BackgroundThe south of Chile constitutes the main cattle milk producing area of the country. Regarding leptospirosis control in Chile, there is neither an official program nor an epidemiological characterization of smallholder dairy farms. This study was carried out to determine Leptospira seroprevalence and to evaluate risk factors associated with seropositivity at herd level in smallholder bovine dairy herds in southern Chile.A cross-sectional study was conducted, and a convenient sample of 1,537 apparently healthy dairy cows was included in the study. Individual blood samples were taken and examined for six selected reference Leptospira serovars by the Microscopic Agglutination Test (MAT).ResultsOf the included herds 75% (52/69) showed serological titers against one or more Leptospira serovar. Leptospira borgpetersenii serovar Hardjo was the serovar most frequently (81%) reported from animals with positive results. The variables considered risk factors for Leptospira seropositivity were calve natural breeding system, using a specific calving area and vaccination against Leptospira. Adult cows in contact with calves weaned, proved to be a protective factor against infection.ConclusionsHerds neglecting the management practices mentioned in this study could represent an important source of Leptospira infection for other herds in the same geographic area, as well as for other animal species.

Accumulation and persistence of hepatitis A virus (HAV) in the mussel Mytilus chilensis was evaluated. Under optimal filtration activity of mussels (temperature 12 degrees C, salinity 3%, feeding twice a day with Dunaliella marina), HAV was concentrated 100-fold from the surrounding water. Similar concentrations of HAV were reached in the filtration apparatus and in the digestive system (hepatopancreas). HAV persisted for about 7 days in mussels. Elimination of HAV from mussels was slower than elimination of poliovirus. Without feeding of mussels (causing low filtration activity), there was no measurable uptake of HAV into mussels, and depuration of HAV from mussels was slower. The ability of mussels to concentrate HAV was used successfully to monitor fecally contaminated river water for the presence of HAV.

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Two novel autoregulators affecting the cyto-differentiation of anthracycline-producing Streptomyces griseus have been isolated from cultures of aerial mycelium-forming progenitor strains and blocked mutants. By spectral (IR, CD, MS, 1H and 13C NMR) methods, the autoregulators are shown to be the diastereomers of 4,5-dihydroxydecanoic acid-4-lactone.

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