Controlling and eliminating is never going to be easy and this issue of the SACEMA Quarterly is devoted to some of the recent developments that have been made in our attempts to manage TB.
Insufficient tuberculosis (TB) case finding constitutes a major barrier to effective TB control. Despite considerable progress in improving healthcare service availability and accessibility, many people worldwide who fall ill with TB have no access to quality care, particularly in countries with a high disease burden. Increasing efforts to close this enormous gap will be crucial in the forthcoming years to effectively reduce TB incidence and mortality worldwide. This article describes opportunities, current challenges and open questions towards intensifying TB case finding.
TB disease has been known by various names for thousands of years, and has of late been described in exquisite biological detail. Yet we still struggle to reliably answer the question: Does a particular person have ‘active’ TB? The available diagnostic tests have several limitations and perform poorly especially in developing countries where they are most needed. We need new point of care diagnostic tests, be able to accurately distinguish between TB infection and TB disease and have tests which accurately predict cure.
With the current situation in South Africa, showing only a modest decline in new TB cases since 2012, new avenues and strategies to identify TB cases need to be explored, tested and implemented. Systematic symptom screening in high risk populations, when this translates to screening everyone in the community, is not very sensitive or cost-effective. The TB programme might therefore consider screening all individuals at primary healthcare facility level, irrespective of their reason for attending. The use of a screening tool with improved sensitivity in comparison to symptom screening alone would be preferable, followed by the current diagnostic algorithm.
Models of HIV and TB are well established and it is tempting to model the combination of HIV and TB by repeating a suitable TB model a number of times corresponding to the various states of HIV. This can, however, lead to a very complex model with tens, if not hundreds of parameters, requiring considerable computing power to run. Fortunately, the time scales over which the two infections progress are very different, allowing us to greatly simplify the problem.
Although a curable disease, tuberculosis (TB) remains a significant cause of mortality worldwide. To create a basis for further research into TB and HIV-associated mortality in Cape Town, we conducted a retrospective analysis of deaths occurring during TB treatment. A binomial log-linear regression model was used to investigate risk factors associated with death during TB treatment. We specifically looked at interactions between HIV infection and various other risk factors towards the risk of death from TB during treatment.
It is known that in high TB incidence settings the rate of recurrent TB disease is much higher than the rate for first-time disease. It is not clear why the rate of reinfection disease can be elevated compared to the rate of primary disease. We set about attempting to estimate the actual values of the risk of reinfection and the rate of progress to disease for the high-incidence community of Ravensmead-Uitsig in Cape Town.
In the SACEMA Quarterly of November 2015 we published an item from Alide Dasnois about compensating miners for the burden of lung disease. On 6 March 2016 City Press published an article titled “Silicosis claims: Anglo has to cough up nearly R500m” which reports on a first step in the process of paying the individual claims.
Alide Dasnois, a South African journalist and former editor of the Cape Times, has written an an article titled “The long battle to get the mines to cough up” which is about compensating miners for the burden of lung disease. The importance of this issue has been highlighted before in a SACEMA Quarterly article by Tony Davies giving an historical overview on occupational lung disease in South Africa.
Household contacts of active TB cases are at increased risk of TB infection and several studies have measured TB prevalence in this key population. The study described here not only measured TB prevalence, but also measured TB and HIV incidence in the household contacts of 729 TB index cases in the Matlosana sub-district in North West Province. We concluded that the efficacy of contact tracing for TB control purposes might be improved by a second intensified case finding visit and by providing preventive treatment against TB for both HIV-infected and HIV-seronegative household contacts of TB cases.