Infectious diseases pose a serious threat to the nation's public health

Infectious diseases pose a serious threat to the nation's public health. Today, experts addressed key developments to the current and future outlook of infectious diseases, highlighting adolescent immunizations, outbreaks and epidemics of infectious diseases, antimicrobial resistance and new developments in HIV medicine, at a press conference sponsored by the National Foundation for Infectious Diseases (NFID).

The Emerging Role of Adolescent Immunizations: Stemming the Tide of Infectious Diseases

The United States immunization program is expanding its focus on adolescent vaccination, but barriers need to be overcome to successfully establish an adolescent vaccination program. These barriers range from difficulty reaching the adolescent population and lack of awareness of new vaccines to vaccine acceptance issues, missed immunization opportunities, inconsistent school requirements, need for multiple doses of some vaccines and costs have created a challenging environment for establishing and sustaining high vaccination rates in adolescents.

In a recently published NFID report, Adolescent Vaccination -- Bridging from a Strong Childhood Foundation to a Healthy Adulthood, public health experts revealed that 35 million adolescents fail to receive at least one recommended vaccine. Low immunization rates in adolescents have many implications including outbreaks of vaccine-preventable diseases, negative effects on quality of life and increased costs associated with managing disease.

The Centers for Disease Control and Prevention (CDC) immunization schedule urges providers to make a special effort to administer recommended vaccines to adolescents if not previously given. These vaccines include hepatitis B, the second dose of measles, mumps and rubella, and varicella. Influenza, pneumococcal and hepatitis A vaccines are recommended for adolescents in high risk groups. Also this year, meningococcal disease vaccination was added to the routine immunization schedule for certain adolescents.

"New strategies to improve adolescent immunization rates and provide other recommended preventive services must be developed and implemented," stated Larry K. Pickering, MD, FAAP, senior advisor to the director of the National Immunization Program at the CDC. "Widespread adolescent immunization will help greatly diminish the negative effects of vaccine-preventable diseases."

Outbreaks and Epidemics of Infectious Diseases - Are we prepared?

Pandemic influenza is an extreme global outbreak, in which persons worldwide are at risk for infection and illness. Today, a new pandemic has the capability of spreading worldwide more quickly than ever before. Pandemic viruses have historically infected one third or more of large populations and have led to millions of deaths.

The structure of the influenza virus has a tendency to change slightly, but frequently over time. This process allows for the introduction of new virus strains which circulate each year. Pandemics occur with larger changes in the influenza virus resulting in new strains to which the entire population may be susceptible.

Avian influenza "bird flu" continues to be an on-going infectious diseases and pandemic threat. Outbreaks have been reported among chickens, ducks and other bird species in multiple Asian countries and human deaths occurred in Thailand, Cambodia, Vietnam, and Indonesia. "Experts believe that the virus is now endemic and likely to remain circulating in the animal population for the foreseeable future, representing an ongoing pandemic threat," said Benjamin Schwartz, MD, senior science advisor, National Vaccine Program Office, a division of the Office of Public Health and Science at the United States Department of Health and Human Services (DHHS).

Dr. Schwartz discussed efforts DHHS is engaged in to enhance the nation's preparedness for infectious diseases outbreaks including surveillance, vaccine development and production, antiviral stockpiling, research and public health preparedness.

"In the event of a pandemic, good surveillance, timely vaccine development and production and the ability to administer vaccine to large numbers of people in a short amount of time will be very important," stated Dr. Schwartz.

The Impact of Antimicrobial Resistance - Where we are ... where we need to be

Antimicrobial resistance -- the capacity of infectious organisms to thwart drug effectiveness -- is a widespread problem. There are several current issues that clinicians and the public should be aware of to ensure preventive measures are taken and the best therapy given. These include the evolving story of community-associated methicillin resistant Staphylococcus aureus, pneumococcal infection and the conjugate pneumococcal vaccine, and health care associated infections for which there are few or no effective drugs remaining. J. Todd Weber, MD, director of the office of antimicrobial resistance at the CDC presented an update on the outlook on antimicrobial resistance.

New Developments in HIV Medicine

Worldwide more women have been affected with HIV and AIDS over the past 20 years than any other life-threatening infectious disease. Women make up nearly half of the 40 million people living with HIV. In sub-Saharan Africa, 60% of those infected with HIV are female and 75% of the infected individuals are between the ages of 15 and 24. Young women aged 15 to 24 are three to six times more likely to be infected with HIV than men in South Africa, Zambia and Zimbabwe. In South Africa one-in-four women is infected with HIV by the age of 22. Women make up half of those infected with HIV in the Caribbean, and one-third in Latin America.

In the United States, the annual number of estimated AIDS cases increased by 15% among women and only 1% among men from 1999 to 2003. The increase is predominated in young women and women of color, particularly African American and Hispanic women who often have limited access to health care. The majority of the infections were due to heterosexual transmission with 19% being attributed to needle injection drug use.

"Fundamental questions regarding the biology of HIV transmission have been difficult to answer because it is hard to examine relevant cells and tissue at the time of HIV acquisition, when the pivotal events are occurring," stated Thomas C. Quinn, MD, MSc, professor of medicine in the division of infectious diseases at Johns Hopkins School of Medicine.

Women are more susceptible to HIV infection than men. Increased susceptibility has been linked to specific cofactors, including the use of hormonal contraceptives and the increased presence of sexually transmitted diseases.

Susceptibility to HIV also varies throughout a women's reproductive life. Adolescent girls appear to be most vulnerable to HIV due to high-risk behavioral activities or because of physiological properties of an immature reproductive system.

"Recent studies have shown increases in the risk of acquiring HIV during pregnancy and during the early postpartum period, which could be attributed to higher levels of progesterone. Controlling the HIV pandemic requires continued attention to gender-related issues which drive the epidemic. Intervention should be multi-faceted and should include making both female and male condoms accessible to all in ways that do not stigmatize," said Dr. Quinn.

Dr. Quinn outlined other interventions including prioritizing the development of female initiated methods of protection such as microbicides; defining the influence of hormones on disease progression and response to treatment; and educating women and men about HIV and other STD's including practicing safe sex, and encouraging them to seek testing and treatment.