GI: Malaria Flashcards
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
Mefloquine [POM]
determined but thought to be related to chloroquine and not involve an anti-folate action - suppressive
resistanvce of P.falciparum to mefloquine is a problem only in some areas of S-east asia
Mefloquine [POM]
Needs stringent risk assessment before use
Taken orally, preferably after a meal and with plenty of liquid.
Adult dose 250mg weekly, starting 2 to 3 weeks before entering a malarious area to assess tolerability, continuing throughout the time in the area and for 4 weeks after leaving the area.
contraindications:
prev history of depression, generalized, anxiety disorder, suicide disorder, epilepsy, convulsions of any origin
a.e - neuropsychiatric
Doxycycline [POM]
Lipophilic and acts intracellularly, binding to ribosomal mRNA and inhibiting protein synthesis – suppressive
Comparable prophylactic efficacy to mefloquine
Doxycycline [POM]
- how to take?
Swallowed with plenty of fluid either the resting or standing position, should NOT lie down - for at least 1 hr after ingestion
adult - 100mg daily, starting 1-2 days before entering a malarious area, continue throughout time in area and for 4 weeks AFTER leaving
contraindications ; children <12, pregnancy, breast-feeding
a.e - oesophagitis, photosensitivity
Atovaquone plus proguanil combination [P]
Atovaquone works by inhibiting electron transport in the mitochondrial cytochrome b-c1 complex, causing collapse in the mitochondrial membrane potential - causal
Action potentiated by proguanil
Prophylactic efficacy against P. falciparum is 90%+
Atovaquone plus proguanil combination [P]
dose
contraindications and adverse effects? ? ?
adult dose 1 tablet daily starting 1-2 days before entering a malarious area, continue throughout time area and for 7 days after leaving area
contraindications - renal impairment
caution in pregnancy and breast-feeding
adverse effects; GO disturbances
Drugs summary
Chloroquine (weekly), proguanil (daily): start one week before travel, for duration of travel AND for four weeks after return
Doxycycline (daily): start 1-2 days before travel, for duration of travel AND for four weeks after return
Mefloquine (weekly): start 2-3 weeks before travel, for duration of travel AND for four weeks after return
Atovaquone/proguanil (daily): start one week before travel, for duration of travel AND for seven days after return
Diagnosis
of MALARIA:
Major reasons for developing malaria
no anti-malarials
inappropriate regimen
non-compliance
Suspected malaria is a medical emergency
Consider malaria in every ill patient who has returned from a malarious area in the previous year, especially in the previous 3 months
