The emergence of untreatable strains of typhoid threatens a new global health emergency that requires urgent collective action, argue experts from the Oxford Martin School in Clinical Infectious Diseases.
Typhoid still affects at least 11 million people every year, with the real figure potentially as high as 18 million. On the eve of the rollout of a new typhoid conjugate vaccine (TCV), the researchers are calling for global health institutions to dedicate new resources to tackling typhoid, which they say has become a neglected disease of poorer countries following its elimination in many high-income countries. Rising antimicrobial resistance and the ongoing outbreak of extensively drug-resistant (XDR) typhoid in Pakistan should be a wake-up call to the international community, they say.
New vaccines offer hope for typhoid control, but one intervention alone will be insufficient for eliminating the disease. Analysing the past and present of typhoid control, the researchers – including historians, immunologists and social scientists – identify a range of actions key to the strategic elimination of typhoid globally.
Their findings include:
• Typhoid is still a major global health issue but is largely unrecognised, due to factors including poor surveillance and the complex dynamics of the disease, including new drug-resistant strains.
• The availability of cheap credit and sustainable financing schemes for affordable water and sanitary systems at the municipal level have an important role to play in typhoid control (as seen in the elimination of typhoid in the UK and US).
• There is a need to pair top-down nation state-led programmes with a greater emphasis on bottom-up approaches, enabling municipal coalitions to develop, adapt, and own locally-tailored water, sanitation, hygiene and health systems.
• A lack of international financing has stalled the spread of sanitary and health infrastructures that played a key role in eliminating typhoid in high-income countries. Instead, the focus in wealthier, typhoid-free countries has been on protecting travellers and preventing typhoid from crossing borders.
• Fragmented global action on typhoid and intensive use of antibiotics to compensate for weak water and healthcare systems have fuelled antimicrobial resistance in low- and middle-income countries.
• Progress on typhoid control will depend on support for independent research and policy decisions within endemic countries to improve water quality.
• The recent advent of a new generation of typhoid conjugate vaccines, which can also be used for children under two years of age, can play an important role until clean water and sanitation are in place for those at greatest risk.
The research was led by Dr Claas Kirchhelle, Dr Samantha Vanderslott and Professor Andrew Pollard, as part of their work on the Oxford Martin Programme on Collective Responsibility for Infectious Disease.
Dr Kirchhelle, of the Wellcome Unit for History of Medicine at the University of Oxford, said: 'Popular notions of typhoid as a disease of the past are a myth. For poorer countries, the spectre of typhoid has never gone away. Over the last decades, international neglect, lacking sanitary infrastructures and vaccine programmes, and compensatory reliance on antibiotics have resulted in a situation where typhoid is increasingly difficult to treat. The current resurgence of extensively drug-resistant (XDR) typhoid bears the biosocial footprint of more than half a century of antibiotic-intensive international neglect.'
Dr Vanderslott, of the Oxford Vaccine Group, added: 'The emergence of untreatable strains needs to be taken far more seriously. Top-down interventions such as vaccination programmes need to be combined with flexible credit to empower local communities, so that they can implement essential infrastructure such as waste disposal, sanitation and clean water systems.'
Progress on the new typhoid vaccine was accelerated by a pioneering use of a controlled human infection model (CHIM) in Oxford - which enabled scientists to test a number of candidate vaccines.
Professor Andrew Pollard, who leads the Oxford Vaccine Group, said: 'The escalating problem of antimicrobial resistance means we need urgently to deploy new interventions to tackle typhoid. The availability and funding of new effective typhoid vaccines give us a critical tool for strengthening global control of typhoid, with the potential to protect vulnerable populations from this disease.'
The full paper, ‘Making a Difference? The past, present and future of typhoid control,’ can be read in Clinical Infectious Diseases.