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Antiparasitic disinfection manifests unjustifiable deficiencies to date (Hiepe, 2010). Though DVG guidelines specify methods for testing disinfectants on protozoa and helminths in the veterinary medical parasitary field, however, test procedures on malignant arthropods are not included. In this work, M. domestica was selected for the investigation of the disin-fectant efficacy test for surface disinfection being a potential representative of malignant arthropods, Victor (1999) and Mielke et al. (2001) had conducted preliminary investigations on M. domestica using a registered cresol-based test preparation. The aim of my own investigations was to test the suitability of this species as an indicator organism. For this purpose, initially M. domestica were bred.
All M. domestica developmental stages (eggs, larvae I, larvae II, larvae III, pupae, imagines) were included in both, the procedural execution and the efficacy tests.
After presenting an analysis of the publications on disinfection and M. domestica, the breeding of the housefly and the execution of the developed test procedures were described in detail. The efficacy tests were carried out using two different test preparations with different active substances. Test preparation 1 (active substances: o-hydroxydiphenyl-fatty acid-eutectic, peracetic acid) is found in the 13th list of disinfectants by DVG (N.N., 2011/1) (Spectrum of efficacy: bactericidal, tuberculocidal, fungicidal, virucidal, antiparasitary (worm eggs, coccidia)).
Test preparation 2 (Active substances: glutaraldehyde, glyoxal, formaldehyde, benzalkonium-chloride, didecyl-dimethylammonium-chloride) is not listed by DVG, but by DGHM and by RKI (Spectrum of efficacy: bactericidal, tuberculocidal, sporicidal, fungicidal, virus inactivating). The disinfectant efficacy tests were performed at every M. domestica stage in the suspension test and the germ carrier test as well; only the adult house flies were exclusively examined in the suspension test. The germ carrier tests were performed with two different materials – poplar and the back side of tiles.
The test procedures and the germ carriers used both proved to be suited for the disinfectant testing. However, the time and labour required for examining certain developmental stages of M. domestica were adversely affected by their ability to move.
As expected, M. domestica exhibited different susceptibilities to the tested active agents at the different stages of their development. It could be proven that M. domestica -eggs is the only developmental stage that did not meet the requirements by DVG (N.N., 2007) specified for A. suum - eggs in comparison, neither in the suspension tests nor in the germ carrier tests of the two test preparations. Thus the M. domestica - egg exhibited the lowest overall susceptibility to the two test preparations (table 1.1-1.3, table 2.1-2.3). The test procedures on M. domestica - eggs and - pupae are recommended as suitable. The consideration of tenacity as well as the execution of the test procedures resulted in this finding. Efficacy tests on holometabolous malignant arthropods should be performed in 2 steps.
Step 1: Test on pupae, step 2: Test on eggs, whereas step 2 should only be performed, if step 1 brought positive findings. The test on heterometabolous insects is only recommended at one developmental stage, the egg. Considering the lower overall efficacy obtained, the material property and seen from an ecological and economic perspective the germ carrier poplar is to be preferred to the back side of tiles.
The established breeding of M. domestica plays a major role in deciding for an indicator organism of malignant arthropods. Own investigations show that the cosmopolite M. domestica is suited as an indicator for disinfectant efficacy tests on malignant arthropods (specifically eggs and pupae of holometabola) in the suspension test and in the germ carrier test as well.