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Disease outbreaks today

Disease outbreaks are caused by different pathogens with different transmission pathways. Watch Jimmy Whitworth and Zabulon Yoti explain this more.
SPEAKER: In this step, I will give an overview of the situation today with disease outbreaks. Despite all the medical and technological progress we have made in recent years, outbreaks of infectious disease are still with us. They can occur anywhere and at any time. We do know that some parts of the world are at more risk of outbreaks. But while we can only anticipate to a limited extent where and when an outbreak may occur, we can certainly make sure that we are prepared for an outbreak whenever one does occur. This map shows all recent outbreaks. And you can see that they occur all over the world. No one is safe from the threat of an outbreak.
However, we do know that this risk is not equal. For example, countries in the tropics are at more risk of vector borne diseases such as dengue, chikungunya, and Zika because these are the places where mosquitoes and other insect vectors thrive.
Countries in Southeast Asia are at higher risk of zoonotic disease shared with livestock because of common backyard farming practices, especially the keeping of chickens and pigs. Countries with weak health systems and those that are fragile or conflict-affected states are at risk of the effects of outbreaks because of a lack of preparedness and ability to prevent or respond to outbreaks. We can predict outbreaks of some infectious diseases– for example, Lassa fever, which occurs seasonally in countries in West Africa in most years due to the increased presence of the Mastomys rat vector in houses. Rift Valley fever affects both livestock and humans.
Outbreaks in humans usually follow a few weeks after an outbreak in livestock, which in turn usually follows increases in mosquito populations after heavy rains and flooding. Outbreaks of cholera can be anticipated in parts of Africa where they regularly occur during the rainy season.
So we can be prepared to respond to outbreaks. This includes good surveillance systems so that we can detect clusters of disease and then respond rapidly to prevent an outbreak from spreading. This outbreak preparedness and response relies on effective front-line reporting in communities. It also needs plans that have been drawn up and resources that are in place to enable an effective response to an outbreak that has occurred. This slide shows a recent map of ongoing outbreak threats around the world. You can see there are threats everywhere, but particularly in tropical regions, and especially in Africa. The WHO regional office for Africa in Brazzaville produces a weekly bulletin about outbreaks and other emergencies.
In any one week, they are typically following between 30 to 50 outbreaks on the continent. Altogether in 2017, WHO supported over 150 substantial public health events in Africa, of which 80% were disease outbreaks. In order to plan for responding to outbreaks, it is helpful to categorise diseases with shared characteristics. For prevention purposes, the source of the outbreak is most useful. And we can use categories such as zoonoses from wild animals, zoonoses from livestock, vector borne diseases, adapted organisms such as those with antimocrobial resistance, and vaccine preventable diseases. For control purposes, the mode of transmission is most useful. And we can use categories such as respiratory spread, close contact, food or water borne diseases, vector borne, or sexually transmitted infections.
Some of the commonest causes of outbreaks are microbial adaptation and change, such as antimicrobial resistance. Ecological changes, such as dams causing flooding in surrounding areas. Changes in land use and development, such as people encroaching into forests for farming who may come into closer contact with wildlife. Climate change, which can affect the distribution of insect vectors.
International travel and trade will increase the movement of people, often by plane, and also the movement of livestock. The increase in human population is leading to more urbanisation, with crowding, poverty, and malnutrition. Human behaviour may increase risks, such as traditional funeral practices or risky sex. The breakdown of public health services and humanitarian crises and conflict can all drive epidemics. All of these various drivers can be categorised as ecological, biological, or behavioural.
The main way of providing health security to populations is through the International Health Regulations. These describe an obligation for all authorities to develop, strengthen, and maintain core public health capacities for surveillance and response to outbreaks. This includes the ability to detect, assess, notify, and report events and to respond to any public health emergency of international concern. The Joint External Evaluation Tool provides a monitoring and evaluation process to ensure that countries are complying with the International Health Regulations. This includes key compliance indicators; scorecards to identify areas for improvement; and continuous reassessment. The Joint External Evaluation aims to improve and ensure continued International Health Regulation compliance.
The International Health Regulations are a legally binding global health security framework agreed to by all 196 WHO member states. This global health security framework aims to prevent, protect against, and provide a public health response to all public health threats. The International Health Regulations will be discussed in more detail later this week in the step on the global architecture around epidemic preparedness and response. This map shows the state of preparedness of countries around the world. As you can see, the countries least prepared are also those most at risk, especially in Africa, parts of Asia, and in South and Central America. At global level, we have built up substantial epidemic intelligence to help us know when something is starting up.
These include networks like ProMED and GOARN or the scanning responses of GPHIN, the Global Public Health Network. This takes news and information from many sources, processes the information, assesses it, and, if necessary, turns it into alert notifications. But the rate-limiting step in preventing the spread of infectious diseases is the response at the front line in communities and health care workers in countries at risk. For this to be effective, there needs to be mutual trust, engagement, investment between the health authorities and the community, with good understanding of the local context. Large outbreaks often occur in places with inadequate human resources. Before the West Africa Ebola outbreak, Guinea, Sierra Leone, and Liberia had among the lowest health worker coverage in the world.
So we need to ensure that we have well-trained health care workers; the supplies necessary to prevent and respond to outbreaks; to have preparedness planning and national action plans; and we need participation from the community right through to the national authorities. All of this requires national commitment and often external international support. This support can come through WHO’s Global Outbreak and Response Network or through regional networks, such as those being developed by Africa CDC, or by external rapid response teams - for example, those from the USA, China, France, Germany, and the UK. And encouragingly, the concept of national Rapid Response Teams is taking off in at-risk countries, such as Nigeria, DRC, Sudan, South Africa, and Indonesia.
Research helps us to develop new, improved tools for responding to outbreaks. And if these are implemented, we can measure the outcomes and their impact through further research. This helps us to achieve WHO’s general programme of work to keep the world safe, reach the vulnerable, and to promote health. We will explore research in more detail next week in the course. Interventions for use in outbreaks can often only be fully evaluated during outbreaks when there were cases of the disease. There is an increasing recognition of the importance of research as a key outbreak response component. The WHO R&D Blueprint for Action to Prevent Epidemics encourages research during responses.
Recent examples include a new Ebola vaccine which was evaluated during the West Africa outbreak and has been used in subsequent outbreaks in DRC. There is now an ethical framework for the Monitored Emergency Use of Unregistered and Investigational Interventions so that new drugs can be tested safely during outbreaks. Real-time pathogen sequencing has moved from being a research tool to being an integral part of an outbreak response. And faster, more accurate diagnostic tests have been researched and become part of routine response to an outbreak.
The big challenges we have today for responding to outbreaks are the extra demand on already weak health systems, which causes late detection of an outbreak. Poor infection prevention and control measures, often leading to transmission in health care facilities, such as hospitals and clinics. Outbreaks often occur in areas affected by conflict. The insecurity, limited access, and breakdown in health systems all prevent effective outbreak response.
The limited investment in research and in documenting and learning from previous outbreaks prevents us from improving our response to future outbreaks. So what can be done for the future? We need to strengthen national health systems and global health leadership. We need to ensure good coordination of stakeholders and good adherence to the International Health Regulations. We also need to be sure that we are prepared for future crises with adequate human and financial resources. There are good examples of best practice that we can build on. Collaborations– North-South and increasingly South-South, such as CARPHA, the Caribbean Public Health Agency. Global collaborations, such as GOARN and EDPLN.
Regional initiatives, such as the West Africa Health Organisation. And stimulus to research, such as with the WHO R&D Blueprint.
To conclude, there is much that needs to be done to keep the world safe from outbreaks, to serve the vulnerable, and to promote health. No single country or organisation can do it alone, so strong partnerships are essential for our future health security.

In the previous step, you learned about the history of outbreaks globally and their impact. In this step, Jimmy Whitworth (LSHTM) and Zabulon Yoti (World Health Organization) explain the drivers of outbreaks today, including how to categorize them based on their source or how they are transmitted. This step also introduces how research can be included as a component of outbreak response and some of the challenges associated with outbreak response and preparedness.

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Disease Outbreaks in Low and Middle Income Countries

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