Muhammad Younus  ( Department of Epidemiology, College of Human Medicine, Michigan State University, East Lansing, MI 48824, USA )
Azfar-e-Alam Siddiqi  ( Department of Epidemiology, College of Human Medicine, Michigan State University, East Lansing, MI 48824, USA )

Dr. Saleem provides a comment on our recent article on the uses and limitations of institutional and surveillance databases in biomedical research in the developing world.¹ We believe that some of the most profound learning experiences arise from the lively exchange of ideas expressed in scientific journals, particularly in the letters to the editor. We therefore feel privileged to participate in this intellectual dialogue.
We thank Dr. Saleem for providing the organizational details of HIV/AIDS surveillance in Pakistan to JPMA readers.  Our comment in the original paper however, applied to the overall development and performance of the population-based disease surveillance systems in developing countries including Pakistan and not specifically to HIV/AIDS.  It is indeed possible that a given disease-specific surveillance may be organizationally well developed and functionally more active than others. Regardless, we view Dr. Saleem's comments as an endorsement, rather than contradiction of our assertion of relatively poor state of disease surveillance systems in Pakistan.  Statements such as (quote) "Surveillance centers spread throughout the country more often serve as diagnostic centers … and have poor overall reporting culture", "Blood banks …leading to much unscreened blood for HIV…", "…government clinics capture only a small and most likely non-representative sample of men and women with STIs…" and "VCT centers…contributing very less to surveillance data" (unquote) coming from a member of an important existing surveillance system, go way beyond our opinion in highlighting the serious shortcomings of these programmes. Additionally even when a well-oiled and functional surveillance system exists, its vulnerability to reporting bias cannot be completely ruled out.^1-6
Our paper's primary focus was to point towards the need for realistic appraisal of surveillance data use in research.  Whether attempting to estimate disease burden or test a specific research hypothesis using surveillance data, acknowledgement of the limitations of source data and discussion of potential biases would assist readers in more meaningful interpretation of the published results.  Our paper was conceived based on observations that the majority of published research in Pakistan utilizing institutional and surveillance databases do not address these potential limitations that can have a significant effect on the overall interpretation of the research results.

1.  Younus M, Siddiqi A, Khan BS, Steffey AL.  Institutional and surveillance database in epidemiologic research in developing countries:  Revisiting some limitations.  J Pak Med Assoc 2008; 58: 138-9.
2.  Ducrot C, Roy P, Morignat E, Baron T, Calavas D. How the surveillance system may bias the results of analytical epidemiological studies on BSE: prevalence among dairy versus beef suckler cattle breeds in France. Vet Res 2003; 34: 185-92.
3.  VAERS data. Vaccine Adverse Event Reporting System. Available at www.http://vaers.hhs.gov/info.htm. [Accessed on: March 16, 2008]
4.  Younus M, Hartwick E, Siddiqi AA, Wilkins M, Davies HD, Rahbar M, Funk J, Saeed M. The role of neighborhood level socioeconomic characteristics in Salmonella infections in Michigan (1997-2007): assessment using geographic information system. Int J Health Geogr 2007; 6: 56.
5.  Chaffin M, Bard D. Impact of intervention surveillance bias on analyses of child welfare report outcomes. Child Maltreat. 2006; 11: 301-12.
6.  Younus M, Wilkins MJ, Arshad MM, Rahbar MH, Saeed AM. Demographic risk factors and incidence of Salmonella enteritidis infections in Michigan. Foodborne Pathog Dis 2006; 3: 266-73.