Putting Typhoid Vaccination on the Global Health Agenda

Although typhoid fever, caused by infection with Salmonella enterica serovar Typhi (often called S. typhi), long ago ceased to be a public health problem in industrialized countries, it is still a substantial cause of illness and death in many developing countries. According to the World Health Organization (WHO), there are 16 million to 33 million cases and 500,000 to 600,000 deaths from typhoid fever annually,¹ though one study conservatively estimated that 22 million cases and 216,000 related deaths occurred in 2000.² This death rate is not much lower than the estimated 270,000 annual deaths from cervical cancer, caused largely by the human papillomavirus (HPV), and is considerably greater than mortality from meningococcal meningitis and Japanese encephalitis.³ But whereas there has been considerable international momentum behind introducing vaccines against HPV and meningococcus, vaccination against typhoid fever has largely fallen off the international radar screen.

Among the major reasons for this apparent neglect is a sense of complacency inspired by the introduction, beginning several decades ago, of relatively inexpensive antibiotics that initially reduced the rate of typhoid-related deaths substantially; unfortunately, these drugs have progressively become ineffective, since the bacterium has developed resistance to them. Another key factor is that the burden of typhoid fever is unknown and is probably underestimated in most developing countries, owing to the difficulty of differentiating the disease from other febrile illnesses, the infrequency of appropriate confirmatory laboratory testing, the reliance in many countries on private health care providers or on self-treatment with antibiotics, and the generally poor disease-reporting systems in developing countries. And unlike dengue fever and meningococcal meningitis, which occur in epidemics that command the attention of the media and political leaders, typhoid fever is largely an endemic illness. Finally, whereas policymakers have prioritized vaccines that reduce the rates of illness and death among children under 5 years of age, typhoid fever has long been considered a disease of school-aged children.

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