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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):
- 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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