Anthropogenic factors and the risk of highly pathogenic avian influenza H5N1: prospects from a spatial-based model

Beginning in 2003, highly pathogenic avian influenza (HPAI) H5N1 virus spread across Southeast Asia, causing unprecedented epidemics. Thailand was massively infected in 2004 and 2005 and continues today to experience sporadic outbreaks. While research findings suggest that the spread of HPAI H5N1 is influenced primarily by trade patterns, identifying the anthropogenic risk factors involved remains a challenge. In this study, we investigated which anthropogenic factors played a role in the risk of HPAI in Thailand using outbreak data from the “second wave” of the epidemic (3 July 2004 to 5 May 2005) in the country. We first performed a spatial analysis of the relative risk of HPAI H5N1 at the subdistrict level based on a hierarchical Bayesian model. We observed a strong spatial heterogeneity of the relative risk. We then tested a set of potential risk factors in a multivariable linear model. The results confirmed the role of free-grazing ducks and rice-cropping intensity but showed a weak association with fighting cock density. The results also revealed a set of anthropogenic factors significantly linked with the risk of HPAI. High risk was associated strongly with densely populated areas, short distances to a highway junction, and short distances to large cities. These findings highlight a new explanatory pattern for the risk of HPAI and indicate that, in addition to agro-environmental factors, anthropogenic factors play an important role in the spread of H5N1. To limit the spread of future outbreaks, efforts to control the movement of poultry products must be sustained.     

New compounds obtained by evolution and oxidation of malvidin 3-O-glucoside in ethanolic medium

Two new colorless phenolic compounds were formed from malvidin 3- O-glucoside incubated in an ethanolic solution. Their structures were characterized by means of one- and two-dimensional NMR analysis and through electrospray ionization-mass spectrometry. As compared to the structure of the initial anthocyanin skeleton, the first new compound showed the presence of two fused five-membered rings replacing the pyran ring and of a carbonyl function on the 2-position. The first five-membered ring was shown to result from the formation of a new linkage between the B ring 6'-position and the C ring 4-position, while the second was a dihydro furan ring with an oxygenated ether linkage between the 8a-position and the 3-position. The second isolated compound was shown to have similar structure with an ethyl ether moiety in the 3-position instead of the glucose moiety. A mechanism explaining the formation of the isolated compounds involving the passage through the chalcone form of the anthocyanin and an oxidation process is proposed.     

How the surveillance system may bias the results of analytical epidemiological studies on BSE: prevalence among dairy versus beef suckler cattle breeds in France

Until recently, epidemiological studies on Bovine Spongiform Encephalopathy (BSE) were based on Mandatory Reporting Systems (MRS) of clinically suspect bovines only, but rapid diagnostic tests were validated in 1999 and are used for targeted surveillance in Switzerland, France and other countries, as a complementary and secondary tool. Data on 30491 cattle issued from a French pilot program targeted at cattle having died on the farm, subjected to euthanasia or sent for emergency slaughter, did not show any significant difference in BSE risk between dairy and beef suckler breeds. The data also revealed that part of the clinical cases of BSE escaped the MRS, which permitted to detect more dairy than beef suckler affected cattle compared to the targeted surveillance in the same period (from August to December 2000) and region (Bretagne, Pays de la Loire and Basse Normandie regions). Analyzing together the data of the targeted surveillance and mandatory reporting system programs with a non-conditional logistic regression, we found that the odds of a dead cow being a BSE case among all dead cattle was 3.2 times higher for dairy breeds compared to beef suckler breeds. This confirmed British findings but points out to the fact that considering either MRS or targeted surveillance data alone may possibly create biases in epidemiological studies on BSE.     

NMR, ESI/MS, and MALDI-TOF/MS analysis of pear juice polymeric proanthocyanidins with potent free radical scavenging activity

The structure of a polymeric proanthocyanidin fraction isolated from pear juice was characterized by NMR, ESI/MS, and MALDI-TOF/MS analyses, and its antioxidant activity was investigated using the DPPH free radical scavenging method. The results obtained from 13C NMR analysis showed the predominance of signals representative of procyanidins. Typical signals in the chemical shift region between 70 and 90 ppm demonstrated the exclusive presence of epicatechin units. The results obtained through negative ESI/MS analysis showed singly and doubly charged ions corresponding to the molecular mass of procyanidins with a degree of polymerization up to 22. The spectra obtained through MALDI-TOF/MS analysis revealed the presence of two series of tannin oligomers. Supporting the observations from NMR spectroscopy, the first series consists of well-resolved tannin identified as procyanidin polymers units with chain lengths of up to 25. A second series of monogalloyl flavan-3-ols polymers with polymerization degree up to 25 were also detected. This is the first mass spectrometric evidence confirming the existence of galloylated procyanidin oligomers in pear fruits. Within each of these oligomers, various signals exist suggesting the presence of several oligomeric tannins. The antioxidant properties of the polymeric fraction were investigated through reduction of the DPPH free radical, and the results obtained showed that the polymeric fraction exhibited a higher antioxidant power compared to those of (+)-catechin and B3 procyanidin dimer.     

Descriptive spatial analysis of BSE in western France

The spatial heterogeneity of Bovine Spongiform Encephalopathy (BSE) was analysed on the 84 cases confirmed in western France (WF) between August and December 2000, when both the Mandatory Reporting System and an active surveillance on cattle at risk were running. Ninety-four percent of these cases were born between June 1993 and June 1996, and we analysed the location at birth. One disease mapping and two clustering methods (Scan of Kulldorff and the method of Besag and Newell) were used. In order to attenuate the contrasts artificially created by the standard disease mapping method (over-dispersion), we estimated the Standard Incidence Ratio (SIR) with a Bayesian method (Poisson-Gamma model) allowing a smoothing of the estimators. The geographical location of interest was the "canton", that divided the total area into 526 geographical units. The background population (2.6 million cattle) was obtained from the Agricultural Census 2000. We tested the hypothesis of a homogenous spatial distribution of the BSE risk where the expected number of BSE cases per unit area was obtained by applying the overall BSE rate in WF to each "canton", standardised on the type of breed, dairy versus beef suckler. The SIR ranged from 0.80 to 2.18 and the spatial distribution of BSE cases was significantly heterogeneous. Two spatial clusters were detected with the spatial scan statistics of Kulldorff and the method of Besag and Newell (18 to 20 observed BSE-cases per cluster with a radius of 45 km) centred on the "département" of C?tes-d'Armor and Mayenne. Another cluster was detected with the method of Besag and Newell (9 observed BSE-cases) in the "département" of Finistère. The results proved that the risk of BSE is linked to the geographical location in the area of the study.     

Risk factors for post-partum anoestrus in Charolais beef cows in France

Data from 248 Charolais cows from 20 herds of the Puisaye region (Yonne, France) were collected during winter 1991–1992 to investigate risk factors affecting post-partum anoestrus. Blood was collected 60 days after calving; diagnosis of cyclicity was established by progesterone radioimmunoassay. Herd variables were housing type, lighting of herd accomodation, use of nutritional flushing and nutritional variables (protein and energy before and after calving), and individual variables were parity, ease of calving, body-condition score and body weight at calving and at Day 60, exposure to bulls and calving period. Sixty days post-partum, 62.1% of cows were cyclic. Logistic regression was used to calculate odds ratio (OR). A random effects model was used to take into account the two levels of variables (animal and herd). Although it was defined subjectively, lighting was the only significant herd-level risk factor. Odds of anoestrus were higher in dark than in light accomodation (OR = 6.2, CI 1.2–33.3). Primiparous cows had a higher anoestrus risk than multiparous cows (OR = 10.2, CI 2.9–36.5). Compared with light cows, heavy or medium weight cows at calving had a lower anoestrus risk (OR = 0.25, CI 0.07–0.91, and OR = 0.20, CI 0.07–0.61, respectively.     

Case-control study on feed risk factors for BSE cases born after the feed ban in France

In France, after the ban on meat and bone meal (MBM) in cattle feeding in June 1990, cases of Bovine Spongiform Encephalopathy (BSE) have continued to be detected in bovines born after that ban (called BAB cases). A case-control study was therefore carried out to determine the way these cases were contaminated. A multivariate conditional model was built adjusting for the production type of the animals and taking into account the herd size. The results confirmed that feeding cattle with proprietary concentrates was at risk for BSE, with an adjusted odds ratio of 6.8 (2.5; 18.7) for the consumption of less or three different proprietary concentrates and 17.6 (5.7; 54.8) for more than three, when comparing with no consumption of proprietary concentrates, considering feeding of bovines before the age of two. The results suggest that cross-contaminations by MBM in bovine concentrates have occurred after 1990. To a lesser extent, on-farm cross-contaminations, i.e. consumption by cattle of feedstuffs initially dedicated to other animals and which could legally contain MBM, have probably also existed, since the presence on farms of poultry fed purchased feed involved an increased risk of BSE with an odds ratio of 1.8 (1.1; 3.0). The use of milk replacers, which often incorporates animal fats, was also at risk with an odds ratio of 1.8 (1.0; 3.1).