14 - Travel Infections

Question 1

Types of traveller’s diarrhea

Answer 1

• Mild = tolerable, not distressing, doesn’t interfere w/ planned activities
• Moderate = distressing or interferes w/ planned activities
• Severe = incapacitating or completely prevents planned activities; all dysentery is considered severe

Question 2

Transmission of TD

Answer 2

Contaminated food and/or water

Question 3

Cause of TD

Answer 3

• Bacteria are most common cause (enterotoxigenic E. coli, shigella spp., campylobacter spp., salmonella spp.)
• • Shigella is more rare but need a very small amount to cause severe TD
• Viral pathogens are 2nd most common cause (norovirus, rotavirus, astrovirus)
• Giardia main protozoal pathogen

Question 4

Sx of bacterial or viral TD

Answer 4

• Sudden onset of bothersome sx
• Can range from mild cramps & urgent loose stools to severe abdominal pain, fever, vomiting, bloody diarrhea
• Vomiting may be more prominent w/ norovirus

Question 5

Duration of TD

Answer 5

• Untreated bacterial diarrhea usually lasts 3-7 days

- Viral lasts 2-3 days

Question 6

Which countries have intermediate and high risk of TD?

Answer 6

• Intermediate risk = eastern Europe, south Africa, some Caribbean islands
• High risk = most of Asia, middle east, Africa, Mexico, central & south America

Question 7

Pt-related risk factors for TD

Answer 7

• Young adults
• Very young at higher risk of severe and/or prolonged TD
• Highest risk = immunocompromised, gastric acid suppression, IBD
• More common in px from low risk countries travelling to moderate or high-risk countries

Question 8

Environment-related risk factors for TD

Answer 8

• Warmer climates where access to plumbing is low => higher stool contamination in environment
• Inadequate electrical capacity => poorly functioning refrigeration => unsafe food storage
• Lack of safe water
• No handwashing stations in food prep areas

Question 9

Higher-risk foods

Answer 9

• Raw or undercooked meats, fish, & shellfish
• Uncooked vegetables, unpasteurized milk, cheese, or fruit juices
• Raw fruits that aren’t peeled (ex: berries)
• Food & beverages from street vendors
• Tap water

Question 10

Non-pharms for TD prevention

Answer 10

• Handwashing (no evidence for reducing TD, but have evidence for preventing diarrhea)
• Alcohol-based hand sanitizer if water not available

Question 11

OTC options for TD prevention

Answer 11

• Bismuth subsalicylate (Pepto-Bismol) 524 mg QID
• Probiotics (harmless, but result are inconclusive)
• Dukoral (oral, inactivated TD & cholera vaccine) for > 2 y/o; effectiveness not demonstrated for TD

Question 12

When should antibiotics be used as prophylaxis for TD?

Answer 12

• Px at high-risk for serious infections or complications (ex: immunocompromised, diabetes, end-stage renal disease, severe IBS)
• Travelling for a short time who can’t tolerate any down time (ex: athletes, professionals)

Question 13

Antibiotics for TD prophylaxis

Answer 13

Cipro or levo 500 mg once daily

Question 14

Goals of tx for TD

Answer 14

• Prevent dehydration and replace fluids
• Decrease duration & severity of sx
• Minimize impact of travel

Question 15

Pharm agents (other than antibiotics) for TD tx

Answer 15

• Loperamide
• • Sx relief; useful adjunct to antibiotics
• • 4 mg stat then 2 mg after each loose stool (max 16 mg/day) for adults
• Bismuth subsalicylate (BSS) 524 mg q30min to max of 8 doses/day

Question 16

Antibiotic for TD tx

Answer 16

• If prophylaxis used, then different antibiotic is used for tx
• Cipro 500 mg BID x 3 days or 750 mg x 1 dose
  OR
• Levo 500 mg once daily x 3 days or 1 g x 1 dose are 1st line
• Azithro may be preferred in certain px (allergies, pregnancy, children, breastfeeding) & regions b/c of resistance
  – 500 mg once daily x 3 days or 1 g x 1 dose
  – 5-10 mg/kg (max 500 mg) once daily x 3 days for children

Question 17

Guidelines for TD tx

Answer 17

• Mild = antibiotics not recommended; loperamide or BSS may be considered
• Moderate = antibiotics (FQs, azithro) may be used; loperamide may be used as adjunctive therapy for moderate-severe or monotherapy in moderate TD
• Severe = antibiotics should be used (azithro preferred); single dose antibiotic regimens may be used
• Good idea to give antibiotics to a backpacker who is more than 24 h away from medical care so that they can self-tx before they can get to medical care

Question 18

Malaria cause, sx, & transmission

Answer 18

• Human disease caused by 5 protozoan parasites
• Sx = fever & flu-like sx (chills, headache, myalgias, malaise); sx can occur at intervals
• Transmitted through bite of infected mosquito; rarely through blood transfusion, organ transplant, needle sharing, or congenitally from mother to fetus

Question 19

Malaria individual risk assessment

Answer 19

• A = awareness (where it occurs in the world)
• B = bite avoidance (sleep in screened accommodations; wear light, long clothing; tuck pants into socks; hours of biting between sunset & sunrise; use DEET 20% or more or icaridin 20% or more)
• C = chemo prophylaxis (see anti-malaria medications)
• D = diagnosis (any pt w/ history of travel to malaria areas should go to emergency to rule out malaria)

Question 20

Which cause of malaria is most likely to progress to severe infection?

Answer 20

P. falciparum

Question 21

Hepatitis A vaccine indications

Answer 21

• All susceptible people > 1 y/o should be vaccinated prior to departure to areas w/ high or intermediate hep A endemicity
• Intermediate risk = Mexico, some Caribbean, Central America, South America, North Africa, Middle East
• High risk = Africa (except North), India, Afghanistan, Pakistan, Bangladesh

Question 22

Hepatitis A vaccine dosing schedules

Answer 22

• Single dose gives protective antibody levels w/in 2-4 weeks, but is indicated regardless of time period before departure
• Full series includes 2 doses ranging from 6-36 months apart (recommended between 6-12 months apart)

Question 23

Hepatitis B vaccine indications

Answer 23

• All travellers to high and intermediate risk areas
• Causes of reduced immune response to hep B vaccine = older age, male, obesity, smoking, route of administration, some chronic underlying diseases

Question 24

Hepatitis B vaccine dosing schedules

Answer 24

• Conventional schedule at 0, 1, and 6 months gives optimal protection by month 7
• Accelerated schedule = 0, 7, and 21 days then 12 months after first dose

Question 25

Indication for combined hep A & hep B vaccine

Answer 25

Non-immune travellers > 1 y/o

Question 26

Dosing schedule for combined hep A & hep B vaccine

Answer 26

• Primary schedule = 0, 1, and 6 months
• 2 doses protect 100% against hep A but only 50-95% against hep B
• Single dose doesn’t provide adequate protection against HAV or HBV
• Accelerated schedule = 0, 7, and 21 days plus 12 months after first dose