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Communicable Diseases
Communicable (infectious) diseases are illnesses caused by specific infectious agents or their toxic products that occur through the transmission of these agents or their products from an infected person, animal, or inanimate reservoir to a susceptible host. Transmission is either direct or indirect through an intermediate plant, animal host, vector or the inanimate environment (Benenson, 1995). The transmission of infection to a person does not always result in disease; the body's defense systems must also break down or weaken. The host persons or vectors may not show signs of illness themselves but are still able to pass on the infection.
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The reduction in incidence of communicable diseases is the most significant public health achievement of the past 100 years. Much of this progress is a result of improvements in basic hygiene, food production and handling, water treatment, the development and use of antimicrobial drugs, and the development and widespread use of vaccines. Notwithstanding the progress that has been made, infectious diseases remain important causes of illness and death in the United States (Public Health Service, 1990).
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Reduction in communicable diseases is a result of improvements in basic hygiene, sanitation, antimicrobial drugs, and vaccines.
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In the past decade we have seen epidemics of both previously unknown infections and old diseases such as tuberculosis. Although HIV/AIDS is notable among the newly emerged communicable diseases, a host of other communicable diseases have been discovered since 1970, such as compylobacteriosis, e. coli O157:H7, and hepatitis C (Turnock, 1997). Health surveillance systems act as our first line of defense against infectious diseases through the early identification of potential health threats. Surveillance programs maintain a baseline of reportable illnesses and seasonal disease trends and remain ready to mobilize medical intervention when trends increase from the norm. The additional fear of biochemical terrorism has amplified the value of health surveillance systems.
In 1998, the Austin/Travis County area experienced a major disease outbreak that demonstrates the importance of health surveillance systems.
The group "A" streptococci (GAS) is a bacteria that generally causes minor illness such as a sore throat, but a person could require hospitalization for serious complications. At this time there are no answers as to why some people experience serious complications or even why certain strains of GAS show up in a particular area. From January through May of 1998, the Austin, Travis County community experienced nine (9) deaths from GAS infections. Sixteen additional GAS cases were reported with serious complications but the individuals survived. Most of the individuals with serious complications from GAS infections had some form of a viral illness before problems with the GAS appeared. In children the viral illness most common was chicken pox and in adults it was flu, both of which can be prevented by safe vaccines.
Prior to December 1997, the Texas Department of Health, Infectious Disease Epidemiology and Surveillance Division had never received reports of even 20 cases of invasive streptococcus in a single month. From December 1997 through May 1998, TDH received reports of 232 invasive GAS cases. One hundred thirty-three cases were reported from 19 contiguous central and coastal Texas counties; 99 invasive GAS cases were reported from the other 235 Texas counties. The Central Texas Counties which reported cases of GAS were Travis, Williamson, Caldwell, Hays, and Bastrop. (Texas Department of Health, 1998, p. 92).
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Vaccine Preventable Diseases
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- In general, significant progress has been made nationally. In 1995, seven vaccine-preventable diseases were at all-time record low levels. The Healthy People 2000 target to reduce indigenous cases of vaccine-preventable diseases to zero cases was met in 1995 for both diphtheria among people 25 and younger and for polio (wild-type virus). Measles was transiently eliminated from the United States in 1993. Since then, all recorded cases have been directly or indirectly imported (United States Department of Health and Human Services [US DHHS], September 2000, Healthy People 2000 Progress Review: Immunization and infectious diseases).
- Healthy People 2000 identified measles as a sentinel measure for vaccine preventable diseases. The presence of measles in a community is an indicator of the need for preventive services and/or problems with access to health care. Because immunization can prevent new cases of measles from occurring, the year 2000 target was zero cases. For pertussis (whooping cough), the Healthy People year 2000 target was no more than a total of 1000 cases nationally (Public Health Service, 1990).
- Viral hepatitis, which includes hepatitis A, hepatitis B, and hepatitis C, is a growing health concern. The greatest concern is damage to the liver resulting in chronic liver disease and cirrhosis. Chronic liver disease and cirrhosis are the ninth leading cause of death in Travis County and the tenth leading cause of death in the MSA and Texas as a whole. A state law passed in 1998 requires the hepatitis B vaccine for children up to age five and expanded to include children up to age 12 in year 2000. Hepatitis A vaccine is not widely used in the local area and there is no vaccine for hepatitis C.
- Healthy People 2000 national targets for Hepatitis B was 40 cases per 100,000 population for all races (Public Health Service, 1990).
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Immunization Registry
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- House Bill 3054, signed into law by Governor Bush in 1997, provided for the creation of a statewide immunization registry to serve as a single repository of accurate, complete, and current immunization records. In 1999, the Texas Board of Health enacted the rules that will guide the implementation of the law. The Texas Department of Health has adopted the computer database "ImmTrac" as the State Immunization Registry, however, participation in the state immunization registry has not been widely accepted as some residents have raised issues of concern about the confidentiality of their child's medical information.
- The Texas Department of Health conducted statewide immunization surveys in 1994, 1996, and 1998. The Texas Immunization Survey (TIS) is a population-based survey designed to assess immunization levels among Texas children 3 through 24 months of age. The 1994 survey was an in-person survey and the 1996 and 1998 surveys were random digit dial telephone surveys. The TIS sample size in 1998 was not large enough to include county specific immunization levels (Texas Department of Health, September 2000, Immunization Survey).
Source: TDH Immunization Survey, http://www.tdh.state.tx.us/immunize/irmain.htm
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Tuberculosis
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- The following persons have a greater than average risk of being exposed to or infected with mycobacterium tuberculosis (TB):
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- Close contacts of a person with infectious TB
- Foreign-born persons from areas of the world where TB is common
- Medically underserved, low-income populations
- The elderly
- Persons living in close communal conditions (correctional facilities, nursing homes, homeless and other shelters)
- Persons with a compromised immune system (Division of Tuberculosis Elimination, September 2000).
- The percentage of TB cases in foreign-born persons continues to increase, with 55 percent of all cases reported in Travis County in 1999 being in individuals born outside the U.S.
- The rate of TB in Travis County and the MSA has consistently been higher than the State as a whole (Austin/Travis County Health and Human Services Department, 1998).
- Bastrop and Caldwell Counties had higher than usual TB rates in 1998 and 1999. Most of these cases are clusters of individuals linked to a single source infection (Bureau of Communicable Disease Control, September 2000).
- The Healthy People 2000 national target was 3.5 cases per 100,000 (Public Health Service, 1990).
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Sexually Transmitted Diseases (STDs)
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- In theory, the necessary knowledge already exists to halt all further spread of STDs. The spread of STDs is driven significantly by human behavior such as people having unprotected sex or using drugs (Potts & Short, 1999).
- Two-thirds of all STDs occur in people ages 15 to 24 (Division of Sexually Transmitted Diseases, September 2000).
- Women are less likely to have noticeable symptoms unless complications occur. Women are then more likely to experience long-term consequences such as infertility, tubal pregnancy, and cervical cancer (Institute of Medicine, 1997).
- Virtually every STD can be passed from a pregnant woman to her fetus or infant. Common STD related problems for infants include low birth weight, premature birth, conjunctivitis, pneumonia, neurologic problems, and congenital abnormalities (Institute of Medicine, 1997).
- No STD should be considered as treated until all partners have also been examined and treated (Institute of Medicine, 1997).
- Cultural, societal, and personal factors may adversely affect a woman's ability to make decisions regarding intercourse or using a condom, which limits her ability to protect herself from sexually transmitted diseases (Potts & Short, 1999).
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Gonorrhea
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- The Healthy People 2000 national objective for gonorrhea was no more than 100 per 100,000 population. Nationally, the gonorrhea incidence rate has decreased by 56 percent, from 300 per 100,000 to 123 per 100,000. However, this rate remains above the Healthy People 2000 objective (Public Health Service, 1990).
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Chlamydia
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- Chlamydia is the most commonly reported STD but reported cases still represent a gross underestimate of the true disease burden.
- In Travis County, the incidence rate of reported chlamydia cases during 1999 for women age 15 to 19 was 3,619.9 per 100,000 and for women age 20 to 14 the rate was 3,095.5 per 100,000 women. In Texas, the 1998 rates for chlamydia among young women age 15 to 19 years and 20 to 24 years were 2,994 cases and 2,431 cases per 100,000 population, respectively (Bureau of HIV and STD, September 2000). Nationally, the 1998 rates of chlamydia for women 15 to 19 years old were 2,359.4 per 100,000 and in 20 to 24 year olds the rates were 1,952.7. per 100,000 (Division of Sexually Transmitted Diseases, September 2000, 1998 Sexually Transmitted Disease Surveillance Report).
- The Healthy People 2000 target rate for sexually active women under 25 years of age was 5 percent (Public Health Service, 1990).
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Syphilis
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- The decline of syphilis (nationally and in Texas) may be partly a result of the reduction in the reservoir of infected IV drug users, many of whom have died of HIV infection or are in long-term incarceration.
- The Healthy People 2000 national target for early syphilis was not more than 4 cases per 100,000 population (Public Health Service, 1990).
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AIDS
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- Acquired immunodeficiency syndrome (AIDS) is the late stage of infection of the human immunodeficiency virus (HIV) and is characterized by severe immunosuppression and co-infection with other opportunistic agents.
- From the beginning of the HIV epidemic in the early 1980s to the end of 1999, over 3,173 AIDS cases have been reported in Travis County. In 1999, there were 257 newly reported AIDS cases. AIDS is generally not identified and reported until late, sometimes several years after initial HIV infection (Bureau of HIV and STD, September 2000).
- In 1999, 10,045 HIV tests were conducted at state-funded HIV counseling and prevention sites in the five counties of the MSA. Of these tests, 69 identified positive HIV infection, which is a positivity rate of 0.68 percent. This low positivity rate may indicate that prevention counseling and testing are not focused on the appropriate population(s) (Bureau of HIV and STD, September 2000).
- Current AIDS cases exhibit the same patterns as those from the beginning of the AIDS epidemic. Those at greatest risk are white homosexual males and IV drug users. However, a closer look at the new infections of HIV indicates a possible shift to heterosexual minorities. While Blacks account for less than ten percent of the total Travis County population, they represent 29 percent of the new HIV infections in 1999.
- HIV infection was the leading cause of lost years of potential life in Blacks for the years of 1989 to 1998 in Travis County (TDH, September 2000, Epigram).
- Blacks show a disproportionately high number of AIDS deaths as compared to the number of AIDS cases reported. Those accessing disease management services are living longer, productive lives. This disparity in AIDS deaths of Blacks suggests that an inappropriately low level of services are being provided to the Black AIDS population.
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