Travel Meds (Malaria and Dengue) Flashcards
Malaria caused by
protozoal parasite plasmodium
- P. Falciparum (highest mortality)
- P. malariae
- P. ovale
- P. vivax
mode of transmission of malaria
- via bites of infected female anopheles mosquitoes
- blood transfusion
- needle sharing
- organ transplantation
- vertical transmission (mother to fetus)
areas at risk of malaria transmission
Africa, South America, Caribbean, Asia (SEA, India- vivax, Middle East)
risk factor of malaria
- exposure (dusk to dawn, endemic area, monsoon season, outdoor activity)
- behaviour (non compliance to chemoprophylaxis, fail to take precaution against bites)
- infants and children <5yo
- pregnancy
- immunocompromised (HIV)
incubation period of malaria
- P. ovale/vivax: 9-18d
- P. falciparum: 7-18d
- P. malariae: 18-40d
initial presentation of malaria
- acute febrile illness
- fever, chills, HA, N/V/D, abdominal pain
- splenomegaly
severe presentation of malaria
- parasitemia
- prostration
- respiratory distress, pulmonary edema
- decrease consciousness, seizures
- bleeding, severe anemia, disseminated intravascular coagulation
- hemoglobinuria, renal failure
- almost always P falciparum, rarely P. vivax
Malaria prophylaxis and management
- Awareness of risk (location, season, activity)
- Bite avoidance (insecticide, cover up)
- Chemoprophylaxis (get right meds, adherence)
- Diagnose (seek med attention immediately, not eligible for self care)
- Vaccination (but v hard due to complexity)
vaccination for malaria
RTS,S/AS01 (Mosquirix)
- phase 3 studied in young children and infants
- pre-qualification granted by WHO
Non pharm for malaria
- avoid perfumes or deodorant
- ear clothes and shoes that minis exposed skin
- choose well screened or air conditioned accomodation
- sleep with netting around beds
- stay indoors between dusk to dawn
- use insect repellent (DEET- Diethyltoluamide)
what drugs for chemoprophylaxis
- chloroquine (P only)
- Atovaquone + Proguanil - Malarone (POM + Exemption)
- Doxycline (POM)
- Mefloquine (P only)
what drugs for chemoprophylaxis
- chloroquine (P only)
- Atovaquone + Proguanil - Malarone (POM + Exemption)
- Doxycline (POM)
- Mefloquine (P only)
MOA of chloroquine
- inhibit DNA and RNA polymerase: by interfering with metabolism and hemoglobin utilisation
- Concentrates in parasite particles to increase pH: inhibiting growth
- Involves aggregates of ferriprotoporphyrin IX acting as chloroquine receptors: membrane damage
dose of chloroquine
adult: 500mg salt (300mg base) weekly
peds: 8.3 mg/kg salt (5mg/kg base) weekly
Administration instructions for chloroquine
Start: 1-2 weeks before
In the endemic area: Take weekly
Return: continue for another 4 weeks
- administer same day each week
Precaution and CI when taking chloroquine
- G6PD deficiency** (increase risk of haemolytic anemia)
- Porphyria (genetics)
- Psoriasis
- Seizure disorders
- Cardiac conduction abnormalities
ADR of chloroquine
common: abdominal cramps, N/V/D/HA
others: agitation, anxiety, hepatitis, rash, ECG changes, tinnitus, hearing loss
other consideration for chloroquine
Preg/lact: Safe
other purpose: rheumatic purpose
alternative to chloroquine
Hydrochloroquine (POM)
- adult dose: 400mg (310mg base) weekly
- peds dose: 6.5mg/kd salt weekly
- administration: same as chloroquine
- reduce retinopathy
resistance of chloroquine
likely effective only in Central America, Caribbean
MOA of malarone
Atovaquone: inhibits mitochondrial electron transport
Proguanil:
- inhibits dihydrofolate reductase
- disrupts deoxythymidylate synthesis
collectively, affect erythrocytic (blood cycle) and exoerythrocytic (liver cycle) development
Dose of malarone
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
administration for malarone
Start: 1-2d before travel
In endemic area: continue daily
Return: continue for next 7d
precaution and CI of malarone
- CrCL <30ml/min
- infants <5kg
- Preg (avoid use if possible)/Lact
ADR of malarone
common: abdominal pain, N/V
others: HA, LFT elevations, hepatitis
other considerations of malarone
increase anticoagulant effects of warfarin
- start chemoprophylaxis early and monitor INR
resistance of malarone
for now its effect in all area
MOA of doxycycline
- inhibit mitochondrial protein synthesis
- decrease activity of mitochondrial enzymes (decrease pyrimidine synthesis)
- may inhibit replication
dose of doxycyline
adult: 100mg OD
peds (>=8yo): 2.2mg/kg OD (max 100mg/d)
Administration of doxycycline
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
precautions and CI of doxycycline
- age <8yo
- Preg/Lact
ADR of doxycycline
Common: increase photosensitivity, abdominal pain, N/V/D
others: HA, esophageal irritation/ulceration
other considerations of doxycycline
- discontinue minocycline
- take SPF 45 sunscreen (photosensitive)
resistance of doxycycline
currently effective in all areas
MOA of mefloquine
- interferes with hemoglobin utilisation in erythrocytes
- binds to heme to form toxic complexes: cell membrane damage
- bingds to parasite 80S ribosomes: inhibit protein synthesis
Dose of mefloquine
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
Administration of mefloquine
Start: 2-3 weeks before
In endemic area: continue weekly
Return: continue for 4 weeks
precaution of mefloquine
- seizure disorders
- psychiatric disorders
- arrhythmia or severe cardiac disorders
ADR of mefloquine
common: dizziness, fatigue, HA/V, abdominal pain, rash
others: seizures, sleep disturbance, vivid dreams, depression, psychosis
other considerations of mefloquine
- Long half life
- safe in preg
resistance of mefloquine
effective in most places except SEA
med change due to intolerance
weekly/daily dose switch to daily dose (never other order!!)
cause of dengue
mosquito-borne viral infection (DENV1-4)
cause of dengue
mosquito-borne viral infection (DENV1-4)
vector for dengue
main: aedes aegypti (Day feeder, lay eggs on clean stagnant water)
secondary: aedes albopictus
distribution of dengue
worldwide in tropics and subtropics regions
- South America
- South Pacific
- South East Asia
mode of transmission of dengue
- mosquito bite
- perinatal transmission
- blood/organ transfusion
- needle stick injury/ lab accident
primary infection of dengue
- infect langerhans cells and other immune cells
- viral dissemination
- inflammatory mediators released from immune cells
- viral clearance
secondary infection of dengue
- antibody-dependent enhancement
- large amounts of inflammatory mediators: endothelial dysfunction, vascular leakage
- loss of coagulation proteins
dengue fever
- high fever (>= 40dC) + 2 or more accompanying symptoms:
- severe HA, pain behind eye, muscle and join pain, N/V, swollen glands, rash - may have hemorrhagic manifestations (petechiae, bruising)
- duration up to 7d
preventing dengue
- minimise mosquito exposure and bites
- vaccination (Dengvaxia; not part of national immunisation program)
dengue vaccination
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
