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Elimination and eradication

 

Introduction

In 1997 a workshop on the Eradication of Infectious Diseases was held to discuss and define the terms elimination and eradication, identify lessons that can be learned from previous and current programs and develop the science of eradication. Mathematical models were discussed at this meeting, and their inference has been informative from the beginning. At that time, only smallpox had been eradicated after decades of intensive control efforts through use of vaccination and surveillance for outbreaks of this deadly disease. Other eradication programmes had failed; yellow fever, malaria, and yaws. Public health professionals became increasingly cautious to proclaim an eradication programme rather than one simply for control.

Since this time world has changed; there is new enthusiasm for eradication. In the 1980s polio was successfully eliminated from the Americas and enormous efforts have been undertaken to eradicate. In veterinary medicine rinderpest has not been reported in animals since 2006 and an intense serological surveillance program was necessary to confirm eradication. Guinea-worm disease is restricted only to 4 countries in sub-Sarahran Africa. For some vector-borne diseases new control tools are becoming available and eradication is once again being discussed.

These exciting public health developments require an informed analysis to help support development of feasible elimination and eradication plans. Central to this is an understanding of the feasibility of eradication and mathematical modelling can have a role. Mathematical and statistical models can be used to inform;

  • The feasibility of moving from control to elimination
  • Whether an epidemic will die out within a period of time
  • The probability that transmission has been eliminated

Especially when there are multiple options for an intervention, it is possible to compare the interventions by estimating the probability of each preferred outcome. Common to many of these themes is the use of data from outbreaks of infectious diseases to understand disease dynamics, and how they can be altered through control activities. The aim of this research theme is to:

  • Share knowledge and experiences in developing mathematical models for the purpose of informing elimination and eradication
  • Develop and refine methodological approaches specific to elimination and eradication.
  • How diagnostic tools and the extent of use affects inference on elimination
People

Kathleen O’Reilly (theme co-ordinator), Paul Fine, Seb Funk, Petra Klepac, Grace Macklin, Amy Pinsent, Richard White

Recent activities

Elimination and Eradication theme trip to Crossness Sewage Treatment works (October 2019)

On what was possibly the coldest day in 2019 we made a trip to Crossness Sewage Treatment works to see how the Victorians dealt with London’s sewage. This is related to elimination and eradication because cholera was a huge public health problem in London before the development of considerable engineering infrastructure to remove waste from contaminating the water supply in London, and sewage sampling is a critical form of surveillance for poliovirus and other pathogens. We were shown round the old treatment works at Crossness sewage by Petra Cox (Outreach Officer). Fascinating insights included the speed at which the project was planned and implemented by Joseph Bazalgette, and the beautiful details of the inside of the pumping station.

location of crossness sewage and image of the steam engines
Location of Crossness and photo taken of the steam engines used to pump sewage into the storage chamber beneath the works (credit: Kevin van Zandvoort).

Elimination and Eradication CMMID seminar (July 2019)

We had a very interesting set of ‘turbo talks’ by researchers within LSHTM who are working on areas linked to elimination and eradication;

Graham Medley – Introduction and perspectives Kath O’Reilly – Polio

 

The meeting allowed us to ruminate over the common threads across these diseases. It was apparent that targets, even if they will not feasibly be met are useful to catalyse progress, but we wondered if this approach will erode with time (“crying wolf” with each new target). Across many diseases it was apparent that surveillance becomes critical as the disease reduces in incidence, and it is often at this time that stakeholders and funders of surveillance may lose interest. A few examples of the ‘freedom from infection’ framework were given, which provide a useful framework to understand the importance of surveillance in near-elimination settings.

  • Amy Pinsent – Trachoma
  • Lindsay Wu – Malaria
  • Lloyd Chapman – Leishmaniasis
  • Tom Sumner – Tuberculosi