Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2009 Nov 10;4(11):e7760.
doi: 10.1371/journal.pone.0007760.

New policies, new technologies: modelling the potential for improved smear microscopy services in Malawi

Andrew Ramsay  1 , Luis E Cuevas, Catherine J F Mundy, Carl-Michael Nathanson, Petros Chirambo, Russell Dacombe, S Bertel Squire, Felix M L Salaniponi, Sera Munthali
Affiliations

New policies, new technologies: modelling the potential for improved smear microscopy services in Malawi

Andrew Ramsay et al. PLoS One. .

Abstract

Background: To quantify the likely impact of recent WHO policy recommendations regarding smear microscopy and the introduction of appropriate low-cost fluorescence microscopy on a) case detection and b) laboratory workload.

Methodology/principal findings: An audit of the laboratory register in an urban hospital, Lilongwe, Malawi, and the application of a simple modelling framework. The adoption of the new definition of a smear-positive case could directly increase case detection by up to 28%. Examining Ziehl-Neelsen (ZN) sputum smears for up to 10 minutes before declaring them negative has previously been shown to increase case detection (over and above that gained by the adoption of the new case definition) by 70% compared with examination times in routine practice. Three times the number of staff would be required to adequately examine the current workload of smears using ZN microscopy. Through implementing new policy recommendations and LED-based fluorescence microscopy the current laboratory staff complement could investigate the same number of patients, examining auramine-stained smears to an extent that is equivalent to a 10 minutes ZN smear examination.

Conclusions/significance: Combined implementation of the new WHO recommendations on smear microscopy and LED-based fluorescence microscopy could result in substantial increases in smear positive case-detection using existing human resources and minimal additional equipment.

PubMed Disclaimer

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

References

    1. World Health Organization. Global Tuberculosis Control: Epidemiology, Strategy, Financing. 2009. WHO Report. WHO/HTM/TB/2009.411. Available: http://www.who.int/tb/publications/global_report/2009/pdf/full_report.pdf (accessed 2009 September 22.)
    1. World Health Organization. Laboratory Services in Tuberculosis Control. 1998. Part II: Microscopy. WHO/TB/98.258.
    1. Mugusi F, Villamor E, Urassa W, Saathoff E, Bosch RJ, et al. HIV co-infection, CD4 cell counts and clinical correlates of bacillary density in pulmonary tuberculosis. International Journal of Tuberculosis and Lung Diseases. 2006;10:663–669. - PubMed
    1. Available: http://www.who.int/tb/dots/laboratory/policy/en/index1.html. Accessed 2009 September 22.
    1. Bonnet M, Ramsay A, Varaine F, Githui W, Gagnidze L, et al. Reducing the number of sputa examined, and thresholds for positivity: an opportunity to optimize smear microscopy. International Journal of Tuberculosis and Lung Diseases. 2007;11(9):953–8. - PubMed

Publication types