Fighting Emerging Infectious Diseases

Preventive measures such eating safe and healthy food, getting vaccinated, and using bug repellent are key steps recommended by CDC and others to prevent the spread of infectious diseases.

CDC's important infectious disease work takes center stage July 11-14 as more than 2,000 leading scientists, physicians, veterinarians, healthcare workers, nurses, climatologists and biologists gather in Atlanta for the seventh International Conference on Emerging Infectious Diseases (ICEID).

CDC and its partners are on the front lines of efforts to identify, prevent, and control emerging infectious diseases. Several of these efforts will be covered during ICEID, including work in the areas of foodborne disease, pneumonia and other respiratory diseases, and dengue.

Tracing the Sources of Foodborne Diseases

Whenever there is an outbreak of infections caused by food, public health officials must identify the likely suspect and trace it back to its source, whether it be the grocery store, food distributor, factory, slaughterhouse, or farm. This past spring, for example, students in several states became ill with bloody diarrhea, and CDC investigators identified Shiga toxin-producing Escherichia coli (E. coli) O145 as the cause of illness. They found that many of the ill individuals had eaten romaine lettuce from the same farm.

In outbreaks where the contaminated food is a single food item, public health authorities generally have an easier time tracking down the source. But outbreak investigations can be extremely difficult when the contaminated food contains multiple ingredients. A good example is the recent outbreak of Salmonella Montevideo, which sickened more than 270 people across the United States.

Investigators had to get innovative to crack this case. With permission from the ill patients and in conjunction with local authorities, public health investigators used shoppers' cards from ill people to view which common food products they ate. This helped them track down the source of contamination. The culprit: Italian-style meats containing black and red crushed pepper contaminated with the same strain of Salmonella as the outbreak strain. These ingredients were traced back to three companies, and the contaminated products were promptly recalled.

These outbreaks show that as food production and delivery systems become more complex, we also need our food safety systems to similarly evolve and to use new tools to track down the sources of contaminated food to help prevent foodborne illnesses.

Preventing Pneumonia – Vaccines Can Help

Every 15 seconds, somewhere in the world, a child dies from pneumonia. Many of these deaths are preventable through vaccination and appropriate treatment.

Pneumonia is a lung infection that can cause mild to severe illness in people of all ages. Signs of pneumonia can include coughing, fever, fatigue, nausea, vomiting, rapid breathing or shortness of breath, chills, or chest pain. Certain people are more likely to become ill with pneumonia:

• Adults 65 years of age or older.
• Children younger than 5 years of age.
• People under the age of 65 years who have underlying medical conditions (like diabetes or HIV/AIDS).
• People 19 through 64 who smoke cigarettes or have asthma.

In the United States, the most common type of bacteria that causes pneumonia is Streptococcus pneumoniae (pneumococcus).  The most common viral causes are influenza, parainfluenza, and respiratory syncytial viruses (RSV). In children younger than 1 year of age, RSV is the most common cause of pneumonia. Other common bacterial and viral causes of pneumonia in the United States include Staphylococcus aureus and adenovirus. Pneumocystis jirovecii, a fungus formerly known as Pneumocystis carinii, is a common cause of pneumonia in patients with AIDS.

There are several ways to prevent pneumonia and other respiratory infections such as colds and the flu:

• Wash your hands regularly.
• Clean hard surfaces that are touched often (like doorknobs and countertops).
• Cough or sneeze into a tissue or into your elbow or sleeve.
• Limit your exposure to cigarette smoke.
• Take steps to treat, control, and prevent conditions like diabetes and HIV/AIDS.
• Get vaccinated. In the United States, several vaccines prevent infections that can cause pneumonia:
  • Pneumococcal.
  • Haemophilus influenzae type b (Hib).
  • Pertussis (whooping cough).
  • Varicella (chickenpox).
  • Measles.
  • Seasonal and 2009 H1N1 influenza (flu) vaccines.

Dengue Re-emerges in Florida

Dengue virus causes as many as 100 million infections and 25,000 deaths worldwide each year, mostly in tropical and subtropical regions.  Between 1980 and 2009, there have been only a handful confirmed, locally acquired dengue cases in the continental United States, mostly along the Texas-Mexico border.  This situation changed in the summer-fall of 2009, when 27 cases of dengue were identified among Key West, Florida, residents.  The outbreak represented the first locally acquired cases of dengue in Florida since 1934.  According to the Florida Department of Health, as of July 9, 2010, another 14 cases of dengue had been reported in 2010. State and local public health officials are working closely with CDC to notify medical providers and the community, and monitor the situation.

Dengue is caused by any one of four related dengue viruses transmitted by mosquitoes.  Symptoms include high fever, aching bones or joints, headache, pain behind the eyes, minor bleeding (for example, bloody nose or gums), and sometimes a rash.   

Dengue viruses are spread through the bite of infected Aedes mosquitoes. These mosquitoes prefer to feed at dusk or dawn but will feed during the day in shady areas or at night if the lights are on. They also tend to live inside or around houses and lay eggs wherever there is standing water (for example, flower vases).

The reemergence of dengue and other mosquito-borne viruses underscores the need for effective ways to rapidly identify and control such outbreaks.

When a person is infected with dengue virus, early recognition and prompt supportive treatment can substantially lower the risk for disease.  There is no dengue vaccine, so the best way to protect yourself is to avoid mosquito bites.  The following steps can help:

• Remove any sort of standing water from in and around your home.
• Wear long-sleeved shirt and long pants.
• Use a mosquito repellent.
• Check windows to make sure screens are in place and don't have any holes where mosquitoes can enter.
• Use air conditioning when possible.

More Information

Resources

• Foodborne Outbreak Team
• Food Safety
• Pneumonia FastStats
• Vaccines and Preventable Diseases
• Dengue

Conference Information

For more details about the International Conference on Emerging Infectious Diseases, July 11-14, 2010, in Atlanta, GA, visit these sites:

• Meeting Information
• Program Information