Positive Birds Research Articles

Prevalence and molecular characterisation of Eimeria species in Ethiopian village chickens.

BackgroundCoccidiosis, caused by species of the apicomplexan parasite Eimeria, is a major disease of chickens. Eimeria species are present world-wide, and are ubiquitous under intensive farming methods. However, prevalence of Eimeria species is not uniform across production systems. In developing countries such as Ethiopia, a high proportion of chicken production occurs on rural smallholdings (i.e. 'village chicken production’) where infectious diseases constrain productivity and surveillance is low. Coccidiosis is reported to be prevalent in these areas. However, a reliance on oocyst morphology to determine the infecting species may impede accurate diagnosis. Here, we used cross-sectional and longitudinal studies to investigate the prevalence of Eimeria oocyst shedding at two rural sites in the Ethiopian highlands.ResultsFaecal samples were collected from 767 randomly selected chickens in May or October 2011. In addition, 110 chickens were sampled in both May and October. Eimeria oocysts were detected microscopically in 427 (56%, 95% confidence interval (95% CI) 52-59%) of the 767 faecal samples tested. Moderate clustering of positive birds was detected within households, perhaps suggesting common risk factors or exposure pathways. Seven species of Eimeria were detected by real time PCR in a subset of samples further analysed, with the prevalence of some species varying by region. Co-infections were common; 64% (23/36, 95% CI 46-79%) of positive samples contained more than one Eimeria spp. Despite frequent infection and co-infection overt clinical disease was not reported. Eimeria oocysts were detected significantly more frequently in October (248/384, 65%, 95% CI 60-69%), following the main rainy season, compared to May (179/383, 47%, 95% CI 42-52%, p < 0.001). Eimeria oocyst positivity in May did not significantly affect the likelihood of detecting Eimeria oocyst five months later perhaps suggesting infection with different species or immunologically distinct strains.ConclusionsEimeria spp oocysts may be frequently detected in faecal samples from village chickens in Ethiopia. Co-infection with multiple Eimeria spp was common and almost half of Eimeria positive birds had at least one highly pathogenic species detected. Despite this, all sampled birds were free of overt disease. Although there was no evidence of a difference in the prevalence of oocysts in faecal samples between study regions, there was evidence of variation in the prevalence of some species, perhaps suggesting regional differences in exposure to risk factors associated with the birds, their management and/or location-specific environmental and ecological factors.

Usutu Virus Persistence and West Nile Virus Inactivity in the Emilia-Romagna Region (Italy) in 2011

BackgroundThe circulation of West Nile virus and Usutu virus was detected in the Emilia-Romagna region in 2008 and 2009. To evaluate the extent of circulation of both viruses, environmental surveillance, based on bird and mosquito testing, was conducted in 2008 and gradually improved over the years.MethodsIn February–March 2009–2011, 5,993 hibernating mosquitoes were manually sampled, out of which 80.1% were Culex pipiens; none tested positive for the viruses. From 2008 to 2011, 946,213 mosquitoes, sampled between May and October, were tested; 86.5% were Cx. pipiens. West Nile virus was detected in 32 Cx. pipiens pools, and Usutu virus was detected in 229 mosquito pools (217 Cx. pipiens, 10 Aedes albopictus, one Anopheles maculipennis s.l., and one Aedes caspius). From 2009 to 2011, of 4,546 birds collected, 42 tested positive for West Nile virus and 48 for Usutu virus. West Nile virus and Usutu virus showed different patterns of activity during the 2008–2011 surveillance period. West Nile virus was detected in 2008, 2009, and 2010, but not in 2011. Usutu virus, however, was continuously active throughout 2009, 2010, and 2011.ConclusionsThe data strongly suggest that both viruses overwinter in the surveyed area rather than being continually reintroduced every season. The lack of hibernating mosquitoes testing positive for the viruses and the presence of positive birds sampled early in the season support the hypothesis that the viruses overwinter in birds rather than in mosquitoes. Herd immunity in key bird species could explain the decline of West Nile virus observed in 2011, while the persistence of Usutu virus may be explained by not yet identified reservoirs. Reported results are comparable with a peri-Mediterranean circulation of the West Nile virus lineage 1 related strain, which became undetectable in the environment after two to three years of obvious circulation.

In vivo screening of five phytochemicals/extracts and a fungal immunomodulatory protein against colibacillosis in broilers

Five phytochemicals/extracts (an extract from Echinacea purpurea, a β-glucan-rich extract from Shiitake, betaine [Betain™], curcumin from Curcuma longa [turmeric] powder, carvacrol and also a recombinant fungal immunomodulatory protein [FIP] from Ganoderma lucidum) cloned and expressed in Escherichia coli were investigated for their anticolibacillosis potential in three chicken experiments, which were conducted in floor pens. Birds that were inoculated with E. coli intratracheally were treated with the phytochemicals/extracts or the FIP and compared with doxycycline-medicated and non-medicated infected broilers. Non-medicated and non-infected birds were used as negative controls. Mortality, colibacillosis lesions and body weight gains were used as parameters. Considering the sum of dead birds and chickens with generalized colibacillosis per group, there was no significant difference between the positive control groups and birds treated with phytochemicals/extracts or the FIP. In contrast, doxycycline-treated birds showed significantly lower mortality and generalized colibacillosis. Moreover, none of the phytochemicals/extracts and the FIP improved recovery from colibacillosis lesions, while all doxycycline-treated broilers recovered completely. The negative control birds and doxycycline-treated groups consistently showed the highest weight gains. Pulsed-field gel electrophoresis of reisolates showed that they were genetically indistinguishable from the inoculation strain. In conclusion, none of the tested phytochemicals/extracts and the FIP significantly reduced the E. coli-induced mortality and generalized colibacillosis, and nor did they improve recovery from colibacillosis lesions.

Descriptive Results of a Prospective Cohort Study of Avian Influenza in the Mekong River Delta of Viet Nam

A prospective cohort study of avian influenza infection in poultry flocks was carried out in the Mekong River Delta of Viet Nam between December 2008 and April 2010. Our objectives were to (i) estimate the prevalence and incidence of avian influenza virus infection and (ii) assess the efficacy of H5N1 vaccination programmes as indicated by the presence of H5 antibody in vaccinated and unvaccinated poultry. Real-time PCR and H5 multiplex assays were used to detect the antigen of avian influenza viruses from swab samples. The haemagglutination inhibition test was used to detect H5 antibody. A total of 17968 swab and 14878 blood samples were collected from 5476 birds over the study period. The overall incidence rate of influenza type A virus infection was 5 (95% CI 4-7) positive birds per 100 bird-months at risk. The overall incidence rate of H5 virus infection was 0.2 (95% CI 0.1-0.5) positive birds per 100 bird-months at risk. Fifty (95% CI 48-52) birds per 100 tested birds were H5 HI positive in the unvaccinated group compared with 71 (95% CI 69-73) birds per 100 in the vaccinated group. Influenza type A and H5 viruses were circulating in village poultry throughout the study period with no recorded signs of clinical disease. This implies that interventions need to be carried out continuously throughout the year rather than only focusing on the established high-risk periods. Broiler ducks had an incidence rate of influenza H5 virus infection approximately four times greater than that of layer ducks and in-contact species. We conclude that broiler ducks are likely to be the main entry route for H5 virus into poultry flocks in the MRD. Control efforts would benefit from understanding why there is a difference between villages in H5 incidence and developing strategies to provide greater protection to broiler ducks.

Extensive recombination detected among beak and feather disease virus isolates from breeding facilities in Poland

Beak and feather disease virus (BFDV) causes the highly contagious, in some cases fatal, psittacine beak and feather disease in parrots. The European continent has no native parrots, yet in the past has been one of the world's biggest importers of wild-caught exotic parrot species. Following the banning of this practice in 2007, the demand for exotic pet parrots has largely been met by established European breeding facilities, which can also supply buyers outside Europe. However, the years of unregulated importation have provided numerous opportunities for BFDV to enter Europe, meaning the likelihood of birds within captive breeding facilities being BFDV positive is high. This study examined the BFDV status of such facilities in Poland, a country previously shown to have BFDV among captive birds. A total of 209 birds from over 50 captive breeding facilities across Poland were tested, and 43 birds from 18 different facilities tested positive for BFDV. The full BFDV genomes from these 43 positive birds were determined, and phylogenetic analysis revealed that these samples harboured a relatively high degree of diversity and that they were highly recombinant. It is evident that there have been multiple introductions of BFDV into Poland over a long period of time, and the close association of different species of birds in the captive environment has probably facilitated the evolution of new BFDV strains through recombination.

Prevalence of Histomonas meleagridis in Broiler Chicken in Different Parts of Mizoram, India

A survey was carried out to detect the overall incidence of histomoniasis in broiler birds in different parts of Mizoram, India. Out of 4000 birds examined, 40 birds were found positive for Histomonas meleagridis revealing 1% infection rate. Heterakis gallinarum was recovered from the caeca of positive birds. Gross lesions were found in caeca and liver. Microscopic examination of stained section of liver tissue revealed numerous circular amoeboid Histomonas meleagridis together with cellular infiltration. The PCR selectively amplified 209 BP of the small subunit ribosomal DNA sequence of Histomonas meleagridis.

Molecular Detection and Genotyping ofChlamydia psittaciin Captive Psittacines from Costa Rica

Oropharyngeal and cloacal swabs from 117 captive psittacine birds presented at veterinary clinics (88) and from shelters/rescue centers of wildlife (29) were collected to determine the prevalence of C. psittaci in captive birds in Costa Rica. Samples were collected during 2009 from a total of 19 different species of parrots, with Ara macao (33), Amazona autumnalis (24), Amazona ochrocephala (21), and Ara ararauna (8) being the most representative species sampled. C. psittaci was detected in four (3.4%) birds using molecular detection (PCR). The positive samples belonged to birds presented at veterinary clinics; three of them were Ara macao and one Amazona ochrocephala. Three birds were adults; all positive birds showed no symptoms of illness and lived in homes with other birds, two in San José and two in Heredia. Sequencing was used to confirm the PCR positive results, showing that two samples of C. psittaci belonged to genotype A, representing the first report of the presence of this genotype in Costa Rica. The detection of this bacterium in captive psittacine birds shows that there is a potential risk for people living or having contact with them and that there is a possibility of infecting other birds.

A cluster of avian malaria cases in a kiwi management programme

AIM: To describe a temporal cluster of avian malaria (Plasmodium spp.) at an Operation Nest Egg™ (ONE) site in Rotorua which caused mortality in a juvenile kiwi and had high population prevalence in brown kiwi (Apteryx mantelli). METHODS: A 70-day-old wild-born captive brown kiwi was submitted for post-mortem examination to Massey University Wildlife Health Centre. Post-mortem examination and histopathology were used to determine the cause of death. Plasmodium specific PCR analysis was subsequently conducted on tissue samples and 108 individual blood samples from living kiwi from five ONE breeding sites and two rowi kiwi crèches. Positive PCR products were sequenced to identify the Plasmodium spp. isolated. Where possible, blood smear microscopic examination was used to determine the level of parasitaemia in the infected kiwi. RESULTS: Plasmodium spp. was detected in the kiwi which died and it showed histopathological evidence of disseminated protozoal infection. A high prevalence of Plasmodium was found in blood samples from kiwi concurrently residing at ONE Rotorua by blood smear microscopy (22/32, 68%) and PCR (25/32, 78%). All kiwi with positive blood smears had only a low level of peripheral parasitaemia at the time of sampling. However, 0/17 additional kiwi sampled at Rotorua 3 weeks after the juvenile's death, 0/23 Rotorua juveniles sampled 1 year later and 0/59 kiwi from the five other locations were positive for Plasmodium by these methods. Sequencing analysis revealed a cosmopolitan Plasmodium (Huffia) elongatum lineage in all positive birds. CONCLUSIONS: This is the first description of an avian malaria (Plasmodium spp.) infection associated with mortality and a high population prevalence in brown kiwi at a ONE site in the 20 years of the programme. The study suggests that this level of infection in a population of kiwi was unusual and provides evidence in support of continued vigilance of disease risks associated with this and other conservation management programmes involving wildlife translocation.

Antecedent Avian Immunity Limits Tangential Transmission of West Nile Virus to Humans

BackgroundWest Nile virus (WNV) is a mosquito-borne flavivirus maintained and amplified among birds and tangentially transmitted to humans and horses which may develop terminal neuroinvasive disease. Outbreaks typically have a three-year pattern of silent introduction, rapid amplification and subsidence, followed by intermittent recrudescence. Our hypothesis that amplification to outbreak levels is contingent upon antecedent seroprevalence within maintenance host populations was tested by tracking WNV transmission in Los Angeles, California from 2003 through 2011.MethodsPrevalence of antibodies against WNV was monitored weekly in House Finches and House Sparrows. Tangential or spillover transmission was measured by seroconversions in sentinel chickens and by the number of West Nile neuroinvasive disease (WNND) cases reported to the Los Angeles County Department of Public Health.ResultsElevated seroprevalence in these avian populations was associated with the subsidence of outbreaks and in the antecedent dampening of amplification during succeeding years. Dilution of seroprevalence by recruitment resulted in the progressive loss of herd immunity following the 2004 outbreak, leading to recrudescence during 2008 and 2011. WNV appeared to be a significant cause of death in these avian species, because the survivorship of antibody positive birds significantly exceeded that of antibody negative birds. Cross-correlation analysis showed that seroprevalence was negatively correlated prior to the onset of human cases and then positively correlated, peaking at 4–6 weeks after the onset of tangential transmission. Antecedent seroprevalence during winter (Jan – Mar) was negatively correlated with the number of WNND cases during the succeeding summer (Jul–Sep).ConclusionsHerd immunity levels within after hatching year avian maintenance host populations <10% during the antecedent late winter and spring period were followed on three occasions by outbreaks of WNND cases during the succeeding summer. Because mosquitoes feed almost exclusively on these avian species, amplification was directly related to the availability of receptive non-immune hosts.

Supplementation of guanidinoacetic acid to broiler diets: Effects on performance, carcass characteristics, meat quality, and energy metabolism

Creatine, (CREA) a central constituent in energy metabolism, is obtained from dietary animal protein or de novo synthesis from guanidinoacetic acid (GAA). Especially in all-vegetable diets, supplemental CREA or GAA may restore the CREA availability in tissues, and hence, improve performance. In this study, 768 one-d-old male Ross 308 broilers were assigned to 1 of 4 diets: negative control, all-vegetable corn-soybean-based; negative control supplemented with either 0.6 or 1.2 g of GAA per kilogram of feed; and positive control (60, 30, and 30 g/kg of fish meal in the starter, grower, and finisher diets, respectively). Each treatment was replicated in 6 pens of 32 birds each. At the end of the grower period (d 26), 2 birds per pen were euthanized for metabolic measurements. Four broilers per pen were selected at slaughter age (d 39) to determine carcass characteristics and meat quality. Compared with the negative control, GAA supplementation resulted in an improved gain:feed ratio (P < 0.05) and ADG (P < 0.05; + 2.7 and + 2.2% for GAA at 0.6 and 1.2 g/kg, respectively) throughout the entire period. Breast meat yield was higher for the GAA diets compared with that of the negative control birds (P < 0.05; 30.6 vs. 29.4%) and was comparable with that of the positive control birds (30.2%). With regard to meat quality, lower ultimate pH values, higher cooking and press fluid losses, and higher color L* values were observed for the GAA diets compared with those of the negative control diet (P < 0.05). These effects were small, however. The GAA and CREA levels in breast meat were lower and higher, respectively, in GAA-fed birds compared with those of the control birds (P < 0.01). The diets did not affect plasma metabolic traits, except that plasma insulin-like growth factor I concentrations were almost twice as high in animals fed 1.2 g/kg of GAA compared with those of all other treatments. The GAA included in all-vegetable diets improved animal performance for the whole rearing period and increased breast meat yield.

Epidemiological study of Chlamydophila psittaci in pet birds in Croatia

A total of 411 samples from birds of different species originating from all counties of the Republic of Croatia have been tested for the presence of Chlamydophila psittaci. The sampling was conducted in pet stores, breeders' aviaries, in a specialized bird clinic and in zoos. The testing included 177 parrots, 169 pigeons, 58 canaries and 7 finches. For the detection of specific C. psittaci antigen a commercial ELISA kit was used- IDEIATM PCE Chlamydia (DAKO Cytomation Ltd., United Kingdom). The samples that were non-specifically positive or doubtful in the ELISA test (a total of 26 samples) were analyzed also by means of polymerase chain reaction (PCR). Diagnostic ELISA method found a total of 17.03% birds positive for chlamydiosis, and after additional testing by PCR a total of 12.65% positive ones were found. According to bird species, the most frequently positive ones were canaries and pigeons (15.52% and 13.02%), and according to the sampling location most of the positive birds were found in pet stores (16.52%), but a high percentage of positive samples were also found in breeders’ aviaries (11.76%). The average positive result for chlamydiosis in 12.65% of tested birds is alarming and it confirms the importance of monitoring bird health and of prescribed legal regulations when it comes to chlamydial diseases, as well as education of persons involved in breeding, keeping or selling birds.

Occurrence of avian bornavirus infection in captive psittacines in various European countries and its association with proventricular dilatation disease

A total of 1442 live birds and 73 dead birds out of 215 bird collections in Spain, Germany, Italy, the UK and Denmark were tested for avian bornavirus (ABV) infection by four different methods. The majority of the birds were psittacines belonging to 54 different genera of the order Psittaciformes. In total, 22.8% of the birds reacted positive for ABV in at least one of the tests. Combined testing of swabs from the crop and cloaca, and serum for the diagnosis of ABV infection in live birds revealed that virus shedding and antibody production coincided in only one-fifth of the positive birds so that the examination of these three samples is recommended for reliable ABV diagnosis. By statistical analysis of this large number of samples, the ABV infection proved to be highly significant (P <0.001) associated with histopathologically confirmed proventricular dilatation disease (PDD) in dead birds as well as with clinically assumed PDD in live birds. However, ABV infection was also detected in psittacines without pathological lesions or clinical signs of PDD. Twelve non-psittacine birds belonging to the genera Aburria, Ciconia, Geopelia, Leucopsar and Pavo were tested negative for ABV infection. Within the order of Psittaciformes, birds belonging to 33 different genera reacted positive for ABV. In 16 of these psittacine genera, the ABV infection was demonstrated for the first time. The present study emphasizes the widespread occurrence of clinically variable ABV infections in Europe by analysing a large number of specimens from a broad range of bird species in several assays.

Lead shot ingestion by mourning doves on a disked field

AbstractPrevious field studies of hunter‐harvested mourning doves (Zenaida macroura) have reported the percentage of birds with ingested lead shot as 0.2–6.5%. To reduce the uncertainty concerning the number of doves that ingest shot, we conducted an experiment to test the proportion of mourning doves that ingested lead shot on the bare soil of a disked field (typical of a managed dove field) to simulate more natural feeding conditions. In each of 3 treatment groups of 80 birds, we exposed 35 birds to low‐density lead shot (1.5 million shot/ha), and35 birds to high‐density lead shot (29.5 million shot/ha), and 10 birds served as controls (no shot). We dosed 5 positive control birds with 2 lead shot each in trials 2 and 3. We scattered lead shot and mixed seed on the loosely packed soil of treatment cages and after 4 days of exposure, 2.9% of doves voluntarily ingested ≥1 lead shot. The proportion of birds that ingested shot when exposed to the high‐density shot treatment (4.9%) was not different (P = 0.098) from that of the low‐density shot treatment (1.0%). Lead concentrations in liver, kidneys, and blood reached maxima of 94.402 ppm, 346.033 ppm, and 13.883 ppm wet mass, respectively. Differences in delta‐aminolevulinic acid dehydratase (ALAD) activity, packed cell volume, and heterophil:lymphocyte ratio (H:L) were greater posttreatment in doves that had ingested shot than in those that did not. The risk posed to mourning doves from lead shot ingestion can be reduced by banning lead shot on management areas or dove fields or disking fields after hunting season to reduce shot availability. © 2011 The Wildlife Society.

Anticoagulant Rodenticide Exposure and Toxicosis in Four Species of Birds of Prey Presented to a Wildlife Clinic in Massachusetts, 2006–2010

Mortalities among birds of prey from anticoagulant rodenticide (AR) toxicosis have been documented in several countries. Reports on extent of exposure within regions of the United States are limited. This study investigated AR exposure and toxicosis in four species of birds of prey (red-tailed hawks [Buteo jamaicensis], barred owls [Strix varia], eastern screech owls [Megascops asio] and great horned owls [Bubo virginianus]) presented to a wildlife clinic in Massachusetts. The aims of this study are to document the proportion of these four species that died or were euthanized due to their presenting injuries that had detectable amounts of ARs in liver tissue; to identify and quantify ARs present; to describe clinical, postmortem, and histopathologic signs of toxicosis; to evaluate potential sublethal effects of AR exposure; and to associate liver AR level with toxicosis. Birds included in the study were sampled without regard to signs of AR toxicosis. Postmortem examinations were conducted, and liver samples were analyzed for AR residues. Of 161 birds tested, 86% had AR residues in liver tissue. The second-generation AR (SGAR) brodifacoum was identified in 99% of positive birds. Mortality from AR toxicosis was diagnosed in 6% of birds. No indications of sublethal effects of exposure were found, and no association between liver brodifacoum level and signs of toxicosis was apparent. Given the high proportion of birds in this study exposed to ARs, specifically brodifacoum, continued monitoring is warranted as new U.S. Environmental Protection Agency regulations on the sale and use of SGARs are enacted.

Seroprevalence of Histomonas meleagridis in pullets and laying hens determined by ELISA

Serum samples from 1120 layers from 56 flocks and 400 pullets from 20 flocks were tested by an indirect sandwich ELISA to investigate the prevalence of antibodies to Histomonas meleagridis...

Influence of production system on the rate of onset of Campylobacter colonization in chicken flocks reared extensively in the United Kingdom

1. Because thermophilic Campylobacter spp. are common in chicken flocks reared extensively, cross-sectional and longitudinal studies were carried out on organic and free-range farms to determine the onset of colonisation (lag phase) and likely sources of flock infection. 2. For 14 organic and 14 free range flocks, there was a difference in lag phases, with the former being colonized at a mean of 14·1 d in comparison with 31·6 d for the latter. Whereas most free-range flocks became colonized when released on to pasture, those reared organically were usually colonized at the housed brooding stage. 3. Further study of organic flocks on three farms over 7 successive crop cycles confirmed that colonisation was strongly influenced by the prevailing husbandry conditions and was not a consequence of the length of the rearing period. 4. Molecular epidemiological investigations on a farm showing the shortest lag phase, using PFGE typing with two different restriction enzymes (SmaI and KpnI) and flaA SVR sequence typing, revealed that potential sources of colonisation for organic chickens were already present on the farm at the time of chick placement. Such sources included the ante area of the brooding house, surrounding pasture and other livestock being kept on the farm. 5. Overall, the study demonstrated that, under UK conditions, the prevalence of colonisation was greater in extensive flocks (95–100%) than it was for conventional broilers (55%), similar to the situation in other countries, but all three management systems showed comparable levels of caecal carriage in positive birds (log10/g 6·2–6·7).

국내 산란계의 주요 바이러스성 질병에 대한 혈청학적 모니터링 결과 및 분석

본 연구에서는 충북대학교 조류질병학실험실에 2009년 한 해동안 의뢰된 산란계의 혈청 검사 결과에 대해 분석하여, 산란계의 주요 질병에 대한 국내 산란계의 면역 상태 및 질병 감염 실태를 파악하였다. 검사 대상 질병은 AI, ND, IB, aMPV, EDS'76, IBD, CIA이었으며, 산란계의 성장 단계에 따라 주령 구간을 나누어 분석하였다. AI, ND, IB는 모체 이행항체가 감소한 후 산란 기간에 걸쳐 혈청 역가가 안정적으로 형성되는 특징을 보여 주었다. 그러나 AI는 모든 주령 구간에 걸쳐 음성인 계군이 존재하는 반면, ND는 3~10 주령 구간의 한 음성 계군을 제외하고 전 주령에 걸쳐 100%의 계군 양성률을 보이고, ND의 평균 GMT가 AI의 평균 GMT보다 높았는데, 이는 두 질병의 백신 정책의 차이에 기인한 것이다. IB의 산란기의 안정적인 역가는 백신 역가에 산란기 전반에 걸친 야외 감염 개체의 존재로 인한 야외 감염 역가가 더해진 것으로 판단된다. aMPV는 2009년에 백신을 실시하지 않았던 질병이므로, 양성 역가를 통해 aMPV의 야외 감염을 추적할 수 있었으며, GMT 변화 및 계군 내양성 개체율의 증가 경향을 통해 일령이 증가할수록 야외 감염률이 증가하는 양상을 파악할 수 있었다. EDS'76은 산란 기간에 걸쳐 높은 양성률과 낮은 변이계수를 보여 야외 감염이 아닌 백신에 의한 역가 형성이 대부분임을 알 수 있었다. IBD의 모체이행항체는 높은 수준으로 이행되는 것을 확인하였으며, CIA는 백신을 적용하지 않은 계군에서 양성과 음성 계군이 모두 존재하였으며, 그 차이는 차단 방역에 기인하는 것으로 판단되었다. 본 연구를 통하여 국내 산란계에서의 혈청 역가 분포를 파악하는데 많은 정보를 얻을수 있었으나, 향후 지속적인 야외 계군의 혈청학적 모니터링이 되어야 할 것으로 판단된다. Serological evaluation for the poultry is important for various reasons, such as designing and assessing the vaccination program and diagnosing diseases and for this reason, serologic tests for the layer flocks have been conducted on a regular basis. Moreover, the nationwide serological survey and analysis are essential to understand the epidemiological status of national poultry industry. In this sense, the study was conducted to evaluate the immune status of the layer flocks with the sera submitted to Avian Disease Laboratory, Chungbuk National University in 2009, and several important viral diseases were selected for evaluation including low pathogenic avian influenza (LPAI), Newcastle disease (ND), infectious bronchitis (IB) and avian metapneumovirus (aMPV). For LPAI and ND, the age-related patterns of geometric mean titer (GMT) changes were similar but there were differences in the flock positive rate and the level of GMT due to the different vaccination policy. In the case of IB, the values of GMT showed that the field infection was more prevalent than expected. For aMPV, positive birds in a flock increased as the layers got older, which reflected the course of field infection because vaccination against aMPV was not allowed in 2009. From this study, the immune status for the main viral diseases in layers became more clarified but this information was limited because of only one year study. Therefore, serological survey needs to be conducted on a yearly basis and furthermore include broilers and breeders for a better understanding of the health status in the national poultry industry.

Toxoplasma gondii: diagnosis of experimental and natural infection in pigeons (Columba livia) by serological, biological and molecular techniques

This study aimed to diagnose experimental and natural Toxoplasma gondii infection in pigeons (Columba livia) by serological, biological and molecular techniques. Twelve pigeons, free of infection, were inoculated with 50 sporulated oocysts of T. gondii (VEG sample) and four remained uninfected controls. Four birds (three infected and one control) were euthanized at 15, 30, 45 and 60 days post-infection (dpi), and their tissues were used to perform a bioassay in mice and nested-PCR using B1 gene as target. Blood was obtained weekly and it was tested for the presence of anti-T. gondii antibodies by the indirect fluorescent antibody test (IFAT) and modified agglutination test (MAT). Seven (58.3%) out of 12 inoculated pigeons were positive by serological techniques and titers ranged between 1:40 and 1:5120 by MAT and between 1:512 and 1:4096 by IFAT. Complete agreement was seen between the results obtained by serological techniques and nested-PCR in seven positive birds. In the bioassay in mice, five (41.7%) out of 12 pigeons inoculated were positive to T. gondii. Only one pigeon died at 23 dpi due to toxoplasmosis. A second study with free-living pigeons was performed for detection of anti-T. gondii antibodies. Birds were captured in the municipalities of São Paulo, Ibiúna and Sorocaba, São Paulo State, Southeastern Brazil. All 126 free-living birds were negative to anti-T. gondii antibodies by MAT (titer < 1:5). Bioassays were performed in mice with tissues from all captured birds and T. gondii was not isolated in any pigeon.

Epidemiology of West Nile Virus: A Silent Epiornitic in Northern Delaware in 2007 without Associated Human Cases

ABSTRACT. We performed a 2-year longitudinal study (2006-2007) of West Nile virus (WNV) infections in wild birds, mosquitoes, and sentinel chickens at 6 WNV-endemic sites in northern Delaware. We determined virus infection rates of Culex pipiens and other mosquito vectors as well as seroprevalence and antibody titers of amplifying hosts. Endemicity status varied widely among the 6 sites based on 3 criteria-mosquito infections, sentinel chicken seropositivity, and wild bird seropositivity. A highly endemic site would display at least 2 of the 3 criteria during each year of the study, while a site with just 1 positive criterion was considered to have low endemicity. Culex pipiens was the principal vector detected at 2 highly endemic sites in 2006 vs. 1 site in 2007. However, in 2006, we also found 2 other WNV-positive vector species as well as an unidentifiable Culex species at 1 highly endemic site, suggesting increased activity at the end of the 1st year of the study. Wild birds were early indicators of WNV at highly endemic sites in mid-July to early August of both 2006-2007. Mosquitoes were positive in mid- to late August, appearing concurrently with seroconverted sentinel chickens, with wild resident birds appearing approximately 4 wk prior to those indicators. Of birds tested with n > or = 9, Northern cardinals had the highest seropositivity rates (47%) followed by Carolina wrens (19%), house sparrows (13%), American robins (13%), tufted titmice (11%), and gray catbirds (9%). The overall seropositive rates in trapped birds increased from 5.0% in 2006 to 20.0% in 2007, while the geometric mean titers of all positive birds increased from 1:34 to 1:47 during the comparable periods. Based on these results, we suggest that an epiornitic in birds occurred in 2007, but that greatly reduced abundance of mosquito vectors caused by an extreme drought largely precluded human infection.

Comparison of immunohistochemistry and polymerase chain reaction for detection of West Nile virus in naturally infected dead birds

Credible vector-borne disease surveillance programs, especially in developing countries with limited resources, must include diagnostic tests that are efficient, inexpensive and simple and safe to administer while maintaining high levels of sensitivity and specificity. Since immunohistochemistry (IHC) includes most of these features, its sensitivity, specificity, predictive positive value (PPV) and predictive negative value (PNV) for West Nile virus (WNv) screening were compared to those of the gold standard, RT-PCR testing of kidney tissue in dead birds. IHC and RT-PCR were performed for WNv antigen on 41 dead birds (belonging to five orders) collected from the northwest region of the Riverside County of California. Fixed tissue sections were screened by IHC using polyclonal antibodies, and frozen kidney tissues were tested with RT-PCR. Kidney screening with IHC showed sensitivity, specificity, PPV and NPV of 95.45%, 73.68%, 80.77% and 93.33%, respectively. Based on WNv screening of kidney tissue, IHC and RT-PCR were in agreement with 95.45% (21/22) for positive dead birds and were in 100% (22/22) agreement when multi-organ screening by IHC was performed. The present study showed that IHC is as equally effective as RT-PCR in screening for WNv in dead birds. Therefore, IHC can effectively serve as a competent screening technique for those disease surveillance agencies that lack expensive RT-PCR technology while promoting safer biohazardous conditions, except at the initial stage of tissue collection.