Bee samples are tested on various parameters. The laboratory test results are linked to the sample ID you created in the BEEP inspection sheet for a specific honeybee colony on a specific date. The results can be interpreted using the information provided below:
For several of the results we have created the categories (cat.) “low” (L), medium (M), and high (H) to make an interpretation of the results easier:
DWV A (= deformed wing virus A); DWV B (= deformed wing virus B); ABPV (= acute bee paralysis virus); CBPV (= chronic bee paralysis virus); BQCV (= black queen cell virus); SBV (= sacbrood virus)
A positive test results means that genome of the virus was found in the sample. In other words, the virus was detected and thus the bees in the sample were infected. However, the virus being present in the bees, does not automatically mean the bees showed symptoms/were sick.
In general, it seems that most honey bee colonies are infected with several viruses, but the majority of these infections do not show visible or notifiable effects on the health of the colonies. However, a high amount of virus in a colony will increase the chance of notifiable effects. Additionally, a combination of factors (several viruses, presence of Varroa mites, other diseases or stressors) can increase the risk of symptoms appearing.
The following table shows virus-respective percentages of the categories per season for all B-GOOD samples received in 2020-2021 for comparison and to enable a better assessment of newly reported results. As an example, 70% of the samples were negative (uninfected) with DWV A in spring, 17% showed a low infection level, 11% a medium infection level, and 2% a high infection level.
AFB (= American foulbrood)
A positive test result means that genome of the causative agent of AFB, Paenibacillus larvae, was found in the sample. The rtPCR test we have used is very sensitive and low amounts of DNA can be detected and it is also possible that traces of dead bacteria might be detected.
Therefore, we always perform a bacteriological test (on culture medium) using the same homogenate of honey bees to confirm the presence of (sufficient amount of) viable spores. We only declare as positive if there are spores germinating on the culture medium. Please also see column “AFB (cfu)”.
Please, don’t worry if there is a positive result for the rtPCR, only if we have additionally a positive result in the bacteriological test we will declare the sample as positive. Then you need to declare the suspicion for AFB to the competent authority responsible for you. However, also we will notify the competent authority of your country about the result, according to the EU Animal Health Law, which is explained here shortly.
Animal Health Law - Regulation 2016-429
CHAPTER 3, Section 4, Article 17
Animal health laboratories
4. In the event that an official laboratory in one Member State conducts diagnostic analyses on samples from animals originating in another Member State, that official laboratory shall notify the competent authority of the Member State from which the samples originated:
(a) immediately of any results indicating the suspicion or detection of a listed disease as referred to in point (a) of Article 9(1);
(b) without undue delay of any results indicating the suspicion or detection of a listed disease as referred to in point (e) of Article 9(1) other than those referred to in point (a) of Article 9(1).
Point (e) of Article 9(1) states "As regards listed diseases for which there is a need for surveillance within the Union". American foulbrood is a listed disease.
AFB (cfu)
This column shows the number of “colony forming units” (cfu), on culture medium that were identified as Paenibacillus larvae. The “colony forming units” represent the number of P. larvae spores that germinated on the culture medium. This bacteriological test is performed if the real-time PCR was positive. Please see above (American foulbrood) for more information.
EFB (= European foulbrood)
A positive test result means that genome of the causative agent of EFB, Melissococcus plutonius, was found in the sample. If EFB is notifiable in your country you should notify this to the competent authority. However, the real-time PCR test we have used is very sensitive and low amounts of DNA can be detected and it is also possible that traces of dead bacteria might be detected.
N. apis (= Nosema apis)
A positive test result means that genome of Nosema apis was found in the sample. In this case we quantify the infection rate of the sample by counting the number of Nosema spores. See the results in column “N. spores”.
N. ceranae (= Nosema ceranae)
A positive test result means that genome of Nosema ceranae was found in the sample. In this case we quantify the infection rate of the sample by counting the number of Nosema spores. See the results in column “N. spores”.
N. spores
This column shows the number of Nosema spores per bee, counted in the sample. However, recent studies have demonstrated that the number of spores per bee can fluctuate depending on bee nutrition and that higher spore counts do not necessarily correlate with honey bee mortality. However, a high number of spores in combination with other factors might increase the detrimental effect of Nosemosis on honey bee health.
Varroa/100 bees
This column shows the infestation rate, the calculated number of Varroa destructor mites per 100 bees
> 100 bees
This column shows if the sample that was used to count the number of Varroa destructor mites was larger than 100 bees. If yes (= “Y”), the sample was washed in ethanol, if no (= “N”) the bees were inspected individually under the microscope. The calculated infestation rate is more representative of the infestation of the hive if a higher number of bees are washed. We recommend to wash about 300 bees.
Malpighamoeba (Malpighamoeba mellifica)
A positive test result means that genome of Malpighamoeba mellifica was found in the sample. The role of M. mellifica for honey bee health is not clear. However, in the past infections with M. mellificae have been suggested to be associated with spring dwindling, dysentery, and to shorten the lifespan of infected bees. As we have no categories for this analysis on M. mellificae, we have set a threshold on a Ct-value of 36,00, all samples with a higher Ct value are considered negative.
If you have any questions, please let us know.