Outbreaks and humanitarian crises

FRANCESCO CHECCHI: I’m going to be talking about the specific features of epidemic prevention and detection and control in populations affected by crises. When we talk about crisis, we are referring specifically to instances of armed conflict, natural disaster, mass displacement, food insecurity, and/or collapse of state functions, keeping in mind that these conditions often occur the same time. At any point, we estimate that about 300 to 500 million people are affected by any of these conditions.

So it’s well known that epidemics occur more frequently and with greater severity in these kinds of crisis settings than in comparable stable situations. But it’s worth understanding why that is particularly and why it is, for example, that in situations of acute food insecurity or mass displacement, epidemic threats, such as measles and cholera, are almost ubiquitous. And really there are two dimensions that explain this increased frequency and severity.

So the first dimension is really the extent to which crises increase the transmission of infectious diseases. There are a variety of risk factors that explain this. These include overcrowding, the fact that acute malnutrition tends to increase in crisis settings, the inadequacy of water and sanitation, the fact that populations often displace to camps with having not received routine vaccination or indeed the fact that health services on reception are sometimes altogether absent. And it’s also important to point out that these risk factors really rarely occur in isolation.

They tend to occur at the same time, and they are very much multiplicative, meaning that their net effect is all the more greater when one or more are present at the same time, and this also explains why we are particularly concerned with outbreaks from the very first few days of people moving into overcrowded, unplanned camps. The second dimension to worry about is severity, or how lethal an epidemic-prone diseases are. It’s a quantity that we refer to as a case fatality ratio. And this quantity, again, tends to increase in crises as a result of a number of factors. First and foremost, once again, the increase in prevalence of acute malnutrition.

There are, however, a number of other risk factors at play as well. So taken together, considering transmission and severity, what we can see is some theoretical reasons why epidemics tend to be more frequent and severe in crisis settings. However, another key difference in crisis settings has to do with who is actually there and usually involved in responding to epidemics. Because these settings feature usually very disrupted or sometimes altogether absent health services, a variety of humanitarian actors step in to provide those health services.

And these include United Nations agencies, such as UNICEF and the WHO, but also a number of INGOs, international NGOs, including Medecins Sans Frontieres, who has a long track record of responding to epidemics, Save the Children, International Rescue Committee, as well as a number increasingly of a local NGOs. The humanitarian response is coordinated through the so-called “Cluster Approach”. It’s a system whereby different sectors of humanitarian action, including health, nutrition, and water and sanitation, are grouped into coordination mechanisms. This is important because unlike stable settings, the response to an epidemic, particularly when one forms an outbreak response team, really needs to consider and engage with these coordination mechanisms. It needs to occur through them, rather than in parallel to them.

In the interest of time, I’m going to mainly focus on four key pillars. The first of these is risk assessment and preparedness. When we talk about risk assessment, we really refer to an analysis of the setting, the key risk factors, the epidemiological profile, in order to actually identify the priority epidemic-prone threats that one needs to worry about.

In terms of preparedness, what we mean is really having a plan, a plan that is widely shared, understood, with clear roles and responsibilities, whereby humanitarian actors can jump into action from day 1 in the event of an epidemic, and that also must include aspects such as the pre-selection of staff to jump into a response, as well as prepositioning standby stocks and supplies of drugs, vaccines, and infrastructure to set up interventions from the start. The second pillar is a set of key preventive interventions that must absolutely not be neglected and must be put into place early on to have the intended effect.

I think here it’s worth mentioning mass vaccination, as well as water and sanitation measures, such as chlorination of water containers and soap distribution. For example, the response to the diphtheria outbreak that occurred among Rohingya refugees in Bangladesh last year has cost many, many millions of dollars and really taken up a lot of precious resources. One could have arguably prevented all of that and also saved lives by vaccinating refugees on arrival with diphtheria, pertussis and tetanus vaccine.

On the other hand, it’s also important to note that interventions, such as a mass vaccination in crisis settings, particularly in overcrowded camps, really need to achieve very high coverage, something like 100% for measles, for example, in order to actually protect populations through what’s known as herd immunity. The third pillar is timely, predictable epidemic alert and response. This basically involves reinforcing or setting up a surveillance system from the very earliest time point of a crisis. One very efficient way of doing so is known as event-based surveillance, whereby humanitarian actors and frontline health workers are trained to immediately report suspected cases or clusters of cases through phone means or social media messaging, toll-free lines and the like.

Event-based surveillance also leverages personal networks and picks up media information as well as community rumours going around of potential outbreaks. The other thing to say about epidemic alert and response is that it’s not just about generating data. It has to include systematic and timely verification, investigation and initial containment of the first clusters of cases. While all of this is eminently doable, in practise, unfortunately, what we often see is delays upon delays upon delays at every single step of the epidemic detection and response process that I’ve just outlined, as we’ve tried to show a few years ago in this systematic review. The last pillar I’d like to talk about is prevention and treatment of acute malnutrition.

This can take a variety of forms, depending on the prevalence of malnutrition on site, ranging from managing severe cases among children to generalised food distributions. I can’t think of a single nutritional emergency I’ve worked in or heard about in which we actually haven’t seen cases of cholera, measles, whooping cough or similar diseases, and this has to do with the fact that, as we saw earlier, transmission of these diseases is greatly enhanced when people are malnourished, and we also saw that the outcomes of, clinical outcomes, of these diseases tend to be a lot worse among children and pregnant women in particular when these people are malnourished. Similarly, many vaccines are less successful in inducing immunity in malnourished people.

So for all the reasons outlined, preventing, controlling acute malnutrition really has to be regarded, in humanitarian settings in particular, as a key pillar of epidemic control.