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Skip to 0 minutes and 13 secondsOLIVIER LE POLAIN: The main purpose of contact tracing is to identify new potential cases among close contacts of known Ebola cases as early as possible in their disease course. And that's very important for several reasons. It is a key element of outbreak control to identify people as early as possible and being able to isolate them as early as possible so as to reduce onward transmission to the community. We know, for example, that in the current outbreak in West Africa, it takes, on average, about five to six days for people to attend Ebola treatment units and those are five to six days during which people have contacts with various people within the household, but also outside the household.

Skip to 0 minutes and 52 secondsAnd with a lot of potential for onward transmission in the community. So identifying people early on in their disease course and isolating them early from the communities is the main purpose. The other reason, of course, is for patients themselves to be identified early and be provided with treatment early on which increases their likelihood of survival and their general outcome and that's very important for the patients as well. Ebola is transmitted through body fluids. So urine, blood, faeces, vomit. And so anyone who's been in direct contact with such fluids will be considered as a contact. Also anyone who's been in direct physical contact with a patient will be considered as a contact.

Skip to 1 minute and 32 secondsAnd then people who've been in contact with their clothes or their bed linen will be considered as contacts. And then a fourth category is anyone who's been in contact or has shared a meal on a daily basis with a known Ebola case and shared a kitchen will be considered as a contact. So essentially, it's mostly household contacts. You can also have contacts in the community with relatives or other community members. And if they have had such contact it would be considered as contact for the contact tracing. An example, for example, is traditional healers who could have been in contact with the patient during the course of illness. There's many different aspects of contact tracing after burials.

Skip to 2 minutes and 10 secondsOf course burials are potential super spreading events if there are community burials because people will be touching the body and many people may be attending the funeral. There are particular individuals who will be more at risk. Those who transport and those who prepare the body and contact tracing, in those circumstances, are generally more than just household contacts or close relatives but will be many more people in the community. There's various ways of finding people-- finding contacts. But essentially, when patients are being admitted or when patients are being identified by case investigation teams in the field, they will be asking questions about their exposures and their contacts over the last few days since the onset of symptoms.

Skip to 2 minutes and 52 secondsWhen patients are very unwell, we'll rely on the family or close relatives to also answer those questions. And sometimes patients may be dead on arrival as well. And so exclusively that would rely on asking questions to relatives. It's sometimes quite difficult to obtain information on contacts simply because patients may not want to give that information out. Because they don't want to give the details of their contacts by fear of stigma, by fear of all sorts of sort of social pressure. And they don't want to give their addresses as well. So there is various challenges in identifying the contacts. Went contacts have been found they'll be followed up for 21 days by the contact tracing teams.

Skip to 3 minutes and 34 seconds21 days is the maximum incubation period for Ebola. And so contacts will be followed up for 21 days after their last exposure with the case. In practise, what happens is that if patients are being admitted to Ebola treatment units, their contacts will be followed up for 21 days after their day of admission. And for those 21 days, the contact tracing teams will do door to door visits of contacts in their households, ask about their signs and symptoms and try to identify anyone who might be unwell. There is challenges, of course, as well as identifying contacts daily because contacts may not be a home. Contacts may move, may be in other places.

Skip to 4 minutes and 13 secondsAnd so that's sometimes difficult to actually be able to interview everyone on the day. But that information is probably sometimes collected from whoever is in the household and there will be asked questions about everyone else in the household. The contact tracing is also an opportunity for community engagement and certainly health awareness messages. And contacts will be told about what to do if they become unwell, how to isolate themselves, what the signs and symptoms are of Ebola, and all health promotion messages. When we found someone with symptoms-- when the contact tracing teams find someone with symptoms, the next step is to inform case investigation teams and ambulance services.

Skip to 4 minutes and 56 secondsContact traces themselves generally are not allowed to touch the patients because they don't have the appropriate gear and equipment with them to do that-- personal protective equipment. Generally they will always ask their questions and keep their distance, a two meter distance from individuals. So the next step is to identify contact case investigation teams for those teams to then properly investigate the case and see whether they meet the case definition should be offered treatment or care in an Ebola treatment unit. One of the main problem is capacity. Certainly when the number of cases is doubling every 20 or 30 days, the number of contacts will increase in that proportion as well.

Skip to 5 minutes and 39 secondsAnd it's very difficult to increase capacity to that level as well. So there's been a lot of challenges with increasing capacity properly. Also because contact tracing teams are generally made of people who are community members, community health volunteers, community health workers, and to increase capacity would actually be pulling out people from other programmes to do contact tracing. So there is challenges in doing that. I know that in many areas, contact tracing has stopped at the peak of the epidemic or where there were too many patients and the system was completely overwhelmed. When the number of cases decrease, certainly contact tracing is something to do because it's a key element of outbreak control.

Skip to 6 minutes and 20 secondsCertainly another challenge as well is community acceptance and how contact tracing is being perceived by communities. And I think contact tracing will probably only work well if communities perceive it as useful, understand the purpose of contact tracing, and that goes hand in hand with community engagement and awareness campaigns.

Contact tracing: theory and practice

Contact tracing aims to identify and monitor contacts of known Ebola cases in order to isolate and investigate them for Ebola as early as possible if they become ill. This should prevent any further transmission and allow those who are ill to get care early, which is likely to improve the disease outcome.

In the video, Dr Olivier Le Polain, who had just returned from Liberia, describes the process and its problems.

Contacts are defined by the modes of transmission of Ebola. Individuals are classified as a contact if they have been in direct physical contact with an infected individual, their body fluids, clothes or bed linen, or shared eating or cooking utensils with them. In practice this usually means most contacts will be household members but there will also be some contacts in the community.

After a funeral there will be many contacts. Those who clean the body are at particularly high risk, but others attending the funeral are also contacts, particularly if they touch the body.

All patients or their relatives are asked to list possible contacts when they arrive at a treatment centre.

Contact tracing teams identify the contacts, follow them daily in their households for 21 days, ask about symptoms and give health promotion messages. The teams maintain a safe distance (2-3 metres away) to avoid getting infected themselves.

If a contact has symptoms that mirror symptoms of Ebola, a case investigation team is called. If they think the contact may have Ebola they are offered care in an Ebola Treatment Unit.

Problems include:

  • Patients may not want to name contacts or may give false addresses because of stigma
  • Addresses may be inaccurate or vague so untraceable
  • Contacts may not be found during the visits
  • Capacity – the number of contacts rapidly becomes very large when the epidemic is expanding, especially in urban areas where the number of contacts per person may be greater than in rural areas. At times capacity has been overwhelmed.
  • Supervision of contact tracers – this has been difficult given the scale of the contact tracing efforts, shortage of staff, challenges with health information systems and data flow.
  • Community acceptance – it is essential that communities understand the purpose of contact tracing. Community engagement is very important.

Consider the number of places you go and people you come into contact with even when you are feeling unwell. How difficult would it be to trace your contacts if you were infectious?

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This video is from the free online course:

Ebola in Context: Understanding Transmission, Response and Control

London School of Hygiene & Tropical Medicine