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B33CAN - Professionalism & Leadership; Clinical & Pharmacy Practice > Malaria; Management, Chemoprophylaxis, Prevention and Global Impact > Flashcards

Malaria; Management, Chemoprophylaxis, Prevention and Global Impact Flashcards

1
Q

How prolific is malaria? Where is it often found? 02:40

A
  • Found in more than 100 countries, affecting 3 billion people
  • Mainly in tropical regions of the world, including:
    • large areas of Africa/Asia
    • Central and South America
    • Haiti and the Dominican Republic
    • Parts of the Middle East
    • Some Pacific Islands
  • Anopheles mosquito not native to the UK; but about 1,400 travellers diagnosed w/malaria from above areas in 2012, with 2 dying (most P. falciparum, with P. vivax next most common)
  • Other strains not as common
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2
Q

How deadly is malaria?

A
  • WHO reports states that 207 million cases of malaria worldwide in 2012
  • 627,000 deaths
    »> Accounts for 10% deaths in Sub-Saharan Africa
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3
Q

How does risk of contracting malaria increase?

A

• Proportional to number of times bitten by Anopheles spp.

  • Asia/South-Central America inhabitants; on average bitten once or twice a year by infective mosquito
  • Sub-Saharan Africa inhabitants; on average bitten 1,000 times a year by P. falciparum infected Anopheles.
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4
Q

What factors affect travellers’ exposure to malaria?

A
  • Optimum conditions for malaria transmission are high humidity and ambient temp. of 20 - 30ºC
  • Doesn’t normally occur in regions with temperature below the 16ºC isotherm (line like equator)
  • Parasite maturation in Anopheles mosquito does not take place > 2000m
  • Seasonal rainfall increases mosquito breeding; malaria is highly seasonal (humidity presence encourages breeding)
  • More common in rural areas (8x higher transmission in a village than a town in Sub-Saharan Africa)
  • Backpackers staying in cheap accommodation have a higher risk of being bitten compared to air-conditioned hotels; holes in malaria nets, windows not sealed etc.
  • Outdoors between dusk and dawn = Anopheles spp. fave time to bite
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5
Q

What is the ABCD approach to malaria prophylaxis?

A
  • Awareness of risk; find out whether you’re at risk of getting malaria before travelling
  • Bite prevention; avoid bites by using insect repellent (DEET), covering arms and legs w/insecticide-treated mosquito net
  • Check whether you need to take malaria prevention tablets; if you do, make sure you take the right antimalarial tablets at right dose, and finish course
  • Diagnosis; seek immediate medical advice if you develop symptoms, including up to a year after returning from travelling
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6
Q

Why is there no malaria vaccine?

A
  • Much more complicated than virus etc.
  • Complexity of life cycle
  • Lots of mutations
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7
Q

What advice is there availible to patients for bite prevention?

A
  • Staying somewhere w/A/C and screening on doors and windows, make sure they’re closed during sleep, sleep under intact mosquito net treated w/insecticide
  • Use insect repellent on skin and in sleep environments, re-apply frequently (most effective contain DEET; diethyltoluamide)
  • DEET not recommended for babies < 2 months old
  • Wear loose-fitting trousers instead of shorts, shirts with long sleeves; particularly important during early evening and night, when mosquitoes prefer to feed (DO NOT EXPOSE SKIN)
    »> No evidence that homeopathic remedies, electronic buzzers, vitamins B1 or B12, garlic, yeast extract spread (Marmite), tea tree oils or bath oils offer any protection
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8
Q

What is the choice of malaria chemoprophylaxis based upon?

A
  • Destination (prophylaxis against which strain?)
  • Medical history, allergies
  • Current medication
  • Previous history w/antimalarials
  • Age
  • Pregnancy
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9
Q

Why take malaria chemoprophylaxis?

A

Can reduce risk of malaria by 90%

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10
Q

What is causal prophylaxis?

A
  • Targets liver (exo-erythrocytic stage) stage
  • Takes 7 days to develop
  • Continue for 7 days after leaving malarious zone
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11
Q

What is suppressive prophylaxis?

A
  • Erythrocytic stage
  • Continue for 4 weeks after leaving malarious zone; need to wait for exo-erythrocytic stages to ‘play their course’ as these drugs are ‘suppressive’; only target RBC stage
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12
Q

Are there any chemoprophylactic options against hypnozoites?

A
  • No prophylactic drugs against these stages (P. vivax, P. ovale)
  • BUT, can be treated
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13
Q

What is the relevant distribution of drug resistant malaria and its different strains?

A
  • Chloroquine-resistant falciparum malaria universal; DO NOT give CQ if suspected P. falciparum
    »> Check ACMP (Advisory Committee on Malaria Prevention for UK Travellers) for up to date information on P. falciparum
  • No recorded resistance to P. ovale
  • 1 resistance to P. malariae
  • CQ-resistant P. vivax about
  • P. vivax w/reduced susceptibility to primaquine (which targets hypnozoite stage)
  • Some P. falciparum resistant to artemisinin
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14
Q

Which phase of malaria infection is Malarone (atovaquone + proguanil) effective against? How is it taken? Efficacy against?

A
  • Prevents development of liver schizonts; causal prophylactic
  • Take for 1-2days before entering & 7 days after leaving endemic area
  • Works on erythrocytic stages too (for treatment as well as prophylaxis)
  • 90% efficacy against P. falciparum, w/efficacy against P. vivax too
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15
Q

What are the S/Es associated w/Malarone (atovaquone + proguanil)? CIs?

A

S/Es:

  • Headache
  • GI upset
  • Skin rash
  • Mouth ulcers

CI:

  • Pregnant/breastfeeding
  • Or in people with renal problems (can accumulate)
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16
Q

How is the quinine analogue Mefloquine (Lariam) taken? Why is is taken this way?

A

• Suppressive prophylactic

  • Take for 21 days before entering, and 28 days after leaving endemic area
  • 21 days prior; associated w/psychotropic S/Es; drug is racemic mix, + enantiomer is antimalarial, - enantiomer is psychotropic
  • 28 days after; no activity in liver stages (only erythrocytic; ‘wait it out’)
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17
Q

When is malaria chemoprophylaxis w/Mefloquine (Lariam) not recommended? What S/Es may present otherwise?

A

Not recommended in:

  • Epilepsy
  • Seizures
  • Depression, or other MH problems, or if familial history of these problems, severe heart or liver problems.

S/Es:

  • Dizziness
  • Headache
  • Sleep disturbances (insomnia, vivid dreams)
  • Psychiatric reactions (anxiety, depression, panic attack, hallucinations) - more common in young men
    »> Hence 21 day pre-period to observe for S/Es
18
Q

How is Doxycycline given for malaria chemoprophylaxis? How does it work?

A
  • Prevents development of erythrocytic stages; suppressive prophylactic
  • Taken for 1-2days before entering, 28 days after leaving
19
Q

Who is Doxycycline CI in, and what are its common S/Es?

A

CI:

  • Pregnant/breast-feeding
  • Children U12 (tetracycline; risk of permanent tooth discolouration)
  • Liver problems
S/Es:
- Sunburn due to photosensitivity
- Stomach upset
- Heartburn
- Thrush
- Taken w/food
>>> Doesn't reduce effectiveness of contraceptive pill
20
Q

When is chloroquine and proguanil taken together for malaria chemoprophylaxis?

A
  • Rarely recommended due to high P. falciparum resistance
  • But, occasionally recommended for certain destinations where P. falciparum is less common than other types e.g. India, Sri Lanka
21
Q

What bad press surrounded Mefloquine (Lariam), and why is this peak?

A
  • Potential psychotropic effects very widely reported

- Could affect adherence; but then result in actual malaria infection.

22
Q

What does ayurvedic medicine say WRT malaria prophylaxis?

A
  • “Stepping out of the home w/an empty stomach is the first thing people should avoid”
    > Not malnourished so not too dumb
23
Q

Which areas result in the greatest no. of malaria deaths from UK travellers?

A
  • P. falciparum
  • Usually where CQ-resistant P. falciparum is endemic
    »> 78% reported cases had not taken any chemoprophylaxis, or the wrong ones (e.g. for wrong strain)
24
Q

What factors affect malaria chemoprophylaxis adherence?

A
  • Effectiveness
  • S/Es
  • Previous experience of antimalarials (everyone blames them for unrelated tings)
  • Dosing convenience
  • Practitioner’s recommendation was important for 63% of travellers
  • Travellers stopping antimalarials early after returning from holiday = big cause
25
Q

What is the clinical presentation of malaria?

A
  • Diagnosed and treat PROMPTLY; full recovery can be expected
  • Incubation period for P. falciparum/vivax/ovale; 8-12 days, with P. malariae having 18 days - 8 weeks (Cheryl Cole was back for a year before showing symptoms… hypnozoites; can be delayed for several months)
  • Pro-dromal symptoms (non-specific):
    • Headache
    • Muscular aches and pains
    • Malaise
    • N&V second week after exposure.
  • Paroxysmal episode of chills and fever (classic fever)
  • Thrombocytopenia; low platelets (haemorrage risk)
  • Jaundice; yellowing, bilirubin in liver
26
Q

What are the three stages of malarial febrile paroxysms (sudden fever)?

A

Cold stage:

  • Marked vasoconstriction, lasts for 30-60 mins
  • Patient feels cold and uncomfortable
  • Marked shivering
  • Temp. rises rapidly, often to as high as 41ºC

Hot stage:

  • Abruptly follows, lasts 2-6 hours
  • Patient intensely hot and uncomfortable
  • Delirium (singing etc.)

Sweating stage:

  • Bedclothes drenched
  • Fatigued and exhausted but otherwise well; often sleeps - exhausting for body
27
Q

What causes malarial febrile paroxysms?

A
  • Schizonts burst out of erythrocytes

- Lots of endotoxins; massive inflammatory response

28
Q

How pathogenic are the different strains of malaria to RBCs etc?

A
  • P. vivax and P. ovale; only young RBCs
  • P. falciparum; attacks all RBCs (much bigger infection of RBCs; release stage much more dramatic, 40,000 - 50,000 merozoites from a cell)
29
Q

How is P. falciparum more peak?

A
  • Much more likely to lead to anaemia (40,000-50,000 merozoites release from one RBC)
  • RBCs are more highly infected; develop knobs and stick to endothelium, causes severe organ damage to kidneys, liver, brain GIT
    »> SERIOUS
30
Q

What occurs when > 2% RBCs are infected?

A
  • P. falciparum normally

- Cerebral malaria & blackwater fever (urine turns black because of blood in urine)

31
Q

What is cerebral malaria?

A
  • Consistent release of pathogen leads to marked rise in temperature
  • Patient experiences rapid deterioration in consciousness (clogging in microvasculature), convulsions, coma, death.
32
Q

What is blackwater fever?

A
  • Dark brown urine from intravascular haemolysis in blood stream, kidneys start to pass metabolites
  • Leads to acute renal failure
    »> ONLY P. falciparum
33
Q

Why can splenic rupture occur from malaria? What can this lead to?

A
  • Spleen enlarged from severe anaemia
  • Jaundice
  • Diarrhoea
34
Q

What metabolic disturbances may arise from malaria complications?

A
  • Acidosis
  • Hypoglycaemia
  • Pulmonary oedema
    »> Ventilator (50% chance mortality)
35
Q

What occurs to children that survive malaria?

A

Permanent effects of malaria:

  • Cerebral palsy
  • Blindness
  • Deafness
  • Cognition & learning
  • 10% have persistent language deficit w/defects
  • Decreased life expectancy
  • Increased epilepsy incidence
36
Q

What is tropical splenomegaly syndrome?

A

Malaria is hyperendemic; response to antimalarial therapy

37
Q

What is the link of malaria to HIV?

A
  • Transmission linked

- HIV prevalent in P. falciparum endemic areas

38
Q

What is the prognosis for pregnant women who are infected w/malaria?

A
  • High maternal mortality

- Risk of LBW and infant mortality too

39
Q

How is severe malaria (usually P. falciparum) treated?

A
  • Quinine dihydrochloride infusion or IM TDS
    • Haemodialysis
    • Respiratory support
    • Glucose
    • Blood transfusions
    • BZDs in children (prevent fitting)
    »> Quinine works on RBC stage only; suppressive, takes a while but reliable
40
Q

What are the S/Es associated w/quinine?

A

Cinchonism (OD of quinine):

  • Tinnitus
  • Vertigo
41
Q

If a patient is infected w/P. vivax/ovale, what are the treated with?

A

14 days of primaquine (PQ) to clear hypnozoites (not in G6PD deficiency)

42
Q

What does emergency standby treatment of malaria entail?

A
  • Speedy treatment of malaria essential
  • Travellers advised to carry a course of emergency treatment if travelling to areas remote from medical attention
  • “If you’ve got the drugs and maybe the symptoms, just take the drugs”

Various emergency treatments:
• Malarone (atovaquone + proguanil)
• Riamet (artemether + lumefantrine)
• Quinine + doxycycline

> > > Patient then needs to seek medical advice ASAP to ensure treatment has been adequate and that no other illness is involved.

B33CAN - Professionalism & Leadership; Clinical & Pharmacy Practice (8 decks)

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