Hi Thanks for choosing HCM for your query. I appreciate your concern for your friend s health. Typhoid is a bacterial infection caused by drinking contaminated water or food. Provision of safe drinking water in most of the developing countries is a big challenge. Ask your friend to drink safe drinking water preferably after boiling it and avoid eating improperly cooked vegetables and poultry. There is a vaccine available which is useful in prevention of typhoid in highly endemic areas. The injectable Vi capsular polysaccharide vaccine (ViCPS vaccine) is given intramuscularly in a single dose. Protection is induced about 7 days after the injection. The protective efficacy 1.5 years after vaccination is about 72%; after 3 years it is about 50%. To maintain protection, re vaccination is recommended every 3 years. Hope your query is being answered. A feedback is highly appreciated.