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Flashcards in MISC - Travel Medicine Deck (41):
1

What pre-travel advice should be given to a pt?

•General advice
–Important to consider route of transmission of different infections to discuss appropriate behavioural advice
–Non- infectious risks eg trauma

•Vaccination
–Update routine
–Travel-related considerations

•Medications
–Eg Malaria prophylaxis, self-Rx for Travellers’ Diarrhea

2

Describe Traveller's diarrhoea
- definition
- attack rate
- recovery

•Usually defined a 3 or more loose stools/day

•Attack rate: 20% - 50% to developing countries

•Usually begins abruptly, generally self-limited
–Most cases resolve in 1-2 days even without treatment
–10% cases last >1 wk
–2% last >1 month
– less than 1% last >3 months

3

Describe the causes of Traveller's diarrhoea
- Acute TD
- Chronic TD

•No recognized cause in 20% -50% of TD

•Acute TD:
–Most commonly identified organism: Enterotoxigenic coli (ETEC), 40-70%
–Watery: ETEC, viral, cholera
–Bloody: Shigella, Salmonella, Campylobacter, Entamoeba histolytica

•Chronic TD:
–Usually > 2 wks
–Parasites (eg Giardia NOT BLOODY STOOL!!!)

4

Practical management of TD
- during travel
- post travel

•During travel:
–Often resolves without treatment

–Don’t give prophylaxis, but give therapy for empiric self treatment of acute TD:
•Quinolone, eg Ciprofloxacin, but increasing resistance (especially Campylobacter in Thailand, India, Nepal)
•Alternative: azithromycin

–Sometimes also give empiric Rx for persistent diarrhoea directed against giardia. Usually tinidazole

•Post travel:
–Investigate with stool micro and culture
–If negative, consider empiric therapy

5

What are the empiric self treatment for acute Traveller's diarrhoea?

Quinolone, eg Ciprofloxacin (but increasing resistance especially Campylobacter in Thailand, India, Nepal)

Alternative: azithromycin

6

What is the empiric Rx for persistent diarrhoea directed against giardia?

Usually tinidazole (an anti-parasitic drug used against protozoan infection)

7

Discuss available pre-travel vaccinations for types below:
- food/water borne
- vector-borne
- respiratory route
- bloody/body fluids
- environmental/animal exposures
- update routine vaccines

•Food/water borne: Hepatitis A, Typhoid,Cholera
•Vector-borne: Yellow fever, Japanese Encephalitis
•Respiratory route: Meningococcal, Influenza, (TB)
•Blood/body fluids: HBV
•Environmental/ animal exposures: Rabies, Tetanus
•Update routine vaccines: MMR, Polio, etc

8

Discuss hepatitis A vaccination

2 doses at least 6 months apart

–If long delay since 1st dose, NO need to re-start full course
–NO booster recommended

Available as hep A vaccine only or in combination with HBV or typhoid

9

Discuss hepatitis E vaccination

There's NONE

During 3rd trimester of pregnancy: associated with up to 20% maternal mortality

10

Discuss typhoid
- organisms causing enteric fever
- risk for travellers

•Enteric fever: Salmonella typhi, S. paratyphi
•Risk for travellers
–Highest for travellers to South Asia (6 - 30 X’s). Also high risk of multi-drug resistance
–Travellers visiting friends or relatives

11

Discuss typhoid vaccine
- (2) types of vaccine. Period of protection
- efficacy
- recommended to whom?

•Injectable polysacchride vaccine (Typherix or Typhim Vi)
–3 yr protection
•Oral: live attenuated vaccine: 4 doses gives 5 yr protection
–Don’t use if pregnant, impaired immunity, taking antibiotics,

12

Discuss cholera vaccine
- clinical Px of cholera
- vaccine composition
- how it is given
- efficacy

•Clinical: profuse, watery diarrhoea
•Cholera vaccine: Dukoral
•Composed of killed V. cholerae O1 organisms and the non-toxic B subunit of cholera toxin
•Oral vaccine, 2 doses given 1-6 weeks apart, efficacy 60-80%
•Cholera rarely a risk for tourist travellers
•Approx 50% reduction in Enterotoxigenic E coli (ETEC)
–Overall reduces TD by about 10-20%
–Only 3 months protection
•Not licensed for TD in Australia

13

Discuss meningococcus
- major epidemic areas in 20th C
- risk areas
- vaccines; types
- travellers vaccine

Major epidemics of serogroup A infection in 5-10 year cycles in the meningitis belt throughout 20th C

•Vaccines recommended for at risk areas
–Sub-Saharan Africa (esp dry season Dec-June)
–Saudi Arabia for pilgrims during Hajj

•Vaccines
–Conjugate vaccine used in childhood: serogroup C only
–POLYSACCHARIDE vaccines (Mencevax/Menomune): protects vs serogrps A,C,Y,W135 for 3 years –less immunogenic
–Conjugate quadrivalent vaccine licensed 2011 (Menveo, Menactra)

•Minimal information re boosters (5 yrs?)
•Which vaccine?
–Most travellers also require protection for serogroups A, Y and W-135, so quadrivalent vaccine usually indicated

Rare to get meningoccaemic septicaemia without meningitis and is commonly misdiagnosed as influenza/flu. Important to check for rashes (although not everyone develops them).

14

Discuss yellow fever
- risk areas
- spread by what
- causes what
- vaccine

Risk areas: Africa, S America
•Acute viral disease spread by mosquitoes
•Causes hepatitis and encephalitis
•Vaccine
–Indicated for all travellers to endemic countries
–Give ≥ 10 days before entry into risk area
–Single dose gives 10 years immunity
–CIs: severe egg allergy, immunodeficiency, pregnancy, infants

15

Discuss hepatitis B vaccine

•Engerix, H-B-VAX II
•Dose: 0, 1, 6 months
•Accelerated schedule: days 0, 7, 21; 12 months
•No need to routinely check antibodies
•Poorer seroconversion in chronic renal failure, immunosuppression
•Risk for travellers
–Generally low
–Consider vaccination if travelling to intermediate or high prevalence areas
–Adventure travellers, Peace Corps volunteers, missionaries, & military personnel, may have increased risk

16

Discuss rabies vaccine
- Pre-exposure prophylaxis
- post exposure treatment!!

•Pre-exposure prophylaxis: occupational risk or travel to rural areas/high endemic countries for >3-6 months
–Three doses 1ml IM days 0, 7, 28

•Post-exposure treatment (PET)
–Give any time after exposure (best w/i 48 hrs)
(1) wound care, may need tetanus toxoid/antibiotics

(2) 4 doses of vaccine (5 in some high risk situations): Days 0,3,7,14 (28). Administer into deltoid or thigh
(If previously immunised, only 2 booster doses (days 0 & 3)

(3) Human rabies immune globulin (HRIG): 20 IU/kg into wound, give within 8 days of starting HDCV

17

How is incubation period important in figuring out the cause of illness in returned traveller? What can be differentiated for example?

Incubation period of > 3 weeks excludes many arboviruses (eg dengue) and viral haemorrhagic fevers

Malaria: shortest incubation = 7-10 days (can be yrs)

18

How is precise travel itinerary/location important in figuring out the cause of illness in returned traveller? What can be differentiated for example?

–eg. Yellow fever in Africa and Latin America, not in Asia
–Japanese encephalitis confined to Asia
–Lassa fever restricted to West Africa

19

Swimming in fresh water in Africa -> exposure to what?

schistosomiasis

20

(3) Most life-threatening illnesses in unwell returned traveller

–Falciparum malaria
–Bacterial sepsis (including enteric fever)
–Viral hemorrhagic fevers (including dengue)

21

List conditions based on incubation period:
- short: less than 10 days
- intermediate: 10-21 days
- long >21 days

Short (less than 10 days): malaria, influenza, Arboviral infections (dengue, yellow fever), plague, Enteric bacterial infections (paratyphoid fever etc), African tick bite fever

Intermediate (10-21 days): malaria, viral haemorrhagic fevers, typhoid fever, relapsing fever (Borrella), Brucellosis, Leptospirosis

Long (>21 days): malaria, HEPATITIS A, B, C, D, Schistosomiasis, Amoebic liver abscess, TB, Filariasis, HIV

Most are less than 30 days except malaria (esp vivax) & viral hepatitis

22

Discuss enteric fever
- causative organisms
- incubation period
- Px
- risk areas
- Cx
- Dx
- Rx

•Caused by Salmonella typhi, S. paratyphi
•Incubation 7-21 days
•Clinical - non specific febrile illness, +/- diarrhoea or constipation, sometimes a rash
•Common: SE Asia, India, Africa, ME, Sth Am
•Cx: bowel perforation
•Diagnosis:
–FBE - normal WCC with “left shift”
–LFT - commonly abnormal (mixed pattern)
–Blood culture - “gram negative bacilli”, stool culture
•Treatment: antibiotics (ceftriaxone or quinolone if sensitive or azithromycin)
•Without treatment, fatality rate is 10-20%

23

Discuss malaria
- main risk areas
- subtypes %
- modes of transmission

•Mainly imported from PNG, India/Pakistan, Africa and Indonesia

•2/3 P vivax, 28% P. falciparum

• Anopheles mosquitoes, congenital, blood transfusion

24

Discuss (4) plasmodia that infect humans

•P. falciparum:
–Almost all deaths/severe disease
–No dormant liver stage, no late relapses
–Often drug resistant
–Medical emergency - diagnosis and exclusion

•P. vivax and P. ovale
–Produce hypnozoites→ may cause late relapses

•P. malariae
–Usually benign
–May persist in blood stream > 30 years

•P. knowlesi

25

What are the symptoms of malaria?

•Similar symptoms for all species

•None is specific, beware false localising symptoms
–Initially resembles flu-like illness
–Fever, chills
–Pain - headache, muscles, back
–Fatigue, malaise
–Nausea, vomiting, diarrhoea
–Cough

•Partial immunity induced by repeated exposure, but wanes

26

What are the severe manifestations and Cx of falciparum malaria?

•Severe disease usually 3-7 days after illness onset

•Endothelial adherence of infected RBCs
–Cerebral malaria, renal failure, ARDS, hypoglycemia, severe anaemia, bleeding

•Mortality: 15-25%

•Factors responsible for death:
–Parasitaemia > 5%
–Delayed presentation, missed or delayed diagnosis
–No chemoprophylaxis
–Extremes of age
–Splenectomy
–Pregnancy

27

How (4) do you diagnose malaria?

•FBE
–May be haemolytic anaemia
–WCC normal - no eosinophilia
–Thrombocytopaenia common ( 95%)

•Thick blood smear

•Thin blood smear for species identification
–Multiple occasions
–Parasite count

•Antigen Capture Tests
–Dipstick tests: finger-prick blood sample
–Rapid diagnosis: 15-20 minutes
–High sensitivity for Pf (95-100%) with >100 parasites/uL
–Sensitivity drops with lower parasite concentrations

28

How do you treat malaria?
- vivax & ovale
- falciparum

•Vivax and ovale malaria:
–Generally chloroquine (blood stage) and then primaquine (liver hypnozoite)
–Choroquine resistant P. vivax: Mainly Irian Jaya, also PNG, Solomon Islands, Myanmar, Guyana -> Treat as for P falciparum

•Plasmodium malariae: choloroquine

Falciparum malaria:
•Riamet / other artesunate combinations
•Malarone
(Historically quinine PLUS doxycycline OR Mefloquine)

Note: Admit patients with P falciparum

29

How many severe malaria present?

–Unable to tolerate oral therapy
–Altered consciousness
–>5% parasitemia
–Jaundice, oliguria, severe anemia, hypoglycemia, acidosis, ARDS

Indications for IV therapy +/- ICU monitoring with P. falciparum

30

Discuss artesunate (anti-malarial drug)

–Faster clearance of parasites and faster defervescence than quinine
–10-50% recrudescence with monotherapy, generally used with mefloquine, malarone or doxycycline
–Side Effects: Cerebellar ataxia, abdo pain/diarr, ALT
–Probably safe in pregnancy, but inadequate data

IV artesunate = treatment of choice for severe malaria
BUT no “approved” formulation in developed countries

31

Name & discuss (4) malaria prophylactic drugs
- period of consumption
- resistance
- SE

1. Mefloquine
─Once weekly, start 2-4 wks before travel, continue 4 wks after return
─Resistance: Cambodia, Thailand and Myanmar
─Significant SE’s: GI, cardiac, neurological, psychotic episodes/seizures
─Safe in the 2nd and 3rd trimesters of pregnancy , avoid in children less than 5kg

2. Doxycycline (covers atypical)
–Dose 100mg orally daily, taken with food
–Start 1 - 2 days before travel, continue for 4 weeks on return
–Side effects: Photosensitivity, GIT upset, vaginal thrush
–Contraindicated in pregnancy & in children less than 8 yrs

3. Malarone
–Dose: 1 tab daily, start 1 day before, continue for 1 week after Expensive
–Not recommended in pregnancy or kids less than 5kg

4. Chloroquine (widespread resistance)

32

What are the symptoms of Dengue fever?
- incubation period

Incubation period usually 3 to 14 days

–Undifferentiated fever

–Classic dengue fever
•Fevers, HA, arthralgias/myalgias, maculopapular rash (70-75%)
•Defervescence for 1- 2 days
•Fever recrudescence, morbilliform rash, skin desquamation
•Convalescence with prolonged lethargy

–Dengue hemorrhagic fever or dengue shock syndrome (severe plasma leakage, severe haemorrhage, severe organ impairment)

33

What infections/diseases does RASH in a returned traveller with fever indicate?

Dengue, typhoid, rickettsial infections, syphillis, gonorrhoea, Ebola virus, Brucellosis

34

What infections/diseases does JAUNDICE in a returned traveller with fever indicate?

Hepatitis, malaria, yellow fever, leptospirosis, relapsing fever

35

What infections/diseases does LYMPHADENOPATHY in a returned traveller with fever indicate?

Rickettsial infections, brucellosis, dengue, HIV, Lassa fever, visceral leishmaniasis

36

What infections/diseases does HEPATOMEGALY in a returned traveller with fever indicate?

Amoebiasis, malaria, typhoid, hepatitis, leptospirosis

37

What infections/diseases does SPLENOMEGALY in a returned traveller with fever indicate?

Malaria, relapsing fever, trypanosomiasis, typhoid, brucellosis, Kala-Azar, typhus, dengue

38

What infections/diseases does HAEMORRHAGE in a returned traveller with fever indicate?

Dengue, meningococcaemia, Lassa fever, Marburg/Ebola viruses, Crimean-Congo haemorrhagic fever, yellow fever, Rift Valley fever, epidemic louse borne typhus, Rocky mountain spotted fever

39

Any fever occurring in a returned traveller whilst away or after return from a malarious area is due to [what] till proven otherwise.

MALARIA

40

FEVER + RASH in a returned traveller:

–Dengue fever, typhoid, rickettsia
–Malaria less likely

41

FEVER + DIARRHOEA in a returned traveller:

Traveller’s diarrhoea, malaria, typhoid/paratyphoid

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