Chapter 4 Hazards from Emerging Pathogens By Dr. Nimal Pathiraja在线视频

Chapter 4 Hazards from emerging pathogens by Nimal

Welcome to this lecture. This lecture is all about food hazards from emerging pathogens. We are going to look at very briefly what are emerging pathogens? What actions can be taken to stop risks off to food from emerging pathogens?

Before we move for what are emerging pathogens? Emerging pathogens, if we want to give a definition. What does it mean? Emerging, or in some cases re-emerging, food-borne problems are commonly considered to be those problems that have recently appeared in a population; have extended to new vehicles of transmission; have started to increase rapidly, in incidence or geographic range; have various causes (ecological, environmental, food production or demographic factors); and have been widespread for many years but only recently identified because of new or increased knowledge or methods of identification and analysis of the disease agent.

If we want to simply find what it means, go back to 50 years ago, we did not have mad cow disease in cows and the mad-cow disease in human. Same way, if we go back to 50 years ago, we did not have Escherichia coli O157 as human disease after eating meat or whatever. Same way, Campylobacter was not a problem in the major scales 50 years ago. And bird flu was not there 50 years ago. It is coming from manure. This is why new emerging pathogens, but these pathogens are coming to us not only from the environment, but also from the food. This is why we are interested about this one. They can be newly-discovered, linked for the first time to disease in humans or to a particular food. A pathogen may also be defined as emerging when significant new strains emerge from an existing pathogen, or if the incidence of a pathogen increases dramatically. Good example, we know that certainly Escherichia strains have caused certain food poisoning in the past, but EHECO157:H7 was not there 50 years ago. This is why EHECO157:H7 is an emerging pathogen.

So what factors affect their emergence, there are many factors affect emergence. Changing in the pathogens. Changing the gene type. And the therapeutic use of an antimicrobial agent. Antimicrobial agent are using in human population and animal population for animal production. This changes the restrain and therefore we have new pathogen. Economic can take developments because of the new method of production, intensive production, we have new virus, new bacteria family. And then finally the poverty and pollution, dietary habits, as you know, we try to eat more raw food compare with 50 years ago. Sashimi, sushi and various other things are good examples. Travel, traveling is very common and migration. Trade of animals and animal food trade is one of the most important food trading in the world, globalization. And new food vehicles of transmission are some of the examples.

We have already said that Escherichia coli O157 are one of the severest problems. It can take human live. It was not there, but it is now referred as to as Enterohaemorrhagic E. coli. This is very serious problem. And they also form certain toxin. And this toxin can cause serious problem. Now cattle are unfortunately appeared to harbor them without any problem. But it can come to us in our meat, milk, and various products are contaminated. It is a major cause of bloody or non diarrhea and often leads to long-term complications such as haemolytic uraemic syndrome.

And there are many times of Enteroaggregative E.coli. And there are increasingly found in many countries and then they also caused watery diarrhea and mucoid diarrhea especially in chicken and lastly in human. So this is a new strain. Because they are coming. They are simply because they are using antibody or product system so differently. This is why we are getting them. It is particularly associated with persistent diarrhea for more than 14 days. These are coming more and more common in the world today.

Listeria monocytogenese. Listeria monocytogenese has been there for long long time. But it has not being a problem with food only for the last 20 to 30 years. It can come to us from much food dietary and from consignment such as cheeses and meat products and so on. But it can survive in certain people like pregnant ladies, children and elderly people. And it is becoming a very serious problem in the world today.

And one another problem is that multidrug-resistant Salmonella typhimurium DT 104. Most of the Salmonella that can cause disease in human are resistant to antibiotics. When the patient goes to the doctors, when they get antibiotics, they don’t response to them. Because they are resistant to antibiotics. This is the same thing. Salmonella enteritidis also come to us from eggs and poultry meat and so on. This is one of the problem again when the complication happen. They cannot be treated. Because they are resistant to many antibiotics. It is the same thing to Campylobacter. Campylobacter is a very tracing disease, but when the complication happens, we have to treat them with antibiotics. But the antibiotics that are normally given for this kind of bacterial infections are now none working because they are now resistant to immune system. So this is a main-made problem. We have to do something about this.

Vibrio vulnificus. It is common problems that is found when there are lots of raw molluscs， shellfish. But when it comes, most of the cases, the people have very serious complications and they died. But what does it mean that if we go back to 20 -25 years ago, this problem is not there. This is why we have identified it as emerging pathogen. Individuals most susceptible to infection with this agent include those with chronic liver disease or chronic alcoholism, or those who are immune compromise. But on the other hand, why we call it emerging? Why we are interested about it? Because they were not there before.

We are at beginning of this lecture we talk about the prions, the mad cow disease. It is something new which was just appeared from the last fifty years though. It is coming from a very small part of DNA. Originally it was found in the United Kingdom. Now it is under control. But it still being does lots of control. Why we are concerned so much about it. Once we get it, it is really difficult to get it out of population. This is why many international organizations are worried about it. This is why many countries are taking lots of actions when they are importing meats from other countries.

SARS is a viral respiratory disease, which happening in this part of the world, particularly started in Hong Kong. And then it spread to much other country between 2002 and 2003. There were about more than 8000 cases and 700 deaths. So why this? This are new things which are emerging, now within a week SARS wear infected to many countries, to 37 countries but the important thing is that food can also be associated with this kind of disease.

And then the one of the thing that we are coming in the modern, in the last five years, is what we know the MERS. MERS is a viral respiratory illness that is coming from camels and camel’s milk, as you know, camel’s yogurt and camel’s meat is very popular in Middle East. Now they are very very careful note to it. And simply because MERS can be transfer into human by eating camel meat, camel milk and camel yogurt. There will influence another one camel, so there are many diseases. MERS is arriving that is new to human. It was first reported in Saudi Arabia in 2012 and has since spread to several other countries, including the United States. Most people infected with MERS-CoV developed severe acute respiratory illness, including fever, cough, shortness of breath and many people died. So that is why scientists are very very worried about it. You see some camel milk, camel yogurt are very popular in Middle East country. Now people are very worried about drinking camel milk.

Hepatitis E virus is another problem. Hepatitis E virus disease has been there for long time, but it is self-limiting. But now what is happening because of the news that it is emerging happen and they will learn that this one it is coming to many parts of the world. It remains endemic in pigs in many parts of the Far East and Africa. And it is also common in some part of Southeast Asia. In some countries, around 80-85% of pigs carry the virus.

However, in some countries there has been an increase in the number of human cases not related to travel to endemic countries. Simply because this is now virus is getting more and more virulent. Because there are various reasons. It can also come to us from shellfish and various other sources. So the hepatitis E virus is a serious problem emerging, from emerging disease. There are different gene types. Original one is different from the one that found in the modern world. Simple because they are changing because of several reasons. So what we can do, answers are very simple. Pig liver should be cooked well, including the deeper areas. But unfortunately, when we eat the part of areas, for example, when we eat hot pot, when we put the pig liver into it, but in the hot pot, the liver may not be fully cooked. So it is likely cooked, and it is very likely that we have hepatitis E.

So how to control emerging pathogens. The key method is that understand the characteristics of the pathogens. This is why scientists are coming in understanding the epidemiology. And use risk assessment with available data. Use science-based methods to control the hazards such as Hazard Analysis and Critical Control Point. So basic point that we are trying to do is that because the globalization, changing in the production methods, using of antibodies and so on. New pathogen are emerging, that they are called emerging pathogens. And we should be careful about them. Because if you are not careful, populations can be infected with this new bacteria and viruses.

Thank you very much.