Sentinel Birds Research Articles

West Nile virus surveillance using sentinel birds: results of eleven years of testing in corvids in a region of northern Italy.

The natural transmission cycle of West Nile virus (WNV) involves birds as primary hosts and mosquitoes as vectors, but this virus can spread to mammals, human beings included. Asymptomatic infected donors pose a risk to the safety of blood transfusions and organ transplants, as WNV can be transmitted through these medical procedures. Since 2009, the region of Emilia-Romagna in northern Italy has been implementing an integrated surveillance system in order to detect WNV circulation in the environment at an early stage. Here we report the results of the two components of the surveillance system, the active testing of corvids and humans, and demonstrate that bird surveillance alone improves a surveillance system based solely on human case detection. As WNV risk reduction measures are applied on a provincial basis, we assessed the ability of this surveillance system component to detect virus circulation prior to the notification of the first human case for each province. Overall, 99 epidemic seasons were evaluated as a result of 11 years (2013-2023) of surveillance in the nine provinces of the region. In this period, 22,314 corvids were tested for WNV and 642 (2.9%) were found to be infected. WNV was generally first detected in birds in July, with sample prevalence peaks occurring between August and September. During the same period, 469 autochthonous human cases were notified, about 60% of which were reported in August. WNV was detected 79 times out of the 99 seasons considered. The virus was notified in birds 73 times (92.4%) and 60 times (75.9%) in humans. WNV was first or only notified in birds in 57 seasons (72.1%), while it was first or only notified in humans in 22 seasons (27.8%). Active surveillance in corvids generally allows the detection of WNV before the onset of human cases. Failure of virus detection occurred mainly in seasons where the number of birds tested was low. Our results show that active testing of a minimum of 3.8 corvids per 100 km2 provides a satisfactory timeliness in the virus detection, but for early detection of WNV it is crucial to test birds between mid-June and mid-August.

Experimental infection of aquatic bird bornavirus 1 (ABBV-1) in Canada geese (Branta canadensis)

Aquatic bird bornavirus 1 (ABBV-1) has a high prevalence of infection in certain North American populations of Canada geese (Branta canadensis), suggesting a possible role of these birds as an ABBV-1 reservoir. The goal of this study was to evaluate the ability of Canada geese to become experimentally infected with ABBV-1, develop lesions, and transmit the virus to conspecifics. One-week-old Canada geese (n, 65) were inoculated with ABBV-1 through the intramuscular (IM) or cloacal (CL) routes, with the control group receiving carrier only. An additional 6 geese were added to each group to test horizontal transmission (sentinel birds). Geese were monitored daily, and selected birds were euthanized at 1, 8, and 15-weeks post infection (wpi) to assess virus replication in tissues and lesion development. At 15 wpi, over 70% of IM birds were infected, while the CL route yielded only 1 infected goose. Of the infected IM geese, 26% developed encephalitis and/or myelitis after 8 wpi. No clinical signs were observed, and no sentinel birds became infected in any group. Only 1 oropharyngeal swab (IM group) tested positive for ABBV-1 RNA, while the water from the enclosures was consistently negative for virus RNA. This study documents successful experimental infection of Canada geese with ABBV-1, with findings comparable to what is described in infection trials with other waterfowl species. However, minimal shedding and lack of environmental dispersal indicate that Canada geese have little potential to disseminate the virus among wild waterfowl, and that other species could be better suited to act as chronic ABBV-1 shedders in the wild.

The importance of in-year seasonal fluctuations for biomonitoring of apex predators: A case study of 14 essential and non-essential elements in the liver of the common buzzard (Buteobuteo) in the United Kingdom

Trace elements are chemical contaminants spread in the environment by anthropogenic activities and threaten wildlife and human health. Many studies have investigated this contamination in apex raptors as sentinel birds. However, there is limited data for long-term biomonitoring of multiple trace elements in raptors. In the present study, we measured the concentrations of 14 essential and non-essential trace elements in the livers of the common buzzard (Buteo buteo) collected in the United Kingdom from 2001 to 2019 and investigated whether concentrations have changed during this period. In addition, we estimated the importance of selected variables for modelling element accumulations in tissues.Except for cadmium, hepatic concentrations of harmful elements in most buzzards were lower than the biological significance level of each element. Hepatic concentrations of certain elements, including lead, cadmium, and arsenic, varied markedly seasonally within years. Their peak was in late winter and trough in late summer, except copper which showed an opposite seasonal pattern. In addition, lead in the liver consistently increased over time, whereas strontium showed a decreasing trend. Hepatic concentrations of cadmium, mercury, and chromium increased with age, whereas selenium and chromium were influenced by sex. Hepatic concentrations of arsenic and chromium also differed between different regions.Overall, our samples showed a low risk of harmful effects of most elements compared to the thresholds reported in the literature. Seasonal fluctuation was an important descriptor of exposure, which might be related to the diet of the buzzard, the ecology of their prey, and human activities such as the use of lead shot for hunting. However, elucidating reasons for these observed trends needs further examination, and biomonitoring studies exploring the effects of variables such as age, sex, and seasonality are required.

Effect of increased ventilation during feeding on broiler breeder biochemical, enzymatical, and electrolytes parameters

Breeders exhibit increased heat stress during and after meal feeding, thus increasing ventilation during and immediately post‐feeding may result in improved productivity and health as well as minimizing physiological stress. This study investigated the effect of increased ventilation during feeding on broiler breeder biochemical, enzymatical, and electrolytes parameters. A total of 288 breeder pullets were obtained from a commercial farm at 21 weeks of age (woa) and assigned to 12 pens (24 birds/pen). Each pen was equipped with two tube feeders, nipple drinkers, fresh pine shaving, and LED lighting. Temperature and lighting were adjusted according to primary breeder recommendations. Feed was provided by a commercial feed mill and meal fed once daily, while water was available ad libitum. Feed was presented at 0730 each day concurrently with the beginning of the photoperiod. Treatments included still air (S, negative control), conventional ventilation with no cool‐down (C, positive control), and variable air speed to mimic a cool‐down ventilation program during and immediately post‐feeding (V). Air speed in the V treatment wind tunnel was increased for three hours to offset the increase in metabolic heat production due to feeding and nesting activity, before returning to the baseline ventilation rate. Three sentinel birds in each pen were identified for physiological monitoring at the beginning of the study. On d 21 (start of treatments), 63 (midpoint), and 105 (end of the treatment period), blood samples (3 mL) were collected between 0800 and 0900 h from the brachial wing vein from each of the three sentinel birds into heparinized syringes within 45 s after birds were caught. The collected blood samples were centrifuged to separate the plasma and used to determine the electrolytes levels, concentration of biochemical (ALB, TBILI, BUN, CREAT, TP, UA, CHOL, LDL‐C, HDL, TRIG, GLUC) parameters and enzyme (ALT, ALP, AMYL, AST, CK, GGT, LDH, LIP) activities using an ACE‐AXCEL automatic analyzer. Results show that ALT, BUN, GLUC, and LDL‐C were affected by treatments. However, woa had significant effects on most examined variables along with few interactions. Plasma CORT was not affected by treatments and time, indicating absence of physiological stress. The results are in broad agreement with those reported in the literature and contribute to our knowledge of increasing ventilation during and immediately post‐feeding on blood metabolites variation in broiler breeders.

Rapid on-site detection of avian influenza virus in wild bird using portable devices and sentinel birds

Rapid on-site detection of avian influenza virus in wild bird using portable devices and sentinel birds

Occurrence of horizontal transmission in layer chickens after administration of an in ovo strain F Mycoplasma gallisepticum vaccine , ,

In ovo vaccination is currently being considered as a means of delivery for live Mycoplasma gallisepticum (MG) vaccines. This study was performed to determine the transmissibility of strain F MG (FMG) from in ovo-vaccinated chicks to non-vaccinated pen mates. Eggs from an MG clean flock were incubated together for 18 D, at which point all live embryonated eggs were either not injected or administered a dilution of an FMG vaccine at 106 CFU per dose, 1 × 104 CFU per dose, 1 × 102 CFU per dose, or 1 CFU per dose. Non-injected eggs were hatched in a separate incubator. Ten non-injected, sentinel birds, and 1 in ovo-vaccinated FMG chick were placed in each of 32 isolation units located in 2 replicate rooms (8 replicates per dose). At 6 wk of age, surviving birds that had been vaccinated in ovo were removed, swabbed for FMG detection by PCR, and bled for serum plate agglutination (SPA) and ELISA testing for the presence of antibodies against MG (1, 2, 6, and all 8 in ovo-vaccinated chicks in the 106, 104, 102, and 1 CFU dosages). At 12 wk of age, the remaining sentinel birds were likewise sampled. No sentinel birds died. The in ovo-vaccinated birds that survived to 6 wk were serologically positive except for 5 birds in the 1 CFU treatment. The percentages of MG-positive sentinel birds and sentinel birds with antibody production against MG at 12 wk from each unit were not different between all MG dosages (P = 0.48, PCR; P = 0.77, SPA; P = 0.85, ELISA). Body weights of the in ovo-vaccinated chicks at 6 wk of age (P = 0.43) and the sentinel birds at 12 wk of age (P = 0.95) were each not affected by FMG treatment. These findings indicate that layer chickens in ovo vaccinated with a live-attenuated FMG vaccine were capable of transmitting FMG to other chicks with which they were in direct contact.

Specific-pathogen-free Turkey model for reoviral arthritis

Turkey arthritis reovirus (TARV) infections have been recognized since 2011 to cause disease and significant economic losses to the U.S. turkey industry. Reoviral arthritis has been reproduced in commercial-origin turkeys. However, determination of pathogenesis or vaccine efficacy in these turkeys can be complicated by enteric reovirus strains and other pathogens that ubiquitously exist at subclinical levels among commercial turkey flocks. In this study, turkeys from a specific-pathogen-free (SPF) flock were evaluated for use as a turkey reoviral arthritis model. One-day-old or 1-week-old poults were orally inoculated with TARV (O'Neil strain) and monitored for disease onset and progression. A gut isolate of turkey reovirus (MN1 strain) was also tested for comparison. Disease was observed only in TARV-infected birds. Features of reoviral arthritis in SPF turkeys included swelling of hock joints, tenosynovitis, distal tibiotarsal cartilage erosion, and gait defects (lameness). Moreover, TARV infection resulted in a significant depression of body weights during the early times post-infection. Age-dependent susceptibility to TARV infection was unclear. TARV was transmitted to all sentinel birds, which manifested high levels of tenosynovitis and tibiotarsal cartilage erosion. Simulation of stressful conditions by dexamethasone treatment did not affect the viral load or exacerbate the disease. Collectively, the clinical and pathological features of reoviral arthritis in the SPF turkey model generally resembled those induced in commercial turkeys under field and/or experimental conditions. The SPF turkey reoviral arthritis model will be instrumental in evaluation of TARV pathogenesis and reoviral vaccine efficacy.

Pathogenicity and transmissibility of a highly pathogenic avian influenza virus H5N6 isolated from a domestic goose in Southern China

Since the first outbreak of H5N6 reported in Laos at 2013, there has been a dramatic increase in H5N6 strains isolated from waterfowl in China, particularly Southern China. However, pathogenicity and transmissibility of the virus in different birds remain largely unknown. In this study, a novel H5N6 virus, termed QY01, that belonged to group C in 2.3.4.4 was isolated from an apparently healthy domestic goose in Guangdong province, southern China in 2016. In order to simulate the natural transmission of different kinds of birds, we evaluated its pathogenicity and transmissibility in chickens, domestic geese and pigeons. To investigate the replication and shedding of QY01 in poultry, chickens, geese and pigeons were inoculated intranasally with 106 EID50 of virus. In addition, to measure intra-species transmission of QY01, three sentinel birds were housed with each group. The results demonstrated that QY01 exhibited a highly pathogenic phenotype, and was transmissible among in chickens and geese. However, the virus did not appear to be pathogenic in pigeons, indicating that this novel H5N6 virus exhibited different host ranges and tissue tropisms, and may pose a substantial risk for the chicken and goose industry. Therefore, continued surveillance for H5N6 AIVs is necessary, and increased attention should be paid to cross-species transmission between waterfowl and terrestrial birds.

Assessment of molecular and genetic evolution, antigenicity and virulence properties during the persistence of the infectious bronchitis virus in broiler breeders.

The infectious bronchitis virus (IBV) causes a highly contagious disease [infectious bronchitis (IB)] that results in substantial economic losses to the poultry industry worldwide. We conducted a molecular and phylogenetic analysis of the S1 gene of Brazilian (BR) IBV isolates from a routinely vaccinated commercial flock of broiler breeders, obtained from clinical IB episodes that occurred in 24-, 46- and 62-week-old chickens. We also characterized the antigenicity, pathogenesis, tissue tropism and spreading of three IBV isolates by experimental infection of specific pathogen-free (SPF) chickens and contact sentinel birds. The results reveal that the three IBV isolates mainly exhibited mutations in the hypervariable regions (HVRs) of the S1 gene and protein, but were phylogenetically and serologically closely related, belonging to lineage 11 of the GI genotype, the former BR genotype I. All three isolates caused persistent infection in broiler breeders reared in the field, despite high systemic anti-IBV antibody titres, and exhibited tropism and pathogenicity for the trachea and kidney after experimental infection in SPF chickens and contact birds. In conclusion, BR genotype I isolates of IBV evolve continuously during the productive cycle of persistently infected broiler breeders, causing outbreaks that are not impaired by the current vaccination programme with Massachusetts vaccine strains. In addition, the genetic alterations in the S1 gene of these isolates were not able to change their tissue tropism and pathogenicity, but did seem to negatively influence the effectiveness of the host immune responses against these viruses, and favour viral persistence.

Colonisation of poultry by Salmonella Enteritidis S1400 is reduced by combined administration of Lactobacillus salivarius 59 and Enterococcus faecium PXN-33

Salmonella Enteritidis remains a significant issue within the poultry industry and one potential solution is to use probiotic bacteria to prevent Salmonella colonisation through competitive exclusion (CE). We demonstrate that combined administration of Lactobacillus salivarius 59 and Enterococcus faecium PXN33 were effective competitive excluders of Salmonella Enteritidis S1400 in poultry. Two models were developed to evaluate the efficacy of probiotic where birds received Salmonella Enteritidis S1400 by a) oral gavage and b) sentinel bird to bird transmission. A statistically significant (p<0.001) 2 log reduction of Salmonella Enteritidis S1400 colonisation was observed in the ileum, caecum and colon at day 43 using combined administration of the two probiotic bacteria. However, no Salmonella Enteritidis S1400 colonisation reduction was observed when either probiotic was administered individually. In the sentinel bird model the combined probiotic administered at days 12 and 20 was more effective than one-off or double administrations at age 1 and 12days. In vitro cell free culture supernatant studies suggest the mechanism of Salmonella Enteritidis S1400 inhibition was due to a reduction in pH by the probiotic bacteria. Our current study provides further evidence that probiotics can significantly reduce pathogenic bacterial colonisation in poultry and that mixed preparation of probiotics provide superior performance when compared to individual bacterial preparations.

Capturing individual‐level parameters of influenza A virus dynamics in wild ducks using multistate models

SummaryDisease prevalence in wildlife is governed by epidemiological parameters (infection and recovery rates) and response to infection, both of which vary within and among individual hosts. Studies quantifying these individual‐scale parameters and documenting their source of variation in wild hosts are fundamental for predicting disease dynamics. Such studies do not exist for the influenza A virus (IAV), despite its strong impact on the global economy and public health.Using capture–recaptures of 3500 individual mallardsAnas platyrhynchosduring seven migration seasons at a stopover site in southern Sweden, we provide the first empirical description of the individual‐based mechanisms ofIAVdynamics in a wild reservoir host.For most years, prevalence and risk ofIAVinfection peaked at a single time during the autumn migration season, but the timing, shape and intensity of the infection curve showed strong annual heterogeneity. In contrast, the seasonal pattern of recovery rate only varied in intensity across years.Adults and juveniles displayed similar seasonal patterns of infection and recovery each year. However, compared to adults, juveniles experienced twice the risk of becoming infected, whereas recovery rates were similar across age categories. Finally, we did not find evidence that infection influenced the timing of emigration.Synthesis and applications. Our study provides robust empirical estimates of epidemiological parameters for predicting influenza A virus (IAV) dynamics. However, the strong annual variation in infection curves makes forecasting difficult. Prevalence data can provide reliable surveillance indicators as long as they catch the variation in infection risk. However, individual‐based monitoring of infection is required to verify this assumption in areas where surveillance occurs. In this context, monitoring of captive sentinel birds kept in close contact with wild birds is useful. The fact that infection does not impact the timing of migration underpins the potential for mallards to spread viruses rapidly over large geographical scales. Hence, we strongly encourageIAVsurveillance with a multistate capture–recapture approach along the entire migratory flyway of mallards.

Avian Influenza Virus and DIVA Strategies.

Vaccination is becoming a more acceptable option in the effort to eradicate avian influenza viruses (AIV) from commercial poultry, especially in countries where AIV is endemic. The main concern surrounding this option has been the inability of the conventional serological tests to differentiate antibodies produced due to vaccination from antibodies produced in response to virus infection. In attempts to address this issue, at least six strategies have been formulated, aiming to differentiate infected from vaccinated animals (DIVA), namely (i) sentinel birds, (ii) subunit vaccine, (iii) heterologous neuraminidase (NA), (iv) nonstructural 1 (NS1) protein, (v) matrix 2 ectodomain (M2e) protein, and (vi) haemagglutinin subunit 2 (HA2) glycoprotein. This short review briefly discusses the strengths and limitations of these DIVA strategies, together with the feasibility and practicality of the options as a part of the surveillance program directed toward the eventual eradication of AIV from poultry in countries where highly pathogenic avian influenza is endemic.

Combined infectious bronchitis virus Arkansas and Massachusetts serotype vaccination suppresses replication of Arkansas vaccine virus

Polyvalent infectious bronchitis virus vaccination is common worldwide. The possibility of vaccine interference after simultaneous combined vaccination with Arkansas (Ark) and Massachusetts (Mass)-type vaccines was evaluated in an effort to explain the high prevalence of Ark-type infectious bronchitis virus in vaccinated chickens. Chickens ocularly vaccinated with combinations of Ark and Mass showed predominance of Mass vaccine virus before 9 days post-vaccination (DPV) in tears. Even when Mass and Ark vaccines were inoculated into separate eyes, Mass vaccine virus was able to outcompete Ark vaccine virus. Although Mass vaccine virus apparently had a replication advantage over Ark vaccine in ocular tissues, Ark vaccine virus appeared to have an advantage in spreading to and/or replicating in the trachea. When chickens vaccinated with Ark or Mass vaccine were housed together, Mass vaccine virus was able to spread to Ark-vaccinated chickens, but the Ark vaccine was not detected in Mass-vaccinated chickens. Only Mass vaccine was detected in tears of sentinel birds introduced into groups receiving both vaccines. Furthermore, Ark vaccine virus RNA was not detectable until 10 DPV in most tear samples from chickens vaccinated with both Ark and Mass vaccines at varying Ark vaccine doses, while high concentrations of Mass virus RNA were detectable at 3–7 DPV. In contrast, Ark vaccine virus replicated effectively early after vaccination in chickens vaccinated with Ark vaccine alone. The different replication dynamics of Ark and Mass viruses in chickens vaccinated with combined vaccines did not result in reduced protection against Ark challenge at 21 DPV. Further studies are needed to clarify if the viral interference detected determines differences in protection against challenge at other time points after vaccination.

Molecular Detection of Lentogenic Strain of Newcastle Disease Virus in Commercial Broiler Chickens Using Sentinel Birds in Iran: The First Report

Molecular Detection of Lentogenic Strain of Newcastle Disease Virus in Commercial Broiler Chickens Using Sentinel Birds in Iran: The First Report

EPIDEMIOLOGICAL HIGHLIGHTS ON SOME VIRUSES ASSOCIATED WITH INCREASED MORTALITY IN CHICKENS BRED IN SHARKIA GOVERNORATE.

In the present study 1317 serum samples obtained from 6 broiler flocks, 2 broiler breeders and 28 commercial layer flocks were examined for HI antibodies of {NDV, IBV (Mass-41, 4/91, and D-274), AIV (H5N1, H5N2, H5N3, H9, H7) and Adenov (EDS­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­76)}. Studying the vaccination protocols in flocks under investigation and their seroconversion had led us to speculate and conclude viral affections in the different localities of Sharkia governorate. Speculating viral affections was a very hard task because the Egyptian market is jammed with a great variety of protective vaccines this was conflicting during result interpretation. Positive immune titers for AIV-H7 in sharkia governorate was detected at June /2014 in (El-salhia, 10th of Ramadan, El-ibrahemia and Abo-hammed) in commercial layer flocks only. The seropositive samples that exceeded the cutoff values were 63 out of 1317 (4.8%). AIV-H9 high seropositive immune titers was constantly found in examined samples although their protective vaccines were neglected. AIV-H5N3 seropositive results was recorded in a totally non vaccinated flocks against H5 which reflect virus circulation in the poultry premises. Seropositive titer for IBV-D274 and EDS76 was recorded in a totally non vaccinated flocks against such antigens., which refer to their role in the total simultaneous incidence of disease and consequent mortality. From another point of view it should be noted that. Vaccinating chicken flocks following a ready made manuscript of the producing companies without prior evaluation of the maternally derived antibodies (MDA) or evaluating the immune titers before taking the decision of vaccination or even considering the disease situation in the area is possible cause for vaccine failure. Sentinel birds inclusion in poultry patches should be taken seriously to give a mirror for the circulating viral agents in the poultry premises. It worth to mention that a parallel bacteriological work was running during investigation of the causes of increased mortality or dropped egg production. This work revealed the isolation of a resistant bacteria of the (Kebseilla spp).

Host group formation decreases exposure to vector-borne disease: a field experiment in a 'hotspot' of West Nile virus transmission.

Animals can decrease their individual risk of predation by forming groups. The encounter-dilution hypothesis extends the potential benefits of gregariousness to biting insects and vector-borne disease by predicting that the per capita number of insect bites should decrease within larger host groups. Although vector-borne diseases are common and can exert strong selective pressures on hosts, there have been few tests of the encounter-dilution effect in natural systems. We conducted an experimental test of the encounter-dilution hypothesis using the American robin (Turdus migratorius), a common host species for the West Nile virus (WNV), a mosquito-borne pathogen. By using sentinel hosts (house sparrows, Passer domesticus) caged in naturally occurring communal roosts in the suburbs of Chicago, we assessed sentinel host risk of WNV exposure inside and outside of roosts. We also estimated per capita host exposure to infected vectors inside roosts and outside of roosts. Sentinel birds caged inside roosts seroconverted to WNV more slowly than those outside of roosts, suggesting that social groups decrease per capita exposure to infected mosquitoes. These results therefore support the encounter-dilution hypothesis in a vector-borne disease system. Our results suggest that disease-related selective pressures on sociality may depend on the mode of disease transmission.

Lethal nephrotropism of an H10N1 avian influenza virus stands out as an atypical pathotype

A nephrotropic H10N1 avian influenza virus (AIV) with an intravenous pathogenicity index (IVPI) of 1.9 and a haemagglutinin monobasic amino acid cleavage site motif, was genetically and phenotypically characterized.Specific pathogen free chickens of 3 or 6 weeks of age were challenged with a 106EID50/0.1mL dose by either oro-nasal or intravenous route, to study the distribution, tissue tropism and virulence of the virus. Direct transmission was tested by introducing sentinel birds on day 4 post infection. Virus shedding and viremia were investigated by means of type A influenza real-time RT-PCR. Dead birds were necropsied and selected organs were collected for histology, immunohistochemistry, and to detect and re-isolate the virus. Serological analyses were carried out to evaluate seroconversion, three weeks from challenge.The oro-nasal challenge of the 6-week-old birds elicited 47% mortality as a result of viremia and massive replication of the virus in the kidneys. Unexpectedly, among birds of 3 weeks of age the same challenge caused 5% mortality and few clinical signs. Surprisingly the intravenous administration of the virus in the 3-week-old birds recorded an IVPI of 2.4.A full genome characterization of the virus could not identify any molecular determinant underlying the observed phenotype.Our findings describe the complex pathobiology of an AIV of the H10 subtype that stands out for its peculiar pathogenicity and tissue tropism in chickens.

No contact transmission of avian bornavirus in experimentally infected cockatiels (Nymphicus hollandicus) and domestic canaries (Serinus canaria forma domestica)

Avian bornaviruses (ABV) are the causative agents of proventricular dilatation disease (PDD), a widely distributed disease of parrots. Distinct ABV lineages were also found in various non-psittacine avian species, such as canaries, but the pathogenic role of ABV in these species is less clear. Despite the wide distribution of ABV in captive parrots and canaries, its mode of transmission is poorly understood: both horizontal transmission via the urofaecal-oral route and vertical transmission are discussed to play a role.In this study we investigated pathology and horizontal transmission of ABV in domestic canaries (Serinus canaria forma domestica) and cockatiels (Nymphicus hollandicus), two natural host species commonly used for experimental ABV infections. ABV inoculation resulted in persistent infection of all inoculated animals from both species. ABV-infected cockatiels exhibited PDD-like symptoms, such as neurologic signs or shedding of undigested seeds. In contrast, infected domestic canaries did not develop clinical disease. Interestingly, we did not detect viral RNA in cloacal swabs and organ samples or ABV-specific antibodies in serum samples of contact-exposed sentinel birds from either species at any time during a four months observation period. Our results strongly indicate that horizontal transmission of ABV by direct contact is inefficient in immunocompetent fully fledged domestic canaries and cockatiels.

VIGILANCIA DIRIGIDA DE INFLUENZA AVIAR EN AVES SILVESTRES USANDO PATOS DOMÉSTICOS (Cairina moschata) COMO CENTINELAS

A targeted surveillance method was applied for the early detection of the Avian Influenza Virus (AIV) in the wild birds of the Puerto Viejo’s wetlands in Cañete, Lima, Peru. Twelve 16-week-old domestic ducks of the Muscovy variety (Cairina moschata) were used as sentinels. The ducks, with negative serology and virus isolation to AIV and Newcastle disease, were introduced to the surrounding areas of the wetlands for 70 days during the 2006 winter in order to interact with the resident wild birds. A preliminary identification of the wild bird species present during the study period was done and the interaction degree between both bird populations was subjectively determined. Health status of sentinel birds was assessed by regular clinical examinations as well as cloacal swab and blood samplings, both for virus isolation and for the detection of antibodies against the AIV by the agar gel immune-diffusion (AGID) test. Throughout the study no antibodies were detected, neither was the AIV isolated. The negative results obtained in the evaluations that were performed under the conditions of the study and the time it lasted suggest the absence of the IVA and its horizontal transmission in the populations of wild birds of the Puerto Viejo’s wetlands.

Susceptibility and intra-species transmission of the H9N2 G1 prototype lineage virus in Japanese quail and turkeys

Avian influenza viruses of the H9N2 subtype have circulated in the poultry population in Asia, Far and Middle East since the mid-1990 s. One of the most widespread lineages established in poultry is the G1 lineage. This lineage has undergone further evolution and reassortment since its first detection in 1997 and G1-like H9N2 viruses still circulate. In this study we have investigated the susceptibility of quail and turkeys to the H9N2 G1-lineage prototype strain (A/quail/Hong Kong/G1/97). Contact transmission experiments were carried out in both avian species. Animals were infected oro-nasally with increasing doses of the virus (10(3)-10(6) EID 50/0.1 ml) and sentinel birds were introduced 4 days post infection (pi) in each experimental group. Quail were more susceptible than turkeys, as they were readily infected with lower challenge doses. Interestingly, infection of turkeys was associated with worse clinical condition. Transmission was detected in both species. Quail infected with a dose less than or equal to 10(4) EID50 transmitted the virus to the sentinels without showing any signs of disease. These findings reinforce the hypothesis that quail may ensure the perpetuation of H9N2 viruses in poultry, acting as a silent reservoir.