The World Health Organisation recently issued a recommendation against the use of blood tests based on antibody response for diagnosing active tuberculosis, both pulmonary and extra-pulmonary. India's Revised National Tuberculosis Control Programme (RNTCP) has endorsed WHO's advice. Unfortunately, with TB, unlike diseases like HIV, the presence or absence of antibodies does not reflect true disease condition. So these blood tests lack the necessary sensitivity or specificity or both to be used as an effective diagnostic tool. When the sensitivity is low, many people with active TB are likely to be wrongly diagnosed and hence will go untreated (false negative); tests with low specificity will result in people with no active TB getting treated with toxic drugs (false positive). That explains why serological testing based on antibody responses has so far not been recommended by the U.S. Food and Drug Administration and other reputed regulators. However, considering that in high prevalence settings like India, while the specificity of sputum smear microscopy testing is better than 99 per cent, the sensitivity is only 60-70 per cent, finding more reliable and inexpensive diagnostic blood tests for TB is a public health imperative.
The world body's recommendation is based on a body of evidence, including a study by its special programme for research & training in tropical diseases (TDR), which looked at 19 commercially available rapid blood tests. The WHO concluded that patient safety is adversely impacted by “commercial serological tests [which] provide inconsistent and imprecise findings.” Unfortunately, notwithstanding the unreliability and prohibitive cost, the private sector in India uses the blood tests on “at least 1.5 million people every year,” according to a report in The Lancet published in January 2011. These tests appear to have been done mostly at the expense of sputum examination. For example, a 2006 WHO report, “Diagnostics for tuberculosis — global demand and market potential,” found that in Tamil Nadu and Delhi, less than one-third of patients underwent sputum examination despite multiple visits while doctors based in west India relied solely on chest X-rays for diagnosis. That the government has to curb the availability of serological antibody tests and undertake awareness-building campaign among doctors and the public on the benefits of sputum tests cannot be over-emphasised. This is vital to public health — considering that in India the incidence rate of TB is a high 168 per 100,000 population and the disease kills two people every three minutes.
Keywords: WHO, Tuberculosis
We need urgent national recognition of TB problem as mortality rate as quoted in Hindu and national statistics 2/3 cases caliculates to 66% mortality rate in a curable disease with proven drugs.It is a shame that concentrated efforts are not undertaken at central and state levels to curtail this huge public health problem as we squander our resources with corruption at every level and false promises to public.what people need is a responsible governament tackling public health issues.
As per number quoted in article incidence of TB is 1.68 million as per 168/100,000 population and 2/3 die every minute this will be a massive number by any standards.We need national awareness for preventing and treating the disease and a need to simplify and standerdise procedures instead of disagreements and make it cost effective and practical as we still be missing cases as nothing is 100% particularly medicine.
The article I am quoting is published in IJMR summary of results for better detection of clinical cases. A significant difference was seen in the sensitivity of different tests, the figures being 74.2 per cent for PCR test, 53.4 per cent for BACTEC culture, 47.1 per cent for LJ medium based culture and 35.2 per cent for ZN smear examination (P<0.05). However, there was no significant difference between different tests as far as specificity was concerned. PCR test sensitivity in pulmonary and extra-pulmonary clinical samples were 74.3 and 71.5 per cent respectively, being significantly higher (P<0.05) when compared with sensitivity of other tests. The mean detection time for M. tuberculosis was 24.0 days by LJ media culture, 12.8 days by BACTEC culture and less than 1 day by smear examination and PCR test.This article can be read in full in google however may be impractical as you need sophisticated lab and dedicated staff.May each state capital can start a reference lab free.
The public health goal is to prevent disease in a country with high prvelance of disease as I worked in TB hospitals and none exists in western countries due to low prevelance of disease in their population from LATE 1960'S.AS 2 PERSONSdie every 3 minutes as reported in Hindu and our national statistics it is imperative and practical to prevent disease by simple 1)intradermal Montouax testing as even para medical personal can perform and read and if +ve prophylaxis with INH once a week under direct supervision for eligible individulas can prevent 30% cases in 5 yrs.2)Diagnosing a case is already too far gone based on simple clinical facts+sputum may identify vast majority of cases.Quantiferon Gold a serum test recommended by cdc but expensive and apparently Bill Gates foundation is subsidising costs as per reports still cannot supersede good clinical evaluation of symptoms and simple tets of sputum widely avialable.we eliminated smallpox,tb can be.
TO Mr. V A Menon: serological tests do reflect true disease in some case such as malaria,typhoid.. But talking about Mantoux test(blood test for TB),we cannot rely upon it totally as it shows positive result even if the person has recieved BCG(vaccine for TB) and has no TB..It may falsely become negative in case of concurrent measles...
Sputum microscopy is not the ideal option - it's used because it's by far the most cost-effective option for low-middle income countries. Unfortunately this 100 year old technology requires 'good quality' sputum (a problem if people have HIV/AIDS, very difficult to get babies/kids to cough up enough sputum containing sufficient bacilli), good quality smear preparation and good quality readers (technicians to read the slide). With very poor resources in rural areas, sputum has to be sent to other centres to process it and get the results back. Sputum microscopy does not give indication of different strains of TB (drug resistant) and has been shown to be ineffective in monitoring the efficacy of a drug regimen. Yet, it's not a bad option and is relatively inexpensive. I've been working on automating the process (imaging etc.) with limited success. There're newer tests (but more expensive) that are far superior. Some countries (e.g. South Africa) have rolled out these technologies.
What India needs is a Patient's Charter (which sets out patients' rights and standard of service they can expect) and Institutions like NICE (National Institute for Clinical Excellence) as in the UK which give guidelines for best clinical practices. Doctors and hospitals have to conduct their professional practices according to the guidelines which are evidence based. Relying solely on chest X-rays for diagnosis of TB is ridiculous as it has long been well known that X-ray is a poor diagnostic tool in this respect. The issue the article addresses should be seen as a symptom of the appalling state of healthcare in India. Government and the opposition have to give serious consideration to this critically important sector.
People and Doctors of India must be told that the Blood Test is not an option for TB diagnosis. Sputum microscopy testing is the only answer for the TB diagnosis.As RNTCP has opposed the blood tests for diagnosing TB, the government is on the right track. But awareness-building in the public is imperative and it is a responsibility of the government.
'Health is wealth' and 'Sound mind in a sound body' must be imprinted on every brain of India.The young generation must be made health concious jointly with the efforts of UNO and Indian government.
A very good editorial once more from The Hindu. Perhaps the only way people can be informed is through newspapers and advertisements in the visual media. Unfortunately, the fact that both diagnosis and treatment of TB are free is not known to a large proportion of people, especially those who might require it.
In addtion, even many doctors are probably not aware that sputum examination has been proved to be the best diagnostic test for pulmonary TB. Unfortunately, there is a common belief that Govt facilities are poor and that only costly investigations and treatment are superior to scientifically proven methods.
May I compliment the Hindu for this forthright editorial and request other readers to disseminate this news to those who might benefit from it most, namely, probably patients with TB?
TB is certainly curable but awareness on basic hygiene factors is lacking in our country . Besides the Media campaigns we can have celebrities support TB prevention campaigns in a big way . There can be foucssed campaigns in states and districts which are affected more by TB .
I am seeking information: Are serological tests reliable enough to say that a patient found positive is definitely a case of tuberculosis and negative is positively not a case?
If answers are 'yes' then it should be used to asses the quality of currently used diagnostic methodologies and seek improvements possible,eg use of computer assisted diagnosis for interpreting digital skiagrams. Methods such increasing the resolution of the images can help in increasing specificity. Serological test can be used to grade the efficacy of diagnostic tools. With less than 70% efficacy in detecting tuberculosis by sputum examination, developing some alternatives for improving diagnosis has to be got fast.
Almost certainly one will have to look at the rollout of more modern tests (although and unfortunately more expensive) to address the emerging strains. That combined with measures to address patient isolation (particularly for MDR/XDR), a comprehensive review and overhaul of infection control methods (e.g. using UVGI systems, ventilation) are a must to tackle this disease. Unfortunately increased urbanisation, leading to high population density and poor living conditions (e.g. insufficient ventilation) will continue to increase the incidence rate. It's a complex problem. A humbling fact is that TB (like HIV) doesn't discriminate and EVERYONE of us is vulnerable. A scarier aspect is that there're signs that BCG vaccination is becoming less effective!
The government should also renew its efforts to engage each and every member of the society, irrespective of the profession, social status and religion, to strengthen the knowledge of causes, symptoms and early care of TB. There is absolutely very little awareness of this disease.
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