Surveillance

extensive drug resistant tuberculosis

Surveillance is the cornerstone of communicable diseases' control strategies.  Because most surveillance systems are affected by data problems, the reliability of the data need to be checked carefully in order to interpret the trends correctly.  I can provide advice on how to analyse the data coming from surveillance systems and how to set up plans to strengthen it. This includes the retrospective analysis of notifiable diseases by taking into account data reliability and lack of representativeness, the use of threshold values for epidemics, and the establishment of standard operating procedures to improve surveillance.

Examples include:
(a) The retrospective analysis of the notification system in Bosnia . An analysis of the data from the surveillance system on notifiable diseases in Bosnia & Herzegovina. As part of EU supported Public Health Reforms II Project, the data related to the cases that were notified between 2008-11 were analysed. The results were value added in understanding the management information system for notifiable diseases, the problems affecting the data reliability and the critical interpretation of trends.

(b) The identification of threshold values for epidemics on the basis of past reporting. Although epidemics are defined as occurrence of cases that are in excess of normal expectancy, there is hardly any guideline on how many cases are in excess. A method that was published in a scientific journal was applied to the historical trends in Bosnia to identify excessive weekly number of cases by disease and geographic areas. Sensitivity, specificity and predictive values of these thresholds were also estimated to provide a sense of how robust the thresholds were in identifying epidemics.

(c) The surveillance system of the first major outbreak of extensive drug resistant (XDR) TB. In 2005, the Church of Scotland hospital in Tugela Ferry, Umzyniathi district, KwaZulu-Natal, started to report increasing numbers of HIV/AIDS patients who were not responding to ART treatment. This brought to light the new XDR strain that was associated with high rates of mortality. Together with other researchers who were working in this district hospital, I was involved in the surveillance system of this XDR epidemic and in testing the family contacts of the index cases. This produced the first estimate of the transmission rates of XDR to the contacts

(d) The surveillance of HIV resistance to Antiretroviral Therapy (ART). Threshold surveys based on women attending antenatal care to check the spread of the HIV resistance to ART to the general population in KwaZulu-Natal.