Drivers of infection with Toxoplasma gondii genotype type II in Eurasian red squirrels (Sciurus vulgaris).

BACKGROUND: In September 2014, there was sudden upsurge in the number of Eurasian red squirrels (Sciurus vulgaris) found dead in the Netherlands. High infection levels with the parasite Toxoplasma gondii were demonstrated, but it was unclear what had caused this increase in cases of fatal toxoplasmosis. In the present study, we aimed to gain more knowledge on the pathology and prevalence of T. gondii infections in Eurasian red squirrels in the Netherlands, on the T. gondii genotypes present, and on the determinants of the spatiotemporal variability in these T. gondii infections. The presence of the closely related parasite Hammondia hammondi was also determined. METHODS: Eurasian red squirrels that were found dead in the wild or that had died in wildlife rescue centres in the Netherlands over a period of seven years (2014-2020) were examined. Quantitative real-time polymerase chain reaction was conducted to analyse tissue samples for the presence of T. gondii and H. hammondi DNA. Toxoplasma gondii-positive samples were subjected to microsatellite typing and cluster analysis. A mixed logistic regression was used to identify climatic and other environmental predictors of T. gondii infection in the squirrels. RESULTS: A total of 178 squirrels were examined (49/178 T. gondii positive, 5/178 H. hammondi positive). Inflammation of multiple organs was the cause of death in 29 squirrels, of which 24 were also T. gondii polymerase chain reaction positive. Toxoplasma gondii infection was positively associated with pneumonia and hepatitis. Microsatellite typing revealed only T. gondii type II alleles. Toxoplasma gondii infection rates showed a positive correlation with the number of days of heavy rainfall in the previous 12 months. Conversely, they showed a negative association with the number of hot days within the 2-week period preceding the sampling date, as well as with the percentage of deciduous forest cover at the sampling site. CONCLUSIONS: Toxoplasma gondii infection in the squirrels appeared to pose a significant risk of acute mortality. The T. gondii genotype detected in this study is commonly found across Europe. The reasons for the unusually high infection rates and severe symptoms of these squirrels from the Netherlands remain unclear. The prevalence of T. gondii in the deceased squirrels was linked to specific environmental factors. However, whether the increase in the number of dead squirrels indicated a higher environmental contamination with T. gondii oocysts has yet to be established.

High prevalence and genetic diversity of Treponema paraluisleporidarum isolates in European lagomorphs.

IMPORTANCE: Syphilis is an ancient disease of humans and lagomorphs caused by two distinct but genetically closely related bacteria (>98% sequence identity based on the whole genome) of the genus Treponema. While human syphilis is well studied, little is known about the disease in the lagomorph host. Yet, comparative studies are needed to understand mechanisms in host-pathogen coevolution in treponematoses. Importantly, Treponema paraluisleporidarum-infected hare populations provide ample opportunity to study the syphilis-causing pathogen in a naturally infected model population without antibiotic treatment, data that cannot be obtained from syphilis infection in humans. We provide data on genetic diversity and are able to highlight various types of repetitions in one of the two hypervariable regions at the tp0548 locus that have not been described in the human syphilis-causing sister bacterium Treponema pallidum subsp. pallidum.

Microstructural differences in the osteochondral unit of terrestrial and aquatic mammals.

During evolution, animals have returned from land to water, adapting with morphological modifications to life in an aquatic environment. We compared the osteochondral units of the humeral head of marine and terrestrial mammals across species spanning a wide range of body weights, focusing on microstructural organization and biomechanical performance. Aquatic mammals feature cartilage with essentially random collagen fiber configuration, lacking the depth-dependent, arcade-like organization characteristic of terrestrial mammalian species. They have a less stiff articular cartilage at equilibrium with a significantly lower peak modulus, and at the osteochondral interface do not have a calcified cartilage layer, displaying only a thin, highly porous subchondral bone plate. This totally different constitution of the osteochondral unit in aquatic mammals reflects that accommodation of loading is the primordial function of the osteochondral unit. Recognizing the crucial importance of the microarchitecture-function relationship is pivotal for understanding articular biology and, hence, for the development of durable functional regenerative approaches for treatment of joint damage, which are thus far lacking.

The pathology of co-infection with Usutu virus and Plasmodium spp. in naturally infected Eurasian blackbirds (Turdus merula).

Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus causing mortality in Eurasian blackbirds (Turdus merula) in Europe. In dead blackbirds, avian malaria co-infection due to mosquito-borne hemosporidians (e.g., Plasmodium spp.) has been reported. In humans, a similar co-infection of a flavivirus, Dengue virus, and Plasmodium spp. is causing increased severity of clinical disease. Currently, the effects of co-infection of arboviruses and hemosporidians in blackbirds remain unclear. This study investigates the rate of USUV and Plasmodium spp. co-infection in found-dead blackbirds (n = 203) from 2016 to 2020 in the Netherlands. Presence of Plasmodium spp. was evaluated by cytology (43/203; 21,2%), histopathology (94/186; 50,5%) and qPCR (179/203; 88,1%). The severity of histological lesions in USUV and Plasmodium spp. co-infected dead blackbirds (121/203; 59,6%) were compared with those in Plasmodium spp. single-infected cases. Additionally, since no knowledge is present on the infection rate on live birds and mosquitoes in the Netherlands, a small group of live blackbirds (n = 12) and selected in the field-collected mosquito pools (n = 96) in 2020 were tested for the presence of Plasmodium spp. The latter was detected in the tested live blackbirds by qPCR (8/10; 80%), and cytology (3/11; 27,3%) and in the mosquito pools by qPCR (18/96; 18,7%). For this study, co-infection between USUV and Plasmodium spp. was observed only in the dead blackbirds. The high Plasmodium spp. presence, associated with lower lesions score, in single infected found dead birds suggest a predominantly smaller pathogenic role as single agent. On the other hand, the higher histological lesion scores observed in USUV and Plasmodium spp. co-infected birds suggests a major pathogenic role for the virus or an increased severity of the lesions due to a possible interplay of the two agents.

Harbor Porpoise Deaths Associated with Erysipelothrix rhusiopathiae, the Netherlands, 2021.

In August 2021, a large-scale mortality event affected harbor porpoises (Phocoena phocoena) in the Netherlands. Pathology and ancillary testing of 22 animals indicated that the most likely cause of death was Erysipelothrix rhusiopathiae infection. This zoonotic agent poses a health hazard for cetaceans and possibly for persons handling cetacean carcasses.

Genomic comparison of mecC-carrying methicillin-resistant Staphylococcus aureus from hedgehogs and humans in the Netherlands.

OBJECTIVES: MRSA carrying the mecC gene (mecC-MRSA) have been found in humans and animals worldwide. A high carriage rate of mecC-MRSA has been described among hedgehogs in different countries. We performed genomic comparison of mecC-MRSA from hedgehogs and humans using next-generation sequencing (NGS) to investigate possible zoonotic transmission in the Netherlands. METHODS: Nasal swabs from hedgehogs (n = 105) were cultured using pre-enrichment and selective plates. Isolates were sequenced using Illumina NGS platforms. These data were compared with sequence data of mecC-MRSA (n = 62) from the Dutch national MRSA surveillance in humans. RESULTS: Fifty hedgehogs were found to be MRSA positive, of which 48 carried mecC. A total of 60 mecC-MRSA isolates derived from 50 hedgehogs were compared with the human isolates. Fifty-nine mecC-MRSA from hedgehogs and all but one isolate from humans belonged to clonal complexes CC130 and CC1943. The mecC gene was located within the SCCmec XI element. Most mecC-MRSA did not carry other resistance genes besides mecC and blaZ. Two human isolates carried erm(C). Isolates differed in the presence of various virulence genes, which were linked to distinct STs and clonal complexes. Some isolates had up to 17 virulence genes, which underlines their pathogenic potential. No genetic clusters of hedgehog and human isolates were found. CONCLUSIONS: mecC-MRSA from hedgehogs and humans mainly belonged to the same two clonal complexes, indicating a common source. No firm evidence for recent zoonotic transmission was found. Further studies are needed to investigate the role of hedgehogs in the occurrence of mecC-MRSA in humans.

Zoonotic Mutation of Highly Pathogenic Avian Influenza H5N1 Virus Identified in the Brain of Multiple Wild Carnivore Species.

Wild carnivore species infected with highly pathogenic avian influenza (HPAI) virus subtype H5N1 during the 2021-2022 outbreak in the Netherlands included red fox (Vulpes vulpes), polecat (Mustela putorius), otter (Lutra lutra), and badger (Meles meles). Most of the animals were submitted for testing because they showed neurological signs. In this study, the HPAI H5N1 virus was detected by PCR and/or immunohistochemistry in 11 animals and was primarily present in brain tissue, often associated with a (meningo) encephalitis in the cerebrum. In contrast, the virus was rarely detected in the respiratory tract and intestinal tract and associated lesions were minimal. Full genome sequencing followed by phylogenetic analysis demonstrated that these carnivore viruses were related to viruses detected in wild birds in the Netherlands. The carnivore viruses themselves were not closely related, and the infected carnivores did not cluster geographically, suggesting that they were infected separately. The mutation PB2-E627K was identified in most carnivore virus genomes, providing evidence for mammalian adaptation. This study showed that brain samples should be included in wild life surveillance programs for the reliable detection of the HPAI H5N1 virus in mammals. Surveillance of the wild carnivore population and notification to the Veterinary Authority are important from a one-heath perspective, and instrumental to pandemic preparedness.

Gross, Histologic and Immunohistochemical Characteristics of Keratoacanthomas in Lizards.

The present study describes the clinical behavior as well as the histopathologic and immunohistochemical characteristics of keratoacanthomas (Kas) in three different saurian species. While Kas presented as two dermal lesions in a bearded dragon (Pogona vitticeps), multicentric Kas were observed in three panther chameleons (Furcifer pardalis) and a veiled chameleon (Chamaeleo calyptratus). Macroscopically, Kas presented as dome-shaped skin tumors with a centralized keratinous pearl and a diameter ranging from 0.1-1.5 cm. In all lizards, Kas were predominantly located at the dorsolateral body wall, and KA of the eyelid was additionally observed in three out of four chameleons. Histologically, KAs presented as relatively well-defined, circumscribed epidermal proliferations that consisted of a crateriform lesion containing a central keratinous pearl with minimally infiltrating borders. In all KAs, a consistent immunohistochemical pattern was observed, with the expression of cyclooxygenase-2, E-cadherin, and pan-cytokeratin. A follow-up period of one to two years was established in all lizards. While no recurrence was observed in the panther chameleons, recurrence of a single keratoacanthoma was observed in the bearded dragon after one year, and in the veiled chameleon, multicentric keratoacanthomas reappeared during a follow-up period of two years. We describe KA as a previously unrecognized neoplastic entity in lizards that constitutes a low-grade, non-invasive but rapidly growing skin tumor that may show a multicentric appearance, especially in chameleons. As previously postulated for dermal squamous cell carcinomas (SCC), artificial ultraviolet lighting may play an important role in the oncogenesis of KAs in lizards. Although dermal SCCs in lizards show similar predilection sites and gross pathologic features, our results suggest that KA should be considered as a histologic variant of SCC that represents a rather benign squamous proliferation in comparison to conventional SCCs. Early diagnosis of KA and reliable discrimination from SCCs are essential for the prognosis of this neoplastic entity in lizards.

Diversity of Hepatozoon species in wild mammals and ticks in Europe.

BACKGROUND: Hepatozoon spp. are tick-borne parasites causing subclinical to clinical disease in wild and domestic animals. Aim of this study was to determine Hepatozoon prevalence and species distribution among wild mammals and ticks in Europe. METHODS: Samples of wild mammals and ticks, originating from Austria, Bosnia and Herzegovina, Croatia, Belgium and the Netherlands, were tested with PCR to amplify a ~ 670-bp fragment of the small subunit ribosomal RNA gene. RESULTS: Of the 2801 mammal samples that were used for this study, 370 (13.2%) tested positive. Hepatozoon canis was detected in samples of 178 animals (3 Artiodactyla, 173 Carnivora, 1 Eulipotyphia, 1 Lagomorpha), H. martis in 125 (3 Artiodactyla, 122 Carnivora), H. sciuri in 13 (all Rodentia), Hepatozoon sp. in 47 (among which Hepatozoon sp. Vole isolate, all Rodentia) and H. ayorgbor in 4 (all Rodentia). Regarding origin, 2.9% (6/208) tested positive from Austria, 2.8% (1/36) from Bosnia and Herzegovina, 14.6% (173/1186) from Croatia and 13.9% (190/1371) from Belgium/the Netherlands. Of the 754 ticks collected, 0.0% (0/35) Hyalomma sp., 16.0% (4/25) Dermacentor spp., 0.0% (0/23) Haemaphysalis spp., 5.3% (24/50) Ixodes and 1.4% (3/221) Rhipicephalus spp. tested positive for Hepatozoon (4.2%; 32/754), most often H. canis (n = 22). CONCLUSIONS: Hepatozoon canis is most present in mammals (especially in Carnivora such as gray wolves and golden jackals) and ticks, followed by H. martis, which was found merely in stone martens and pine martens. None of the rodent-associated Hepatozoon spp. were detected in the ticks, suggesting the possible implication of other arthropod species or non-vectorial routes in the transmission cycle of the hemoprotozoans in rodents. Our findings of H. canis in ticks other than R. sanguineus add to the observation that other ticks are also involved in the life cycle of Hepatozoon. Now that presence of Hepatozoon has been demonstrated in red foxes, gray wolves, mustelids and rodents from the Netherlands and/or Belgium, veterinary clinicians should be aware of the possibility of spill-over to domestic animals, such as dogs.

Mass Mortality Caused by Highly Pathogenic Influenza A(H5N1) Virus in Sandwich Terns, the Netherlands, 2022.

We collected data on mass mortality in Sandwich terns (Thalasseus sandvicensis) during the 2022 breeding season in the Netherlands. Mortality was associated with at least 2 variants of highly pathogenic avian influenza A(H5N1) virus clade 2.3.4.4b. We report on carcass removal efforts relative to survival in colonies. Mitigation strategies urgently require structured research.

Evidence of Hearing Loss and Unrelated Toxoplasmosis in a Free-Ranging Harbour Porpoise (Phocoena phocoena).

Evidence of hearing impairment was identified in a harbour porpoise (Phocoena phocoena) on the basis of scanning electron microscopy. In addition, based on histopathology and immunohistochemistry, there were signs of unrelated cerebral toxoplasmosis. The six-year old individual live stranded on the Dutch coast at Domburg in 2016 and died a few hours later. The most significant gross lesion was multifocal necrosis and haemorrhage of the cerebrum. Histopathology of the brain revealed extensive necrosis and haemorrhage in the cerebrum with multifocal accumulations of degenerated neutrophils, lymphocytes and macrophages, and perivascular lymphocytic cuffing. The diagnosis of cerebral toxoplasmosis was confirmed by positive staining of protozoa with anti-Toxoplasma gondii antibodies. Tachyzoites were not observed histologically in any of the examined tissues. Ultrastructural evaluation of the inner ear revealed evidence of scattered loss of outer hair cells in a 290 µm long segment of the apical turn of the cochlea, and in a focal region of ~ 1.5 mm from the apex of the cochlea, which was compatible with noise-induced hearing loss. This is the first case of concurrent presumptive noise-induced hearing loss and toxoplasmosis in a free-ranging harbour porpoise from the North Sea.

Highly Pathogenic Avian Influenza A(H5N1) Virus in Wild Red Foxes, the Netherlands, 2021.

We detected infection with highly pathogenic avian influenza A(H5N1) virus clade 2.3.4.4b in 2 red fox (Vulpes vulpes) cubs found in the wild with neurologic signs in the Netherlands. The virus is related to avian influenza viruses found in wild birds in the same area.

Pathology and Pathogenesis of Eurasian Blackbirds (Turdus merula) Naturally Infected with Usutu Virus.

The Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus. Despite its continuous circulation in Europe, knowledge on the pathology, cellular and tissue tropism and pathogenetic potential of different circulating viral lineages is still fragmentary. Here, macroscopic and microscopic evaluations are performed in association with the study of cell and tissue tropism and comparison of lesion severity of two circulating virus lineages (Europe 3; Africa 3) in 160 Eurasian blackbirds (Turdus merula) in the Netherlands. Results confirm hepatosplenomegaly, coagulative necrosis and lymphoplasmacytic inflammation as major patterns of lesions and, for the first time, vasculitis as a novel virus-associated lesion. A USUV and Plasmodium spp. co-infection was commonly identified. The virus was associated with lesions by immunohistochemistry and was reported most commonly in endothelial cells and blood circulating and tissue mononucleated cells, suggesting them as a major route of entry and spread. A tropism for mononuclear phagocytes cells was further supported by viral labeling in multinucleated giant cells. The involvement of ganglionic neurons and epithelial cells of the gastrointestinal tract suggests a possible role of oral transmission, while the involvement of feather follicle shafts and bulbs suggests their use as a diagnostic sample for live bird testing. Finally, results suggest similar pathogenicity for the two circulating lineages.

The Legend of the Buffalo Chest.

BACKGROUND: The "buffalo chest" is a condition in which a simultaneous bilateral pneumothorax occurs due to a communication of both pleural cavities caused by an iatrogenic or idiopathic fenestration of the mediastinum. This rare condition is known by many clinicians because of a particular anecdote which stated that Native Americans could kill a North American bison with a single arrow in the chest by creating a simultaneous bilateral pneumothorax, due to the animal's peculiar anatomy in which there is one contiguous pleural space due to an incomplete mediastinum. RESEARCH QUESTION: What evidence is there for the existence of buffalo chest? STUDY DESIGN AND METHODS: The term "buffalo chest" and its anecdote were first mentioned in a ''personal communication'' by a veterinarian in the Annals of Surgery in 1984. A mixed method research was performed on buffalo chest and its etiology. A total of 47 cases of buffalo chest were identified in humans. RESULTS: This study found that all authors were referring to the article from 1984 or to each other. Evidence was found for interpleural communications in other mammal species, but no literature on the anatomy of the mediastinum of the bison was found. The main reason for this research was fact-checking the origin of the anecdote and search for evidence for the existence of buffalo chest. Autopsies were performed on eight bison, and four indeed were found to have had interpleural communications. INTERPRETATION: We hypothesize that humans can also have interpleural fenestrations, which can be diagnosed when a pneumothorax occurs.

Circulation of Babesia Species and Their Exposure to Humans through Ixodes Ricinus.

Human babesiosis in Europe has been attributed to infection with Babesia divergens and, to a lesser extent, with Babesia venatorum and Babesia microti, which are all transmitted to humans through a bite of Ixodes ricinus. These Babesia species circulate in the Netherlands, but autochthonous human babesiosis cases have not been reported so far. To gain more insight into the natural sources of these Babesia species, their presence in reservoir hosts and in I. ricinus was examined. Moreover, part of the ticks were tested for co-infections with other tick borne pathogens. In a cross-sectional study, qPCR-detection was used to determine the presence of Babesia species in 4611 tissue samples from 27 mammalian species and 13 bird species. Reverse line blotting (RLB) and qPCR detection of Babesia species were used to test 25,849 questing I. ricinus. Fragments of the 18S rDNA and cytochrome c oxidase subunit I (COI) gene from PCR-positive isolates were sequenced for confirmation and species identification and species-specific PCR reactions were performed on samples with suspected mixed infections. Babesia microti was found in two widespread rodent species: Myodes glareolus and Apodemus sylvaticus, whereas B. divergens was detected in the geographically restricted Cervus elaphus and Bison bonasus, and occasionally in free-ranging Ovis aries. B. venatorum was detected in the ubiquitous Capreolus capreolus, and occasionally in free-ranging O. aries. Species-specific PCR revealed co-infections in C. capreolus and C. elaphus, resulting in higher prevalence of B. venatorum and B. divergens than disclosed by qPCR detection, followed by 18S rDNA and COI sequencing. The non-zoonotic Babesia species found were Babesia capreoli, Babesia vulpes, Babesia sp. deer clade, and badger-associated Babesia species. The infection rate of zoonotic Babesia species in questing I. ricinus ticks was higher for Babesia clade I (2.6%) than Babesia clade X (1.9%). Co-infection of B. microti with Borrelia burgdorferi sensu lato and Neoehrlichia mikurensis in questing nymphs occurred more than expected, which reflects their mutual reservoir hosts, and suggests the possibility of co-transmission of these three pathogens to humans during a tick bite. The ubiquitous spread and abundance of B. microti and B. venatorum in their reservoir hosts and questing ticks imply some level of human exposure through tick bites. The restricted distribution of the wild reservoir hosts for B. divergens and its low infection rate in ticks might contribute to the absence of reported autochthonous cases of human babesiosis in the Netherlands.

What a stranded whale with scoliosis can teach us about human idiopathic scoliosis.

Scoliosis is a deformation of the spine that may have several known causes, but humans are the only mammal known to develop scoliosis without any obvious underlying cause. This is called 'idiopathic' scoliosis and is the most common type. Recent observations showed that human scoliosis, regardless of its cause, has a relatively uniform three-dimensional anatomy. We hypothesize that scoliosis is a universal compensatory mechanism of the spine, independent of cause and/or species. We had the opportunity to study the rare occurrence of scoliosis in a whale (Balaenoptera acutorostrata) that stranded in July 2019 in the Netherlands. A multidisciplinary team of biologists, pathologists, veterinarians, taxidermists, radiologists and orthopaedic surgeons conducted necropsy and imaging analysis. Blunt traumatic injury to two vertebrae caused an acute lateral deviation of the spine, which had initiated the development of compensatory curves in regions of the spine without anatomical abnormalities. Three-dimensional analysis of these compensatory curves showed strong resemblance with different types of human scoliosis, amongst which idiopathic. This suggests that any decompensation of spinal equilibrium can lead to a rather uniform response. The unique biomechanics of the upright human spine, with significantly decreased rotational stability, may explain why only in humans this mechanism can be induced relatively easily, without an obvious cause, and is therefore still called 'idiopathic'.

Challenges in the Assessment of Bycatch: Postmortem Findings in Harbor Porpoises (Phocoena phocoena) Retrieved From Gillnets.

Bycatch is considered one of the most significant threats affecting cetaceans worldwide. In the North Sea, bottom-set gillnets are a specific risk for harbor porpoises (Phocoena phocoena). Methods to estimate bycatch rates include on-board observers, remote electronic monitoring, and fishermen voluntarily reporting; none of these are systematically conducted. Additionally, necropsies of stranded animals can provide insights into bycatch occurrence and health status of individuals. There are, however, uncertainties when it comes to the assessment of bycatch in stranded animals, mainly due to the lack of diagnostic tools specific for underwater entrapment. We conducted a literature review to establish criteria that aid in the assessment of bycatch in small cetaceans, and we tested which of these criteria applied to harbor porpoises retrieved from gillnets in the Netherlands (n = 12). Twenty-five criteria were gathered from literature. Of these, "superficial incisions," "encircling imprints," and "recent ingestion of prey" were observed in the vast majority of our confirmed bycatch cases. Criteria like "pulmonary edema," "pulmonary emphysema," and "organ congestion" were also frequently observed, although considered unspecific as an indicator of bycatch. Notably, previously mentioned criteria as "favorable health status," "absence of disease," or "good nutritional condition" did not apply to the majority of our bycaught porpoises. This may reflect an overall reduced fitness of harbor porpoises inhabiting the southern North Sea or a higher chance of a debilitated porpoise being bycaught, and could result in an underestimation of bycatch rates when assessing stranded animals.

Iron Regulation in Elderly Asian Elephants (Elephas maximus) Chronically Infected With Mycobacterium tuberculosis.

Restriction of nutrients to pathogens (nutritional immunity) is a critical innate immune response mechanism that operates when pathogens such as Mycobacterium tuberculosis have the potential to evade humoral immunity. Tuberculosis is of growing concern for zoological collections worldwide and is well-illustrated by infections of Asian and African elephants, where tuberculosis is difficult to diagnose. Here, we investigated hematological parameters and iron deposition in liver, lung, and spleen of three Asian elephants (Elephas maximus) infected with Mycobacterium tuberculosis. For reference purposes, we analyzed tissue samples from control M. tuberculosis-negative elephants with and without evidence of inflammation and/or chronic disease. Molecular analyses of bacterial lesions of post mortally collected tissues confirmed M. tuberculosis infection in three elephants. DNA sequencing of the bacterial cultures demonstrated a single source of infection, most likely of human origin. In these elephants, we observed moderate microcytic anemia as well as liver (mild), lung (moderate) and spleen (severe) iron accumulation, the latter mainly occurring in macrophages. Macrophage iron sequestration in response to infection and inflammation is caused by inhibition of iron export via hepcidin-dependent and independent mechanisms. The hepatic mRNA levels of the iron-regulating hormone hepcidin were increased in only one control elephant suffering from chronic inflammation without mycobacterial infection. By contrast, all three tuberculosis-infected elephants showed low hepcidin mRNA levels in the liver and low serum hepcidin concentrations. In addition, hepatic ferroportin mRNA expression was high. This suggests that the hepcidin/ferroportin regulatory system aims to counteract iron restriction in splenic macrophages in M. tuberculosis infected elephants to provide iron for erythropoiesis and to limit iron availability for a pathogen that predominantly proliferates in macrophages. Tuberculosis infections appear to have lingered for more than 30 years in the three infected elephants, and decreased iron availability for mycobacterial proliferation may have forced the bacteria into a persistent, non-proliferative state. As a result, therapeutic iron substitution may not have been beneficial in these elephants, as this therapy may have enhanced progression of the infection.

Fatal Chlamydia avium Infection in Captive Picazuro Pigeons, the Netherlands.

In 2016, an outbreak of Chlamydia avium infection occurred among Picazuro pigeons (Patagioenas picazuro) living in an aviary in the Netherlands. Molecular typing revealed a unique strain of C. avium. Our findings show that C. avium infection, which usually causes subclinical infection, can cause fatal disease in pigeons.

Pathological Findings in White-Beaked Dolphins (Lagenorhynchus albirostris) and Atlantic White-Sided Dolphins (Lagenorhynchus acutus) From the South-Eastern North Sea.

In the North Sea, white-beaked dolphins (Lagenorhynchus albirostris) occur regularly and are the second most common cetacean in the area, while their close relative, the Atlantic white-sided dolphin (Lagenorhynchus acutus), prefers the deeper waters of the northern North Sea and adjacent Atlantic Ocean. Though strandings of both species have occurred regularly in the past three decades, they have decreased in the southern North Sea during the last years. Studies describing necropsy findings in stranded Lagenorhynchus spp. are, to date, still scarce, while information gained through post-mortem examinations may reveal valuable information about underlying causes of this decline, including age structure and the reproduction status. Therefore, we retrospectively assessed and compared the necropsy results from fresh Lagenorhynchus spp. stranded along the southeastern North Sea between 1990 and 2019. A full necropsy was performed on 24 white-beaked dolphins and three Atlantic white-sided dolphins from the German and Dutch coast. Samples of selected organs were taken for histopathological, bacteriological, mycological, parasitological and virological examinations. The most common post-mortem findings were emaciation, gastritis and pneumonia. Gastritis and ulceration of the stomach was often associated with an anisakid nematode infection. Pneumonia was most likely caused by bacterial infections. Encephalitis was observed in three animals and morbillivirus antigen was detected immunohistochemically in one case. Although the animal also showed pneumonic lesions, virus antigen was only found in the brain. Parasitic infections mainly affected the gastro-intestinal tract. Lungworm infections were only detected in two cases and no associations with pathological alterations were observed. Stenurus spp. were identified in two of three cases of parasitic infections of the ears. Twelve of the 26 white-beaked dolphins stranded in Germany were found between 1993 and 1994, but there was no evidence of epizootic disease events or mass strandings during the monitored period.