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 they 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 1000 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 called 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% 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
vector, so called vector borne diseases. Malaria alone killed about 10 to 20% of those
who didn't manage to get immunity to malaria. Again, children and people were not immune
from abroad. What about the women? Well, that was a risky
business 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% of all women died in childbirth.
Why did they die? Because of streptococcal 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 could 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 anti-toxin derived from a horse that was injected with a microbe and then you withdraw
the serum, and inject it into someone you want to protect from the microbe.
So a so-called anti toxin. Emile Roux, from France, he found out that
this could be working against diphtheria, a very frightening disease of 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 a 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 anti toxin diphtheria vaccine in the United States and the effect
on mortality. We will 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'll come back to that.
Now there's the question burning "is there then a clear-cut correlation between the introduction
of anti-toxins and vaccines against common child infections and the declining mortality
rate?" 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 et cetera.
Let's have another example where there's a clear cut correlation between American invention
and the impact. Here is one example where you can look into
the correlation between the advent of the highly anti-retroviral treatment and the deaths
from AIDS. And you'll see, from 1995, there's 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 is 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 in 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 blood-sucking kissing bugs.
They will bite you at night in your humble hut and up to a 100 million people were 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 ten million cases.
And again, the question comes up, why is it going down? Is it because of new anti microbials?
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 insecticides,
the walls in the house. So it's a success story.
Let's take a less successful story about a similar disease, an African disease, namely
sleeping sickness. I'll show you the two transmitters of a 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'll 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 Savanna. Might be a tsetse fly following you.
It will bite you. Sometimes they can bite through your clothes.
And then you'll get a nasty boil, where the trypanosomes are injected, and then you'll
get African trypanosomiasis. So we have two questions.
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.
Lastly, you could also add spraying. Why are we not spraying against African trypanosomiasis?
Because the tsetse flies are in the savanna. You can't spray every tree on the savanna.
The reservoir of the parasites are in the game animal.
You can't kill even the very popular antelopesand the lions in the savanna.
So we have remedies for African trypanosomiasis. But some of them are 50, 100 years old and
pretty toxic, and that's why we still call them a neglected disease.