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28 Mar 2011 10:02
In South Africa the detection of tuberculosis (TB) has mostly been limited to passive case-finding, which is when individuals with symptoms are diagnosed after consulting a health practitioner. But because TB is an airborne disease it is vital that all those who are infected are diagnosed and put on treatment as soon as possible to avoid further transmission.
Although staff at public health facilities and NGOs make people aware of the symptoms of TB and encourage them to be screened, implementing an active case-finding strategy in households of people already diagnosed with TB would mean earlier diagnosis.
Active case-finding involves actively locating, diagnosing, treating and following up with TB patients in communities.
This method of identifying TB patients enables household members also to be placed on TB treatment if they are found to have the disease, or to be provided with preventative therapy.
One study that compared active and passive case-findings in households found that active case-findings yielded nine times more TB cases, with a higher number of people placed on TB prophylaxis treatment, than those identified through passive case-finding. Employing both approaches would reduce the further transmission of TB in communities.
The active case-finding approach has been shown to be particularly important in picking up childhood TB, as children are less mobile than adults and therefore more likely to be infected within their household. Childhood TB has recently been recognised as an important cause of mortality in children in developing countries.
Active case-finding will be conducted in the Greater Sekhukhune district in Limpopo and the Ekurhuleni North subdistrict in Gauteng by Aurum, a TB and HIV research and implementation unit that has worked with the health department on HIV and TB projects for several years.
The Sekhukhune and Ekurhuleni project, which will trace patients who are diagnosed with TB at primary healthcare clinics, will use the same methods that were employed by Aurum in a 2009 research study, which evaluated and traced TB contact in Rustenburg in the North West province.
Once a patient was diagnosed with TB at one of the 12 clinics in the Rustenburg area healthcare workers—having obtained consent from the patient—visited his or her home. There, nurses offered health education about TB and HIV to family members and screened them for symptoms of active TB, followed by the collection of their sputum for testing if the person was suspected of having TB. Onsite HIV counselling and testing was also provided. Members of the household were referred to the appropriate health facility for treatment, where needed.
Between April and December 2009 563 patients with TB were identified; 84% had a subsequent household visit and 2 214 household members were screened for symptoms of TB. Sputum for TB testing was obtained from 540 (24,4%) of the contacts who were suspected of having TB. Seventy (3,2%) of these household members were diagnosed with TB. This figure is higher than the national average of 0,96% among the general population.
Forty-three percent of these cases were diagnosed by TB culture testing, a lengthier but more reliable test in which the bacilli are cultured in a laboratory. Seventeen percent were identified through smear microscopy, the fastest and most commonly used test, in which sputum samples are examined under a microscope.
The remaining 40% of TB cases identified among household contacts were diagnosed on clinical suspicion due to the symptoms the person showed. The high rate of diagnosis was achieved using sputum culture. Smear microscopy alone would have missed the majority of cases among TB patients’ household contacts.
Fifty-five percent of these household members with TB also tested positive for HIV. Including the household contacts who were not found to have TB, 711 (61%) who were over the age of 16 (and therefore eligible for HIV testing) consented to being tested for HIV - and 23% were found to be positive.
In the areas where Aurum will now be working it is being proposed that 15 360 households should be visited annually. This would mean that roughly 61 450 of their close contacts would be screened for TB.
Complicating matters further is the fact that half-a-million people worldwide are estimated to have drug-resistant (DR) TB—and only 7% of these cases have been detected. Fewer than 3% of those infected are on effective treatment. “The most important way to stop the spread of drug-resistant TB is to diagnose it as quickly as possible and put people on treatment as soon as one can.
Once people are on treatment they are less infectious and no longer spread the disease,” said Dr Jennifer Hughes, the coordinator of a Médicins Sans Frontières/Doctors Without Borders’ (MSF) project on drug-resistant TB in Khayelitsha.
Asanda, a 46-year-old HIV-positive man living in the township, was diagnosed with sputum smear-negative pulmonary TB in October 2010 and was put on the standard first-line TB treatment at his local clinic. He started antiretroviral therapy two months later. A month after that he became unwell, with increased coughing and fever, and a chest X-ray confirmed his worsening condition. His sputum was again tested and it was discovered that he had become smear-positive for TB.
The sample was sent for further culture and drug-sensitivity testing. The sputum culture results demonstrated resistance to isoniazid and rifampicin, confirming that Asanda had multidrug-resistant (MDR) TB. However, by this stage, Asanda had been admitted to hospital due to the further deterioration in his condition. He began the standard treatment regimen for DR-TB, but died a few days later.
Under current South African health policies, only certain groups of patients are screened for drug resistance. These groups include TB patients who have received TB treatment previously, close contacts of confirmed DR-TB patients, high-risk groups such as healthcare workers, miners and prisoners, as well as patients who have a poor clinical response to TB treatment.
Had Asanda been eligible to be screened for DR-TB from the outset, he could have been correctly diagnosed before it was too late. If more rapid diagnostics had been available to all people suspected of having TB Asanda could have started DR-TB treatment earlier and his death might have been prevented. South Africa has one of the highest burdens of DR-TB globally, with close to 10 000 patients having been diagnosed with MDR-TB in 2009. A survey carried out in Khayelitsha in 2008 and 2009 found that 5,2% of new TB cases and 11,1% of previously treated cases were due to drug-resistant strains.
If applied to the actual number of cases diagnosed in 2008, these figures indicate that if all TB cases in Khayelitsha were to be screened for DR-TB, close to 400 would be diagnosed each year. This is in spite of noteworthy outcomes when treating the more prevalent drug-sensitive TB, for which the cure rate is 78%.
Since 2007, in response to the growing epidemic of DR-TB in Khayelitsha, MSF, the City of Cape Town and the Western Cape government have been carrying out a pilot project to provide treatment to DR-TB patients at primary care level. Patients are started on DR-TB treatment and collect their medication daily at their nearest clinic.
Nationally, DR-TB patients generally have to be hospitalised for at least the first six months of treatment (although it is usually for up to two years) in overburdened DR-TB hospitals. The Khayelitsha model is based on the understanding that DR-TB is mainly transmitted by patients who are not on treatment. Consequently, the major objective is to increase the detection of cases, decrease the time it takes to diagnose patients with the condition, initiate treatment, improve treatment outcomes and optimise infection control.
Although case detection is only about 50%, it has improved, with the number of cases diagnosed in Khayelitsha increasing from 118 in 2006 to 231 in 2009 as a result of the intensive training of healthcare workers, the promotion of increased awareness of DR-TB and the more effective management of DR-TB patients at primary care level.
In 2009 only 29% of DR-TB cases diagnosed in Khayelitsha were new cases. However, based on the 2008-2009 survey, more than half of all cases in Khayelitsha should be in this category. According to MSF, it is likely that we are missing a large proportion of new DR-TB cases using the current case detection strategy.
“These data highlight the need to screen all TB cases for TB drug resistance to allow for early diagnosis, treatment and prevention of the further spread of DR-TB,” said Dr Hughes. “It requires improved access to more rapid diagnostic techniques, which would allow a larger number of samples to be screened.”
To improve the screening of DR-TB patients’ close contacts data recording forms have been developed to collect information on those contacts who have been identified through household visits. All DR-TB contacts are offered screening, focusing on those at high risk such as children younger than five, people with HIV staying with patients with DR-TB, as well as people with chronic illnesses. Those at high risk are encouraged to go for sputum screening and others to attend a clinic if they display DR-TB symptoms. Contacts are then given a letter advising the clinic healthcare worker to screen for DR-TB.
More than 80% of patients diagnosed in 2009 and 2010 were started on treatment. The average time it took to initiate treatment decreased from 71 days in 2007 to 33 days in 2010. Continuing with treatment is guided by the availability of second-line drug susceptibility results, which were received in close to 90% of patients, increasing from only 35% in 2007.
Twenty percent of patients found to have initially undetected second-line resistance in 2009 and 2010 were able to receive an effective regimen from the outset, preventing the development of further resistance while waiting for second-line drug susceptibility results. In 2010 71% of patients started treatment at their local clinic. Fifteen percent began treatment at the community-based, sub-acute in-patient facility in Khayelitsha and only 14% were admitted to the area’s DR-TB hospital, thereby reducing the demand for scarce hospital beds and allowing clinically stable patients to remain in their communities.
“In most places across the country there are waiting lists to get a bed in the centralised DR-TB hospitals. This means that a patient cannot be put on to treatment and is likely to become more ill unnecessarily and to transmit the disease in the community,” said Dr Hughes. “In most places patients with DR-TB are being treated outside the hospital because of bed space.
Because it is not policy to treat DR-TB outside hospitals, clinics that are treating patients for DR-TB do not have the same kind of support structure and training that the staff have in a decentralised project. What our programme shows is that decentralisation is not absolutely impossible in other settings,” she said.
Among patients diagnosed with DR-TB in Khayelitsha in 2008, 62% were alive 18 months after diagnosis. Given that 76% of all DR-TB patients are also living with HIV, this is a significant improvement on the statistics reported elsewhere in the world.
You don’t have to have a cough to be infected
When a person infected with TB coughs, sneezes or sings, releasing the TB bacilli into the air, the people around that person are at risk of inhaling these particles, especially in overcrowded or poorly ventilated places. If other people inhale the TB bacilli, they are at risk of becoming infected with latent or inactive TB.
Globally, one-third of the world is latently infected with TB, though roughly 90% to 95% of people without HIV will never go on to develop active TB. While most people think that coughing for more than two weeks is the main symptom of TB, this is only the case for people with TB of the lungs. TB can exist in many other parts of the body, such as the abdomen, blood, brain and spine. People with HIV are also less likely to present with a cough because their immune systems are so weak, their bodies do not react to the TB.
Other signs of active TB are:
If you are suffering from these symptoms, it is recommended that you be tested for TB.
TB in HIV-positive people
About 70% of South Africans living with TB are co-infected with HIV. HIV dramatically increases the risk of developing active TB. People living with HIV are 20 to 37 times more likely to get TB. Consequently, TB is the leading cause of death among people with HIV in most of the world and in South Africa.
The WHO recommends the implementation of what are known as the “three Is” to better prevent, detect and treat TB in HIV-positive people.
The three Is are:
The WHO also recommends that all HIV-infected people who also have TB are initiated on to antiretroviral therapy, regardless of their CD4 count.
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