Transatlantic spread of highly pathogenic avian influenza H5N1 by wild birds from Europe to North America in 2021.

Highly pathogenic avian influenza (HPAI) viruses of the A/Goose/Guangdong/1/1996 lineage (GsGd), which threaten the health of poultry, wildlife and humans, are spreading across Asia, Europe, Africa and North America but are currently absent from South America and Oceania. In December 2021, H5N1 HPAI viruses were detected in poultry and a free-living gull in St. John's, Newfoundland and Labrador, Canada. Our phylogenetic analysis showed that these viruses were most closely related to HPAI GsGd viruses circulating in northwestern Europe in spring 2021. Our analysis of wild bird migration suggested that these viruses may have been carried across the Atlantic via Iceland, Greenland/Arctic or pelagic routes. The here documented incursion of HPAI GsGd viruses into North America raises concern for further virus spread across the Americas by wild bird migration.

No evidence for homosubtypic immunity of influenza H3 in Mallards following vaccination in a natural experimental system.

The Mallard (Anas platyrhynchos) is an important reservoir species for influenza A viruses (IAV), and in this host, prevalence and virus diversity are high. Studies have demonstrated the presence of homosubtypic immunity, where individuals are unlikely to be reinfected with the same subtype within an autumn season. Further, evidence for heterosubtypic immunity exists, whereby immune responses specific for one subtype offer partial or complete protection against related HA subtypes. We utilized a natural experimental system to determine whether homo- or heterospecific immunity could be induced following experimental vaccination. Thirty Mallards were vaccinated with an inactivated H3, H6 or a sham vaccine and after seroconversion were exposed to naturally infected wild conspecifics. All ducks were infected within 2 days and had both primary and secondary infections. Overall, there was no observable difference between groups; all individuals were infected with H3 and H10 IAV. At the cessation of the experiment, most individuals had anti-NP antibodies and neutralizing antibodies against H10. Not all individuals had H3 neutralizing antibodies. The isolated H3 IAVs revealed genetic dissimilarity to the H3 vaccine strain, specifically substitutions in the vicinity of the receptor-binding site. There was no evidence of vaccine-induced homosubtypic immunity to H3, a likely result of both a poor H3 immune response in the ducks and H3 immune escape. Likewise, there was no observed heterosubtypic protection related to H6 vaccination. This study highlights the need for experimental approaches to assess how exposure to pathogens and resulting immune processes translates to individual and population disease dynamics.

Circannual variation in blood parasitism in a sub-Saharan migrant passerine bird, the garden warbler.

Knowing the natural dynamics of pathogens in migratory birds is important, for example, to understand the factors that influence the transport of pathogens to and their transmission in new geographical areas, whereas the transmission of other pathogens might be restricted to a specific area. We studied haemosporidian blood parasites of the genera Plasmodium, Haemoproteus and Leucocytozoon in a migratory bird, the garden warbler Sylvia borin. Birds were sampled in spring, summer and early autumn at breeding grounds in Sweden, on migration at Capri, Italy and on arrival and departure from wintering staging areas in West Africa: mapping recoveries of garden warblers ringed in Fennoscandia and Capri showed that these sites are most probably on the migratory flyway of garden warblers breeding at Kvismaren. Overall, haemosporidian prevalence was 39%, involving 24 different parasite lineages. Prevalence varied significantly over the migratory cycle, with relatively high prevalence of blood parasites in the population on breeding grounds and at the onset of autumn migration, followed by marked declines in prevalence during migration both on spring and autumn passage. Importantly, we found that when examining circannual variation in the different lineages, significantly different prevalence profiles emerged both between and within genera. Our results suggest that differences in prevalence profiles are the result of either different parasite transmission strategies or coevolution between the host and the various parasite lineages. When separating parasites into common vs. rare lineages, we found that two peaks in the prevalence of rare parasites occur; on arrival at Swedish breeding grounds, and after the wintering period in Africa. Our results stress the importance of appropriate taxonomic resolution when examining host-parasite interactions, as variation in prevalence both between and within parasite genera can show markedly different patterns.

Haemosporidian blood parasites in European birds of prey and owls.

Avian blood parasites have been intensively studied using morphological methods with limited information on their host specificity and species taxonomic status. Now the analysis of gene sequences, especially the mitochondrial cytochrome b gene of the avian haemosporidian species of Haemoproteus, Plasmodium, and Leucocytozoon, offers a new tool to review the parasite specificity and status. By comparing morphological and genetic techniques, we observed nearly the same overall prevalence of haemosporidian parasites by microscopy (19.8%) and polymerase chain reaction (PCR) (21.8%) analyses. However, in contrast to the single valid Leucocytozoon species (L. toddi) in the Falconiformes we detected 4 clearly distinctive strains by PCR screening. In the Strigiformes, where the only valid Leucocytozoon species is L. danilewskyi, we detected 3 genetically different strains of Leucocytozoon spp. Two strains of Haemoproteus spp. were detected in the birds of prey and owls examined, whereas the strain found in the tawny owl belonged to the morphospecies Haemoproteus noctuae. Three Plasmodium spp. strains that had already been found in Passeriformes were also detected in the birds of prey and owls examined here, supporting previous findings indicating a broad and nonspecific host spectrum bridging different bird orders.

Gene segment reassortment between American and Asian lineages of avian influenza virus from waterfowl in the Beringia area.

Since prehistoric times, the Bering Strait area (Beringia) has served as an avenue of dispersal between the Old and the New Worlds. On a field expedition to this area, we collected fecal samples from dabbling ducks, geese, shorebirds, and gulls on the Chukchi Peninsula, Siberia, and Pt. Barrow, Alaska, and characterized the subtypes of avian influenza virus present in them. Four of 202 samples (2%) from Alaska were positive for influenza A virus RNA in two independent polymerase chain reaction (PCR)-based screening assays, while all shorebird samples from the Chukchi Peninsula were negative. Subtypes H3N8 and H6N1 were recorded once, while subtype H8N4 was found in two samples. Full-length sequences were obtained from the three unique isolates, and phylogenetic analysis with representative sequences for the Eurasian and North American lineages of influenza A virus showed that one HA gene clustered with the Eurasian rather than the North American lineage. However, the closest relative to this sequence was a North American isolate from Delaware described in 2002, indicating that a H6 spillover from Asia has established itself in North America.

Species diversity of campylobacteria in a wild bird community in Sweden.

AIMS: To analyse the occurrence and host species distribution of campylobacteria species in shorebirds, geese and cattle on grazed coastal meadows in Sweden. METHODS AND RESULTS: Species identification was performed through a polyphasic approach, incorporating Amplified Fragment Length Polymorphism (AFLP) profiling, 16S RNA gene sequence analysis together with extensive phenotypic characterization. From 247 sampled birds and 71 cattle, we retrieved 113 urease positive thermophilic Campylobacter (UPTC) and 16 Campylobacter jejuni ssp. jejuni isolates. Furthermore, 18 isolates of Helicobacter canadensis, and five isolates that potentially represent a new genus of micro-aerophilic, spiral and Gram-negative bacteria were isolated. The distribution of bacterial species on hosts was uneven: all H. canadensis isolates were retrieved from geese, while all but one of the Campylobacter lari UPTC isolates were found in shorebirds. AFLP type distribution of Camp. lari UPTC isolates among individual, resampled and breeding-paired Redshank birds generally indicated a constant shift in strain populations over time and absence of geographical clustering. CONCLUSIONS: The large number of isolated campylobacteria, including species that are zoonotic enteropathogens, indicates that these wild birds potentially may serve as reservoirs of human infections. However, despite a common environment, the different host species largely carried their own campylobacteria populations, indicating that cross-species transmission is rare. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study is one of few that provide data on the occurrence of campylobacteria in wild animals, adding information on the ecology and epidemiology of micro-organisms that are of public health concern.

Diversities and similarities in PFGE profiles of Campylobacter jejuni isolated from migrating birds and humans.

AIMS: To genetically sub-type Campylobacter jejuni strains isolated from migratory birds, and to compare these with clinical strains collected in the same area and corresponding time period, with the aim to increase our knowledge on sub-types occurring among wild birds and their possible impact on human disease. METHODS AND RESULTS: We sub-typed C. jejuni strains from migrating birds (n = 89) and humans (n = 47), using macrorestriction profiling by pulsed-field gel electrophoresis. Isolates from migrant birds often exhibited sub-types with higher levels of similarity to isolates from birds of the same species or feeding guild, than to isolates from other groups of birds. Likewise, could the vast majority of sub-types found among the migrant bird isolates not be identified among sub-types from human cases. Only two bird strains, one from a starling (Sturnus vulgaris) and one from a blackbird (Turdus merula), had sub-types that were similar to some of the human strain sub-types. CONCLUSIONS: Isolates from one bird species, or feeding guild, often exhibited high similarities, indicating a common transmission source for individuals, or an association between certain sub-types of C. jejuni and certain ecological guilds or phylogenetic groups of birds. Sub-types occurring among wild birds were in general distinctively different from those observed in patients. The two bird isolates that were similar to human strains were isolated from bird species that often live in close associations with human settlements. SIGNIFICANCE AND IMPACT OF STUDY: Wild birds have often been mentioned as a potential route for transmission of C. jejuni to humans. Our study demonstrates that strains isolated from birds most often are different from clinical strains, but that some strain similarities occur, notably in birds strongly associated with human activities.

A new nested polymerase chain reaction method very efficient in detecting Plasmodium and Haemoproteus infections from avian blood.

Recently, several polymerase chain reaction (PCR)-based methods for detection and genetic identification of haemosporidian parasites in avian blood have been developed. Most of these have considerably higher sensitivity compared with traditional microscope-based examinations of blood smears. These new methods have already had a strong impact on several aspects of research on avian blood parasites. In this study, we present a new nested PCR approach, building on a previously published PCR method, which has significantly improved performance. We compare the new method with some existing assays and show, by sequence-based data, that the higher detection rate is mainly due to superior detection of Plasmodium spp. infections, which often are of low intensity and, therefore, hard to detect with other methods.

Campylobacter jejuni in black-headed gulls (Larus ridibundus): prevalence, genotypes, and influence on C. jejuni epidemiology.

Campylobacteriosis is a zoonotic disease in which birds have been suggested to play an important role as a reservoir. We investigated the prevalence of Campylobacter jejuni subsp. jejuni in black-headed gulls (Larus ridibundus) in southern Sweden with the aim of examining the nature of C. jejuni infection in this bird species. Birds were sampled in four sampling series each year during 1999 (n = 419) and 2000 (n = 365). Longitudinally sampled C. jejuni isolates from individual gulls were subjected to macrorestriction profiling (MRP) by pulsed-field gel electrophoresis to investigate the genotypical stability during the natural course of infection. Furthermore, a subset (n = 76) of black-headed gull isolates was compared to isolates from broiler chickens (n = 38) and humans (n = 56) originating from the same geographic area. We found a pronounced seasonal variation in C. jejuni carriage, with the highest rates found in late autumn. MRP similarities were higher between isolates of human and broiler chicken origin, than between those of wild bird origin and either of the other two hosts. However, identical MRPs were found in two gull isolates and one human isolate after digestion with two restriction enzymes, strongly indicating that they may have been colonized by the same clone of C. jejuni. The MRPs most prevalent in gull isolates did not occur among isolates from humans and broiler chickens, suggesting the existence of a subpopulation of C. jejuni adapted to species-specific colonization or environmental survival.

Cross-species infection of blood parasites between resident and migratory songbirds in Africa.

We studied the phylogeny of avian haemosporidian parasites, Haemoproteus and Plasmodium, in a number of African resident and European migratory songbird species sampled during spring and autumn in northern Nigeria. The phylogeny of the parasites was constructed through sequencing part of their mitochondrial cytochrome b gene. We found eight parasite lineages, five Haemoproteus and three Plasmodium, infecting multiple host species. Thus, 44% of the 18 haemospiridian lineages found in this study were detected in more than one host species, indicating that host sharing is a more common feature than previously thought. Furthermore, one of the Plasmodium lineages infected species from different host families, Sylviidae and Ploceidae, expressing exceptionally large host range. We mapped transmission events, e.g. the occurrence of the parasite lineages in resident bird species in Europe or Africa, onto a phylogenetic tree. This yielded three clades, two Plasmodium and one Haemoproteus, in which transmission seems to occur solely in Africa. One Plasmodium clade showed European transmission, whereas the remaining two Haemoproteus clades contained mixes of lineages of African, European or unknown transmission. The mix of areas of transmission in several branches of the phylogenetic tree suggests that transmission of haemosporidian parasites to songbirds has arisen repeatedly in Africa and Europe. Blood parasites could be viewed as a cost of migration, as migratory species in several cases were infected with parasite lineages from African resident species. This cost of migration could have considerable impact on the evolution of migration and patterns of winter distribution in migrating birds.

Development and evaluation of assays for the determination of total and pancreatic amylase at 37 degrees C according to the principle recommended by the IFCC.

OBJECTIVES: The aim of our study was a) to optimize assays for measurement of total (T-) and pancreatic (P-)amylase at 37 degrees C based on the principle recommended by the IFCC at 30 degrees C, b) to evaluate the analytical performance of these assays in a multicentric study and c) to establish reference intervals for serum and urine for either method. METHODS: Optimized conditions for 37 degrees C were elaborated with regard to substrate concentration, pH, inorganic additives and glucosidase activity. The cleavage pattern of the EPS substrate was studied by HPLC. Liquid ready-to-use reagents for T- and P-amylase were provided to six European laboratories. RESULTS: The assays showed good performance characteristics (median intraassay CVs 1.0% for T- and 1.3% for P-amylase, median interassay CVs 3.0% for either assay, dynamic range 15-fold URL for T- and 30-fold for P-amylase), high correlation with the previous EPS methods (r > 0.996, slope 0.43, intercept < 5 U/L) in serum, heparin plasma and urine and good analytical specificity of the P-amylase assay (residual S-amylase activity 2.4%). Serum reference ranges were found to be 28 to 100 U/L for T- and 13 to 53 U/L for P-amylase (n = 775); URLs in urine were estimated as 490 U/L or 280 U/g creatinine for males and 450 U/L or 380 U/g creatinine for females with total amylase. CONCLUSION: We believe that these assays based on the 30 degrees C IFCC recommendation represent a further improvement in amylase methodology at 37 degrees C and merit broad application in clinical routine.

Does the uncertainty of commonly performed glucose measurements allow identification of individuals at high risk for diabetes?

Revised recommendations for diagnosis of diabetes introduce the intermediary risk group of impaired fasting glucose (IFG), defined as individuals with a fasting blood-glucose concentration between 5.6 and 6.0 mmol/l. We apply the concept of uncertainty to identifiable steps of sampling and measuring blood-glucose. Since many instruments in primary health care measure plasma-glucose and report results as blood-glucose and vice versa, factors affecting the transformation are also considered. The study identifies the measurement procedure as the major source of uncertainty, closely followed by preanalytical sources. The estimated uncertainties indicate that the presently available procedures do not allow identification of IFG by a single investigation. The approach to establish an uncertainty budget can be used to evaluate the clinical usefulness of measurements.

Successful intravenous immunoglobulin therapy for severe and persistent astrovirus gastroenteritis after fludarabine treatment in a patient with Waldenström's macroglobulinemia.

A 78-year-old male with Waldenström's macroglobulinemia was after 23 years of conservative treatment given fludarabine phosphate in 1993 because of disease progression. Three weeks after the third fludarabine course he presented with a 5-day-history of watery diarrhoea, nausea and vomiting. Stool cultures were negative but a semiquantitative electron microscopy method demonstrated massive amounts of astrovirus (> 10(14) particles/ml). Symptomatic treatment was given but since his condition deteriorated, high-dose intravenous immunoglobulin (IvIg) treatment, 0.4 g/kg for four days was initiated. Within twenty-four hours all symptoms disappeared and the patient was discharged after a few days. A stool sample collected after two weeks demonstrated 10(7) particles/ml and after four weeks no astrovirus could be detected. The association between fludarabine and this opportunistic infection and the potential role of high dose IvIg treatment are discussed.

Waldenström's macroglobulinemia with the AML/MDS-associated t(1;3)(p36;q21).

Two unusual, and perhaps causally related, clinical and cytogenetic features in a patient with Waldenström's macroglobulinemia are presented. Firstly, during the progression of the primary macroglobulinemia bone destruction and hypercalcemia occurred. Secondly, a t(1;3)(p36;q21) was found as the sole clonal chromosomal abnormality. This translocation is characteristic of acute myeloid leukemia (AML) and myelodysplastic syndromes with a high propensity for progressing to AML. The t(1;3) has previously never been reported in a lymphoproliferative disorder. Since the abnormality is associated with acute transformation of cells of the myelopoietic lineages, it is possible that the t(1;3), found in cells of lymphoid origin in the present case, not only induced the neoplastic process as such but also brought about the unusually malignant tumor progression.