TYPHOID ORAL & INJECTABLE vaccines
KEY POINTS
Salmonella typhi is a foodborne bacterium. So, it is readily acquired from a broad range of foods, including dairy products. Since it is excreted in the feces of humans and a number of animals, the decreased risk of infection correlates with cleanliness of food and food preparation and adequacy of cooking.
Given the above, typhoid is one of the commonest vaccines recommended for foreign travel, as the traveler’s food is likely most often handled by others and cleanliness is uncertain.
Protection from salmonella infection with this vaccine is relative, such that food heavily contaminated with these germs can overwhelm the immunity and lead to disease, although it may be less severe and non-fatal. However, the vaccine should not create apathy about the quality and cleanliness of ingested food and fluids.
Disease: Typhoid (enteric) fever is an intestinal tract infection by a bacterium, Salmonella typhi, which can spread into the bloodstream and lymphatic system, causing potential infection of many organs, preferentially the arterial circulatory system, liver, bone marrow, gallbladder, and virtually anywhere else.
Incubation: 1 – 3 weeks
Course:
1. Several weeks – months
a. Symptoms:
i. High fever
ii. Headache
iii. Diarrhea/Constipation
iv. Abdominal Pain
v. Rash
2. Complicated typhoid can be fatal (30%) or severely damaging.
3. Some can become chronic carriers, shedding S. typhi in their feces, permanently; many shed it for 1 ½ – 3 months.
Prevalence:
Typhoid is worldwide (200,000 deaths/yr), but most evident in developing countries in Asia, India, the Middle East, Africa, the Caribbean, and Central/South America.
70% of U.S. typhoid cases are from international travel.
Transmission:
Person-to-person by the fecal-oral route from contaminated food, water, and beverages. So, in areas of the world where the water supply and general level of human hygiene are marginal, risk for typhoid is high.
Treatment: Antibiotics
Prevention:
1. Drink bottled water and beverages.
2. Avoid uncooked food (salads, puddings, etc.).
3. Eat only thoroughly cooked food/seafood.
4. Only eat fruit and vegetables you can peel yourself.
5. Vaccines
a. Injectable (intramuscular)/Typhim Vi (killed)
i. 2 years of age or older
ii. Single-dose; at least 2 weeks pre-travel
iii. Efficacy = 50 – 80%
iv. Booster: Every 2 years
v. Side-Effects:
1. Most common: Injection site pain, swelling for 1 – 2 days
2. Occasional flu-like symptoms, headache, tremor, abdominal pain, nausea, diarrhea, neck pains
vi. Precautions/Contraindications
1. Phenol allergy
2. No data on safety with pregnancy, but it is a killed vaccine (so, unlikely a risk to the fetus)
3. If moderately, actively ill, wait until well to take the vaccine.
4. Immunocompromised CAN take the vaccine.
b. Oral/Vivotif (live)
i. 6 years of age or older
ii. 4 doses (1 every other day); at least 2 weeks pre-travel
1. Efficacy = 50 – 80%
2. Booster: Every 5 yrs.
iii. Side-Effects: Fewer than with Typhim; rarely can have fever, headache, nausea, abdominal pain, rash, hives.
6. Precautions/Contraindications,
a. Not to be taken with vomiting or having diarrhea.
b. No data on safety with pregnancy (and it is a live vaccine, so requires deliberation and caution).
c. Antibiotics should be avoided 3 – 7 days (depending on half-life of antibiotic) before and after oral (live) typhoid vaccine.
d. Contraindicated in immunocompromised persons:
i. AIDS (CD4 T-Cell count 200-500; discuss with physician)
ii. Chemotherapy
iii. Radiation therapy
iv. Cancer
v. Immune-suppressant medications (steroids, etc.)
e. If moderately ill, wait until well to take vaccine
7. Vaccine Targets
a. Traveling to developing countries, especially remote locations
b. Traveling where there are sanitation problems
c. Travelers with weakened immune systems
d. Travelers with deficient/low gastric acid – after partial or complete stomach resection; chronic antacids; stomach ulcer medications
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