Travel Medicine Flashcards
What are the “big 3” DDx for fever in the returned travellor with no localising symptoms? What is the incubation period for each?
Dengue: 4-5 days
Malaria: 1-4 weeks (usually 2 weeks)
Typhoid: 7-28 days (usually 3 weeks)
Which species of plasmodia causes almost all deaths and cases of severe malaria?
P. falciparum
What causes typhoid?
Salmonella enteritica serotype typhi, paratyphi
typhoid
1st week: rising (“stepwise”) fever, bacteraemia
2nd week: abdo pain, rash (“rose spots”: faint salmon-coloured macules on trunk and abdo)
2rd week: hepatosplenomegaly, intestinal bleeding and perforation (related to ileocaecal lymphatic hyperplasia of peyer’s patches, may occur with secondary bacteraemia and peritonitis
typhoid
Constipation more common than diarrhoea
Called enteric fever because it replicates in the gut
typhoid
Often emperic due to low sensitivity and specificity of available Ix
Typhoid treatment
Ciprofloxacin: 10 days ?PO (treatment of choice but growing problem of resistance)
Ceftriaxone: 7-14 days IV (requires hospital stay)
List 5 features which suggest a serious infection
Rigors Acute onset (presents to hospital within hours and deteriorates quickly) Profound effect on the patient Severe headache N+V in absence of diarrhoea
What travel vaccines should be considered with travel to a tropical area?
Hepatitis A
Typhoid (+ yellow fever if endemic area)
Malaria prophylaxis (depending on area)
24 year old female planning on travelling as a tourist to Kenya, Tanzania Ethiopia, South Africa for 2/12
Born in Australia
Thinks she is up to date with her childhood vaccinations but has brought no documentation with her
What issues need to be discussed?
General advice: consider route of transmission of different infections to discuss appropriate behavioural advice (advice regarding safe food and drink, insect avoidance, respiratory exposures, environmental and animal exposures, blood-borne infection, sexual encounters), consider non-infectious risks (e.g. trauma)
Vaccination: update routine, travel-related considerations
Medications: e.g. malaria prophylaxis, self-Rx for travellers’ diarrhoea
What pre-travel advice should be given regarding food?
“Boil it, cook it, peel it or forget it”
All raw food is high risk: avoid salads, uncooked veg, unpasteurized milk and cheese
Eat food that has been cooked and is still hot, or fruit that can be peeled
Undercooked and raw meat, fish and shellfish are high risk
Avoid food from street vendors
What pre-travel advice should be given regarding water?
If chlorinated tap water is unavailable or sanitation is poor, only the following are safe to drink: beverages (eg. tea, coffee) made with boiled water, canned or bottled beverages, beer and wine
Avoid ice and avoid brushing teeth with tap water
How can travellers minimise exposure to prevent vector-borne infections?
Sleep in screened and/or air conditioned room
Avoid outside activities esp between dusk and dawn
Cover arms and legs
Use insect repellents (tropical-strength DEET)
Permethrin impregnated clothing/mosquito nets
Use an insecticide aerosol in the room
How else (besides minimising exposure) might a traveller protect against vector-borne infection?
Malaria prophylaxis
Give 2 examples of infections commonly seen in travellers which can be acquired through respiratory exposures
Influenza
Meningococcus
Give 2 examples of infections commonly seen in travellers which can be acquired through environmental and animal exposures
Rabies
Tetanus
Altitude
Give 2 examples of infections commonly seen in travellers which are blood-borne
HBV
HCV
HIV
Traveller who has returned home after a 2/12 trip in India comes to see you complaining of diarrhoea
Said they had a bad episode of diarrhoea in the 1st week of their trip which were resolved, they were then okay for most of their trip but since the last 2 days of their trip the diarrhoea has returned
Have now been home for 2 weeks
Ix and Mx?
Stool MCS
If negative, consider empiric therapy
How is travellers’ diarrhoea usually define?
3 or more loose stools/day
What is the “attack rate” of travellers’ diarrhoea?
20-50% in developing countries
Describe the typical natural Hx of travellers’ diarrhoea
Usually begins abruptly, generally self-limited
Most cases resolve in 1-2 days even without treatment (10% last >1 week, longer than that is relatively uncommon)
In what % of cases of travellers’ diarrhoea is there no identifiable cause?
20-50%
What are the common causative organisms in acute travellers’ diarrhoea?
ETEC (40-70%) Viral Cholera Shigella Salmonella Campylobacter Entamoeba histolytica
Which of the common causes of acute travellers’ diarrhoea produce watery diarrhoea vs blood diarrhoea?
Watery: ETEC, viral, cholera
Bloody: Shigella, Salmonella, Campylobacter, Entamoeba histolytica
How long does travellers’ diarrhoea need to last for it to be classified as chronic?
Usually >2 weeks
What are the common causes of chronic travellers’ diarrhoea?
Parasites (e.g. Giardia)
How should travellers’ diarrhoea be managed during travel?
Often resolves without treatment
Don’t give prophylaxis but give therapy for empiric self-treatment of acute TD
Sometimes also give empiric Rx for persistent diarrhoea directed against Giardia
What agents can be used for empiric self treatment of travellers’ diarrhoea?
Quinolone (e.g. ciprofloxacin; note increasing resistance, esp of Campylobacter in Thailand, India, Nepal)
Azithromycin (alternative)
For persistent diarrhoea (directed against Giardia): tinidazole
List 3 food/water borne infections for which there is a pre-travel vaccine available
Hepatitis A
Typhoid
Cholera
List 2 vector-borne infections for which there is a pre-travel vaccine available
Yellow fever
Japanese encephalitis
List 3 respiratory borne infections for which there is a pre-travel vaccine available
Meningococcal
Influenza
(TB)
List 1 blood/body fluid borne infection for which there is a pre-travel vaccine available
HBV
List 3 environmental/animal borne infections for which there is a pre-travel vaccine available
Rabies
Tetanus
What routine vaccines are important to update pre-travel?
MMR
Polio
Others
What regions is hepatitis A endemic in?
SE Asia
Africa
South America
What % of HAV infections are asymptomatic in children
70%
What demographic has an increased risk of mortality from HAV?
> 50 years
What is the usual schedule for HAV vaccination?
2 doses at least 6/12 apart
If long delay since 1st dose, no need to restart full course
No booster recommended
In what forms is the HAV vaccine available?
HAV only
In combination with HBV or typhoid
Who does the NHMRC recommend the HAV vaccine for?
Recommended for all travellers to, and all expatriates living in, moderately to highly endemic areas (includes all developing countries; “investment” for young, elderly at risk of complications)
Who should be screened for pre-existing natural immunity when considering HAV vaccination? What should you do if unsure?
Born
Is there a vaccine for HEV?
No
What is the major complication with HEV?
Associated with up to 20% maternal mortality if acquired in the 3rd trimester of pregnancy
What circumstances confer the greatest risk for travellers of acquiring enteric fever?
Travel SE Asia (6-30x risk; also high risk of multi-drug resistance)
Travellers visiting friends or relatives
What type of vaccine are Typherix and Typhim Vi?
Injectable polysaccharide
How many years of protection are afforded by the injectable typhoid vaccine?
3
What forms of typhoid vaccine are available?
Injectable (polysaccharide)
Oral (live attenuated)
How many years of protection are afforded by the oral typhoid vaccine?
4 doses provide 5 year protection
Who does the NHMRC recommend be vaccinated against typhoid? When should vaccination be completed?
All travellers ≥2 years of age going to endemic regions
Vaccinated should be completed at least 2 weeks before travel
Who is at increased risk of typhoid and therefore strongly recommended to be vaccinated?
Individuals travelling to endemic regions to visit friends and family
What is Dukoral?
Oral cholera vaccine
What is the cholera vaccine composed of?
Killed V. cholerae O1 organisms and non-toxic B subunit of cholera toxin
How is the cholera vaccine administered?
Oral vaccine, 2 doses given 1-6 weeks apart
What is the efficacy of the cholera vaccine?
60-80%
Are tourist travellers at risk of cholera?
Rarely
What other disease may the cholera vaccine protect against? When should it be used for this purpose?
Travellers’ diarrhoea (provides approx 50% reduction in ETEC; overall reduces TD by about 10-20% but only provides 3 months protection)
NB Not licensed for TD in Aus, consider off-label use if underlying GI disease, immunosuppression
What is the difference between the flu seasons in the Southern and Northern Hemisphere, and the tropics?
Southern: April-Sep
Northern: Nov-March
Tropics: throughout the year
Where are the “at-risk” areas for meningococcus, for whic vaccination is recommended?
Sub-Saharan Africa (esp dry season Dec-June)
Saudi Arabia for pilgrims during Hajj
What vaccines are available for meningococcus? Which serogroup is covered by each? How long is the protection afforded by each?
Conjugate vaccine: serogroup C (used in childhood)
Polysaccharide (Mencevax/Menomune): serogroups A,C,Y,W135 (cover for 3 years; less immunogenic)
Conjugate quadrivalent vaccine (Menveo/Menactra): serogroups A,Y,W135 (cover for ?5 years)
Which meningococcal vaccine is typically administered to travellers?
Quadrivalent (most travellers also require protection for serogroups A,Y,W135)
What is yellow fever? How is it spread? What does it cause?
Acute viral disease
Spread by mosquitoes
Causes hepatitis and encephalitis
For which populations is the yellow fever vaccine indicated?
All travellers to endemic countries
When should the yellow fever vaccine be given?
≥10 days before entry into risk area
How long does the yellow fever vaccine offer protection for?
10 years
List 4 CIs to yellow fever vaccine
Severe egg allergy
Immunodeficiency
Pregnancy
Infants
High prevalence areas for HBV
Africa SE Asia Middle East Pacific Islands Amazon River basin Parts of Caribbean
What is the name of the HBV vaccine?
Engerix
H-B-VAX II
When are the 3 doses of the HBV vaccine given routinely?
0, 1 and 6 months
Describe the accelerated schedule for the HBV vaccine
Days 0, 7, 21 and then again at 12 months
Is there a need to routinely check HBV Abs?
No
What factors may result in poorer seroconversion following HBV vaccination?
CKD
Immunosuppression
When should HBV be considered as a travel vaccine?
Consider if travelling to intermediate or high prevalence areas (risk is generally low)
Adventure travellers, Peace Corps volunteers, missionaries and military personnel may have increased risk (i.e. people travelling to endemic areas either long-term or for frequent short terms is the advice of the NHMRC)
When should pre-exposure prophylaxis be considered for rabies?
Occupational risk
Travel to rural areas/high endemic countries for >3-6/12
How is pre-exposure prophylaxis for rabies administered?
3 doses 1mL IM days 0, 7, 28
Describe the principles of post-exposure treatment (PET) for rabies
Give any time after exposure (but best within 48 hours):
1) Wound care, may need tetanus toxoid/Abx
2) 4 doses of vaccine (5 in some high risk situations) on days 0, 3, 7, 14 (28), administered into deltoid or thigh (if previously vaccinated, only 2 booster doses are required on days 0 and 3)
3) human rabies immunoglobulin (HRIG): 20IU/kg into wound, given within 8 days of starting HDCV
24 year old female returns from 2/12 trip to Africa
Has been home for 3/7 and presents with a fever
Additional info?
Incubation period
Precise travel itinerary
Type of exposures
How does knowledge of the incubation period of a returned travellers’ illness aid diagnosis?
> 3 weeks: excludes many arboviruses (e.g. dengue) and viral haemorrhagic fevers
Shortest incubation for malaria is 7-10 days (can be years)
How does knowledge of precise travel itinerary of a returned travellers’ illness aid diagnosis?
Yellow fever is endemic in Africa and Latin America but NOT Asia
Japanese encephalitis confined to Asia
Lassa fever restricted to West Africa
What kinds of infectious disease does swimming in fresh water in Africa predispose to?
Schistosomiasis
What are the 4 most common syndromes seen in the unwell returned traveller?
Travellers’ diarrhoea
Respiratory tract infections
Skin problems (infections, rash, bites)
Febrile illnesses
What life-threatening illnesses must be considered in the unwell returned traveller?
Falciparum malaria
Bacterial sepsis (including enteric fever)
Viral haemorrhagic fevers (including dengue)
What is the typical incubation period for illness seen in returned travellers? What are the exceptions?
Most
What is the typical incubation period for enteric fever?
7-21 days
What are the clinical symptoms of enteric fever?
Non-specific febrile illness +/- diarrhoea or constipation, sometimes a rash
In what areas is enteric fever common?
SE Asia India Africa Middle East South America
What is one serious complication of enteric fever?
Bowel perforation
How is enteric fever diagnosed?
FBE: normal WCC with “left shift”
LFT: commonly abnormal (mixed pattern)
Blood culture: Gram negative bacilli, stool culture
How is enteric fever treated?
Abx (ceftriaxoe or quinolone if sensitive, or azithromycin)
What is the fatality rate of enteric fever without treatment?
10-20%
How many cases of malaria are seen in Australia annually?
~700 cases per year
