The lives of 134,000 MDR-TB and XDR-TB patients will be saved in 2007-2008 if the US$ 2.1billion response plan is fully funded and fully implemented.
Global Response Plan
2007
2008
Total
MDR-TB Cases on Treatment
60,000
100,000
160,000
XDR-TB Cases on Treatment
6,000
10,00
16,000
Lives Saved
49,000
85,000
134,000
US$ Total
$882m
$1,273m
WHO to convene second Global XDR-TB Task Force meeting in April 2008. XDR-TB country data included in the global TB drug resistance report, to be published February 2008.
Missions to identify and provide support and technical assistance carried out in Lesotho, Malawi, Mozambique, Namibia, Swaziland, South Africa and Zambia. International staff deployed in Lesotho and South Africa, with funding to support Swaziland post, and two regional posts. Rapid surveys completed to assess XDR-TB extent in Botswana and Swaziland. Generic protocols developed for countries. National training courses planned for Botswana, Ivory Coast, Mexico and South Africa by end of 2007.
Lesotho National Reference Laboratory restructured with first results generated with support from FIND, Partners In Health and WHO.
Green Light Committee strengthened to review and approve increasing number of applications for second-line anti-TB drugs.
TB partners engaged in MDR-TB and XDR-TB management expansion activities, e.g. TBCAP in infection control, regional training courses in Africa, Americas, Middle East and South East Asia.
The Global Plan to Stop TB revised to include a doubling of the numbers of MDR-TB treatments by 2015 and latest XDR-TB costings.
Revised guidelines on programmatic management of drug-resistant TB in preparation and includes guidance on human rights approach and community-based MDR-TB care.
Revised infection control guidelines for health care facilities being finalized. Global consultation at WHO in October 2007 recommended a national level infection control framework is also needed.
Development of new approach to recording and reporting of drug-resistant TB cases.
WHO TB laboratory strengthening responsibilities reorganized and business plan for laboratory expansion drafted.
WHO/PEPFAR consultation recommended PEPFAR make immediately available US$50m for TB/HIV, including funds to expand infection control, and strengthen laboratories.
Health ministers endorsed XDR-TB emergency actions in 2007 World Health Assembly resolution. European Ministers back XDR-TB actions in 2007 Berlin TB Declaration.
New Developments and Perspectives
“The history of tuberculosis (TB) has been one of scientific, medical and political failure.” With this disturbing statement, The Lancet’s editors introduced an issue dedicated to TB that was released on the occasion of the World TB Day 2006 (Zumla 2006). According to the Global TB Control Report released one year later by the World Health Organization (WHO), the good news is that “the worldwide TB epidemic has leveled off for the first time since the disease was declared a public health emergency in 1993.” The bad news is that “at the current rate of progress, the 1990 prevalence and mortality rates will not be halved worldwide by 2015.” The Global Plan to Stop TB needs to triple investment in order to achieve such a goal (World Health Organization 2007).
TB is the only disease ever declared a global emergency by the WHO. Paradoxically, although we count on effective − and proven cost-effective interventions for its control, TB continues to cause great mortality and suffering, especially in poor and less-developed countries. Its association with the HIV/AIDS pandemic forms a lethal combination. In addition, multidrug resistant (MDR) TB and the recently-described extensively drug resistant (XDR) TB – with further resistance to key second-line drugs and virtually incurable – severely complicate the management and control of the disease worldwide (Dorman 2007, Shah 2007).
As repeatedly stated, one third of the world’s population is latently infected with Mycobacterium tuberculosis and 10 % of these people will develop active disease at some point in their life. Almost 8.8 million new cases of TB were reported in 2005, and 1.6 million deaths were attributed to the disease. Asia and Sub-Saharan Africa accounted for 7.4 million new cases of TB worldwide (World Health Organization 2007).
Yet, it was not long ago that we envisaged and proudly announced the elimination of TB by the end of the last millennium. Indeed, in the late ’70s and early ’80s, it was thought that TB could be eradicated from most developed and industrialized countries. TB was already regarded as a disease from the past and started to be neglected by medical doctors, scientists and agencies in charge of its control. However, this never became a reality, mainly due to the appearance of antibiotic resistance, and therefore, TB continues to be the big killer it was in the pre-antibiotic
CDC’s Role in Preventing Extensively Drug-Resistant Tuberculosis (XDR TB)
The Centers for Disease Control and Prevention (CDC) is collaborating with other federal agencies and international partners to raise awareness and enhance strategies for TB prevention worldwide by
Strengthening TB services for people living with HIV/AIDS
The President’s Emergency Plan for AIDS Relief (PEPFAR), through funding and technical support, helps host countries strengthen laboratory infrastructure, provide staff training, and screen patients who are HIV-infected for TB. Host countries are working to improve patient management, drug-resistance surveillance, and monitoring and evaluation efforts.
Assembling outbreak response teams
Teams of subject matter experts from CDC are prepared to be rapidly deployed to help host country governments and the World Health Organization (WHO) when outbreaks occur or other needs are identified.
Improving access to TB drugs
As a member of the Green Light Committee and through support of the Global Drug Facility, CDC is helping to increase access to quality-assured, lower-cost second-line drugs to treat drug-resistant TB.
Developing international TB testing standards
These recommendations are being designed to ensure more accurate and rapid detection and treatment of drug-resistant TB. They will include standards for second-line drug susceptibility testing, new anti-TB drug regimens, and better diagnostic testing.
Building capacity of health care providers
By providing technical support and training, CDC helps to build the capacity of frontline health care providers to diagnose and ensure completion of treatment, which aids in preventing drug resistance.
Reconvening the Federal TB Task Force
This task force was originally created to respond to the emergence of multidrug-resistant tuberculosis (MDR TB) in the U.S. in the 1990s. Today, the Federal TB Task Force is developing an action plan to combat XDR TB.
Providing technical assistance to expand program capacity
CDC and partners are working directly with host countries to implement improved infection control measures, rapid case detection, effective treatment, and drug resistance surveillance.
Supporting TB communication and education efforts
Information on XDR TB is being disseminated regularly and widely. This information is regularly updated on the CDC and partner websites, as well as being presented at national and international conferences and events.
TB
still on the rise!
Tuberculosis still kills almost two
million people a year worldwide and,
despite the availability of curative
treatment for three decades; the incidence
is on the rise in many countries.
The international target is to detect
70% of pulmonary sputum positive cases
and treat 85% of these successfully.
In the DOTS era what
is urgently needed is clear and unambiguous
advice for people running tuberculosis
control programmes along with practical
advice for fieldworkers. Case detection,
treatment, and monitoring have to
be redefined in terms of newer developments
such as molecular epidemiology and
DNA amplification. The emphasis should
still be in support of affordable
evidence-based investigations and
treatment considering the fact that
poorer and less developed economies
are involved. National and International
initiatives should aim at preventing
drug resistance, weeding out irrational
prescribing practices and forming
guidelines for standardizing treatment
in order to curb HIV infection and
multi drug-resistance (MDR), the two
most important reasons for the persistent
TB epidemic.
Source: Health
Initiative.Org
TB
- Global Scenario
About 2.2 million
new cases of TB occur every year.
The Revised National Tuberculosis
Control Programme (RNTCP) envisages
to enhance the cure rate to 85 per
cent as compared to less than 40 per
cent in the earlier programme. The
new concept of Directly Observed Treatment
Short Course (DOTS) has been initiated
to bring better compliance, increased
treatment success rate and to avoid
drug resistance. The programme is
presently covering a population of
200 milllion. It has been decided
to cover a population of about 500
million under DOTS by 2002.
This fact Sheet on
Tuberculosis (TB) and DOTS treatment
is included here because HIV increases
a person's susceptibility to infection
with Mycobacterium tuberculosis. Compared
to an individual who is not infected
with HIV, an individual infected with
HIV has a 10 times increased risk
of developing TB. The presence of
TB may allow HIV to multiply more
quickly. This may result in more rapid
progression of HIV and AIDS. Pulmonary
TB is the most common in HIV patients,
although other forms of TB, such as
lymphadenopathy and meningitis, are
frequently found.
The information which follows addresses
the diagnosis, treatment and prevention
of TB.
A
Major Killer
Tuberculosis (TB) is a serious public
health, social and economic problem,
estimated to cause 8 million cases
world wide each year. Although the
DOTS (Directly Observed Treatment
-Short Course) strategy has been proven
to cure more than 85% patients, only
a small fraction of cases (16%) have
access to these curative regimens.
There are more than 1.9 million deaths
due to TB each year. TB kills more
youth and adults than any other infectious
disease. The disease burden is heaviest
in developing countries , where 95%
of the cases occur. Even in developed
countries, TB is re-emerging as a
public health concern. The main reasons
for the increasing global burden of
disease are:
increasing poverty, social upheaval
and crowded living conditions in
developing countries and inner city
populations in developed countries;
inadequate health coverage and
poor access to health services;
inefficient TB control programmes,
with low cure rates, because of
inadequate and interrupted treatment;
reluctance to report TB suspects
to poorly administered programmes;
impact of the HIV epidemics, mainly
in Africa and Asia;
lack of political leadership and
commitment to implement, sustain
and expand DOTS.
TB causes more maternal
deaths than any other single cause
of maternal mortality, estimated to
be in the order of more than one million
women per year. It is the commonest
cause of death in AIDS patients, because
it is reactivated by the failing immune
system. It impacts children because
they are left without care by their
parents' illness and an unknown number
of children themselves fall ill and
die of TB annually. The tools for
controlling TB are in hand, but wider
application of the DOTS strategy is
desperately needed. This will require
a coalition of health workers, policy
makers and the public who have a right
to freedom from TB.
Every second, someone in the world
is newly infected with TB.
Nearly one percent of the world's
population is newly infected with
TB each year.
Overall, one-third of the world's
population, about 2 billion people,
are infected with tuberculosis.
200 million people worldwide,
or 10% of those infected, will develop
active TB and be able to infect
others for 3 decades.
6 - 8 million news cases of TB
are diagnosed each year.
In the last 100 years, 200 million
people have died of TB.
TB
kills 8,000 people a day - that
is 2-3 million people each year.
It kills more people than either
AIDS or malaria. In fact, TB is
the biggest killer of young people
and adults in the world today.
TB spreads through the air and
is highly contagious. On average,
a person with infectious TB infects
10-15 others every year.
People infected with TB do not
necessarily become ill - the immune
system creates a barrier around
the bacilli that can remain dormant
for years. 10% of infected people
(who do not have HIV/AIDS) develop
active TB at some point during their
lifetime.
Patients develop a persistent
cough (sometimes with blood in the
sputum), fever, weight loss, chest
pain and breathlessness.
The currently recommended treatment
is a drug combination that must
be taken for 6-8 months.
Human and
Economic Impact
TB strikes people in their most
productive years, i.e. between the
ages of 15 to 44.
TB is the leading killer of women
aged 15 to 44, surpassing all causes
of maternal mortality.
TB kills more adults than all
other infectious diseases combined.
TB is the leading killer of people
infected with HIV worldwide.
More than one-quarter of all avoidable
adult deaths are caused by TB.
India has about 2.2 million new
cases every year including about
1 million sputum positive cases.
0.5 million people in India die
from TB every year.
One sputum positive case can infect
10 - 15 healthy individuals in one
year.
TB
& HIV
HIV and MDRTB will make the
TB epidemic much more severe unless
urgent action is taken.
One in three HIV-infected people
worldwide is coinfected with the
TB bacterium.
TB is responsible for the death
of one out of every three people
with HIV/AIDS worldwide.
People who are HIV-positive
and infected with TB are 30 times
more likely to develop active
TB than people who are HIV-negative.
The TB bacterium enhances HIV
replication and might accelerate
the natural progression of HIV
infection.
Because of the increased spread
of HIV in sub-Saharan Africa,
the number of TB cases in that
region will double to 4 million
new cases per year soon after
2005.
Almost half of HIV patients
in sub-Saharan Africa develop
active TB, whereas only 5% to
10% of individuals infected with
TB and not infected with HIV develop
active TB.
TB
& Women
TB is the single biggest killer
of young women.
Over one million women may needlessly
die from TB this year. They are
breadwinners, mothers, daughters
and wives.
TB
& Children
Over 100,000 children may needlessly
die from TB this year.
Hundreds of thousands of children
will become TB orphans this year.
Multi
Drug Resitant (MDR) - TB
Drug-resistance can develop
when patients get the wrong drugs,
drug supply is unreliable or patients
stop taking their medicines because
they feel better.
In countries that are poor,
MDR-TB that cannot be treated
with standard medicines can be
a death sentence.
MDR-TB is at least 100 times
more expensive to cure.
Cost
of TB
Eighty percent of TB victims
are in the most economically productive
years of their lives.
TB sends many self-sustaining
families into poverty. If the
breadwinner of a family is not
properly diagnosed or treated,
he or she will lose, on an average,
a full year of work.
What
if we do nothing?
A person who has TB and is never
diagnosed or treated loses on
an average a full year of work.
Over 900 million women are infected
with TB. This year two and a half
million women will get sick from
TB and one million will die. Most
of these women will be aged between
15 and 44 years.
Multi-Drug Resistant Tuberculosis
(MDR-TB) is at least 100 times
more expensive to cure than non
MDR-TB.
TB
in Prisons
The
institutional system with the greatest
impact on TB is the world’s
prison system.
TB is transmitted by the airborne
spread of infectious droplets, usually
when an infectious person coughs.
Crowding and poor ventilation favour
its transmission. People in institutions
cannot choose to walk away from these
conditions in order to protect themselves
from TB. Whether the setting is prisons,
detention centres for asylum seekers,
penal colonies, prisoner of war camps,
or secure hospitals, institutionalization
greatly increases vulnerability to
TB.
Though no judge would condemn a wrongdoer
to "infection with tuberculosis,"
that has become the sentence for many
prisoners. It has been argued that
"because tuberculosis is easily
diagnosed, treatable, and curable
but may lead to death if neglected,
contracting tuberculosis and not getting
treatment because of poor prison conditions
may be considered to be a violation
of human rights."
While these minimum level goals should
be pursued by every State, it is clear
from the burgeoning of TB, multidrug-resistant
TB (MDR-TB), and HIV within the world’s
prison systems that it will take considerably
more political will to ensure care
for prisoners’ health and, by
extension, that of the prisoners’
home communities.
On any given day, there are an estimated
8 to 10 million people incarcerated
worldwide and their numbers are increasing.
The prevalence of TB in prisons is
higher, sometimes considerably higher,
than in the general population. Mortality
rates for TB among prisoners are high.
For every person in prison on any
given day, four to six more will pass
through the system that year. Released
prisoners, as well as prison staff
and visitors can, in a sense, bring
the prison home.
As with data
on other subpopulations that are particularly
vulnerable to TB, collection and analysis
of prison data should be disaggregated
so that discrimination can be detected
and action taken.
In the U.S. State of Texas, for example,
an inmate was found to have had undiagnosed
TB for several months. Screening revealed
that 106 of his fellow inmates and
11 jail employees were infected with
M. tuberculosis. Alarmed, jail authorities
contacted 3 000 released inmates who
might have been infected over those
several months. Only 50 appeared for
screening, of whom 12 had positive
skin tests; 2 950 remain somewhere
in the community and are likely unaware
that they may be infected with TB.
Prisoners are predominantly male (90–95
per cent worldwide), young (15–44
years old), from socio economically
disadvantaged populations, and belong
to minority groups. Independent of
these pre-existing vulnerability factors,
prisons conditions themselves foster
transmission of TB and increase the
likelihood of an inmate developing
active TB. Prisons worldwide are characterized
by overcrowding and poor ventilation,
hygiene and nutrition. All these factors
directly contribute to TB transmission
and may promote reactivation of latent
infection and progression to disease.
Prisons are also a locus of HIV infection,
a significant risk factor for acquiring
and developing TB.
Pre-trial detention centres are often
of worse quality than the prisons
proper, and may pose special problems
for TB transmission. In addition,
individuals detained in such centres
can be among the most mobile within
the prison system, transferring often
from holding centre to court room
to jail or back into the community.
Control of TB inside prisons is critical
for control of TB in the general population,
but designing effective policies and
programmes requires information. It
is important that data on TB in prisons
be reported in a transparent way that
will allow it to be separated out
from data on cases within the general
community. Though countries are encouraged
to report on TB in prisons, data from
ministries in charge of prisons, usually
the Ministry of Justice, are rarely
incorporated into health statistics.
It is feared that this results in
"underestimates of the severity
of the problem of tuberculosis both
in prisons and in the general community."
Both the prison population and the
general community have the right to
protection from TB generated in prisons
and other institutions. Yet "recognition
of tuberculosis as a specific health
problem in prisons does not necessarily
lead to action."Prisoners are
not cured, remain infectious, and
may develop drug resistance. Prisons
have become "both amplifiers
and propagators of a problem created
within the larger community"—MDR-TB.
Prison health services may be reluctant
to begin treatment for a chronic illness
for inmates they feel may be released
soon, e.g. pre-trial prisoners or
those nearing the end of their sentences.
Prisons also do not provide a particularly
supportive environment for prisoners
who do begin treatment to complete
it, and many may stop as soon as their
symptoms abate. Some prisoners may
also avoid diagnosis because they
are afraid their release may be held
up until they complete treatment.
(Paradoxically, some prison inmates
may try to get on TB programmes even
if they do not have the disease, or
may deliberately expose themselves
to infection, because of the perceived—and
in some cases quite real—benefits
of better care in the hospital.)
An effective national TB programme
must include prisons and institutions
if it is to provide universal access
to effective TB diagnosis and treatment.
In 1997 in Baku, Azerbaijan, at a
meeting on TB control in prisons,
participants called on States to exercise
the political will to take the necessary
steps without which "tuberculosis
will increase death among prisoners
and their families, and the prison
staff and the community."
Holding a prisoner beyond his or her
release date in order to complete
TB treatment, or refusing treatment
because the person may not be in prison
long enough to complete it, need to
be considered in light of the Siracusa
Principles. Certainly, in both cases,
a "less intrusive and restrictive
means to reach the same goal"
is available—the orderly integration
of released prisoners into a TB programme
in the public health system. In the
absence of such an alternative, "public
health and prison health officials
face many dilemmas in delivering services
that risk challenging, or even impinging
on, the rights of prisoners. The poorer
the country and the fewer the resources
allocated to prison health, the more
extreme may be those dilemmas."
No matter how limited the country’s
resources, however, prisoners have
the right to health care that meets
community standards and is equivalent
to what is available to the general
population.
TB is not an unavoidable consequence
of incarceration and can be controlled
through the application of DOTS
based programmes and improvements
in prison conditions.
Effective TB control in prison
protects prisoners, staff, visitors
and the community at large
The level of TB in prisons has
been reported to be up to 100 times
higher than that of the civilian
population.
Cases of TB in prisons may account
for up to 25% of a country's burden
of TB.
Late diagnosis, inadequate treatment,
overcrowding, poor ventilation and
repeated prison transfers encourage
the transmission of TB infection.
HIV infection and other pathology
more common in prisons (e.g. malnutrition,
substance abuse) encourage the development
of active disease and further transmission
of infection.
Multidrug
resistant tuberculosis (MDR-TB) in prisons
High levels of MDR-TB have been
reported from some prisons with
up to 24% of TB cases suffering
from MDR forms of the disease.
Factors that encourage the spread
of TB in prisons also promote
the spread of MDR forms.
Prisoners may self-treat because
of barriers to access to medical
care with supplies of anti-TB
drugs available through visitors
or internal markets. However such
supplies are usually erratic and
unregulated and promote further
development of MDR-TB.
Why
is TB in prisons important?
Prisons act as a reservoir for
TB, pumping the disease into the
civilian community through staff,
visitors and inadequately treated
former inmates. TB does not respect
prison walls.
Improving TB control in prisons
benefits the community at large.
Community TB control efforts cannot
afford to ignore prison TB.
Prisoners have the right to
at least the same level of medical
care as that of the general community.
Catching TB is not part of a prisoner's
sentence.
Drawing attention and resources
to the problem of TB in prisons
is likely to lead to an overall
improvement in prison conditions,
the health of inmates and human
rights.
What
is the solution?
The priority strategy must be
the widespread implementation
of the DOTS package in the incarcerated
population. Every prisoner should
have unrestricted access to the
correct diagnosis and treatment
of TB.
Delays in the detection and
treatment of TB cases must be
minimised to reduce further transmission
of infection and pressures to
self-treat TB.
Unregulated, erratic treatment
of TB in prisons should cease.
Urgent action is needed to integrate
prison and civilian TB services
to ensure treatment completion
for prisoners released during
treatment.
Measures to reduce overcrowding
and to improve living conditions
for all prisoners should be implemented
to reduce transmission of TB.
Where MDR-TB is established
and a functional DOTS programme
is in place and accessible to
all prisoners, a DOTS-Plus pilot
programme should be considered.
Tuberculosis,
HIV seroprevalence and intravenous drug
abuse in prisoners.
HPA MRU, Dept of Microbiology and
Infection, King's College Hospital
(Dulwich), East Dulwich Grove, London
SE22 8QF, UK. francis.drobniewski@kcl.ac.uk.
High rates of tuberculosis (TB)
and HIV are believed to exist in
Russian prisons. Prisoners with
TB were studied in order to identify
the following:
prevalence
of HIV, and risk factors for HIV
and other blood-borne virus infections.
clinical and
social factors that might compromise
TB treatment effectiveness and/or
patient adherence and, hence,
encourage treatment failure. A
1-yr cross-sectional prevalence
study of 1,345 prisoners with
TB was conducted at an in-patient
TB facility in Samara, Russian
Federation. HIV and hepatitis
B and/or C co-infection occurred
in 12.2% and 24.1% of prisoners,
respectively, and rates were significantly
higher than in civilians. Overall,
48.6% of prisoners used drugs,
of which 88.3% were intravenous
users. Prisoners were more likely
to be intravenous drug users and
HIV positive compared with civilians
with TB, and 40.2% of prisoners
shared needles. Two-thirds of
prisoners (68.6%) had received
previous TB drug therapy (frequently
multiple, interrupted courses)
and were significantly more likely
than civilians to have had previous
therapy consistent with the high
drug-resistance rates seen. Prisons
are major drivers of the tuberculosis
and HIV epidemics. Novel strategies
are needed to reduce the spread
of blood borne diseases, particularly
in intravenous drug users.
PMID: 16055879 [PubMed - in process]
General
TB spreads
through the air and is highly
contagious. On average, a person
with infectious TB infects 10-15
others every year.
People infected
with TB do not necessarily become
ill - the immune system creates
a barrier around the bacilli that
can remain dormant for years.
10% of infected people (who do
not have HIV/AIDS) develop active
TB at some point during their
lifetime.
Patients develop
a persistent cough (sometimes
with blood in the sputum), fever,
weight loss, chest pain and breathlessness.
The currently
recommended treatment is a drug
combination that must be taken
for 6-8 months.
HIV/AIDS, TB and malaria kill 6 million people every year;
nearly 2 million deaths are caused by TB.
To read the Fact
Sheet presented by WHO - Click Here
Multidrug-Resistant Tuberculosis Fact Sheet
April 2007
Multidrug-resistant tuberculosis (MDR TB) is a form of tuberculosis that is resistant to two or more of the primary drugs (isoniazied and rifampin) used for the treatment of tuberculosis. Extensively drug-resistant TB (XDR TB) is TB resistant to at least isoniazied and rifampin among the first-line anit-TB drugs and among second-line drugs, is resistant to any fluoroquinolone and at least one of three injectable drugs.
Resistance to one or several forms of treatment occurs when the bacteria develops the ability to withstand antibiotic attack and relay that ability to newly produced bacteria. Since that entire strain of bacteria inherits this capacity to resist the effects of the various treatments, resistance can spread from one person to another. On an individual basis, however, inadequate treatment or improper use of the anti-tuberculosis medications remains an important cause of drug-resistant tuberculosis. Drug-restistant TB is difficult and costly to treat and can be fatal.
In 2005, the CDC reported that 7.8 percent of tuberculosis cases in the U.S. were resistant to isoniazid, the first line drug used to treat TB.
The CDC also reported that 1.2 percent of tuberculosis cases in the U.S. were resistant to both isoniazid and rifampin. Rifampin is the drug most commonly used with isoniazid.
Overall, 124 cases of MDR-TB cases were reported in 2005, which remained constant from the previous year.
Only 27 percent of primary MDR-TB cases were in U.S. born persons. The percentage of U.S. born persons with MDR-TB has remained stable at approximately 0.6 percent since 2000. The proportion of MDR-TB cases continued to disproportionately affect foreign-born persons in the United States. Among this group, MDR-TB cases has increased from 26 percent in 1993 to 81.5 percent of cases in 2005.
The World Health Organization estimates that up to 50 million persons worldwide may be infected with drug resistant strains of TB. Also, 300,000 new cases of MDR-TB are diagnosed around the world each year and 79 percent of the MDR-TB cases now show resistance to three or more drugs.
A strain of MDR TB originally develops when a case of drug-susceptible tuberculosis is improperly or incompletely treated. This occurs when a physician does not prescribe proper treatment regimens or when a patient is unable to adhere to therapy. Improper treatment allows individual TB bacilli that have natural resistance to a drug to multiply. Eventually the majority of bacilli in the body are resistant.
Once a strain of MDR TB develops it can be transmitted to others just like a normal drug-susceptible strain. Airborne transmission has been the cause of several well-publicized cases of nosocomial (hospital-based) outbreaks of MDR TB in New York City and Florida. These outbreaks were responsible for the deaths of several patients and health care workers, a majority of whom were co infected with HIV.
MDR-TB has been a particular concern among HIV-infected persons. Some of the factors that have contributed to the number of cases of MDR-TB, both in general and among HIV-infected individuals are:
Delayed diagnosis and delayed determination of drug susceptibility, which may take several weeks
Susceptibility of immunosuppressed individuals for not only acquiring MDR-TB but for rapid disease progression, which may result in rapid transmission of the disease to other immunosuppressed patients
Inadequate respiratory isolation procedures and other environmental safety conditions, especially in confined areas such as prisons
Noncompliance or intermittent compliance with antituberculosis drug therapy.
MDR-TB is more difficult to treat than drug-susceptible strains of TB. The success of treatment depends upon how quickly a case of TB is identified as drug resistant and whether an effective drug therapy is available. The second-line drugs used in cases of MDR-TB are often less effective and more likely to cause side effects.
Tests to determine the resistance of a particular strain to various drugs usually take several weeks to complete. During the delay the patient may be treated with a drug regimen that is ineffective. Once a strain's drug resistance is known, an effective drug regimen must be identified and begun. Some strains of MDR-TB are resistant to seven or more drugs, making the identification of effective drugs difficult. To deal with this problem, it is recommended that newly discovered cases of TB in populations at high risk for MDR-TB be treated with four drugs rather than the standard three as part of initial treatment.
Treatment for MDR-TB involves drug therapy over many months or years. Despite the longer course of treatment, the cure rate decreases from over 90 percent for nonresistant strains of TB to 50 percent or less for MDR-TB.
Because it is difficult for some people to successfully complete their tuberculosis treatment, several innovations have been developed. One of these is the use of incentives and enablers, which may be transportation, tokens or food coupons that are given to patients each time they appear at the clinic or doctor's office for treatment. Incentives and enablers are combined with the use of directly observed therapy (DOT). DOT is a system of treatment in which the patient is administered his or her medication by a nurse or other health worker and observed taking the medication.
FDA has approved Rifater, a medication that combines the three main drugs (isoniazid, rifampin, and pyrazinamide) used to treat tuberculosis into one pill. This reduces the number of pills a patient has to take each day and makes it impossible for the patient to take only one of the three medications, a common path to the development of MDR-TB.
In June 1998, the U.S. Food and Drug Administration approved the first new drug for pulmonary tuberculosis in 25 years. The drug, rifapentine (Priftin), has been approved for use with other drugs to fight TB. One potential advantage of rifapentine is that it can be taken less often in the final four months of treatment --once a week compared with twice a week for the standard regimen.
In 2006, a study in Africa revealed the presence not only of multidrug-resistant (MDR) tuberculosis but also what is now known as extensively drug-resistant (XDR) tuberculosis in patients infected with HIV. The Centers for Disease Control and Prevention and the World Health Organization reported the existence of XDR-TB in 17 countries including 4 percent of cases here in the United States.
