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5 lessons for the future of typhoid control

April 17, 2019 by Laura Kallen

The future of typhoid control faces many threats, but elimination may one day be feasible.

The 11th International Conference on Typhoid and Other Invasive Salmonelloses brought together more than 400 experts to discuss the road ahead for typhoid prevention and control.

The 11th International Conference on Typhoid and Other Invasive Salmonelloses brought together more than 400 experts to discuss the road ahead for typhoid prevention and control.

The global momentum to take on typhoid has never been higher.

Why? There are many reasons— deadly outbreaks of new drug-resistant typhoid strains, the 2017 World Health Organization (WHO) prequalification of a new typhoid conjugate vaccine (TCV), the opening of funding for that vaccine from Gavi, the Vaccine Alliance in 2018, and rising water-related threats due to climate change, to name a few.

As part of the Typhoid Vaccine Acceleration Consortium (TyVAC), PATH recently attended the 11th International Conference on Typhoid & Other Invasive Salmonelloses in Hanoi, Vietnam, a gathering of more than 450 researchers, policymakers, and advocates dedicated to taking on typhoid.

After an inspiring and energizing week, five key lessons rose to the surface to influence our work going forward.

1. We are only one mutation away from untreatable typhoid.

Dangerous drug resistance mutations of typhoid are popping up independently in diverse locations, and they’re spreading—and mutating—quickly. The past few years have seen the emergence of extensively drug-resistant (XDR) typhoid in Pakistan. Today, we are only a one-point mutation away from extremely drug-resistant (“XXDR”) typhoid, which would not respond to any current antibiotics. The acceleration of drug-resistant typhoid has brought real consequences, such as longer duration of illness, higher treatment costs, and higher case fatality.

2. Typhoid conjugate vaccines work, and we really, really need them.

These newly available tools are a typhoid game-changer, and they have come at a crucial time. Compared with previous typhoid vaccines, typhoid conjugate vaccines provide long-lasting protection, require only dose, and, crucially, can be given to children as young as 6 months of age as part of routine immunization. The conference offered many exciting updates on the evaluation and global uptake of these new vaccines, but some of the most exciting news came from the Typhoid Vaccine Acceleration Consortium, which announced positive preliminary typhoid conjugate vaccine efficacy results from a clinical trial in Nepal. With these newly available vaccines, the future of typhoid prevention looks bright.

3. To take on typhoid in the long term, the typhoid community will need to start collaborating with the WASH community.

We’ve long known that society-level improvements in water and sanitation (e.g., water treatment, pipes, and sewage systems) can essentially eliminate typhoid from a population, which is what happened in North America and Europe. This type of development, however, can take decades—if not centuries—to happen in a sustainable way. For much of sub-Saharan Africa and Asia, improvements in water, sanitation, and hygiene (WASH) are happening, but slowly, which is why vaccines are so crucial in the short term. But while vaccines are urgent as a short-term solution, especially given the rising threat of drug resistance, we cannot ignore or put off long-term WASH solutions any longer. We need to integrate WASH solutions with vaccines and broader typhoid control efforts—especially given the threats of water shortages and contamination in the wake of climate change. This is a WASH engineering problem, and in the words of Stephen Luby from Stanford University, the typhoid community needs to “take an engineer to lunch!”

4. There is still uncertainty in typhoid burden data, but we cannot let uncertainty justify paralysis.

The question of “when is enough data enough?” continues to challenge the typhoid community as it does many other topics in global health. With TCVs available through Gavi funding, many countries are now deciding whether or not to apply for support to introduce the vaccine. One of the longstanding complexities of typhoid, however, is that it is difficult and expensive to diagnose. Surveillance data is therefore limited, especially in low-income countries. The overriding message of the conference was that, while there is always room for improvement in typhoid surveillance and burden data, we already know enough in most typhoid-endemic countries to know that we need to do something. We cannot let the remaining uncertainty justify inaction on the available, operable solution of typhoid conjugate vaccines.

5. Climate change, urbanization, and other emerging priorities make the future of typhoid control uncertain, but we have to press on.

One of the most inspiring presentations at the conference was from John Crump at the University of Otago, who made the case that typhoid elimination—the “e” word—is feasible. Given the current landscape, it could be possible in as few as three decades. That landscape, however, could change dramatically with “chaotic shocks” from climate change, urbanization, and other emerging health and development priorities, including increasingly mobile populations. Water supplies could diminish or become contaminated. New diseases similar to Ebola could pop up. Conflicts could upend vaccination programs.

The future is uncertain, but as with all efforts for the good of humanity, we must press on. Thanks to new vaccines, new research, and new momentum, the possibility of eliminating typhoid as a threat to human health is now closer than ever.

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