 Epidemics have been part of the human condition and of history and they have sometimes been very devastating. Historically speaking remember the plague which completely reshaped the economy of Europe and when a local outbreak becomes global and spreads all over the world we call it a pandemic. So what I'll do is to discuss four epidemics that are quite different and the first one is still active at the moment and has been in the headlines of the last year and that is an epidemic caused by virus named Zika. Now Zika was a virus that was accidentally discovered in Uganda. Zika is the name of a forest and it was discovered during research on yellow fever in 1947 and for years it was actually a virus looking for a disease. It was isolated now and then and you can see over time here between Nigeria case and then in Kenya and some cases in Pakistan but everything changed in 2014 when there were some serious outbreaks in the South Pacific. Clinically an infection with Zika for an adult particularly is not that bad. It's a bad flu with some rash and that's most of the cases are not more severe than that. But then about more than a year ago we saw the spread of Zika's wildfire in Brazil and then across Latin America at least the the warmer parts of Latin America, South America, the Caribbean and then with some cases about 210 indigenous cases in Florida or Miami and also in Texas at the border with Mexico. Zika is transmitted by a mosquito called Idus egypti. Now that's a mosquito that also can transmit other viruses. Yellow fever, we have a very effective vaccine but has caused some epidemic in Angola and in the Democratic Republic of Congo about a year ago, Shikungunya and Dengue. So this is a virus and an epidemic that is very much linked to climatic conditions also to poverty because in Latin America it's often people living in slums that you know we're affected because there's stagnant water that are breeding grounds for mosquitoes. This is not an abstract painting but it is the evolution of the temperature, the average temperature on earth and last year was the hottest year ever in history recorded and you can't see more or less the you know the continents but yellow is the hottest increase in temperature and red also abnormally warm temperatures and that means that epidemics like Zika but also Dengue, maybe yellow fever even Shikungunya will increase and will continue to come back because the mosquito will now invade territories where before it was too cold. Now Ebola is a completely different virus which was first isolated and found in northern Zaire, now Democratic Republic of Congo. I was part of the team that isolated the virus and also that investigated the epidemic, the first epidemic which was happening around a mission hospital in the rainforest where about 300 people died with a case fatality rate of 90% in other words 90% of people who became infected died and also that included 11 out of 17 hospital workers and that's going to be very typical for future epidemics. It is affecting in the first place the caregivers either in the family or you know in the hospital and the healthcare workers and that's a pattern that we've seen. Now what we found also is that you need really very close contact with contaminated body fluids so someone who's sick they're vomiting, bleeding, heavy diarrhea and or someone who has just died and the corpse is full of virus. Since 1976 there have been like 25 outbreaks of Ebola all in Central Africa, Congo, the two congos a bit in Uganda, South Sudan and so on but never really getting beyond that and the reason is that you needed such close contact and also that communication in these areas limited but here also everything changed at the end of 2013 when in Guinea in a place called Pekedu which is at the border with Liberia and Sierra Leone where these three countries come together that a child died of Ebola was in December 2013 and it took them three months to find out that this was Ebola first because nobody was looking for Ebola in an area of West Africa because the dogma was this is a Central African problem but also there's no laboratory infrastructure no public health system and countries coming out of civil war in the case of Liberia and Sierra Leone professionals have left the country the health systems are really at collapsed and the countries were really being reconstructed in a very positive way Guinea coming out of decades of corrupt dictatorship so we had a you know a perfect storm that made that the virus spread like wildfire it spread through three countries and what was new in contrast to previous epidemics is this was no longer an affair of rural areas small towns but capital cities were involved and slum areas and so on and the major reason that this became such a big epidemic is was the lack of action lack of action in first place because of ignorance we didn't know and then in the beginning it was only some local communities and Midsançon Frontier no doctors without borders they were active the local governments had no experience they know what to do and the international community led by WHO was inactive and took about five additional months between the initial diagnosis and the declaration that this was a problem in August that was precious time that we lost we have all these new epidemics have something in common that is that their so-called zoonosis that the the virus can live outside the human body in animals and is happy in West Africa we had an epidemic that caused 11,000 deaths out of 27,000 people died including 500 healthcare workers now you have to imagine that in Liberia for example in 2011 there were 51 registered physicians for a population of about 5 million people in Sierra Leone about double but for the populations with bigger so with all these deaths of nurses and doctors that made the situation much much worse than before in terms of human resources the country shut down schools commerce came to a halt agriculture and so on in the healthcare system also and and it is not impossible that more people died actually from treatable conditions women dying while giving birth children dying from malaria children because they were not in you know vaccinated against measles because the country came to a standstill and the health system collapse Ebola illustrates how a something that used to be a local outbreak when the right conditions are there can explode now putting that in a bigger context in the future what are the pressures that are promoting Ebola outbreaks and that is population pressure deforestation people getting more in contact with the potential virus reservoir and then of course also international travel we had cases in Spain in the UK there was someone in Norway and also of course in the US next we go to the biggest epidemic of modern times and that is HIV the first report on HIV was published in 1981 in June 1981 five gay men in California and in the meantime cumulatively about 70 million people 70 million people who have been infected all connected in somewhere another because they had sex with each other they share needles had a blood transfusion or their mother you know had HIV the data we're showing here start in 1990 so about nine years after the discovery of or the first report of AIDS and you see that in these nine years already the virus had spread all over the world every single country in the world has reported cases except North Korea the virus has really been spreading the worst way in Africa it's not that the whole of Africa is very badly affected some countries in West Africa have a lower HIV prevalence and some cities in Europe but when you look at southern Africa which has really become the epicenter of the epidemic you can see that the virus was spreading and spreading and then thanks to quite some aggressive programs the number of cases of new cases this is what it gives you is coming down similar situation in in East Africa however let's not forget that this is not over there are still two million new infections every year of HIV and when you're a young woman in South Africa in KwaZulu Natal your probability of becoming HIV positive today is between four to nine percent every single year in other words by 40 it's about 40 percent of women particularly women are infected in men it's a bit lower and when you take Asia for example the virus spreads non unexpectedly first in Thailand with its sex industry but then quite effective programs and brought it down to much lower levels and in India also major spread in the beginning but then a gradual decrease the biggest headache at the moment I would say in terms of the spread of HIV is perhaps very unexpected for most of you and that is it the former Soviet Union Ukraine has been known to have quite a serious epidemic driven by injecting drug use but it is in Russia where the number of new cases is continues to increase at about a good hundred thousand a year and that in a country with a declining population and that's a result of the absence of effective policies of bad policies not dealing with injecting drug use problem we have effective interventions but they're not being used this is a virus that again is a zoonosis the ancestor of the human immunodeficiency virus comes from chimpanzees the chimpanzee virus it illustrates that we can in modern times have a sexually transmitted infection that is spreading all over the world and that will continue don't believe anybody who tells you that the end is in sight it's not true as long as we don't have a vaccine I don't believe that we can stop and end this epidemic we've done a good job in some places and a bad job in others and we've really brought down new infections and mortality particularly has gone down in a big way but a big way still is so that 1.1 million people died from AIDS last year so that's another detail and it's still the major cause of death in sub-Saharan Africa now we've been very successful historically in bringing down infections thanks to antibiotics hygiene vaccines and vaccines are the best buy in public health there's a growing lack of confidence if not more resistance against vaccines overall the news is good less than 1% of people in the world would disagree with that but there are a number of countries particularly in Europe we take Italy and France and then also again the Russia and in China that are really not thinking that vaccines are that good for children and that's to a certain extent correlated with the belief that vaccines may not be safe again Europe in France more than 40% of people think that vaccines are not safe and we can see some in other countries as well this is ironic we have something that works very well that is actually safe has saved millions of lives and we know when vaccine coverage goes down that we have epidemics let's make sure that one of the best tools we have in public health we don't don't throw it away for reasons that are hard to understand and let me know end with an epidemic that is not caused by a microbe completely different but that's really a major major concern for the future and that's obesity and associated problems and in one generation the number of obese people has more than doubled in the world it is really spreading like an epidemic sometimes like an infectious diseases and when you look at the world it is the South Pacific that has the highest prevalence of obesity with over 50% of adults being heavily obese followed by the Gulf so the Arabia and the Gulf States where it's about 40% and then we have of course also in high income countries where obesity continues to you know to grow about every year however it's no longer just a problem of high income countries or of rich people as it used to be in high income countries it's often people who are you know of the poor socioeconomic strata but we see when we take a country like South Africa today the proportion of women who are obese is the same as we find in the United States and that in spite of a major HIV epidemic that's going on at the same time and then when we take India we have still 200 million people who are underweight and there's a lot of stunting and so on but we also have already about 30 million people who are overweight that's also a challenge in terms of policy what do you do with that and this is a result of as we all know urbanization changing lifestyle lack of exercise and so on and and it's going to be far more complex to deal with this type of epidemic obesity than with infectious diseases because it's not going to be a simple solution this is where behavior economics this is where all kinds of interventions should come all together it is totally unpredictable what will come and that which epidemic will be next and also there will be new epidemics that we then never heard of think of HIV which came out of the blue and in California they talk about the big one the big one is an earthquake which will come tomorrow or a hundred years from now or not silicon and the value will be wiped out one day and in our field the big one will be probably an influenza epidemic like the Spanish flu which killed about 50 million people after World War one more than in the in the whole of the you know the war and one day this will happen and we must make sure we are ready for that