GI: Malaria

Question 1

What type of infection is Malaria?

Answer 1

Parasitic infection

Question 2

How is it transmitted?

Answer 2

bite of infected mosquito

Question 3

stats, curable??

Answer 3

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

Question 4

Malaria and travel from UK

Answer 4

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

Question 5

Who is at high risk of malaria?

Answer 5

migrants
pregnant women
those with no spleen
children
elderly

Question 6

Different Plasmodia, different outcomes?

Answer 6

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

Question 7

What is ABCD?
Travellers to malarious regions

Answer 7

Awareness of risk
Bite avoidance
Chemoprophylaxis
Diagnosis

Question 8

Awareness of risk

Answer 8

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

Question 9

Malaria life cycle

Answer 9

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

Question 10

What are the symptoms of Malaria?

Answer 10

central - headache
skin - chills, sweating
respiratory - dry cough
spleen - enlargement
stomach - nausea, vomiting
Back - pain
muscular - fatigue, pain
systemic - fever

Question 11

Major feature of severe or complicated falciparum malaria in adults?

Answer 11

impaired consciousness or seizures

Renal impairment

Hypoglycaemia

Pulmonary oedema or actute resp distress syndrome (ARDS)

Haemoglobinuria

Question 12

What are the major features or complicated malaria in children?

Answer 12

impaired consciuousness or seizures

Hypoglycaemia\severe anaemia
prostration

Question 13

Level of risk of exposure to malaria and what affects it

Answer 13

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

Question 14

Bite prevention

Answer 14

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.

Question 15

Repellents – 1st line

Answer 15

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

Question 16

Repellents - others

Answer 16

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

Question 17

What other ways can you prevent a bite?

Answer 17

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.

Question 18

What does not work against Malaria?

Answer 18

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

Question 19

Chemoprohylaxis

Answer 19

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

Question 20

Drugs to treat

Answer 20

Mefloquine (weekly)
Doxycycline (daily)
Proguanil and atovaquone (daily)
Chlorowuine (weekly)
Proguanil (daily)

Question 21

Chloroquine [P]

Answer 21

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

Question 22

Chloroquine
Dose, contraindications, adverse effects

Answer 22

take by mouth with food

adult dose 310mg (2tablets)

contraindications; concomitant amiodarone, epilepsy

a.e - Gi disturbances, headachem, convulsions, skin reactions

Question 23

Proguanil [P]

Answer 23

Converted to active metabolite cyclkoguanil which inhibits enzyme dihydrofolate reductase and interferes wiyh synthesis of folic acid - suppressive and causal

Question 24

Proguanil [P]

Answer 24

take by mouth with food

aduklt dose 200mg, starting 1 week before entering

caution; renal impairement, pregannacy

a.e - gi disturbance, mouth unclers, stomatitis

Question 25

Mefloquine [POM]

Answer 25

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

Question 26

Mefloquine [POM]

Answer 26

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

Question 27

Doxycycline [POM]

Answer 27

Lipophilic and acts intracellularly, binding to ribosomal mRNA and inhibiting protein synthesis – suppressive
Comparable prophylactic efficacy to mefloquine

Question 28

Doxycycline [POM]
- how to take?

Answer 28

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

Question 29

Atovaquone plus proguanil combination [P]

Answer 29

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%+

Question 30

Atovaquone plus proguanil combination [P]
dose
contraindications and adverse effects? ? ?

Answer 30

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

Question 31

Drugs summary

Answer 31

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

Question 32

Diagnosis
of MALARIA:

Answer 32

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