Sometimes after updating antivirus databases, you can see that the number of registries (threat types) has decreased in databases. It dues to an optimization of antivirus databases (threat signatures) frequently done by Kaspersky Lab virus analysts.
This optimization aims to improve the quality and reduce the size of antivirus databases issued for Kaspersky Lab users. This optimization is always in progress so the number of threat types can be dynamic. At the same time Kaspersky Lab specialists recommend watching that antivirus databases are up to date on your computer. Do not forget to update them regularly.