Travel Meds (Malaria and Dengue) Flashcards

1
Q

Malaria caused by

A

protozoal parasite plasmodium
- P. Falciparum (highest mortality)
- P. malariae
- P. ovale
- P. vivax

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2
Q

mode of transmission of malaria

A
  1. via bites of infected female anopheles mosquitoes
  2. blood transfusion
  3. needle sharing
  4. organ transplantation
  5. vertical transmission (mother to fetus)
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3
Q

areas at risk of malaria transmission

A

Africa, South America, Caribbean, Asia (SEA, India- vivax, Middle East)

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4
Q

risk factor of malaria

A
  1. exposure (dusk to dawn, endemic area, monsoon season, outdoor activity)
  2. behaviour (non compliance to chemoprophylaxis, fail to take precaution against bites)
  3. infants and children <5yo
  4. pregnancy
  5. immunocompromised (HIV)
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5
Q

incubation period of malaria

A
  1. P. ovale/vivax: 9-18d
  2. P. falciparum: 7-18d
  3. P. malariae: 18-40d
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6
Q

initial presentation of malaria

A
  1. acute febrile illness
  2. fever, chills, HA, N/V/D, abdominal pain
  3. splenomegaly
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7
Q

severe presentation of malaria

A
  1. parasitemia
  2. prostration
  3. respiratory distress, pulmonary edema
  4. decrease consciousness, seizures
  5. bleeding, severe anemia, disseminated intravascular coagulation
  6. hemoglobinuria, renal failure
  7. almost always P falciparum, rarely P. vivax
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8
Q

Malaria prophylaxis and management

A
  1. Awareness of risk (location, season, activity)
  2. Bite avoidance (insecticide, cover up)
  3. Chemoprophylaxis (get right meds, adherence)
  4. Diagnose (seek med attention immediately, not eligible for self care)
  5. Vaccination (but v hard due to complexity)
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9
Q

vaccination for malaria

A

RTS,S/AS01 (Mosquirix)
- phase 3 studied in young children and infants
- pre-qualification granted by WHO

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10
Q

Non pharm for malaria

A
  1. avoid perfumes or deodorant
  2. ear clothes and shoes that minis exposed skin
  3. choose well screened or air conditioned accomodation
  4. sleep with netting around beds
  5. stay indoors between dusk to dawn
  6. use insect repellent (DEET- Diethyltoluamide)
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11
Q

what drugs for chemoprophylaxis

A
  1. chloroquine (P only)
  2. Atovaquone + Proguanil - Malarone (POM + Exemption)
  3. Doxycline (POM)
  4. Mefloquine (P only)
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11
Q

what drugs for chemoprophylaxis

A
  1. chloroquine (P only)
  2. Atovaquone + Proguanil - Malarone (POM + Exemption)
  3. Doxycline (POM)
  4. Mefloquine (P only)
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12
Q

MOA of chloroquine

A
  1. inhibit DNA and RNA polymerase: by interfering with metabolism and hemoglobin utilisation
  2. Concentrates in parasite particles to increase pH: inhibiting growth
  3. Involves aggregates of ferriprotoporphyrin IX acting as chloroquine receptors: membrane damage
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13
Q

dose of chloroquine

A

adult: 500mg salt (300mg base) weekly
peds: 8.3 mg/kg salt (5mg/kg base) weekly

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14
Q

Administration instructions for chloroquine

A

Start: 1-2 weeks before
In the endemic area: Take weekly
Return: continue for another 4 weeks

  • administer same day each week
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15
Q

Precaution and CI when taking chloroquine

A
  1. G6PD deficiency** (increase risk of haemolytic anemia)
  2. Porphyria (genetics)
  3. Psoriasis
  4. Seizure disorders
  5. Cardiac conduction abnormalities
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16
Q

ADR of chloroquine

A

common: abdominal cramps, N/V/D/HA
others: agitation, anxiety, hepatitis, rash, ECG changes, tinnitus, hearing loss

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17
Q

other consideration for chloroquine

A

Preg/lact: Safe
other purpose: rheumatic purpose

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18
Q

alternative to chloroquine

A

Hydrochloroquine (POM)
- adult dose: 400mg (310mg base) weekly
- peds dose: 6.5mg/kd salt weekly
- administration: same as chloroquine
- reduce retinopathy

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19
Q

resistance of chloroquine

A

likely effective only in Central America, Caribbean

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20
Q

MOA of malarone

A

Atovaquone: inhibits mitochondrial electron transport

Proguanil:
- inhibits dihydrofolate reductase
- disrupts deoxythymidylate synthesis

collectively, affect erythrocytic (blood cycle) and exoerythrocytic (liver cycle) development

21
Q

Dose of malarone

A

Adult: atovaquone 250mg/ proguanil 100mg (1 tab OD)
Peds: atovaquone 62.5mg/proguanil 25mg (per tab)
- 5-8kg: 1/2 tab OD
- >8-10kg: 3/4 tab OD
- >10-20kg: 1 tab OD
- > 20-30kg: 2 tabs OD
- >30-40: 3 tabs OD

22
Q

administration for malarone

A

Start: 1-2d before travel
In endemic area: continue daily
Return: continue for next 7d

23
Q

precaution and CI of malarone

A
  • CrCL <30ml/min
  • infants <5kg
  • Preg (avoid use if possible)/Lact
24
Q

ADR of malarone

A

common: abdominal pain, N/V
others: HA, LFT elevations, hepatitis

25
Q

other considerations of malarone

A

increase anticoagulant effects of warfarin
- start chemoprophylaxis early and monitor INR

26
Q

resistance of malarone

A

for now its effect in all area

27
Q

MOA of doxycycline

A
  1. inhibit mitochondrial protein synthesis
  2. decrease activity of mitochondrial enzymes (decrease pyrimidine synthesis)
  3. may inhibit replication
28
Q

dose of doxycyline

A

adult: 100mg OD
peds (>=8yo): 2.2mg/kg OD (max 100mg/d)

29
Q

Administration of doxycycline

A

Start: 1-2d before travel
In endemic area: continue daily
Return: continue for next 4 weeks

swallow whole, take with water, stand and sit >= 30min

30
Q

precautions and CI of doxycycline

A
  1. age <8yo
  2. Preg/Lact
31
Q

ADR of doxycycline

A

Common: increase photosensitivity, abdominal pain, N/V/D
others: HA, esophageal irritation/ulceration

32
Q

other considerations of doxycycline

A
  • discontinue minocycline
  • take SPF 45 sunscreen (photosensitive)
33
Q

resistance of doxycycline

A

currently effective in all areas

34
Q

MOA of mefloquine

A
  1. interferes with hemoglobin utilisation in erythrocytes
  2. binds to heme to form toxic complexes: cell membrane damage
  3. bingds to parasite 80S ribosomes: inhibit protein synthesis
35
Q

Dose of mefloquine

A

adult: 250mg salt (228mg) weekly
peds dose regimen:
- <=9kg: 5mg/kg salt weekly
- 9-19kg: 1/4 tab weekly
- 19-30kg: 1/2 tab weekly
- 30-45kg: 3/4 tab weekly

36
Q

Administration of mefloquine

A

Start: 2-3 weeks before
In endemic area: continue weekly
Return: continue for 4 weeks

37
Q

precaution of mefloquine

A
  • seizure disorders
  • psychiatric disorders
  • arrhythmia or severe cardiac disorders
38
Q

ADR of mefloquine

A

common: dizziness, fatigue, HA/V, abdominal pain, rash
others: seizures, sleep disturbance, vivid dreams, depression, psychosis

39
Q

other considerations of mefloquine

A
  • Long half life
  • safe in preg
40
Q

resistance of mefloquine

A

effective in most places except SEA

41
Q

med change due to intolerance

A

weekly/daily dose switch to daily dose (never other order!!)

42
Q

cause of dengue

A

mosquito-borne viral infection (DENV1-4)

43
Q

cause of dengue

A

mosquito-borne viral infection (DENV1-4)

44
Q

vector for dengue

A

main: aedes aegypti (Day feeder, lay eggs on clean stagnant water)
secondary: aedes albopictus

45
Q

distribution of dengue

A

worldwide in tropics and subtropics regions
- South America
- South Pacific
- South East Asia

46
Q

mode of transmission of dengue

A
  • mosquito bite
  • perinatal transmission
  • blood/organ transfusion
  • needle stick injury/ lab accident
47
Q

primary infection of dengue

A
  1. infect langerhans cells and other immune cells
  2. viral dissemination
  3. inflammatory mediators released from immune cells
  4. viral clearance
48
Q

secondary infection of dengue

A
  1. antibody-dependent enhancement
  2. large amounts of inflammatory mediators: endothelial dysfunction, vascular leakage
  3. loss of coagulation proteins
49
Q

dengue fever

A
  1. high fever (>= 40dC) + 2 or more accompanying symptoms:
    - severe HA, pain behind eye, muscle and join pain, N/V, swollen glands, rash
  2. may have hemorrhagic manifestations (petechiae, bruising)
  3. duration up to 7d
50
Q

preventing dengue

A
  1. minimise mosquito exposure and bites
  2. vaccination (Dengvaxia; not part of national immunisation program)
51
Q

dengue vaccination

A

Dengvaxia
- 3 doses over 12 months
- 4 years of protection
- overall efficacy decrease dengue by 60%, severe dengue by 80%
- more effective for DENV1 and 2 type
- not part of national immunisation program since can trigger secondary infections which are worse