The fox tapeworm Echinococcus multilocularis has foxes and other canids as definitive host and rodents as intermediate hosts. However, most mammals can be accidental intermediate hosts and the larval stage may cause serious disease in humans. The parasite has never been detected in Sweden, Finland and mainland Norway. All three countries require currently an anthelminthic treatment for dogs and cats prior to entry in order to prevent introduction of the parasite. Documentation of freedom from E. multilocularis is necessary for justification of the present import requirements.

Highly pathogenic avian influenza (HPAI, Gs/Gd lineage) was introduced to Europe in 2005 and has since caused numerous outbreaks in birds. The 2020–2021 season was the hitherto most devastating when considering bird numbers and duration in Europe. Surveillance data, virologic results and epidemiologic investigations from the 2020–2021 outbreaks in Sweden were analysed. Subtypes H5N8 and H5N5 were detected on 24 farms with poultry or other captive birds. In wild birds, subtypes H5N8, H5N5, H5N1, H5N4, H5Nx were detected in 130 out of 811 sampled birds. There was a spatiotemporal association between cases in wild birds and poultry. Based on phylogeny and epidemiology, most of the introductions of HPAI to commercial poultry were likely a result of indirect contact with wild birds. A definite route of introduction to poultry could not be established although some biosecurity breaches were observed. No spread between farms was identified but airborne spread between flocks on the same farm was suspected. Our findings exemplify the challenges posed by the continuously changing influenza viruses that seem to adapt to a broader species spectrum. This points to the importance of wild bird surveillance, compliance to biosecurity, and identification of risk factors for introduction on poultry farms.

Tularemia is a zoonosis caused by the bacterium Francisella tularensis. It has a wide host range, which includes mammals, birds and invertebrates. F. tularensis has often been isolated from various species of small rodents, but the pathology in naturally infected wild rodent species has rarely been reported. Herein, we describe the pathology of tularemia in two naturally infected wild yellow-necked mice (Apodemus flavicollis). To visualize F. tularensis subsp. holarctica, indirect immunofluorescence and immunohistochemistry were applied on tissue sections. Real time polymerase chain reaction detected the bacterium in samples from liver and spleen in both mice. The only finding at necropsy was splenomegaly in one of the mice. Histological examination revealed necrotic foci in the liver associated with mild inflammation in both mice. Immunohistochemistry and indirect immunofluorescence showed bacteria disseminated in many organs, in the cytoplasm of macrophages, and intravascularly. The two yellow-necked mice died of an acute disease caused by tularemic infection disseminated to many organs. Further investigations of naturally infected small rodents are important to better understand the variability in pathological presentation caused by infection by F. tularensis subsp. holarctica, as well to elucidate the importance of small rodents as transmitters and/or reservoirs.

Increased numbers of human infections with Chlamydia psittaci have been associated with bird feeding activities in southern Sweden. Information on occurrence and genotype of C. psittaci in garden birds in Sweden is required to corroborate this finding but data are limited. Additionally, pathogenicity of C. psittaci for garden birds is poorly understood. In this study, C. psittaci infection was investigated in 275 garden birds representing 22 species submitted for wildlife disease surveillance between 2009 and 2019. PCR was used to detect C. psittaci DNA in liver and lung. Positive samples were genotyped, additional PCR was performed on feces, and tissues were examined microscopically. C. psittaci was found in six (2.2 %) birds; three great tits (Parus major), two feral (Columba livia) and one wood pigeon (Columba palumbus). Two great tits and the wood pigeon had inflammatory lesions associated with C. psittaci. In the great tits and wood pigeon, C. psittaci genotype A, the cause of most human cases, was detected. Genotype B, considered endemic in pigeons, was detected in the feral pigeons. Low incidence of C. psittaci in dead Swedish garden birds was similar to studies on apparently healthy Swedish birds. Pathological findings were consistent with C. psittaci being fatal in half of the positive birds, which also had higher bacterial loads in feces. This highlights the risk for human infection via infected garden birds, especially regarding great tits and pigeons.