
elderly
Different Plasmodia, different outcomes?
P. falciparum
Causes the most severe disease because of micorvascular effects
Only species likely to be fatal in healthy patients
Can cause death within days of symptom onset
P. vivax, P. ovale, P. malariae, and P. knowlesi
Typically do not compromise vital organs
Mortality rare and mostly due to splenic rupture or uncontrolled hyperparasitaemia in asplenic patients
What is ABCD?
Travellers to malarious regions
Awareness of risk
Bite avoidance
Chemoprophylaxis
Diagnosis
Awareness of risk
Public Health guidance:
Advise pt that while no regimen is 100% effective, the better you follow guidelines the more likely you are to avoid infection
Make use of visual aids to show malaria distribution
Discuss preventative measures based on individual risk – need full medical history
Provide written information
Malaria life cycle
Bite prevention acts at the start of the cycle
“Causal” prophylaxis acts on the parasite in the liver
“Suppressive” prophylaxis acts on the parasite in the RBCs
What are the symptoms of Malaria?
central - headache
skin - chills, sweating
respiratory - dry cough
spleen - enlargement
stomach - nausea, vomiting
Back - pain
muscular - fatigue, pain
systemic - fever
Major feature of severe or complicated falciparum malaria in adults?
impaired consciousness or seizures
Renal impairment
Hypoglycaemia
Pulmonary oedema or actute resp distress syndrome (ARDS)
Haemoglobinuria
What are the major features or complicated malaria in children?
impaired consciuousness or seizures
Hypoglycaemia\severe anaemia
prostration
Level of risk of exposure to malaria and what affects it
Number of bites: higher = increased risk
Temperature, altitude and season: usually 20-30C, lower than 2,000m, often worse in rainy season
Rural versus urban location: higher in rural areas
Type of accommodation: well-sealed, air-conditioned rooms reduce risk
Patterns of activity: being outdoors between dusk and dawn when Anopheles mosquitoes bite
Length of stay: longer stays = increased risk
Bite prevention
Effective bite prevention should be the 1st line of defence against malarial infection
Bite times vary between mosquito species, but mostly dusk till dawn
Africa: most bites around midnight so protection overnight particularly important
South America and South East Asia: higher risk in evening before retiring indoors.
Repellents – 1st line
50% DEET (N,N-Diethyl-meta-toluamide)
Can damage plastics!
Follow re-application instructions carefully
Ensure do not come into contact with eyes or mouth
Only use on exposed areas of skin
Not recommended for infants below the age of 2 months
Benefit outweighs risk in pregnancy
Repellents - others
Eucalyptus citriodora oil, hydrated, cyclized (eucalyptus citriodora): provides protection for several hours
Icaridin (Picaridin): protection equivalent to 20% DEET
3-ethlyaminopropionate: shorter duration of action than DEET
Oil of citronella: short-lived protection, not recommended
What other ways can you prevent a bite?
Insecticides: permethrin and other synthetic pyrethroids are used to kill resting mosquitoes in a room
Nets: all travellers to malaria-endemic areas should sleep under an insecticide-treated mosquito net – efficacy estimated at 50%
Clothing: Within the limits of practicality, cover up with loose-fitting clothing, long sleeves, long trousers and socks if out of doors after sunset, to minimise accessibility to skin for biting mosquitoes.
What does not work against Malaria?
Herbal remedies: none proven
Homeopathy: none proven
Buzzers: “completely ineffective”
Vit B1: not effective
Vit B12: not effective
Garlic: not effective
Yeast extract: no evidence
Tea tree oil: not effective
Bath oils/emollients: none have evidence
Alcohol: not effective
Chemoprohylaxis
Drug choice needs to be appropriate for destination
Use NaTHNaC, MIMS, BNF to find what needs to be used
Need to consult at least 2-3 weeks before travel ideally
Protection not absolute
Causal prophylaxis: liver stage – need to be continued for 7 days post-exposure
Suppressive prophylaxis: RBC stage – need to take for 4 weeks post-exposure
Drugs to treat
Mefloquine (weekly)
Doxycycline (daily)
Proguanil and atovaquone (daily)
Chlorowuine (weekly)
Proguanil (daily)
Chloroquine [P]
Concentrated in the malaria parasite lysosome and is thought to act by interfering with malaria pigment formation - suppressive
Chloroquine-resistant falciparum malaria is now everywhere other than Central America north of the Panama Canal and in Haiti and Dominican Republic
Remains effective against most P. vivax, all P. ovale, P. knowlesi, and virtually all P. malariae
Chloroquine
Dose, contraindications, adverse effects
take by mouth with food
adult dose 310mg (2tablets)
contraindications; concomitant amiodarone, epilepsy
a.e - Gi disturbances, headachem, convulsions, skin reactions
Proguanil [P]
Converted to active metabolite cyclkoguanil which inhibits enzyme dihydrofolate reductase and interferes wiyh synthesis of folic acid - suppressive and causal
Proguanil [P]
take by mouth with food
aduklt dose 200mg, starting 1 week before entering
caution; renal impairement, pregannacy
a.e - gi disturbance, mouth unclers, stomatitis
