E-DRUG: Chlamydia trachomatis, blindness and azithromycin

["Blaine P. Carmichael, PA-C" <bpcarmichael@stic.net>]

E-DRUG: Chlamydia trachomatis, blindness and azithromycin
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A LEADING CAUSE OF BLINDNESS MAY BE CONTROLLED BY SIMPLE
COURSE OF ORAL ANTIBIOTIC

A study published in the Aug. 21 issue of "The Lancet"
provides evidence that treating entire communities with a
short course of the oral antibiotic azithromycin is more
effective than the standard six-week course of daily
tetracycline ointment in controlling development of
trachoma.  Children are particularly vulnerable to infection
by the bacterium "Chlamydia trachomatis", which results in
trachoma, a leading cause of preventable blindness in the
world.

"We have known for decades that we had the antibiotics to
successfully treat this disease when cases developed, but we
didn't seem to have the right drug delivery method to
control the infection over time.  Now we know that we do,
and we are very excited at the promise of these results,"
says Julius Schachter, Ph.D., professor of laboratory
medicine at the University of California at San Francisco
(UCSF) and lead investigator of the study.

Trachoma affects the inner eyelid.  Of the nearly 600
million people living in trachoma endemic areas, 150 million
have active disease as conjunctivitis.  After repeated
episodes, which begin in childhood, scarring occurs, and the
eyelids turn inward causing damage to the cornea.  Total
blindness occurs in middle to late life.  In endemic
communities, 25 percent of individuals age 50 to 60 may
become blind.  Blind adults may not be able to earn a living
and can be an economic burden to families and communities.

"Six million people around the world are blind or severely
disabled due to this disease," says Anthony S. Fauci, M.D.,
director of the National Institute of Allergy and Infectious
Diseases (NIAID).  "Treatment of trachoma with azithromycin
provides long-term benefits not usually available for people
in developing countries."  Thomas C. Quinn, M.D., of NIAID
and Johns Hopkins University is a co-author of the study.
NIAID, the Edna McConnell Clark Foundation, Abbott
Laboratories and Pfizer Inc supported the study.

Since the 1950s, the standard treatment for trachoma has
been daily application of tetracycline ointment in the
inflamed eye for six weeks.  In the UCSF study, researchers
compared the effect of the two antibiotic regimens on
infection rates in villages located in trachoma endemic
areas where transmission of infection is high.  The villages
were in the African countries of Egypt, The Gambia and
Tanzania.  Village-by-village comparison of treatments
showed that three doses of oral azithromycin at one-week
intervals reduced levels of chlamydial infection
significantly more than the standard tetracycline regimen
delivered by health providers.  Furthermore, village-wide
treatment with azithromycin resulted in a 60 to 90 percent
decrease in infection rates a year later.

The authors conclude that the effective reduction of
chlamydial infection, coupled with the ease of
administration, make azithromycin an important component of
trachoma control programs.  Although azithromycin costs more
than tetracycline ointment, the expense may be offset by the
higher costs of distributing and administering multiple
doses of the ointment.

Treatment with antibiotics is one of several steps in a
comprehensive trachoma control strategy called SAFE: Surgery
for advanced disease; Antibiotics to treat and prevent
infections; Face washing and good personal hygiene; and
Environmental improvements, such as better access to clean
water and sanitation and health education.  The strategies
of SAFE, including treatment with azithromycin, may provide
substantial benefit to people in endemic areas by reducing
both individual infections and persistence of infection in
low-prevalence areas.

"Last November, as a result of these research findings,
Pfizer and the Edna McConnell Clark Foundation pledged $66
million to eliminate blinding trachoma.  A key component is
Pfizer's donation of Zithromax,(r) their trade name for
azithromycin, which the World Health Organization (WHO) now
recommends for the treatment of trachoma," says Penny
Hitchcock, D.V.M., chief of the sexually transmitted
diseases branch of the NIAID.  Pfizer and the Edna McConnell
Clark Foundation founded the International Trachoma
Initiative, an independent agency using azithromycin in the
SAFE strategy to control trachoma in Tanzania, Morocco,
Mali, Ghana and Vietnam.

"C. trachomatis" infects not only the eyes, but the nose,
throat, genital tract and rectum as well.  The eye infection
is transmitted easily from person to person by hand-to-eye
contact, possibly aided by flies attracted to the sticky
discharge from the eyes.  In earlier studies in Tanzania and
The Gambia, many children who had been treated with topical
tetracycline showed evidence of recurring infection within
weeks of treatment.  The ointment treats only eye infections
and is very short-acting.  Oral antibiotics that work
throughout the body are more effective for treating trachoma
than antibiotic ointment.  Although short-acting oral
antibiotics also can be used to treat the infection, the
need for repeated doses makes them less effective compared
with fewer doses of a longer-acting oral antibiotic.

According to the "Lancet" report, short-course azithromycin
proved to be an efficient and effective way to treat many
people.  "In our study, the advantage of oral azithromycin
will be even greater because of the good compliance that can
be achieved," says Dr. Schachter.  "In these studies, health
care workers made extraordinary efforts to administer
topical tetracycline.  In most treatment programs for
endemic trachoma, eye ointment is provided to families for
treatment, so topical drug delivery is probably lower than
in this study."

As the study designers expected, at all sites the prevalence
of trachoma was highest in children-greater than 30 percent
in children younger than 10 years old.  Traditionally,
children have been targeted for intervention, but an
appreciable number of older individuals also tested positive
for the bacterium.

"A goal for this study was to assess control of trachoma
through treatment of entire communities," Dr. Schachter
explains.  "This study not only shows that a short course of
oral antibiotic achieves greater patient compliance than the
longer term traditional treatment, but that control of this
disease can be achieved through treatment of all individuals
within a community. The results indicate that with
azithromycin, trachoma control is an attainable goal."

NIAID is a component of the National Institutes of Health
(NIH).  NIAID conducts and supports research to prevent,
diagnose and treat illnesses such as HIV disease and other
sexually transmitted diseases, tuberculosis, malaria, asthma
and allergies.  NIH is an agency of the U.S. Department of
Health and Human Services.

Press releases, fact sheets and other NIAID-related
materials are available on the NIAID Web site at
http://www.niaid.nih.gov.
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Reference:
J. Schachter, et al. Azithromycin in control of trachoma.
"Lancet" 354(9180):630-63 (1999).

CONTACT:
NIAID Office of Communications and Public Liaison
(301) 402-1663
UCSF/SFGHMC News Office
(415) 476-2557

--
Blaine P. Carmichael, PA-C
bpcarmichael@stic.net
C0-Moderator, PRIMARYPA Clinical discussion List
VP Association of Family Practice Physician Assistants
Disease Detection and Prevention National CME Conference
San Antonio, Texas November 4-7, 1999
AFPPA  http://www3.ns.sympatico.ca/yngdoc/

[How much more does azithromycin cost than doxy or tetracycline? WB]
  
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