Connecting the Dots

There’s been some press about Methicillin Resistant Staph Aureus (MRSA) the last week that has caused some to question the role of pigs and pork in how this bug moves and affects people.  One article implied that since a strain found in some people in the UK was the same as a strain that has been found in pigs those people must have been infected by eating pork.

One thing that we’ve learned over many years of studying bacteria – how they move, how they adapt, how they infect, how they cause illness – is that rarely are things as clear as connecting dots.  Foodborne outbreaks of disease are one thing.  You can interview people that are sick and people that aren’t; find out what the sick people ate that the others didn’t; test the food that looks to be involved; and match that bug up with what you find in the sick people.  The dots are connected.  But when you investigate how bacteria move in a population it very often is not that clear at all.

This MRSA issue is a great example.  Apparently none of these three people in the UK had direct contact with pigs so the assumption was made that they were infected by eating pork.  But did they live with dogs, cats, or some other pet?  We know that MRSA has been found in dogs, cats, horses, pet birds, turtles, rabbits, and a variety of food animals like pigs, chickens, sheep and cattle.  And researchers in Germany and Austria have found the identical strain that came from the people in the UK in dogs and horses and other food animals.

I know that the Dutch have been studying MRSA for quite a few years.  Their food safety authority, the National Institue for Public Health and Environment, and the Dutch Animal Health Service don’t consider MRSA to be a food safety threat.

The Centers for Disease Control and Prevention (CDC), here in the U.S., sent a letter to Congress in response to a question from a U.S. Representative that said that there is no documented role for meat consumption or handling in MRSA transmission and that none of the investigations of community-associated MRSA infections in the United States has identified animal exposure as a risk factor for infection.  The CDC also says that the most commonly found strain of MRSA in pigs is not associated with community-associated MRSA infections in the United States,  such as those acquired at hospitals, gymnasiums, assisted living facilities, etc.

All this should give some reason to pause – but not a reason to stop.  We do need to know more about MRSA and how it acts and moves between people and animals, animals and people and people and people.  But in the mean time, I don’t think it makes sense to jump to conclusions when there are so many questions yet to be answered.

So, what is going on and what can be done right now?  Just because we don’t have all the answers doesn’t mean that we should sit and wait.  Farmers are working every day with their animals.  People have pets.  Everybody trades bacteria and viruses every day when passing money, greeting someone by shaking their hand, opening a door, riding in a cab or doing just about everything else that we do as a normal part of life.

MRSA seems to like to live in the nose, and it isn’t sexy, but general hygiene and frequently washing your hands is the place to start.  Even though MRSA probably isn’t a food borne issue, there are plenty of bacteria that are.  Wash your hands and cooking utensils after handling raw meat of any kind.  Cook your food to its proper temperature.  Put it in the refrigerator right away after the meal.  And heat it back up to at least 140 degrees before eating those leftovers.

For farmers working with pigs, there is a lot of research going on.  Dr. Tara Smith, at the University of Iowa found that in some pork production operations up to 70 percent of the animals carry MRSA.  And she also found that other farms didn’t have it at all.  We need to know why there’s a difference.  And we need to know if there is anything that can be done to keep the bug from passing between animals and people.

- Dr. Paul Sundberg