The association between highly pathogenic avian influenza (HPAI) subtype H5N1 outbreak risk in poultry in 161 Romanian villages (October 2005 to June 2006) and environmental and anthropogenic factors was investigated. Village outbreak risk was associated with a village being <5 km from a major road (odds ratio [OR] 5.27, 95% confidence interval [CI] 1.21-22.9) or a river/stream (OR 1.97, 95% CI 1.06-3.72). Outbreak risk in the first part of the epidemic was associated with a village being <5 km from a major road (OR 3.31, 95% CI 1.10-9.98) or a regularly flooded land area (OR 5.08, 95% CI 1.08-23.9); whereas outbreak risk in the second part of the epidemic was associated with a village being <5 km from a river/stream (OR 5.5, 95% CI 1.69-18.9). Results suggest that both environmental and anthropogenic factors influence the risk of HPAI subtype H5N1 outbreaks in village poultry populations.
Three different methods were used for estimating the basic reproductive number (R0) from data on 110 outbreaks of highly pathogenic avian influenza (HPAI) subtype H5N1 that occurred in village poultry in Romania, 12 May to 6 June 2006. We assumed a village-level infectious period of 7 days. The methods applied were GIS-based identification of nearest infectious neighbour (based on either Euclidean or road distance), the method of epidemic doubling time, and a susceptible-infectious (SI) modelling approach. In general, the estimated basic reproductive numbers were consistent: 2.14, 1.95, 2.68 and 2.21, respectively. Although the true basic reproductive number in this epidemic is unknown, results suggest that the use of a range of methods might be useful for characterizing epidemics of infectious diseases. Once the basic reproductive number has been estimated, better control strategies and targeted surveillance programmes can be designed.
-The aim of this study was to evaluate a range of statistical and geostatistical methods for their usefulness in providing insights into how highly pathogenic avian influenza (HPAI) subtype H5N1 might spread through a national population of village poultry. The insights gained allow the generation of disease dispersion hypotheses. The case study data set consisted of 161 outbreaks of HPAI subtype H5N1 in village poultry reported in Romania between
Highly pathogenic avian influenza (HPAI) virus subtype H5N1 threatens poultry production and human health. Understanding the role that migratory waterfowl play in introducing and maintaining this infection is critical to control the outbreaks. A study was conducted to determine if the occurrence of HPAI subtype H5N1 outbreaks in village poultry in Romania, 2005-2006, was associated with proximity to populations of migratory waterfowl. Reported outbreaks--which could be grouped into three epidemic phases--and migratory waterfowl sites were mapped. The migratory waterfowl site closest to each outbreak was identified. The distances between outbreaks occurring in phase 1 and 2 of the epidemic and the closest migratory waterfowl site were significantly (P<0.001) less than in phase 3, but these distances were only useful in predicting when outbreaks occurred during phase 1 (October-December, 2005) of the epidemic. A spatial lag (rho=0.408, P=0.041) model best fit the data, using distance and [distance]*[distance] as predictors (R2=0.425). The correlation between when outbreaks were predicted to occur and when they were observed to occur was 0.55 (P=0.006). Results support the hypothesis that HPAI virus subtype H5N1 infections of village poultry in Romania during the autumn of 2005 might have occurred via exposure to migratory populations of waterfowl.
In recent years, wild birds have introduced multiple highly pathogenic avian influenza (HPAI) H5N1 virus infections in Romanian poultry. In 2005 HPAI infections were widespread among domestic poultry and anecdotal reports suggested domestic pigs may also have been exposed. We sought to examine evidence for zoonotic influenza infections among Romanian agriculture workers. Between 2009 and 2010, 363 adult participants were enrolled in a cross-sectional, seroepidemiological study. Confined animal feeding operation (CAFO) swine workers in Tulcea and small, traditional backyard farmers in Cluj-Napoca were enrolled, as well as a non-animal exposed control group from Cluj-Napoca. Enrollment sera were examined for serological evidence of previous infection with 9 avian and 3 human influenza virus strains. Serologic assays showed no evidence of previous infection with 7 low pathogenic avian influenza viruses or with HPAI H5N1. However, 33 participants (9.1%) had elevated microneutralization antibody titers against avian-like A/Hong Kong/1073/1999(H9N2), 5 with titers ≥ 1:80 whom all reported exposure to poultry. Moderate poultry exposure was significantly associated with elevated titers after controlling for the subjects' age (adjusted OR = 3.6; 95% CI, 1.1-12.1). There was no evidence that previous infection with human H3N2 or H2N2 viruses were confounding the H9N2 seroreactivity. These data suggest that H9N2 virus may have circulated in Romanian poultry and occasionally infected man.
BackgroundIn this prospective study we sought to examine seroepidemiological evidence for acute zoonotic influenza virus infection among Romanian agricultural workers.MethodsSera were drawn upon enrollment (2009) and again at 12 and 24 months from 312 adult agriculture workers and 51 age-group matched controls. Participants were contacted monthly for 24 months and queried regarding episodes of acute influenza-like illnesses (ILI). Cohort members meeting ILI criteria permitted respiratory swab collections as well as acute and convalescent serum collection. Serologic assays were performed against 9 avian, 3 swine, and 3 human influenza viruses.ResultsDuring the two-year follow-up, a total of 23 ILI events were reported. Two subjects' specimens were identified as influenza A by rRT-PCR. During the follow-up period, three individuals experienced elevated microneutralization antibody titers ≥1∶80 against three (one each) avian influenza viruses: A/Teal/Hong Kong/w312/97(H6N1), A/Hong Kong/1073/1999(H9N2), or A/Duck/Alberta/60/1976(H12N5). However, none of these participants met the criteria for poultry exposure. A number of subjects demonstrated four-fold increases over time in hemagglutination inhibition (HI) assay titers for at least one of the three swine influenza viruses (SIVs); however, it seems likely that two of these three responses were due to cross-reacting antibody against human influenza. Only elevated antibody titers against A/Swine/Flanders/1/1998(H3N2) lacked evidence for such confounding. In examining risk factors for elevated antibody against this SIV with multiple logistic regression, swine exposure (adjusted OR = 1.8, 95% CI 1.1–2.8) and tobacco use (adjusted OR = 1.8; 95% CI 1.1–2.9) were important predictors.ConclusionsWhile Romania has recently experienced multiple incursions of highly pathogenic avian influenza among domestic poultry, this cohort of Romanian agriculture workers had sparse evidence of avian influenza virus infections. In contrast, there was evidence, especially among the swine exposed participants, of infections with human and one swine H3N2 influenza virus.
Highly pathogenic avian influenza (HPAI) H5N1 virus incursions from migrating birds have occurred multiple times in Romania since 2005. Beginning in September 2008 through April 2013, seasonal sentinel surveillance for avian influenza A viruses (AIVs) using domestic geese (Anser cygnoides) and ducks (Anas platyrhynchos) in the Danube Delta was established by placing 15 geese and 5 ducks at seven sites. Tracheal and cloacal swabs, and sera collections (starting in 2009) were taken monthly. We studied a total of 580 domestic birds and collected 5,520 cloacal and tracheal swabs from each and 2,760 sera samples. All swabs were studied with real-time reverse transcription polymerase chain reaction (rRT-PCR) for evidence of AIV. Serological samples were studied with hemagglutination inhibition assays against avian H5, H7, and H9 influenza viruses. From 2009 to 2013, 47 swab specimens from Cot Candura, Enisala, and Saon screened positive for AIV; further subtyping demonstrated that 14 ducks and 20 geese had cloacal evidence of H5N3 carriage. Correspondingly, 4 to 12 weeks after these molecular detections, sentinel bird sera revealed elevated HI titers against H5 virus antigens. We posit that domestic bird surveillance is an effective method to conduct AIV surveillance among migrating birds in delta areas.
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