Diagnostic Techniques of Soil-Transmitted Helminths: Impact on Control Measures

Abstract

Soil-transmitted helminth (STH) infections are common in the tropical and subtropical countries. The burden of disease is highest in endemic areas with limited access to good quality water supply and poor sanitary conditions. Major approaches to control and reduce morbidity caused by worm infections include the periodic deworming of pre-school and school-aged children with anthelminthic drugs. Population-based studies and individual patient management including interventional studies can only be successful when accurate diagnostic techniques are used. The lack of appropriate diagnostic tools providing accurate results concerning both infectious status and intensity of infection-as these two factors vary in regions of low infection intensities-is a major challenge. Currently, available techniques show limited sensitivity and specificity and as such, a combination of several techniques is usually used to diagnose the large variety of parasite species. The objective of this review was to describe the advantages and disadvantages of the different available techniques for the diagnosis of STH infections and to highlight their use in control programs.

Keywords: control measures; diagnostics; intestinal helminths; soil-transmitted helminths.

Figure 1

Suggested use of diagnostic techniques for helminth control.

Figure 2

Operating steps for the direct smear technique. Adapted from (WHO 1994).

Figure 3

Operating steps for the Kato-Katz technique. Adapted from open source web images.

Figure 4

Formol-ether sedimentation of parasites after centrifugation. Adapted from Cheesbrough 2009, WHO 1994.

Figure 5

Operating steps of the Harada-Mori technique. Adapted from open source web images.

Figure 6

Operating steps of the McMaster technique. Adapted from open source web images.