Molecular typing of Avipoxvirus and analysis of Dutch bird sanctuary data

Abstract

Avipoxvirus An outbreak of Avipoxvirus occurred in birds in the region of Naarden, The Netherlands, during the period of September-October 2016. The most likely explanation for this outbreak is an increased mosquito activity. However, other possible reasons have to be excluded. Another possible explanatory factor is that there is a single circulating virulent Avipox strain. Hence, it is important to know if there is only one, or different subtypes of the virus who played a role in this outbreak. For this purpose, all birds are tested (between and within species). Investigations for detection and differentiation of Avipoxvirus strains were carried out by the use of a polymerase chain reaction PCR and further nucleotide sequence analysis. With pre-selected primers, which framed a region within the 4b core protein gene (587 bp fragment), we were able to detect Avipox-specific DNA from 35 different birds (63,4% positive). Comparative phylogenetic analysis, clade differentiation, showed a nucleotide similarty of 64.4%-100%. All of the tested lesions of Common wood pigeons (Columba palumbus) and City pigeon (Columba livia) fall in Clade A2. The sequenced lesser black-backed gull strain was grouped within clade B1. It is the first time that the family of Laridae is described in phylogenetic studies. Analysed strain originating from a Eurasian magpie (Pica pica), show that it is placed in clade C. No difference was found between in Avipoxvirus clade difference between the virus in the cutaneous and the diphteric lesion. Collectively, our data does not support that a clonal strain of pox virus is behind the Naarden outbreak. This suggests other factors were proably important, e.g., mosquito activity. More adequate sampling and other method for virus isolation is possible as described by previous literature. It is effective but costly and more time consuming but worthwhile to consider and could gave a better result in PCR and sequence analysis. Monitoring of pox-like lesions at different bird sanctuaries could gave better understanding of understanding the epidemiological triad; host (virulence), environment (vector, climate) and pathogen interactions (susceptibility, co-infection). Furthermore, this study also contributes to the broader understanding of the phylogenetic diversity and relationship of species within Avipoxvirusses.

Haarlem data analysis Bird sanctuary Haarlem has a database containing information on the birds submitted to the sanctuary in 2016. The database is primarily used for financial accountability. It is not yet used for gaining insight into the nature and timing of the problems in submitted species. Besides this, efficacy of treatments of the different patients is not consistently analysed. Seasonal and graphical trends in the top 10 submitted bird species as well as treatment efficacy in case of trauma, wound or an infection is analysed. Aims are to identify spatio-temporal patterns in the submitted specimen and treatment efficacy analysis in submitted species. In conclusion, with regards to surveillance, when there are sudden peaks in numbers submitted in species that have only one brood/clutch per breeding season and a short breeding period, it is important to make sure this is not the usual breeding season peak. While when sudden peaks occur in species that have multiple broods and an extended breeding season, this should immediately raise alarm and warrant further investigation. We found that the composition of the sample obtained from coastal areas versus inland did differ (p < 0.0001). In the coastal area, there is a higher proportional level of Charadriiformes and less Columbiformes in comparison to the inland areas. No difference was found between Passeriformes and Anseriformes. Extrapolating this to surveillance, this suggests that different sanctuaries will provide information on different bird species, depending on where the habitat types they cover. It is relevant to perfom such analyses when starting to work with a sanctuary to understand which birds species health status will be well refelcted in the area they cover. We looked into the diagnosis in relation to survival, especially when medical treatment was given. We found that, for the three most common bird species in this cohort, there was no difference in the success of medical treatment as measured by release of the bird for trauma and infection, but there was for wound treatment (p < 0.01513). Possibly this has to do with differences in the underlying cause of the wound. Collectively, we can conclude that some of the patterns observed in the submissions are explained by biological and ecological characteristics of the bird species. Understanding of normal submission patterns, including normal peaks and relative numbers of different species is necessary to help DWHC place unusual patterns. Analysing consecutive years will give a better picture of the actual patterns in submitted species.