1. History of elimination
2. Microelimination
3. Microelimination and hepatitis C
4. Context considerations 

1. History of elimination

In the early 1960s, ideas about defining the stages of eradication of diseases were circulating. This was the beginning of the campaign against smallpox. Much was learned with the experience of elimination and eradication smallpox, rinderpest, and the regional elimination of some other diseases. The Dahlem Workshop of 1997 and the Atlanta Conference of 1998 were major steps in analysing the nature of elimination as more than a step on the way to eradication.

The proposed definitions of elimination were strict:

• Elimination of infections: Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; surveillance and continued measures to prevent re-establishment of transmission are required. Examples: poliomyelitis in most countries, Guinea worm in Asia, malaria in Europe
• Elimination of disease: Reduction to zero of the incidence of a specified disease in a defined geographical area as a result of deliberate efforts; continued intervention measures are required, as it may not be possible to reduce risk to zero. Example: neonatal tetanus (It is not possible to eliminate the bacterium, but universal immunisation and antiseptic measures can eliminate tetanus.)

In practice, the working definitions are looser, usually defining an acceptable number of new cases. (This number may be 1.) Many implementers consider elimination achieved when the disease is no longer endemic, and new cases are imported, as long as surveillance shows transmission at a low enough level to prevent re-establishment of persistent transmission in the area.

Micro-elimination

2. Microelimination

Microelimination was proposed by Lazarus et al. as a way to deal with the scale and cost of elimination in the strict senses in larger geographic areas. Particularly in places where the drug needed for microelimination were expensive, elimination was a difficult goal for authorities to prioritise. The authors point out that national efforts are typically slow to start, but smaller actors can already take action.

Lazarus points out the usefulness of eliminating hepatitis in networks of people who present hazards to each other, such as detainees in one facility, or people tending to be exposed to transmission risk in a defined geographical area. In addition, microelimination defines populations with a higher likelihood of having hepatitis C infection, such as patients with advanced liver disease, or who have shared needles in drug injecting networks.

To implement micro-elimination, global expertise can inform local efforts of new developments in diagnosis, treatment, and prevention. However, local expertise is the key to identifying the networks of people at risk and bringing them and the diagnosis and treatment together. Local stakeholders know who the key populations are, how to approach the their leaders and members, what messages will engage their values, and what will be the practical ways to measure successes and failure. Bringing together all stakeholders and creating the whole project from from the planning through to the evaluation together is key.

Hepatitis C micro-elimination

3. Microelimination and hepatitis C

As there is no vaccine for hepatitis C, the way to eliminate it is to treat and prevent. Systematic testing and treatment — treating all of one group and then moving on to the next — lowers the risk of reinfection. The key to effective microelimination is identifying these groups, and making sure they have the knowledge and autonomy to make decisions about testing and treatment. The approaches will be quite different in a context where most people are well educated and there is an egalitarian cultural background, and in another where people do not know the basics science of health and some are marginalised. The approach must be adapted to each context, and involve the community. People must understand what the issues and choices are. Without the involvement and support of the community, fewer people will accept the offer of testing and treatment. Rumours may spread. Misunderstandings and stigma can last for many years afterwards. Always proceed with transparency, patience, empathy, and honesty.

HCV microelimination context