Typhoid fever all but disappeared from Western countries in the 20th century through massive improvements in water and sanitation. It happened after causing untold misery and death in its newly industrialising but unsanitary cities. Tragically, much of the rest of the world is still grappling with typhoid. The World Health Organisation (WHO) estimates as many as 21 million cases of typhoid annually; the disease is responsible for 220,000 avoidable deaths every year. And without urgent action, the fear is that the number of cases could rapidly escalate - particularly in Africa.
Until recently, it was thought that Asia, and particularly India, was the area worst hit by the disease. Prior global estimates for the burden found that South-Central and East-Central Asia experienced the highest incidence of typhoid fever, with more than 100 cases per 100,000 person-years of observation; Africa was estimated to have a moderate incidence (10 to 100 cases per 100,000 person-years of observation).
But new research, funded by the Bill & Melinda Gates Foundation, reveals a concerning reality about typhoid in sub-Saharan Africa. This research titled, "What Have We Learned from the Typhoid Fever Surveillance in Africa Program?", undertaken by Stephen Baker, Joachim Hombach and Florian Marks under the auspices of the International Vaccine Institute, dispels the notion that typhoid is a minor problem in Africa.
Data from the research describes remarkably high incidence rates in three of 13 of the African surveillance sites. Additionally, high incidence rates were observed specifically in children less than 15 years of age. These figures are comparable to the case in Asia, and again show that children between the ages of two and 14 years bear the global brunt of the burden of typhoid fever. Significantly, the incidence rates of typhoid fever in many of the Africa countries were equivalent to, or indeed greater than, incidences reported in parts of Asia in the early 2000s. In fact, the incidence in some areas is as high as in Asia.
Major outbreaks have been recently reported in Malawi, Uganda and Zimbabwe. Further, current demographic trends in Africa fuel a potential danger for a rapid rise in disease prevalence.
Those most at risk from typhoid are children living in densely-populated urban areas with inadequate water and sanitation. And Africa is in the midst of a population boom that suggests by 2050, more than half of its population will live in cities. That is the equivalent of the current population of China!
Without major changes, rapid and unregulated urbanisation may result in millions residing in crowded slums with poor likelihood of safe water or developed sanitation. This could be a hotbed for a massive spread of typhoid, as well as other water-borne diseases like cholera.
The public health challenge could be made even worse by the emergence of multidrug-resistant typhoid in Zambia and Malawi. Infections caused by these strains already lead to more severe illnesses and higher death rates because they cannot effectively be treated by antibiotics.
More than ever, vaccines are central to reduce typhoid's threat while the world follows through on its water and sanitation improvements as part of the Sustainable Development Goals (SDGs) agenda. The Bill & Melinda Gates Foundation has recently prioritised typhoid, alongside pneumonia and diarrhoeal infections, in its commitment to fight diseases that hit hard among the poor and most vulnerable.
In supporting the development of new, better vaccines to give long-lasting immunity to young children, we are also determined to help improve surveillance systems to accurately identify and measure typhoid cases. And we will work with partners to put in place a two-pronged response to the disease: vaccines, coupled with improvements in water and sanitation.
Typhoid poses a major health challenge to the African continent. But we also know how successful new vaccines have been in tackling a wide range of diseases, including rotavirus infections and meningococcal meningitis in Africa.
We are much farther along in the fight against typhoid than we were a hundred years ago. Concerted and coordinated control efforts can prevent a 19th century health risk becoming a 21st century crisis in sub-Saharan Africa.
Anita Zaidi Is Director of Enteric Diarrhoeal Diseases Programme At the Bill & Melinda Gates Foundation.