Table 5.

Changes in information, data, and activities regarding Cryptosporidium and Giardia in Norway since 2009

Area of changes	2009	2020
Diagnosis of human infection	Diagnostics generally performed by microscopy or antigen testing. Few medical microbiology laboratories analyse for parasites and both training and experience is lacking. No reference laboratory.	Several laboratories use molecular methods for diagnosis of parasitic infections. These may be of higher sensitivity than older methods and also the algorithm for testing may be broader as many pathogens can be tested simultaneously in a multiplex format. A reference laboratory is being established.
Reporting of human infection	Only giardiasis reportable.	Cryptosporidiosis also reportable as from 2012. Numbers of cases have risen for both infections from around 2016 (see Table 2, supplementary data).
Water treatment and distribution.	Around 50% of the population receive drinking water that has been treated with UV.	Around 85% of the population receive drinking water that has been treated with UV. Although there seem to be more ozonisation in water treatment plants, other effective methodologies (such as membrane filtration) has not expanded so much. Most large waterworks have upgraded their treatments to be effective against parasite contamination.
Water analyses	No accredited laboratories and few water suppliers request analysis of water samples.	One laboratory in Norway accredited for analysis of water for these parasites, however several laboratories offer this service without being accredited. Around 870 samples of raw water and 230 samples of treated drinking water were analysed between 2009 and 2018. Although most samples were negative, some positive reports are recorded, generally with low numbers of parasites. See also text.