Worried About Infectious Diseases? Expect the Familiar

How concerned do Americans need to be about contracting serious infectious diseases? With ongoing reports about diseases like anthrax and avian influenza ("bird flu"), many of us have begun to ask about our risk factors for acquiring something new and truly gruesome.

For years, medical communities in developed countries have been able to focus on chronic disease because infectious disease rates had declined sharply due to vaccines, medications, and public health measures protecting food and water. But as airplane travel became increasingly common, the world - and its diseases - became more interconnected.

Infections don't pay attention to borders, and "exotic" diseases such as West Nile Virus are on the rise is places we never would have expected them. Still, most of us who live in highly developed countries and only travel to typical tourist destinations don't have a great chance of acquiring diseases such as dengue or typhoid fever.

In reality, most of us have a much greater risk from the infectious illnesses we're already familiar with.

Common Infections a More Likely Threat
The real threats are the ones we forget to think about - those familiar, widespread bacteria and viruses that invade our homes and healthcare facilities, or sneak up on us during our normal rounds of work and school. "Many infectious diseases are highly preventable, often with a vaccine or simple sanitary measures," says Medical College of Wisconsin Assistant Professor Rick Gillis, MD. With a bit of knowledge and some common sense you can go a long way toward preventing them.

Food- and Water-Borne Infections
By some estimates, contaminated food sickens 76 million Americans every year. The most commonly recognized food-borne infections are those caused by Campylobacter, Salmonella, E. coli and the Noroviruses.

Campylobacter causes fever, diarrhea, and abdominal cramps. It is the most commonly identified bacterial cause of diarrheal illness in the world. The bacteria live in the intestines of healthy birds, and most raw poultry meat has Campylobacter on it. Eating undercooked chicken (or food that has been contaminated with juices from raw chicken) is the most frequent source of Campylobacter infection.

Salmonella bacterium is widespread in the intestines of birds, reptiles and mammals. The illness it causes, salmonellosis, typically includes fever, diarrhea and abdominal cramps. In people with poor underlying health or weakened immune systems, it can invade the bloodstream and cause life-threatening infections.

Salmonella can be spread to humans in a variety of foods, usually of animal origin. The most recent Salmonella outbreak, though, originated in produce.

E. coli O157:H7 commonly exists in cattle and similar animals. Human become ill after consuming food or water that has been contaminated with microscopic amounts of cow feces. The illness it causes is often a severe and bloody diarrhea and painful abdominal cramps, often without fever. In 3% to 5% of cases, a complication called hemolytic uremic syndrome (HUS) can occur several weeks after the initial symptoms. This severe complication includes temporary anemia, profuse bleeding, and kidney failure.

For more information, see Avoiding E. Coli Infection.

Noroviruses (sometimes called calciviruses or Norwalk-like viruses) are an extremely common cause of food-borne illness, though they are rarely diagnosed, because the laboratory test is not widely available. It causes sudden gastrointestinal illness, usually with more vomiting than diarrhea, which resolves within two days. Unlike many food-borne pathogens with animal reservoirs, Norwalk-like viruses are thought to spread primarily from one infected person to another. For instance, infected kitchen workers can contaminate food as they prepare it if they have the virus on their hands. Infected fishermen have contaminated oysters as they harvested them.

Careless food handling and improper cooking often set the stage for the growth of disease-causing organisms, notes Dr. Gillis. The key to preventing most cases of these illnesses is very basic: washing your hands, cutlery and counters during preparation, and cooking food well, will help you avoid transmission.

Influenza
Every year about 36,000 Americans die due to complications from the flu. More than 200,000 people are hospitalized from flu complications; 20,000 of them are children younger than 5 years old.

Most flu deaths, as well as a vast number of common flu cases, could be avoided by one simple step, Dr. Gillis says: vaccination. Getting a vaccine is especially important for people at high risk for serious flu complications, including young children, pregnant women, people with chronic health conditions like asthma, diabetes or heart or lung disease, and people 65 and older. People who live with or care for those at high risk should also get a flu vaccine to protect their high-risk contact.

For more information, see To Prevent the Flu, Schedule Vaccine Now.

Hospital-Acquired Infections
The US Centers for Disease Control and Prevention (CDC) estimates that each year up to 2 million patients in the United States acquire an infection in the hospital, and nearly 100,000 of these patients die as a result.

Hospital infections continue to thrive due to multiple factors including the increasing number of older patients, patients with chronic diseases and those with weakened immune systems, in addition to a growing number of invasive procedures. People in long-term care, patients who undergo multiple procedures, and those who are severely ill are at higher risk for hospital-acquired infection, notes Dr. Gillis.

The CDC reports that many hospital-acquired infections are caused by improper handwashing by staff and patients; the organization publishes free hand hygiene guidelines for health care workers, including information on the use of alcohol-based rubs.

Also at issue in healthcare settings are staph infections, which can cause serious problems such as surgical wound infections and pneumonia. "In the past, most serious staph infections were treated with common antibiotics like methicillin," explains Dr. Gillis. "But treatment has become more difficult because staph bacteria have become resistant to various antibiotics, including the commonly used ones related to penicillin." These resistant bacteria are called methicillin-resistant Staphylococcus aureus, or MRSA.

For more information, see MRSA Infections on the Rise, But Treatable If Caught Early and In the Hospital: Who Are All Those People?.

STDs
The incidence of HIV/AIDS and other sexually-transmitted diseases varies widely around the world, with more cases typically seen among populations with less access to health care and to education about preventive measures. But even in countries like the US, where information (and condoms) are widely available, STDs take a huge toll on public health.

A 2008 CDC study estimates that one in four (26 percent) young women between the ages of 14 and 19 in the United States - or 3.2 million teenage girls - is infected with at least one of the most common sexually transmitted diseases: human papillomavirus (HPV), chlamydia, herpes simplex virus, and trichomoniasis.

"There are 19 million new STD cases every year, almost half of them among young people ages 15 to 24. These statistics point to an increasing need for patient education, especially for adolescents," Dr. Gillis says.

For more information, see For Some STDs, the Numbers Are Still Increasing and STD Prevention: Get to Know Your Partner.

Common Infections, Huge Impact
Information about the infectious diseases with which we're already familiar can sound so familiar that it's easy to forget how dangerous they really are. But their toll on the public health and personal lives of Americans is anything but ordinary. Infectious diseases not only affect us on an individual level, they have devastating effects on our health system and economy. When it comes to infectious diseases, it's fine to prepare for the worst, but realistically you should get ready for the same old thing.

Rick Gillis, MD, practices at the Sargeant Internal Medicine Clinic.

This article includes information from the Centers for Disease Control and Prevention and the National Center for Preparedness, Detection, and Control of Infectious Diseases (NCPDCID).

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.