TB Guidelines Call for TB Screening and Treatment for All HIV-Infected
All HIV-infected individuals should be screened
for tuberculosis (TB), and if infected with TB should be provided
treatment to prevent the development of active TB disease. However,
both preventive and curative TB treatment regimens for HIV-infected
people must be carefully evaluated to ensure that they do not
cause serious drug interactions with the latest therapies for
HIV. New guidelines from the Centers for Disease Control and
Prevention (CDC) outline in detail the proper evaluation and
treatment of TB in HIV-infected individuals.
According to the guidelines, published in a
special October issue of the Morbidity and Mortality Weekly
Report, the most important consideration is to avoid the
use of one of the most popular TB drugs, rifampin, in combination
with protease inhibitors or non-nucleoside reverse transcriptase
inhibitors (NNRTIs), two of the latest available treatments
for HIV infection. Rifampin can seriously impair the effectiveness
of these antiretrovital therapies.
"Treatment Options Must Be Carefully
Considered to Prevent Interactions with HIV Drugs."
While HIV-infected individuals previously had
to stop taking their HIV medications until TB therapy could
be completed, another drug (rifabutin) allows continuation of
both regimens. Rifabutin provides the first alternative to rifampin
and should generally be used instead of rifampin in all patients
taking either protease inhibitors or NNRTIs. Additionally, because
of potential side effects and concerns about drug-resistance,
health care providers should provide directly observed therapy
(DOT) to HIV-infected individuals and carefully monitor them
for adverse side-effects and progress.
In addition to avoiding drug interactions,
providers can now offer HIV-infected individuals new short-course
regimens for preventive treatment. Recent studies have found
that a two-month course of multi-drug therapy to prevent active
TB is an effective alternative to the year-long regimen of isoniazid
previously prescribed for people co-infected with HIV and TB.
The shorter regimen is easier to comply with and limits the
time patients have to adhere to both TB and HIV regimens.
Critical Need for TB Prevention Among HIV-infected
The guidelines also underscore the importance
of identifying TB infection among people with HIV. Because HIV
infection so severely weakens the immune system, people infected
with both HIV and TB have a 100 times greater risk of developing
active TB disease and becoming infectious to others, compared
to people not infected with HIV. Early diagnosis and effective
treatment of TB among HIV-infected persons is critical to cure
TB disease, minimize the negative effects of TB on the course
of HIV, and interrupt the cycle of transmission to others. The
CDC guidelines therefore recommend that all HIV-infected individuals
be tested for TB infection and that all individuals being treated
for TB be counseled and tested for HIV.
TB is an airborne, potentially fatal lung disease
that now kills more people worldwide than any other infectious
disease. Worldwide, TB accounts for one-third of deaths among
HIV-infected individuals. It is critical for the optimal treatment
of both diseases, that health care providers be familiar with
and implement the new TB screening and treatment guidelines
for individuals with HIV. Moreover, continued efforts to eliminate
TB as a public health problem will be essential to reduce its
toll overall and among HIV-infected populations.
Copies of the recommendations can be obtained
from the NCHSTP Office of Communications by calling (404)639-8063,
or you can download the document from the Division of TB Elimination
Web site at http://www.cdc.gov/nchstp/tb.
Spongiform Encephalopathies: What Do We Know?
Transmissible spongiform encephalopathies (TSE) are degenerative
diseases that destroy the brain. While the exact mode of transmission
of these diseases is unknown, research indicates that these
diseases may be caused by a protein-like infective material
(prion). TSE tend to have very long incubation periods and have
been described in many types of animals, including man. TSE
are incurable and inevitably fatal. Although some of these conditions
have been clinically recognized for years, we still have much
to learn about these diseases.
What is "mad cow disease"? Bovine
Spongiform Encephalopathy (BSE) is popularly known as "mad
cow disease". This is a TSE that affects cattle. Affected
cattle behave abnormally, have difficulty moving, lose weight
in spite of eating well, and die within six months after their
onset of symptoms. BSE was first recognized in Great
Britain in 1986, and it is believed that the disease was transmitted
to cattle by feeding them meal made from meat and bone of sheep
infected with scrapie (see Scrapie on next page). Great
Britain has prohibited feeding practices that are believed to
be associated with the transmission of BSE and their number
of new cases continues to decline. Unfortunately, cattle in
other countries have been diagnosed with BSE and control efforts
Do we have BSE in the United States? According
to the United States Department of Agriculture (USDA), BSE has
not been detected in the U.S., despite active surveillance that
include three components. First, cattle that were imported into
the U.S. from Great Britain before those imports were banned
in 1989 were traced. As of September 1997, none of these showed
any signs of BSE. Second, the USDA is conducting surveillance
within the U.S. to look for BSE. USDA and State veterinarians
routinely conduct field investigations of cattle with neurological
disease. Third, USDA officials identify cattle that are showing
signs of neurological disease in slaughterhouses. The brains
from these cattle, as well as the brains of rabies-negative
cattle from veterinary diagnostic labs, are examined for signs
of BSE. No evidence of BSE in U.S. cattle has been seen.
What is Creutzfeldt-Jakob Disease (CJD)? CJD
is a TSE that affects humans. No cause for most cases of CJD
(80-85%) is ever identified. There is an inherited form of CJD
associated with a specific chromosome pattern that accounts
for 5-10% of cases. Fewer than 1% of CJD cases are associated
with medical procedures. Such procedures include neurosurgical
procedures that were conducted using contaminated instruments,
and transfer of contaminated central nervous system tissue (including
optic nerves from corneal transplants) and extracts (i.e., growth
hormone). CJD has been recognized since the 1920s, and
typically affects individuals between the ages of 60 and 75.
People diagnosed with CJD usually die within a year of their
onset of symptoms.
What is the New Variant of CJD? A
New Variant of CJD (nv-CJD)
has been described. In 1995, five young people (<29 years
old) died in the U.K. from CJD. However, these cases of CJD
were different from the "classical" CJD that had been
previously recognized. The patients were younger, they experienced
an unusual clinical course with a longer duration of illness,
and at autopsy they were found to have brain lesions that were
different from those in most CJD patients. As of September 1998,
26 cases of nv-CJD have been identified in persons from the
U.K. and one from France.
Do we know that nv-CJD is related to BSE? While
a definitive answer is not available yet, there is strong epidemiologic
and laboratory evidence to support a link between nv-CJD and
BSE. First, cases of nv-CJD have appeared only in geographical
areas where there was also BSE. Second, the time interval from
when people would have first been exposed to BSE (1984-1986)
to the time when cases began to appear (1994-1996) is consistent
with known incubation periods for CJD. Finally, laboratory studies
have shown that inoculation of BSE-infected brain tissue into
mice or monkeys can result in these animals developing illnesses
similar to nv-CJD. It is likely that people were exposed to
BSE by eating infected cattle.
What is being done about CJD in the U.S.? The
Centers for Disease Control and Prevention (CDC) monitors the
occurrence of CJD in the U.S. by analyzing death certificate
information. The rate of CJD in the U.S. has remained relatively
stable from 1979 through 1995, with a low of 0.8 cases per million
in 1980 and a high of 1.1 cases per million in 1987. CJD deaths
in persons who are less than 30 years of age remain extremely
rare in the U.S, with fewer than five cases per billion
per year. (In contrast, in the U.K., at least 13 of the 23 patients
who died with nv-CJD were younger than 30.)
Do we have nv-CJD in the U.S.? The CDC
is looking for nv-CJD through active surveillance in five areas:
Minnesota, Oregon, Connecticut, the San Francisco Bay area of
California, and metropolitan Atlanta, Georgia. The CDC also
has an ongoing national project where medical records of any
CJD victims younger than 55 years of age are thoroughly reviewed.
Such a review was recently conducted on a 29-year-old Utah resident
who had been diagnosed with CJD. While there had been concern
that this patient might have had nv-CJD (because of the young
age or onset), molecular and biochemical testing have confirmed
that the patient has "classical" CJD, and not
nv-CJD. The CDCs surveillance efforts have not found any evidence
that nv-CJD is occurring in the U.S..
Do we have other CJD victims in Utah? What
about nv-CJD? Yes. From 1980 to 1998, there have been an
average of 1.6 deaths due to CJD per year. There is a great
deal of variability in the number of cases from year to year.
For example, in 1989 there were six deaths from CJD identified,
and in 1998 there have been seven cases (and six deaths) while
there were no deaths identified in 1981, 1987, and from 1990
through 1993. While we do have CJD in Utah, there is no evidence
to suggest that we have nv-CJD.
Are there other TSEs in animals or humans?
a TSE that affects sheep, and rarely goats. This condition has
been recognized for over 200 years. Affected sheep become nervous
and tremble, or they develop an intense itch over their entire
body. They will rub or bite their wool off in an attempt to
relieve the itch, are unable to feed or rest properly, and will
die within six months of onset of their illness. The disease
may be spread from mothers to their offspring, or from one sheep
to another via respiratory secretions. As mentioned previously,
some experts believe that the feeding of meal made from meat
and bone of scrapie-infected sheep to cattle may have resulted
in the development of BSE.
Another TSE of concern in the U.S. is Chronic
Wasting Disease of Deer and Elk (CWD). This was first recognized
in 1967 in deer in Colorado. It has been found in elk and other
wild and domestic ruminants, primarily in Colorado and Wyoming,
and in other parts of the U.S., Canada and Great Britain. The
symptoms are similar to those of BSE, and affected animals generally
die within six months of their onset of illness.
There are other
TSE that occur in animals, such as Feline Spongiform Encephalopathy
and Transmissible Mink Encephalopathy.
TSE that occur
in humans also include Kuru,Gerstmann-Straussler Sheinkers
Syndrome, and Fatal Familial Insomnia. These are
extremely rare diseases.
Can TSE be spread from one kind of animal to
another? Much remains unknown about TSE, but experts believe
that this is possible. The scenario that may have occurred with
scrapie, BSE and nv-CJD would support this possibility.
What can be done to prevent the spread of TSEs?
Our best understanding
of these diseases is that they are difficult to transmit from
one person to another. While everything is not known about the
transmission of these diseases, there are some common sense
things to do to avoid possible exposure.
1. Animals that appear to be sick or wasting
should not be used for human consumption. (It would also be
wise not to feed them to other animals.)
2. Hunters and other persons processing carcasses
should avoid direct contact with brain and spinal cord tissues.
Rubber gloves could be worn while processing the carcasses to
3. Specific guidelines exist for health care
workers who may be doing autopsies of CJD victims or for morticians
who may be embalming them. These can be obtained from the Bureau
of Epidemiology (801-538-6191), or from the Centers for Disease
Control and Prevention.
Recommendations on how to prevent TSE will
undoubtedly change as we gain a better understanding of these
Report of Diseases of Low Frequency
Year-to-Date January 1 - December 31, 1998
(including a comparison for same time period 1994 -1997)
Department of Health, Bureau of Epidemiology
Monthly Morbidity Summary - December
1998 - Provisional Data
The Epidemiology Newsletter is
published monthly by the Utah Department of Health, Division
of Epidemiology and Laboratory Services, Bureau of Epidemiology,
to disseminate epidemiologic information to the health care
professional and the general public.
Send comments to: The Bureau of Epidemiology Box 142104 Salt
Lake City, UT 84114-2104 or call (801) 538-6191
Approval 8000008: Appropriation 3705
Rod Betit, Executive Director, Utah Department of Health,
Charles Brokopp, Dr.P.H., Division of Epidemiology and Laboratory
Craig R Nichols, MPA, Editor, State Epidemiologist, Director
Bureau of Epidemiology
Cristie Chesler, BA, Managing Editor