Good morning, my name is Professor Ib Bygbjerg. I'm going to talk about infectious diseases and how are they impacting global health, how have them been impacting them over the last two centuries and over the last two decades. So let us start with the good old days. Before, in the 19th century, most people didn't live long, maybe 40, 50 years, and the children were those who were dying. Many of them, up to 500 per 1,000 live-born died before the age of five. You wouldn't imagine that the world's highest mortality ever recorded was in New York City in 1902, and New York was also the place where you had the most children born per couple. And why did they die? Well, they died from infectious diseases, and we call them children's diseases, but they were often combined with malnutrition. What about the adults and the adolescents? Well, infectious diseases also took their toll. In Europe, in the 19th century, about five out of, or 5 to 10 percent died from tuberculosis. What about the tropics? They had TB as well, but they also had tropical malaria and a lot of other diseases that are transmitted by vectors, so-called vector-borne diseases. Malaria alone killed about 10 to 20 percent of those who didn't manage to get immunity to malaria. Again, children and people who were not immune, from abroad. What about the women? Well, there was a risk abuse to give birth in these days, not only because of bleeding and other obstetric complications, but women also died from childbed fever or puerperal sepsis. One example is the Royal Hospital in Copenhagen, Denmark where in the worst years, 50 percent of all women died in childbirth. Why did they die? Because of streptococcus septicemia. And who transmitted it? Well, it was unfortunately the doctors and the midwives. How did it happen? Well, nobody knew that they should wash their hands, so the antiseptic procedures that was only introduced in the mid of the 19th century by Semmelweis and Lister were unknown. So, we had to discover the microbes also, and before discovering them, you could still do something that was reducing the transmission. You would wash your hands, you would have proper sanitation and drinking water even without knowing the causes of cholera and puerperal sepsis. So the first bacterium was only identified, most people think it was Robert Koch who discovered the tuberculosis bacillus in 1882 or the cholera Vibrio in 1883, but it was actually a Norwegian who discovered the first one, and that was the microbe causing leprosy, Armauer Hansen. So, here we are seeing a picture of the fathers of anti-infective tools. We have Semmelweis who started the disinfection to avoid childbed fever. And here is a picture showing what it looked like at the Royal Hospital when they had discovered that it pays off to wash your hands. So now there was even a hand wash in the hospital. You can see from this slide that it's installed, so it must have been after Semmelweis. After the discovery of the microbes, we began to discover how to combat them not only by disinfection and hygiene, but also by attacking them. And one of the first developments was development of an antitoxin derived from a horse that was injected with the microbe, and then he will withdraw the serum and inject it into someone you want to protect from the microbe, so the so-called antitoxin. Émile Roux from France, he found out that this could be working against diphtheria a very frightened disease on children. And then later on, Emil von Behring from Germany discovered that he could even produce a vaccine and combining the two. With these two tools, we should of course expect we could now combat diphtheria and similar diseases. So, let us see the graph here and see whether it was the effect of the antitoxin and the vaccine or whether it could be something else. So, here is a graph showing the time relation between intervention and antitoxin diphtheria vaccine in the United States and the effect on mortality. And we would see that irrespective of this, there was already a decline. If we look into another disease like whooping cough, it has been declining already for decades, and it was only the last two decades or so where the vaccine had a real impact. So we may ask ourselves, are these vaccines the only way to combat infections? And on the next slide, we can also see what it looks like in England and Wales where they were looking into, more specifically, the vaccine against pertussis. We will see there was a very high death rate up to 1950, but it was actually only in 1951 that the vaccine was introduced, so something must have happened in between. We will come back to that. Now there's the question burning. Is there, then, a clear-cut correlation between the introduction of antitoxin and vaccines against common child infections and the declining mortality rates? And if that's not the case, what else? And the answer is not that clear-cut even if we would like to, as medical persons, to say we did it, but it was actually the socio-economic conditions that were improved, better housing, nutrition, etc. Having said this, we should admit that in the last few decades, there has been a major success in combating child diseases also in developing countries, which shouldn't be forgotten. We'll come back to that when we discuss about developing countries, Millennium Development Goals, etc. Let's have another example where there is a clear-cut correlation between medical intervention and the impact. Here is one example where you can look into the correlation between the advent of the highly antiretroviral treatment and the death from AIDS. And you will see from 1995, there is a drop dramatic from the death rate at least in parts of the world, but you will also see that the number of HIV cases are getting up because now they don't die. So the cumulative rate of HIV is going up, but the deaths from AIDS is going down. So we can modify infectious diseases a lot, but we shouldn't forget that prevention as well as treatment should go hand in hand. Let's go to the tropics, the so-called neglected diseases. There are at least 25 neglected diseases of the world, but let us take two examples, one from Latin America, which is a very old disease. It's named Chagas disease, and it is transmitted by some nasty creatures called bloodsucking kissing bugs that'll bite you at night in your humble hut. And up to 100 million people are suffering from this chronic disease which in the end would kill them by destroying their heart and internal organs. Now we are down to less than 10 million cases. And again, the question comes up, why is it going down? Is because of new antimicrobials, a new effective vaccine, or something else? Well, the answer is, we don't have any effective treatment for Chagas disease, and we don't have any vaccines either. So, why did it disappear? Because of better socio-economic conditions, improved housing, cement, a sack of cement will do the job, electricity, which would scare away the kissing bugs, and then of course also spraying with insecticide the walls of the house. So it's a success story. Let's take a less successful story about a similar disease, now an African disease named the sleeping sickness. I'll show you the two transmitters of the disease called South American Trypanosomiasis and African Trypanosomiasis. It's the same kind of microbes, but the transmission is totally different and therefore, the way to combat them is also different. Taking the Latin American or South American first, here we have the nasty little creatures transmitting the parasite. They are the so-called kissing bugs. They come out at night from the crevices of the hut. They'll bite you primarily around the eye and then they will go back and hide, but the parasites are now in you. When it comes to African sleeping sickness, it is something you attain on the savannah. There'll be a tsetse fly following you. It will bite you. Sometimes, they can bite through your clothes and then you will get a nasty boil where the Trypanosomes are injected, and then you'll get African Trypanosomiasis. So we have two question. How do we control Latin American Trypanosomiasis? How do we control African Trypanosomiasis? Well, they're not transmitted by the same vectors. The one is living in mud huts with lack of electricity, so give a sack of cement and electricity and the disease is under control largely. You could also add spraying. Why are we not spraying against African Trypanosomiasis? Because the tsetse flies are in the savannah. You can't spray every tree on the savannah. The reservoir of the parasites are in the game animal. You can't kill even the very popular antelopes and the lions in the savannah. So, we have remedies for African Trypanosomiasis, but some of them are 5000 years old and pretty toxic, and that's why we still call them neglected disease.
