Can Preening Contribute to Influenza A Virus Infection in Wild Waterbirds?

Wild aquatic birds in the Orders Anseriformes and Charadriiformes are the main reservoir hosts perpetuating the genetic pool of all influenza A viruses, including pandemic viruses. High viral loads in feces of infected birds permit a fecal-oral route of transmission. Numerous studies have reported the isolation of avian influenza viruses (AIVs) from surface water at aquatic bird habitats. These isolations indicate aquatic environments have an important role in the transmission of AIV among wild aquatic birds. However, the progressive dilution of infectious feces in water could decrease the likelihood of virus/host interactions. To evaluate whether alternate mechanisms facilitate AIV transmission in aquatic bird populations, we investigated whether the preen oil gland secretions by which all aquatic birds make their feathers waterproof could support a natural mechanism that concentrates AIVs from water onto birds' bodies, thus, representing a possible source of infection by preening activity. We consistently detected both viral RNA and infectious AIVs on swabs of preened feathers of 345 wild mallards by using reverse transcription–polymerase chain reaction (RT-PCR) and virus-isolation (VI) assays. Additionally, in two laboratory experiments using a quantitative real-time (qR) RT-PCR assay, we demonstrated that feather samples (n = 5) and cotton swabs (n = 24) experimentally impregnated with preen oil, when soaked in AIV-contaminated waters, attracted and concentrated AIVs on their surfaces. The data presented herein provide information that expands our understanding of AIV ecology in the wild bird reservoir system

Outbreak of Eimeria kofoidi and E. legionensis coccidiosis in redlegged partridges (Alectoris rufa)

An outbreak of coccidiosis occurred in red-legged partridges is reported. At the post-mortem examination the birds showed a mucous haemorrhagic enteritis, mostly in the duodenal intestinal tract. Direct microscopic examination of intestinal content revealed the presence of a high number of oocysts. After incubation, on the basis of the morphological features, two species of coccidia were identified: Eimeria kofoidi and E. legionensis

Serological evidences showing the involvement of free-living pheasants in the influenza ecology

From 1995 to 2002, 219 sera were collected in Northern Italy from wild pheasants, in order to establish the possible involvement of these Galliformes birds in the influenza ecology. A serological survey for avian influenza viruses (AIVs) was carried out by ELISA test in order to detect type A influenza antibodies. The overall seroprevalence was 12.3%, with yearly values ranging from 0% to 42.5%. No antibodies against either H5 or H7 AIV subtypes were found by hemagglutination-inhibition test. Data from 16 recaptured birds, among 113 animals banded for individual identification, showed seroconversions in 2 pheasants. Our results indicate AIV circulation in free-living pheasants; the involvement of this land-based bird species in influenza ecology is discussed

Active surveillance for Avian Influenza viruses in wild birds and backyard flocks in Northern Italy during 2004-2006

International audienceFollowing the avian influenza (AI) epidemics that occurred in Italy between 1997 and 2003, the Italian Ministry of Health in collaboration with veterinary authorities promoted, funded and implemented a national surveillance programme. The main objectives of the surveillance effort were to identify avian influenza viruses (AIVs) circulating in wild birds and to investigate the role of backyard poultry flocks in the dynamics of infection in a densely populated poultry area (DPPA). Over two years (2004-2006) 164 backyard flocks and 4,083 wild birds (mainly migratory Anseriformes and Charadriiformes) were sampled in three regions in the North of Italy. Samples collected were screened by means of real time reverse transcriptase-polymerase chain reaction (RRT-PCR) and the positive samples were processed for attempted virus isolation in embryonated fowl's specific pathogen free (SPF) eggs. At the end of the study period 27 low pathogenic avian influenza (LPAI) viruses had been isolated from backyard flocks and 49 strains obtained from wild birds. Of these 26 belonged to the H5 or H7 subtype and were closely related to contemporary low pathogenic strains of Eurasian lineage. The findings confirm that backyard free range farming is at high risk for AIVs introduction, and the role of wild waterfowl in the introduction and perpetuation of LPAI viruses during the winter season in Southern Europe

Is there a relation between genetic or social groups of mallard ducks and the circulation of low pathogenic avian influenza viruses?

We investigated the circulation dynamics of low pathogenic avian influenza viruses (LPAIVs) in the mallard (Anas platyrhynchos) reservoir in Italy. In particular, we evaluated the temporal distribution of virologic findings by combining virus isolation data with a new population genetic-based study approach. Thus, during 11 consecutive sampling periods (wintering periods between 1993/94 and 2003/04), categorised into 40 sampling sub-periods, cloacal swab samples were collected from 996 wild and 16 captive-reared mallards, to be screened by RT-PCR before attempting influenza A virus isolation in embryonated eggs. Forty-eight LPAIVs were isolated from wild mallards and antigenically characterised by haemagglutination-inhibition and neuraminidase-inhibition assays. When considering LPAIV antigenic subtypes in which more than one mallard tested virus isolation positive (H1N1, n. 22; H2N3, n. 2; H5N3, n. 2; H6N5, n. 3; H6N8, n. 2; H7N3, n. 3; H11N6, n. 5), at least two birds infected with a specific HN subtype clustered within one same sampling sub-period. In the context of the novel population genetic approach, total DNA was extracted from a subset of 16 captive-reared and 65 wild ducks (2000/01 and 2001/02 sampling periods) to assess genetic diversity by amplified fragment length polymorphisms (AFLP) markers. Analyses of AFLP results showed that captive-reared mallards clustered together, whereas two main independent clusters characterised the distribution pattern of most wild mallards. Within this subset of samples, nearly identical H7N3 LPAIV strains were isolated from two wild mallards belonging to the same genetic cluster. Blood sera were also collected from the above subset of mallards and examined for antibodies to the homologous H7N3 virus strain. Four out of six wild mallards testing H7N3-seropositive by haemagglutination-inhibition assay (2001/02 period) belonged to the genetic cluster including H7N3 virus shedding ducks. Overall, our data raise the possibility of an enhanced transmission and circulation of LPAIVs in genetic or social groups of wild mallards, gathered in flocks possibly related by parentage and/or geographic origin

Long-Term Serological Investigations of Influenza A Virus in Free-Living Wild Boars (Sus scrofa) from Northern Italy (2007–2014)

Influenza A viruses (IAV) have been repeatedly demonstrated to circulate in wild suid populations. In this study, serum samples were collected from 2618 free-ranging wild boars in a protected area of Northern Italy between 2007 and 2014, and firstly screened by enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies against IAV. The ELISA-positive samples were further tested by hemagglutination inhibition (HI) assays performed using antigen strains representative of the four major swine IAV (sIAV) lineages circulating in Italy: avian-like swine H1N1, pandemic-like swine H1N1, human-like swine H1N2 and human-like swine H3N2. An overall seroprevalence of 5.5% (145/2618) was detected by ELISA, with 56.7% (80/141) of screened sera tests positive by HI assay. Antibodies against H1N1 subtypes were the most prevalent beginning in 2009—with the highest detection in the first quarter of the year—until 2013, although at a low level. In addition, antibodies to H3N2 subtype were found during six years (2007, 2009, 2010, 2011, 2012 and 2014) whereas H1N2 antibodies were detected in 2012 only. Of the HI-positive samples, 30% showed reactivity to both H1N1 and H3N2 subtypes. These results provide additional insight into the circulation dynamics of IAV in wild suid populations, suggesting the occurrence of sIAV spillover events from pigs to wild boars