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New tool available in the fight against TB
New tool available in the fight against TB
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD>By Thuria Ghaleb
Nov 7, 2006, 12:41
</TD></TR></TBODY></TABLE>
Researchers at Oxford University have developed a new vaccine for TB that they say can substantially strengthen defense against infection when combined with BCG (Bacillus Calmette-Guerin), the vaccine currently in wide use.
The new vaccine will be especially effective in the developing world, where there is an increasing number of cases. The BCG vaccine can prevent TB for 15 years but it is not effective for all people. In Britain, it is believed that BCG is effective in just a third of people who take it.
This vaccine does not prevent infection, but it does strengthen the immune system of first-time TB patients. As a result, serious complications are less likely to develop. BCG is used widely in developing countries. The new vaccine, called M*A 85 A, was studied and tested for three years at Oxford University.
A clinical study divided participants into three groups. Two groups had not been vaccinated with BCG. One group was subsequently vaccinated with BCG, and the other was given the new vaccine. The third group was given M*A 85 A, compounded with the BCG that they had taken in the past.
The results show that the new vaccination is safe and produces a large number of T cells that work to prevent disease. More T cells were produced in subjects that had been vaccinated with BCG prior to receiving the new vaccine. There is a plan to test the new vaccine in Gambia, West Africa, where TB is widespread.
Seventy-year old Ahsan al-Khawlani?s story with tuberculosis started one year ago. He came to the National Tuberculosis Institute in Sana?a, searching for help. ?His disease was the most serious and infectious kind of tuberculosis, pulmonary smear positive last year,? said Dr.Hamood Mahyub, doctor and manager of the NTI.
?I followed up his condition for two months while he was under the Directly Observed Treatment Short-course program (DOTS). When he felt better he left the institute. We tried to convince him to continue his treatment under our supervision, but he refused. He came back later in worse condition after a serious relapse, due to carelessness in taking the medicine,? Dr. Mahyub said. Pulmonary tuberculosis is a common and deadly contagious bacterial infectious disease of humans and animals, caused principally by a type of bacterium called Mycobacterium tuberculosis or tubercle bacillus (TB).
It produces lesions on bodily organs, especially the lungs. It can involve the central nervous system, lymphatic system, circulatory system, genitourinary system, bones and joints. TB is an airborne disease. The bacteria get into the air when an infected person coughs, sneezes, shouts, speaks or spits. The bacteria is not transmitted by casual contact.
In susceptible individuals, the organisms may then multiply and spread through lymphatics to the lymph nodes, and through the bloodstream to other areas, such as lungs, bones, and kidneys. Without effective therapy, the disease becomes progressively worse. The risk of contracting TB increases with the frequency of contact with people who have the disease, with crowded or unsanitary living conditions and with poor nutrition.
?This disease is an economic one. It is influenced by the economic state of the patient, ?said doctor Mahyub. About 40,000 infectious particles can be produced by a single sneeze. One cough from a pulmonary TB patient produces up to 3000 droplets. People with prolonged, frequent, or intense contact are at highest risk of becoming infected, with an estimated 22 percent infection rate.
A person with untreated, active tuberculosis can infect 10-15 other people per year. If untreated, the death rate for these active TB cases is more than 50 percent. Tuberculosis of the lung is characterized by minor cough, mild fever, fatigue, unintentional weight loss, coughing up blood, night sweats, phlegm producing cough, wheezing, excessive sweating, chest pain and difficulty breathing.
However, a person infected with TB may show no symptoms, since the bacilli can remain inactive for several years. Between five and ten percent of those infected with TB can expect to develop active TB at some point in their lives. This percentage changes, however, with other factors contributing to a weakened immune system.
Tuberculosis is not, however, highly contagious compared to some other infectious diseases. Only about one in three close contacts with a TB patient, and fewer than 15 percent of more remote contacts, are likely to lead to infection. At the NTI, the employees complain about the hazards of their work environment. ?We are constantly to this infectious disease,? Ahmed Abu Taleb said. Co-worker Abdu al-Shawkani agreed.
?There are no precautionary measures to avoid infection. We are compelled to work hard here at low wages. Ten people working in different departments here have been infected,? he said. Doctors complain of their patients? negligence regarding their state of health. ?They do not continue their DOTS treatment once they start feeling better. They are often uneducated, which makes our work more difficult,? said Dr. Hamoud.
?The media does not help to eliminate this problem by educating people about the dangers of this disease, its causes and means of avoiding infection. The available resources are insufficient. The government and the Global Fund to Fight Tuberculosis try to help but it is still not enough,? he said.
Some patients also complained, ?Medicine is not available in the tuberculosis centers in some of the governorates,? said Hayel al-Kawm, a patient suffering from pulmonary smear positive TB. ?I?ve been suffering from this disease for five months. I am forced to wait for two to four weeks just to get medicine. It is a disaster for me when I cannot find it,? he said.
Infection does not always mean disease; in fact, it usually does not. At least nine of ten patients who harbor Mycobacterium tuberculosis do not have symptoms or physical evidence of active disease, and their x-rays remain negative. They are not contagious; however, they do form a pool of infected patients who may get sick at a later date and then pass on TB to others.
It is thought that more than 90 percent of cases of active tuberculosis come from this pool. An estimated 5 percent of infected persons get sick within 12-24 months of being infected. Tuberculosis can be a difficult disease to diagnose, due mainly to the difficulty in culturing this slow-growing organism in the laboratory. A complete medical evaluation for TB must include a medical history, a chest x-ray, and a physical examination.
Individuals exposed to tuberculosis should be skin tested immediately, (a positive skin test indicates prior TB exposure), and a follow-up test should be done at a later date, if the initial test is negative. Prompt treatment is extremely important in controlling the spread of tuberculosis for those who have already progressed to active TB disease.
According to the World Health Organization, 8 million people become ill with tuberculosis, and 2 million people die from the disease worldwide, every year. In 2004, around 14.6 million people had active TB disease with 9 million new cases reported. Tuberculosis is the world?s greatest infectious killer of women of reproductive age and the leading cause of death among people with HIV AIDS. Yemen registered 9,063 cases of tuberculosis at the National Tuberculosis Institute in 2005, according to Abdul-Bari al-Hammadi, statistics officer at the NTI.
?351 have had a relapse after being treated because of their ignorance and misuse of the medication,? he said. ?Hodeidah governorate has 603 cases, the highest number in the country. Sayoun has the fewest number of cases; there are only ten.
This means that for every 100,000 people in Yemen, there are 40 TB cases,? he said. Perhaps with the arrival of the promising new vaccine, those numbers will go down steadily.
http://www.yobserver.com/article-11172.php
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD>By Thuria Ghaleb
Nov 7, 2006, 12:41
</TD></TR></TBODY></TABLE>
Researchers at Oxford University have developed a new vaccine for TB that they say can substantially strengthen defense against infection when combined with BCG (Bacillus Calmette-Guerin), the vaccine currently in wide use.
The new vaccine will be especially effective in the developing world, where there is an increasing number of cases. The BCG vaccine can prevent TB for 15 years but it is not effective for all people. In Britain, it is believed that BCG is effective in just a third of people who take it.
This vaccine does not prevent infection, but it does strengthen the immune system of first-time TB patients. As a result, serious complications are less likely to develop. BCG is used widely in developing countries. The new vaccine, called M*A 85 A, was studied and tested for three years at Oxford University.
A clinical study divided participants into three groups. Two groups had not been vaccinated with BCG. One group was subsequently vaccinated with BCG, and the other was given the new vaccine. The third group was given M*A 85 A, compounded with the BCG that they had taken in the past.
The results show that the new vaccination is safe and produces a large number of T cells that work to prevent disease. More T cells were produced in subjects that had been vaccinated with BCG prior to receiving the new vaccine. There is a plan to test the new vaccine in Gambia, West Africa, where TB is widespread.
Seventy-year old Ahsan al-Khawlani?s story with tuberculosis started one year ago. He came to the National Tuberculosis Institute in Sana?a, searching for help. ?His disease was the most serious and infectious kind of tuberculosis, pulmonary smear positive last year,? said Dr.Hamood Mahyub, doctor and manager of the NTI.
?I followed up his condition for two months while he was under the Directly Observed Treatment Short-course program (DOTS). When he felt better he left the institute. We tried to convince him to continue his treatment under our supervision, but he refused. He came back later in worse condition after a serious relapse, due to carelessness in taking the medicine,? Dr. Mahyub said. Pulmonary tuberculosis is a common and deadly contagious bacterial infectious disease of humans and animals, caused principally by a type of bacterium called Mycobacterium tuberculosis or tubercle bacillus (TB).
It produces lesions on bodily organs, especially the lungs. It can involve the central nervous system, lymphatic system, circulatory system, genitourinary system, bones and joints. TB is an airborne disease. The bacteria get into the air when an infected person coughs, sneezes, shouts, speaks or spits. The bacteria is not transmitted by casual contact.
In susceptible individuals, the organisms may then multiply and spread through lymphatics to the lymph nodes, and through the bloodstream to other areas, such as lungs, bones, and kidneys. Without effective therapy, the disease becomes progressively worse. The risk of contracting TB increases with the frequency of contact with people who have the disease, with crowded or unsanitary living conditions and with poor nutrition.
?This disease is an economic one. It is influenced by the economic state of the patient, ?said doctor Mahyub. About 40,000 infectious particles can be produced by a single sneeze. One cough from a pulmonary TB patient produces up to 3000 droplets. People with prolonged, frequent, or intense contact are at highest risk of becoming infected, with an estimated 22 percent infection rate.
A person with untreated, active tuberculosis can infect 10-15 other people per year. If untreated, the death rate for these active TB cases is more than 50 percent. Tuberculosis of the lung is characterized by minor cough, mild fever, fatigue, unintentional weight loss, coughing up blood, night sweats, phlegm producing cough, wheezing, excessive sweating, chest pain and difficulty breathing.
However, a person infected with TB may show no symptoms, since the bacilli can remain inactive for several years. Between five and ten percent of those infected with TB can expect to develop active TB at some point in their lives. This percentage changes, however, with other factors contributing to a weakened immune system.
Tuberculosis is not, however, highly contagious compared to some other infectious diseases. Only about one in three close contacts with a TB patient, and fewer than 15 percent of more remote contacts, are likely to lead to infection. At the NTI, the employees complain about the hazards of their work environment. ?We are constantly to this infectious disease,? Ahmed Abu Taleb said. Co-worker Abdu al-Shawkani agreed.
?There are no precautionary measures to avoid infection. We are compelled to work hard here at low wages. Ten people working in different departments here have been infected,? he said. Doctors complain of their patients? negligence regarding their state of health. ?They do not continue their DOTS treatment once they start feeling better. They are often uneducated, which makes our work more difficult,? said Dr. Hamoud.
?The media does not help to eliminate this problem by educating people about the dangers of this disease, its causes and means of avoiding infection. The available resources are insufficient. The government and the Global Fund to Fight Tuberculosis try to help but it is still not enough,? he said.
Some patients also complained, ?Medicine is not available in the tuberculosis centers in some of the governorates,? said Hayel al-Kawm, a patient suffering from pulmonary smear positive TB. ?I?ve been suffering from this disease for five months. I am forced to wait for two to four weeks just to get medicine. It is a disaster for me when I cannot find it,? he said.
Infection does not always mean disease; in fact, it usually does not. At least nine of ten patients who harbor Mycobacterium tuberculosis do not have symptoms or physical evidence of active disease, and their x-rays remain negative. They are not contagious; however, they do form a pool of infected patients who may get sick at a later date and then pass on TB to others.
It is thought that more than 90 percent of cases of active tuberculosis come from this pool. An estimated 5 percent of infected persons get sick within 12-24 months of being infected. Tuberculosis can be a difficult disease to diagnose, due mainly to the difficulty in culturing this slow-growing organism in the laboratory. A complete medical evaluation for TB must include a medical history, a chest x-ray, and a physical examination.
Individuals exposed to tuberculosis should be skin tested immediately, (a positive skin test indicates prior TB exposure), and a follow-up test should be done at a later date, if the initial test is negative. Prompt treatment is extremely important in controlling the spread of tuberculosis for those who have already progressed to active TB disease.
According to the World Health Organization, 8 million people become ill with tuberculosis, and 2 million people die from the disease worldwide, every year. In 2004, around 14.6 million people had active TB disease with 9 million new cases reported. Tuberculosis is the world?s greatest infectious killer of women of reproductive age and the leading cause of death among people with HIV AIDS. Yemen registered 9,063 cases of tuberculosis at the National Tuberculosis Institute in 2005, according to Abdul-Bari al-Hammadi, statistics officer at the NTI.
?351 have had a relapse after being treated because of their ignorance and misuse of the medication,? he said. ?Hodeidah governorate has 603 cases, the highest number in the country. Sayoun has the fewest number of cases; there are only ten.
This means that for every 100,000 people in Yemen, there are 40 TB cases,? he said. Perhaps with the arrival of the promising new vaccine, those numbers will go down steadily.
http://www.yobserver.com/article-11172.php