Typhoid Fever Overview
Typhoid fever is an acute, systemic infection that represents an important cause of morbidity and mortality in the developing world with nearly 22 million cases and 216,500 deaths annually worldwide.1 Although largely an endemic disease, typhoid fever has epidemic potential. Data mainly from Asia, Africa and Latin America show that typhoid fever continues to be a public health problem in these areas. People from industrialized countries may contract the infection mainly while traveling to endemic regions.1, 2
Typhoid fever is caused by the bacterium Salmonella Typhi. The infection is transmitted via the fecal-oral route with most cases and deaths occurring among populations that lack access to safe drinking water and adequate sanitation, hygiene and treatment.1-3
The illness has non-specific symptoms, making it difficult to distinguish clinically from other febrile illnesses that might be endemic or cause epidemics in the same geographic areas, such as paratyphoid fever, dengue and malaria.1 Symptoms of the disease usually develop one to three weeks after exposure. Persons with typhoid fever usually have a sustained fever as high as 103° to 104°F (39° to 40°C). They may also feel weak, or have stomach pain, headache or loss of appetite. In some cases, patients have diarrhea (in children), constipation (in adults), a rash of flat, rose-colored spots.2,3
Serious complications occur in up to 10% of typhoid fever patients, especially in those who have been ill longer than two weeks and have not received proper treatment. Estimates of case-fatality rates in typhoid fever range from 1% to 4%. Humans are the only reservoir and approximately 1–4% of patients become “asymptomatic carriers”, suffering no symptoms but still being capable of infecting others.1, 2
Appropriate antibiotics shorten the duration of fever and the bacterial shedding and reduce the case-fatality rate. However, resistance to available antibiotics is common, and the prevalence of resistance is increasing.1-3
Safe water, adequate sanitation, appropriate personal and food hygiene and vaccination are the most effective strategies for prevention and control.1-3
Vivotif (Typhoid Vaccine Live Oral Ty21a) is a live attenuated typhoid fever vaccine for oral administration. In the U.S.*, Vivotif is indicated for the immunization of adults and children greater than 6 years of age against disease caused by Salmonella Typhi.4 It has been on the U.S. market for more than 20 years and is currently licensed in 27 countries.
More than 1.4 million doses of Ty21a have been administered in controlled clinical trials and more than 150 million doses of Vivotif have been marketed world-wide. The overall symptoms from clinical trials were shown to be abdominal pain, nausea, headache, fever, diarrhea, vomiting and skin rash; only the incidence of nausea occurred at a statistically higher frequency in the vaccinated group as compared to the placebo group. Post-marketing surveillance has revealed that adverse reactions are infrequent and mild.4
*For more details, please check the local approved product information.
1. Date K.A. et al, Typhoid Fever Surveillance and Vaccine Use - South East Asia and Western Pacific Regions, 2009-2013. Morbidity and Mortality Weekly Report, Vol. 63, No.39, October 3, 2014
2. Typhoid Vaccines: WHO Position Paper, Weekly Epidemiological Record, No. 6, 2008, Vol. 83, p 49–60
3. Centers for Disease Control and Prevention, Yellow Book 2016, Chapter 3 Typhoid & Paratayphoid Fever, http://wwwnc.cdc.gov/travel/yellowbook/2016/infectious-diseases-related-... accessed August 13, 2015
4. Vivotif – package insert USA, September 2013