In
5-10% of LTBI cases, M.tb will
enormously replicate and massive destruction of the lung causes the
characteristic clinical signs of pulmonary TB. Tuberculosis
control means a reduction in the prevalence and incidence of disease in
the community.
CONTROL
MEASURES
•CURATIVE COMPONENT: case finding and treatment.
•PREVENTIVE COMPONENT: BCG
vaccination.
CASE FINDING TOOLS:
# Sputum examination –
reliability, cheapness and easy of direct microscopic examination has made it
number one case finding method all over the world.
# Fluorescence microscopy –
performed with auramine
stain and advantages are the speed of examination. The field of view is 5-10 times
bigger. Scanning of one length of smear will require only 1-2 minutes.
# Chest x-ray:
useful for the diagnosis of smear-negative pulmonary TB and TB in children.
# The standard test for detecting LTBI is
tuberculin skin testing(Mantoux)
using purified protein derivatives of M.tb.
Tuberculosis Blood Test
•IGRA –
Interferon-gamma release assay – is a way to find out if you have TB
germs in your body. TB blood test can be done instead of a Mantoux
test.
Two kinds – quantiferon – TB
- T-spot TB
Children, less than 5 years
should have a mantoux test
instead of the TB blood test. Most people with a positive TB blood test have
latent TB infection.
# MDR – TB(multidrug resistance TB) –
bacillary resistance to both rifampicin and isoniazid. The management of MDR-TB
usually necessitates use of injectable agents(amikacin, kanamycin or
capreomycin) for 4 to 6 months and second line oral drugs (Ethionamide, cycloserine,
fluoroquinolones, kanamycin and viomycin) FOR SEVERAL YEARS.
# XDR –TB(extensively drug-resistant) with
reduced susceptibility to second-line drugs is even more difficult to treat.
Shorter, simpler and preferentially oral regimens for MDR-TB and XDR-TB are
urgently needed.
CURRENT VACCINE BCG
Types
of New development in Vaccines:
PROPHYLACTIC VACCINES
•Given
in an apparently healthy person to prevent infection, primary disease, latent
infection and reactivation.
•Two
types-
•Pre-exposure TB vaccine- use
in newborns or young infants (MVA85A,
rBCG30)
•Post-exposure TB vaccines-
given post-infancy like school children, adolescents or adults, who have either
been vaccinated or latently infected or both, these vaccines reduce the progression
to active disease (H56, ID93)
MVA85A (modified vaccinia Ankara 85A) is a new-generation vaccine against tuberculosis developed by researchers at Oxford
University. This vaccine produces higher levels of long-lasting cellular
immunity when used together with the older TB vaccine BCG. Phase
I clinical trials have been completed and phase
II clinical trials are currently underway in South Africa,
were not
expected to be finished until late 2015, with efficacy trials running in
parallel from 2009 to 2019.
By contrast,
results
published
in 2015 bring further
doubt
on the efficacy of the vaccine.
rBCG30 (recombinant Bacillus Calmette-Guerin 30) is a
live vaccine,
consisting of BCG genetically modified to produce abundant amounts of a 30kDa
antigen (Antigen 85B) that has been shown to produce a strong immune response
in animals
and humans.
The H56 fusion protein is the vaccine developed to boost BCG in individuals with and without an existing TB
infection and is
currently undergoing clinical phase 2 testing.
ID93 Vaccine
gives protection
and long-lived
Immunity
in
candidate against Clinical Mycobacterium tuberculosis (HN878) Isolate.
THERAPEUTIC VACCINES:
- M. INDICUS PARANII vaccine
- M. VACCAE
- RUTI
- DAR-DAR
Having a test as sensitive as culture and
a rapid as microscopy and treatment that is shorter and able to eliminate
dormant bacilli will have a major impact on TB CONTROL.
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