Navigation Links
A new more effective tuberculosis screening test for HIV victims
Date:3/5/2008

World Health Organization (WHO) figures show that each year an estimated 9 million new cases of tuberculosis (TB) arise in the world. The growth of this disease remains particularly strong in Africa owing to a high proportion of HIV patients (nearly 13% compared with less than 1% in Asian countries for example). This region of the world is experiencing accelerating advance of a deadly combination of AIDS and TB, developed because the virus weakens the immune system of TB-infected individuals. A person infected by HIV who is also contaminated with Kochs bacillus bears a greater risk of developing active TB than a non HIV-infected individual. Latent TB infection diagnosis has for several decades been founded on a positive response to the tuberculin skin test (TST). However, TSTs reliability is limited in highly TB-endemic geographical settings because the presence in the environment of mycobacteria similar to that which causes TB plus the BCG vaccination people receive in early infancy can skew the results. Moreover, in HIV-carrying patients, the sensitivity of the test is drastically reduced owing to their inability to develop an allergic reaction, the very basis of the skin test. TB is a strong contributing factor to HIV mortality, therefore it is of crucial importance to be able to diagnosis latent infection early in order to adopt an appropriate treatment and prevent the development of the full disease.

The development of new IGRA3 tests is based on in vitro measurement of T-cells secretion of interferon- when challenged with antigens specific to Mycobacterium tuberculosis, the bacterium causing tuberculosis. Such assays now provide a means of getting round the drawbacks of the tuberculin skin test (TST). Yet, although these new screening methods are more effective than TST in a situation of low TB endemicity, their validity in populations subject to high risk of latent TB infection still has to be clearly established. Results recently published of an investigation conducted in Senegal, coordinated by IRD in conjunction with other scientific institutions,1 yield important information on the comparative efficiency of the immunological method and the standard TST. The research team set up two cohorts of patients living in the Dakar area: the first one made up of HIV-infected individuals but with no detected TB; the second consisting of TB patients and people from the treatment centre who had been in contact with them during a given period.

For the first cohort, 285 adults newly infected by HIV and showing no clinical or radiological sign of TB were selected at the Fann National University Hospital Centre (Dakar) between 2003 and 2004. An ELISPOT test and a TST were performed for each patient at the beginning of the study. The TST indicated that 21% (53/247) of them had a TB infection at the moment of the test. However, this proportion reached 51% (125/247) with the ELISPOT test. It appears therefore that the latter is more sensitive than the TST whatever the stage of development of the disease. Nevertheless the ability to respond to the ELISPOT test decreases with the decrease in CD4 lymphocyte count, which appears to indicate the limits of this type of test in severely immunosuppressed individuals, as advanced-stage HIV infected patients can be.

In parallel, a cohort of 243 TB patients was followed up for 2 years. The objective this time was to determine the ability of the ELISPOT test to predict, among people living in contact with these individuals, those who run the greatest risk of developing the disease. Between January 2004 and March 2005, 3072 contacts were identified for the whole set of TB patients. Preliminary results showed the sensitivity of the two tests to be comparable with this cohort, although ELISPOT is doted with a better specificity since it is not influenced by recent BCG vaccination.

The data gathered from the studies must now be analysed in greater detail in order to determine if the new tests based on measurement of the immune response to M. tuberculosis-specific antigens can serve as a reliable diagnostic method for TB infection in geographical areas where the disease is endemic and BCG coverage is strong. Such investigations should also found out if in the future these tests could be used as markers of the development of the disease within a given population.


'/>"/>

Contact: Press Office
fichesactu@paris.ird.fr
33-014-803-7607
Institut de Recherche Pour le Dveloppement
Source:Eurekalert

Related medicine news :

1. Colgate Announces 11% Dividend Increase Effective 2nd Quarter 2008
2. Cause of effectiveness discovered for a cirrhosis treatment useful in 40 percent of patients
3. Effective Healthy Eating and Physical Activity Initiatives Can Reduce Health Disparities
4. Prime Therapeutics Introduces Efficiency Program to Help Employers Understand How to Most Effectively Spend Pharmacy Dollars
5. UC study: New devices less effective in thwarting brain aneurysm recurrence
6. Building an Effective Sales Force to Serve the U.S. Hospital Market
7. Vaccine/antibody therapy effective, milder side effects in melanoma and ovarian cancer
8. Chemotherapy After Breast Cancer Surgery Effective for Older Women, Too
9. Natural Nutrition Announces Effectiveness of Forward Split of Common Stock Following 2007 Record Revenue Year
10. Two Studies Cast Further Doubt on the Effectiveness of Low GI/GL Diets for Weight Loss
11. Inexpensive Online Pain Education Program for Physicians as Effective as Live Presentations by National Experts
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/26/2016)... ... June 26, 2016 , ... On June 10-11, 2016, A ... 2016 Cereal Festival and World’s Longest Breakfast Table in Battle Creek, MI, where the ... history as home to some of the world’s leading providers of cereal and other ...
(Date:6/26/2016)... ... June 26, 2016 , ... ... have been diagnosed with endometriosis. These women need a treatment plan to not ... comprehensive approach that can help for preservation of fertility and ultimately achieving a ...
(Date:6/25/2016)... (PRWEB) , ... June 25, 2016 , ... "With 30 ... their specific project," said Christina Austin - CEO of Pixel Film Studios. , ... and all within Final Cut Pro X . Simply select a ProHand generator ...
(Date:6/25/2016)... , ... June 25, 2016 , ... On Friday, June ... a Bronze Wellness at Work award to iHire in recognition of their exemplary accomplishments ... of the 7th annual Maryland Workplace Health & Wellness Symposium at the BWI Marriott ...
(Date:6/24/2016)... ... , ... June 19, 2016 is World Sickle Cell Observance Day. In an ... of holistic treatments, Serenity Recovery Center of Marne, Michigan, has issued a ... Cell Disease (SCD) is a disorder of the red blood cells, which can cause ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... 2016 Research and Markets ... Electronics 2015-2025: Applications, Technologies, Forecasts" report to ... In-Mold Electronics, Smart Skin, Structural Health Monitoring, Composite ... Structural electronics involves electronic and/or electrical components and ... dumb structures such as vehicle bodies or conformally ...
(Date:6/24/2016)... -- According to a new market research ... Safety Pen Needles), Needle Length (4mm, 5mm, 6mm, 8mm, ... Purchase (Retail, Non-Retail) - Trends & Global Forecasts to ... for the forecast period of 2016 to 2021. This ... 2021 from USD 1.65 Billion in 2016, growing at ...
(Date:6/23/2016)... 23, 2016 Research and Markets has ... - Forecast to 2022" report to their offering. ... for the patients with kidney failure, it replaces the function ... the patient,s blood and thus the treatment helps to keep ... in balance. Increasing number of ESRD patients ...
Breaking Medicine Technology: