Travel Medicine Flashcards
From what age can someone be vaccinated against Hepatitis A
12 months
What kind of virus is hepatitis A
RNA
How long can the hepatitis A virus survive outside of a host?
Weeks in water, marine sediment, shellfish or soil
Several hours on hands, longer in food kept at room temperature
Is the hepatitis A virus susceptible to heat or freezing?
No
Transmission of hepatitis A
Foecal-oral route
Can also occur (mostly through this route) via direct person-to-person contact, sexual contact and blood transfusions
Incubation period of hepatitis A
15-50 days
How does the outcome of hepatitis A infection differ between children and adults?
Children are generally asymptomatic whereas 75% of infected adults will develop icteric disease
This is why in areas with high endemic rates, children tend to be infected early thus clinical disease is uncommon in locals
Most common causes of hepatitis A infection in Australians
Travel to an area with higher rates
Common outbreaks from contaminated food/water
Should we check for natural immunity against hepatitis A prior to vaccination?
Yes - in those born prior to 1950 and in those with a past history of unexplained hepatitis or jaundice
(If anti-HAV IgG present, vaccination not required)
Presentation of hepatitis A
Prodromal phase: - Lasts 4-10 days - Fever, malaise, weakness - Anorexia, nausea and vomiting Acute hepatitis phase: - Dark urine often first sign - Jaundice and pale stools 1-2 days later - Associated with gradual resolution of systemic prodromal symptoms - Hepatic pain and pruritus may occur
Liver function returns to normal within a month usually
10% can have prolonged or relapsing symptoms over 6-9 months, however chronic infection does not occur
Management of hepatitis A
Supportive only
Vaccination not required in someone who has been infected
Contraindications to hepatitis A vaccination
Allergy to previous HAV vaccine or components
Allergy to Yeast if giving HepA/B combination vaccine
Safe in all others (including pregnancy, immunosuppression etc. - though seroconversion rates may be lower)
Who should you recommend Hepatitis A vaccination to?
- ATSI children (routine vaccination schedule)
- Travellers to intermediate or high endemicity areas (Asia, Africa, South America, SouthEast Europe and Middle East)
- Those living in remote areas
- Occupational risk (healthcare workers, especially in ATSI communities)
- Those with lifestyle risk (IVDU, MSM)
- Pre-existing chronic liver disease or chronic hep B/C infection
- those with intellectual disabilities
How many doses required to complete Hepatitis A primary vaccination course?
2
1st provides at least 12 months immunity
2nd should be given 6-18 months after first (recommendation depends on brand)
Boosters not considered to be necessary at current
What pathogens cause enteric fever
S. typhi or S. paratyphi
Where are the highest endemic rates of typhoid/paratyphoid
Indian subcontinent
Also high in Asia (except Japan and Singapore), Africa and Middle East
What is the risk of a traveller contracting enteric fever
1:3000 for a traveller spending 4+ weeks in a high risk area
How common is it to develop carrier status after typhoid fever
Up to 5% will continue to shed the pathogen for >1y
Typical incubation period for typhoid/paratyphoid
7-14 days (range 3-60)
Clinical presentation of typhoid/paratyphoid (enteric fever)
Fever - increases with disease progression Dull frontal headache Malaise Myalgia Anorexia Dry cough
Less commonly: Constipation (sometimes diarrhoea in children) Abdo pain Relative bradycardia Splenomegaly Rash "Rose spots"
What is the typical typhoid rash
Rose spots
- erythematous blanching papules, mostly on anterior trunk (also on back and proximal limbs)
- 2-3mm in diameter
- each lasts 3-5 days
Potential complications of typhoid
(Typically occurring after 14 days of illness)
- GI bleeding
- bowel perforation (most commonly ileal)
- typhoid encephalopathy
Tests to diagnose typhoid
No test is really ideal
Gold standard is blood culture
May also be sporadically cultured in urine or stool
To whom would you recommend a typhoid vaccination
Anyone >2y travelling to moderate-high risk countries
How soon before travel should typhoid vaccination be provided
At least 2 weeks prior to travel
Are repeat doses required for typhoid vaccination?
Only 3 yearly boosters are required. The primary course is just the one dose.
Treatment of typhoid
Azithromycin OR ciprofloxacin (as long as not acquired in India or SouthEast Asia)
Note that fever takes 3-5 days to subside despite antibiotic therapy, and patients may feel worse during this time
High risk areas for malaria
Highest risk generally: Africa, Oceania
Moderate: Asia, South America
Low: Central America
Most common malarial parasite in Africa v Asia
Africa; Plasmodium falciparum
Asia/Pacific: Plasmodium vivax
Different malaria parasites and their incubation periods
P. falciparum 9-14 days (non-relapsing)
P. Malariae 18-40 days (non-relapsing)
P. vivax 12-18 days usually, some strains up to 10 months (relapsing)
P. ovale 12-18 days (relapsing)
Recommendations for non-medical prophylaxis against malaria
Personal protection methods from dusk to dawn (when anopheles mosquito is active)
- light, loose, long clothing covering arms and legs
- Insect repellent containing 20-40% DEET
- mosquito nets +/- permethrin impregnantion
Main malaria chemoprophylaxis options
Doxycycline 100mg/day from 2 days prior to exposure to 4 weeks after
Mefloquine 250mg/week for 2-4 weeks prior, for 4 weeks after
Malarone 1 tab daily from 1 day prior to 1 week after
Contraindications to doxycycline
Age <8y
Pregnancy
Breastfeeding
Common side effects to doxycycline
Nausea, indigestion, photosensitivity, vaginal candidiasis
Benefits of using doxycycline as malarial chemoprophylaxis
Cheap
Protects against some other tropical diseases
Can be commenced at short notice
Suitable for long term use
Downfalls of using doxycycline as malarial chemoprophylaxis
Contraindications
Unsuitable for use in children <8y
Contraindications to mefloquine
1st trimester of pregnancy Children <5kg History of epilepsy Psychiatric illness (including anxiety and depression) Cardiac conduction disorders Other medications that prolong QT
Common side effects of mefloquine
Headache Nausea Sleep disturbance Vivid dreams Dizziness Rarely: precipitate depression/anxiety/psychosis
Benefits of using mefloquine as malarial chemoprophylaxis
Can be used long term
Suitable for children
Downfalls of mefloquine as malarial chemoprophylaxis
Cost
Potential side effects
Contraindications
Needs to be started 2-4 weeks prior to travel
Contraindications to malarone
Pregnancy, breastfeeding
Common side effects of malarone
Headache, nausea
Benefits of using malarone as malaria chemoprophylaxis
Minimal side effects
Paediatric dose available
Can be commenced at short notice (1 day prior to exposure)
Downfalls of using malarone as malaria chemoprpphylaxis
Very expensive
Not licensed for use long term (due to lack of data, not known risks)
Clinical presentation of malaria
Fever in returned traveller - may come and go or be constant PLUS influenza-like symptoms mostly - chills - headache - myalgia/arthralgia - malaise - profuse sweating - nausea, lack of appetite - diarrhoea - abdominal pain - cough - anaemia +/- jaundice Symptoms CAN occur intermittently
Signs of severe malaria
Seizures Confusion Kidney failure Acute respiratory distress syndrome Coma
Incubation period of malaria
7 days to several months or more after being bitten by infected mosquito (depends on specific parasite)
Diagnosis of malaria
Blood smear microscopy: parasitised red cells
OR rapid diagnostic tests (less accurate, cannot differentiate between different species and cannot quantify)
PCR testing - takes a long time, but more sensitive than microscopy
First line treatment of malaria
Artemether + lumefantrine (though there are additional considerations for specific species)
IV treatment for severe disease
Daily parasite count until negative
Repeat CBE and microscopy at 7 days and 28 days post treatment completion
Individuals at highest risk for severe/complicated traveller’s diarrhoea
- insulin dependent diabetics
- congestive heart failure
- advanced cancer
- HIV infection
- Inflammatory bowel disease/other bowel abnormalities
- reactive arthritis
- reduced gastric acidity
- HLA-B27 positive individuals
Most common causes for traveller’s diarrhoea
Bacterial (50-80%) - ETEC most common - EIEC - EAEC - Shigella - Campylobacter - Salmonella Norovirus (10-20%) Protozoans only should be considered in those with diarrhoea >14 days or >72 hours despite 3 days antibiotics
How effective is the cholera vaccine?
> 90% effective against vibrio cholera only
No significant evidence for reduction of traveller’s diarrhoea overall or of ETEC
Recommendations for giving cholera vaccine
Consider in individuals with increased risk of severe of complicated traveller’s diarrhoea, OR in people travelling to an area with recent epidemic
Recommendations for self-management of traveller’s diarrhoea
Hydration maintenance is main goal!
Oral rehydration solution always if diarrhoeal illness + loperamide
If symptoms worsen or persist >24 hours, add in antibiotics
If moderate-severe from the start, loperamide + antibiotics as initial management
Recommended loperamide dose in setting of traveller’s diarrhoea
2 tabs (4mg) stat, then 1 tablet (2mg) after each bowel motion to max of 8 tabs per day
Recommended antibiotics and dosing for self-management of traveller’s diarrhoea
Ciprofloxacin 500mg stat OR BD for 72 hours
Norfloxacin 400mg stat or BD for 72 hours
Azithromycin 500mg daily for 3 days
Kids:
Azithro 10-25mg/kg (make sure the pharmacist does not mix it up, give sterile water and instructions on how to doso)daily for 3 days OR
cipro/norflox 10mg/kg BD
Usually single dose is adequate, but if symptoms continue, continue for up to 3 days (if still persisting then take Tinidazole 2g stat in case of protozoa)
Another name for schistosomiasis
Bilharzia
Where is schistosomiasis sfound
Throughout Africa (mostly sub-Saharan), parts of Asia, South America, the Caribbean, the Middle East
Typical incubation period of schistosomiasis
14-84 days (many people subclinical or asymptomatic)
Where does schistosomiasis lodge
S. mansoni and S. japonicum lodge in the mesenteric venous plexus of the liver
S. haemtobium lodges in the venous plexus of the lower urinary tract
Note that Africa has both Mansoni and haematobium species endemic
Route of infection with schistosomiasis
Direct skin contact with contaminated fresh water - even if only for 1 minute
Advising travellers to prevent risk of schistosomiasis
- advise no swimming in freshwater or wading through wetlands barefoot etc. in endemic areas EVEN FOR 1 MINUTE
- Don’t listen to locals who claim the water is “safe”
- DON’T listen to locals/other travellers who advise to take an immediate dose of praziquantel (ineffective and can worsen things)
- encourage serological testing 3 months after exposure if does swim in the water, even if asymptomatic
- warn of the serious complications (myocarditis, pericarditis, seizures, ataxia, motor paralysis)
Presentation of acute schistosomiasis
AKA Katayama fever (tends to occur in travellers from non-endemic countries) Few weeks after exposure - abdopain - diarrhoea - cough - fever - fatigue \+/- hepatosplenomegaly \+/- eosinophilia Spontaneous resolution over weeks
Earliest symptom
of schistosomiasis
Mild itching/papular dermatitis at sign of parasite penetration 12-24 hours after infection
“Swimmer’s itch”
Symptoms of chronic schistosomiasis infestation
Tends to occur more in persons from endemic areas
Depends on the species
S. mansoni and S. Japonicum (as they lodge in the liver vessels);
- diarrhoea/constipation
- blood in stool
- abdo pain
- colonic polyposis/portal hypertension, pulmonary hypertension can occur
S. haemotobium lodges in vessels of LUT
- dysuria/cystitis
- haematuria
- long term: infertility, ureteral obstruction, hydronephrosis, bladder cancer
Serious complications of acute schistosomiasis disease
Myocarditis
Pericarditis
Neurological manifestations (seizures, motor paralysis, ataxia)
Diagnosis of schistosomiasis
In acute disease: based on exclusion of other infections and a thorough exposure history
Chronically:
- test stool and/or END sample urine for ova
- can also check serology, but can be difficult to interpret
Who should be tested for chronic schistosomiasis infestation
All travellers to endemic areas who have had ANY freshwater exposure (3 months after return)
Migrants from endemic areas
Treatment of schistosomiasis
Acute disease:
- supportive, need to discuss with ID specialist (mostly prednisolone, +/- antimalarials but they may worsen disease, so need to check with specialist!)
Periodic serological testing should then be undertaken
Chronic:
Praziquantel 20mg/kg per dose, 2 doses 4h apart
If had positive urine/stool, repeat samples 2-3 months after treatment
Serological testing should not be used as proof of cure
CBE can be repeated >12 weeks to ensure eosinophilia resolves
Countries where Japanese Encephalitis occurs
Most Asian countries (except Singapore), Papua New Guinea, outer Torres Strait Islands of Australia
Occurs particularly in rural areas
Months of most likely transmission of Japanese Encephalitis
India and SouthEast Asia (including Bali): year round
May-September in China, Korea and Japan
March - October in the further sound subtropical areas
morbidity and mortality rate in Japanese Encephalitis
30% fatality rate of symptomatic infections in humans
60% of survivors (especially children) will have permanent neurological sequelae
Risk factors of contracting Japanese Encephalitis
Dawn, dusk, or night visits to rice growing areas
Living in villages near rice paddies and farm animals
Soldiers/aid workers/missionaries/students/researchers in endemic areas in the wet season
Risk factors for developing severe infection with japanese encephaltisi
Age >50y or child
Dual neurological infection (e.g. with mumps)
Compromised blood-brain barrier (e.g. Cochlear implants, shunts)
Pregnancy
Chronic conditions (solid organ transplants, hypertension, CVD, DM, CKD)
Risk of Japanese encephalitis while pregnant
Risk of miscarriage in the first and second trimesters
Pathogen/mosquito responsible for japanese encephalitis
Culex mosquito + specific flavivirus.
Enzootic cycle between vertebrate hosts (mostly pigs and egrets) and the mosquito
Feeds outdoors from dusk to dawn and breeds in flooded rice paddies and marsh environments
No person-to-person transmission
Prevention of Japanese Encephalitis
Mosquito precautions
Avoidance of high risk activities (e.g. visiting rice fields dusk-dawn)
Advice about the disease to traveller to endemic areas
Advice about risks and benefits of vaccination
Vaccines available for Japanese Encephalitis
Jespect/Ixiaro OR Imojev
Jespect/Ixiaro:
- inactivated vaccine
- 2 doses given 28 days apart (can try accelerated course 7 days apart if necessary)
- Approved from 18y, can be given from 2mo
- booster 1-2 years after primary course
- Safe in pregnancy
- approx $150 per dose
Imojev:
- recombinant live vaccine (attenuated strain of yellow fever virus with JE genes)
- single dose
- booster maybe needed after 5y
- booster for kids 1-2 yearsa fter primary dose
- not suitable for children <9 mo
Clinical features of Japanese Encephalitis
Widespread encephalomyelitis of white matter, thalamus, brainstem and spinal cord
In adults:
- headache
- meningism
- fever
- confusion/altered consciousness
(Can present as simple febrile illness, acute flaccid paralysis or aseptic meningitis)
Children often present with seizures (75%)
Treatment of Japanese Encephalitis
Supportive management only
- close observation
- fluids, analgesia, antipyretics
Diagnosis of Japanese Encephalitis
Serum or CSF specific anti-JE IgM antibodies
Highest risk countries for rabies (11)
India, Nepal, Sri Lanka, Thailand, Philippines, Vietnam, El Salvador, Guatemala, Peru, Colombia, Ecuador
Factors affecting how quickly rabies virus is taken up into CNS (thus how high risk a lesion is)
Density of nerve endings in bitten area (highest in the hands)
Proximity of bite site to CNS (highest in the face)
Severity of bite
Incubation period of rabies
Ranges from 1-12 weeks to several years - dependent on site and severity of bite
Clinical features of Rabies
Prodromal symtpoms:
(Non-specific)
fever, anorexia, cough, headache myalgia, sore throat, fatigue, vomiting, anxiety/agitation/apprehension
Parasthesiae or fasciculations can occur in proximity of the wound
“Furious encephalitic rabies” - classic, most common form
- aerophobia/hydrophobia
- disorientation
- bizarre or hyperactive behaviour
- autonomic instability (hypersalivation, hyperthermia, hyperventilation)
Death occurs within 12 days
“Paralytic/dumb rabies” - 30% of cases
- more protracted and less distinctive
- loss of sensation
- weakness
- pain
- progressive flaccid paralysis
Travel advice to prevent rabies
Avoid approaching stray animals
Stay aware of surroundings to avoid surprising stray dogs
Avoid carrying or eating food around monkeys
Avoid contact with bats (esp. cavers)
Who should be offered rabies pre-exposure vaccination
High risk adults (veterinarians, animal handlers, wildlife officers, people living in or travelling to rabies endemic areas esp if >1 month)
Children living in or visiting rabies areas
People travelling to isolated regions with limited access to appropriate medical care
Pre-exposure rabies vaccinations
Same as post-exposure vaccine but different delivery schedule
2 avail in Aus:
- Human diploid cell rabies vaccine (HDCV): inactivated virus, contains inactivated virus, neomycin and human serum albumin
- Purified chick embryo cell vaccine (PCECV): contains inactivated virus, neomycin, bovine gelatin, egg protein, chlortetracycline and amphotericin B
Both are given IM to deltoid if >12 mo
3x doses at 0, 7 and 28 days
Serological testing required for people with impaired immunity 2-3 weeks later
Safe in pregnancy
HDCV should be used for people with anaphylaxis to eggs
Post-exposure wound care for possible rabies
Thorough wound cleansing and disinfection (lots of soap/detergent and water, followed by betadine)
Delay suturing where possible - infiltrate with HRIG and delay for at least several hours
ADT/Antibiotics as indicated
Post-exposure prophylaxis to
rabies management in someone who does NOT have documented pre-exposure vaccination
rabies immunoglobulin should be instilled into the wound no later than 7 days after first rabies vaccine dose - give the remaining into the opposite side deltoid
Give rabies vaccine on day 0, 3, 7, 14, 28-30 (5 doses in total)
Post-exposure rabies prophylaxis in someone who DOES have documented pre-exposure vaccination
Appropriate wound management
RIG not necessary
2x doses IM vaccine booster doses on days 0 and 3
Altitude at which altitude sickness starts to occur
Unlikely to occur <2500m
Large cities that travellers may not recognise are at risk of altitude sickness developing
Cusco, Peru (3400m)
Lhasa, Tibet (3600m)
La Paz, Bolivia (3700m)
Physiological changes that occur with high altitude
Initial:
- hyperventilation
- increased sympathetic tone ( increase HR, BP and cardiac output)
- vasoconstriction of pulmonary vasculature
- cerebral vasodilation secondary to hypoxia
Later changes:
- increased EPO -> increased Hb production
- diuresis -> increased haematocrit
- decreased muscle mass
- increased vascularity
Risk factors for altitude illness
- ascending to >2800m in one day
- prior history of AMS ascending >2800m
- anyone ascending >500m/day at altitudes >3000m
- Anyone with history of severe AMS or HAPE/HACE
Not related to physical fitness, alcohol, cigarettes, gender, load carried, recent respiratory illness etc.
Absolute contraindications to high altitude travel
Severe COPD Unstable asthma Severe IHD Severe or uncontrolled heart failure Pulmonary hypertension Complicated pregnancy
Relative contraindications to high altitude travel
Moderate COPD Stable angina Previous cerebrovascular disease Poorly controlled DM Recurrent arrhythmias Uncomplicated pregnancy >36 weeks gestation
Recommendations to prevent altitude illness in travellers
- slow ascent to allow for acclimatisation (300-500m/day >3000m altitude)
- A day’s rest every 3-4 days
- Resting in first 48h of arriving at places of high altitude
- 24h delay after uncomplicated dive (1 week minimum after recompression therapy)
Common high altitude conditions and other risks at high altitude
High altitude headache (HAH) Acute Mountain Sickness (AMS) High altitude cerebral oedema (HACE) High altitude pulmonary oedema (HAPE) DVT more common at high altitudes (same recommendations as for flying)
Medications that can be used for the PREVENTION of altitude illness
High altitude headache: Ibuprofen 600mg TDS (yes, 600 is not a typo)
Acute mountain sickness: Acetazolamide 125mg BD (off label use)
High altitude pulmonary oedema: Nifedipine SR 60mg daily (either 30mg 12 hourly or 20 mg 8 hourly) - does not reduce AMS
Presentation and immediate management of high altitude conditions:
HAH: headache at high altitude, settles after 10-15 minutes wit oxygen, resolves with regular NSAID and decrease in altitude
AMS: Headache within 6-36 hours of high altitude PLUS either GI upset, fatigue/weakness, dizziness, difficulty sleeping. Usually resolves with 2-4 days rest and no further altitude rise, if severe needs O2 and dexamethasone to prevent HACE
HACE: AMS symptoms 24-36 hours after high altitude arrival PLUS impaired mental state and/or ataxia. Medical emergency: immediate reduction in altitude of at least 300m, IV dex and O2
HAPE: can develop independently of AMS 2-4 days after high altitude. Cough/dyspnoea/reduced exercise tolerance/chest tightness, creps/high RR and HR, cyanosis
Urgent rapid descent of 1000m at least, O2, nifedipine
