W9 Malaria

Question 1

What is Malaria?

Answer 1

• Potentially serious Plasmodia sp. parasitic infection
• Transmitted by bite of infected mosquito (vector)

Question 2

Malaria and travel from UK
Who are at risk? (1)
Who are at high risk?(4)

Answer 2

• 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
• All travellers visiting areas where malaria occurs are at risk
• Most at risk are migrants to the UK who were born in malaria risk areas and return to visit friends and relatives in their country of birth
• Others at higher risk include:
• Pregnant women
• Those with no spleen
• Children
• Elderly

Question 3

Different Plasmodia, different outcomes

Answer 3

• 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 4

Travellers to malarious regions
What does ABCD stand for?

Answer 4

• A wareness of risk
• B ite avoidance
• C hemoprophylaxis
• D iagnosis

Question 5

Malaria life cycle

Answer 5

• 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 6

Symptoms of malaria:

Answer 6

Headache (Central)
Fever (Systemic)
Fatigue, Pain (Muscular)
Pain (Back)
Chills, Sweating (Skin)
Dry cough (Respiratory)
Enlargement (Spleen)
N & V (Stomach)

Question 7

Clinical signs and symptoms of malaria:

Answer 7

Fever, sweats or chills
Malaise (vague discomfort)
Myalgia
Diarrhoea
Cough

Question 8

Level of risk of exposure to malaria and what affects it:

Answer 8

• Number of bites: higher = increased risk
• Temperature, altitude and season: usually 20-30C, lower than 2,000m, often worse in the 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 9

Bite prevention:
What are the most likely bite times?

Answer 9

• Effective bite prevention should be the first 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 10

What Repellent is 1st line for malaria?
Not reccomended for..?

Answer 10

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 11

What are some other less common Repellents ? (4)

Answer 11

• 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 12

Other ways to prevent bites (3)

Answer 12

• 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 mosquitoe

Question 13

Things that don’t work

Answer 13

• 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 14

ABCD:
C= Chemoprophylaxis

Answer 14

• 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 15

What drugs are used to treat malaria? (5)

Answer 15

Mefloquine (weekly)
Doxycycline (daily)
Proguanil and atovaquone (daily) [P]
Proguanil (daily) [P]
Chloroquine (weekly) [P]

Question 16

What is Chloroquine [P]?

Answer 16

• 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 the Dominican Republic
• Remains effective against most P. vivax, all P. ovale, P.Knowles, and virtually all P. malariae

Question 17

Chloroquine
Directions?
Dose?
C/I?
AE?

Answer 17

• Take by mouth with food
• Adult dose 310mg (2 tablets) weekly, starting 1 week before
  entering a malarious area, continuing throughout the time in
  the area and for 4 weeks after leaving the area
• Contraindications: concomitant amiodarone, epilepsy
• Adverse effects: GI disturbances, headache, convulsions, skin
  reactions

Question 18

What is Proguanil [P]?
What is it converted to?

Answer 18

• Antimalarial medication
• Converted to an active metabolite cycloguanil which inhibits the enzyme dihydrofolate reductase and interferes with the synthesis of folic acid – suppressive and causal
• There are very few regions in the world where the local P.falciparum strains are fully sensitive to proguanil

Question 19

Proguanil [P]
Directions?
Dose?
C/I?
AE?

Answer 19

• Take by mouth with food
• Adult dose 200mg (2 tablets) daily, starting 1 week before
  entering a malarious area, continuing throughout the time in the area and for 4 weeks after leaving the area.
• Caution: renal impairment, pregnancy
• Adverse effects: GI disturbance, mouth ulcers and stomatitis
  (particularly when used with chloroquine

Should NOT be taken in pregnancy

Question 20

What is Mefloquine [POM]

Answer 20

• Mode of action has not been determined but is thought to be unrelated to that of chloroquine and not to involve an anti-folate action –suppressive
• The protective efficacy of mefloquine is 90%+
• Significant resistance of P. falciparum to mefloquine is a problem only in some areas of South-East Asia

Question 21

Mefloquine [POM]
Directions?
Dose?
C/I?
AE?

Answer 21

• 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: current or previous history of depression, generalized anxiety
  disorder, psychosis, schizophrenia, suicide attempts, suicidal thoughts, self-endangering behaviour or any other psychiatric disorder, epilepsy or convulsions of any origin
• Adverse effects: neuropsychiatric

Question 22

What is Doxycycline? [POM]

Answer 22

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

Question 23

Doxycycline [POM]
Directions?
Dose?
C/I?
AE?

Answer 23

• To be swallowed with plenty of fluid in either the resting or standing position and the recipient should not lie down for at least 1 hour after ingestion
• Adult dose 100mg daily, starting 1 to 2 days before entering a malarious area, continuing throughout the time in the area and for 4 weeks after leaving
• Contraindications: children <12, pregnancy, breast-feeding
• Adverse effects: oesophagitis, photosensitivity

Question 24

Atovaquone plus proguanil combination [P]
How does it work?
What is its efficacy against P.falciparum?

Answer 24

• 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 25

Atovaquone plus proguanil combination [P]
Directions?
Dose?
C/I?
AE?

Answer 25

• Adult dose 1 tablet daily starting 1 to 2 days before entering a malarious area, continuing throughout the time in the area
  and for 7 days after leaving the area
• Contraindications: renal impairment
• Caution in pregnancy and breast-feeding
• Adverse effects: GI disturbances

Question 26

Drugs summary for Antimalarials

Answer 26

• 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 27

ABCD
D= Diagnosis
What are the major reasons for developing malaria? (3)
Which patients should you consider that have malaria?

Answer 27

1. no anti-malarials
2. inappropriate regimen
3. 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