Malaria; Management, Chemoprophylaxis, Prevention and Global Impact Flashcards
(42 cards)
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
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
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.
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
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
6
Q
Why is there no malaria vaccine?
A
- Much more complicated than virus etc.
- Complexity of life cycle
- Lots of mutations
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
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
9
Q
Why take malaria chemoprophylaxis?
A
Can reduce risk of malaria by 90%
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
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
12
Q
Are there any chemoprophylactic options against hypnozoites?
A
- No prophylactic drugs against these stages (P. vivax, P. ovale)
- BUT, can be treated
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
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
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)
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’)
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
What is the clinical presentation of malaria?
- 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
What are the three stages of malarial febrile paroxysms (sudden fever)?
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
What causes malarial febrile paroxysms?
- Schizonts burst out of erythrocytes
| - Lots of endotoxins; massive inflammatory response
28
How pathogenic are the different strains of malaria to RBCs etc?
- 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
How is P. falciparum more peak?
- 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
What occurs when > 2% RBCs are infected?
- P. falciparum normally
| - Cerebral malaria & blackwater fever (urine turns black because of blood in urine)
31
What is cerebral malaria?
- Consistent release of pathogen leads to marked rise in temperature
- Patient experiences rapid deterioration in consciousness (clogging in microvasculature), convulsions, coma, death.
32
What is blackwater fever?
- Dark brown urine from intravascular haemolysis in blood stream, kidneys start to pass metabolites
- Leads to acute renal failure
>>> ONLY P. falciparum
33
Why can splenic rupture occur from malaria? What can this lead to?
- Spleen enlarged from severe anaemia
- Jaundice
- Diarrhoea
34
What metabolic disturbances may arise from malaria complications?
- Acidosis
- Hypoglycaemia
- Pulmonary oedema
>>> Ventilator (50% chance mortality)
35
What occurs to children that survive malaria?
Permanent effects of malaria:
- Cerebral palsy
- Blindness
- Deafness
- Cognition & learning
- 10% have persistent language deficit w/defects
- Decreased life expectancy
- Increased epilepsy incidence
36
What is tropical splenomegaly syndrome?
Malaria is hyperendemic; response to antimalarial therapy
37
What is the link of malaria to HIV?
- Transmission linked
| - HIV prevalent in P. falciparum endemic areas
38
What is the prognosis for pregnant women who are infected w/malaria?
- High maternal mortality
| - Risk of LBW and infant mortality too
39
How is severe malaria (usually P. falciparum) treated?
- 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
What are the S/Es associated w/quinine?
Cinchonism (OD of quinine):
- Tinnitus
- Vertigo
41
If a patient is infected w/P. vivax/ovale, what are the treated with?
14 days of primaquine (PQ) to clear hypnozoites (not in G6PD deficiency)
42
What does emergency standby treatment of malaria entail?
- 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.
