Page 42 - Epidemiological studies on tuberculosis control and respiratory viruses

Chapter 7
of infectious patients and their contacts (6). Despite the advantages of WGS, its full public health potential remains to be investigated given the challenges of performing WGS on direct clinical material. Until then, the discriminatory power of molecular typing of M. tuberculosis isolates by VNTR typing could be improved by using it in combination with spoligotyping as proposed by de Beer and colleagues (8), since this has been shown to result in slightly increased discriminatory power (9) (10).
Impact of preventive TB treatment among contacts of pulmonary TB patients
To achieve TB elimination in low-incidence countries, were most cases of active TB occur due to reactivation of previously controlled latent TB infection (LTBI), health care systems have to identify TB cases at an earlier stage (2). Preventive treatment can be an effective tool to reduce the individual risk of progression to TB, and the risk of transmission to susceptible individuals in their environment. In countries where TB incidence in the general population is low, targeted testing for LTBI followed by initiation of preventive treatment, should be performed among high-risk groups (2). Therefore, contact investigations are an essential component of the tuberculosis control and elimination strategy in most low-incidence countries (11). The impact of preventive treatment is largely determined by the rate of progression to disease in the absence of preventive treatment, by the adequate identification and diagnosis of contacts with an increased risk of progression from latent infection to clinical TB, and by treatment success.
Main conclusions and implications
In chapter 3 and 4, surveillance data from the electronic system of the TB department at the GGD (Public Health Service [PHS]) Amsterdam were used to study contact investigation outcomes in the period 2002-2011. Based on these findings several opportunities to improve the impact of contact investigations on TB control in the Netherlands were identified.
In chapter 3 we found that, during 2008-2011, more than one third of the contacts of PTB patients reported to the PHS Amsterdam, who were eligible for LTBI screening, were not screened, and that about half of the contacts diagnosed with LTBI did not start preventive TB treatment. Despite the effectiveness of preventive treatment in high risk populations, suboptimal acceptance rates among both patients and
122