Isolation of Leptospira interrogans serovar Hardjoprajitno from a calf with clinical leptospirosis in Chile.

BACKGROUND: Although Leptospira isolation has been reported in Chilean cattle, only serological evidence of serovar Hardjo bovis infection has been routinely reported. The present report provides characterization of the pathological presentation and etiology of a clinical case of leptospirosis in a calf from the Los Rios Region in Chile. CASE PRESENTATION: In a dairy herd in southern Chile, 11 of 130 calves died after presenting signs such as depression and red-tinged urine. One of these calves, a female of eight months, was necropsied, and all the pathological findings were consistent with Leptospira infection. A urine sample was submitted to conventional bacteriological analysis together with highly specific molecular biology typing tools, in order to unravel the specific Leptospira specie and serovar associated with this clinical case. A significant finding of this study was that the obtained isolate was confirmed by PCR as L. interrogans, its VNTR profile properly matching with L. interrogans Hardjoprajitno as well as its specific genomic identity revealed by secY gen. CONCLUSION: Leptospira interrogans serovar Hardjoprajitno was associated with the investigated calf clinical case. This information adds to the value of serologic results commonly reported, which encourage vaccination improvements to match circulating strains. In addition, this finding represents the first case report of this serovar in Chilean cattle.

A cross sectional observational study to estimate herd level risk factors for Leptospira spp. serovars in small holder dairy cattle farms in southern Chile.

BACKGROUND: The 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). RESULTS: Of 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. CONCLUSIONS: Herds 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.

Genetic diversity of bovine viral diarrhoea virus (BVDV) from Peru and Chile: [revision] / Diversidade genética de vírus da diarréia viral bovina (BVDV) do Peru e Chile: [revisão]

Twenty-five BVDV strains, detected in serum from persistently infected cattle from Peru (n=15) and Chile (n=10) were genetically characterized. The phylogenetic analysis based on the 5' UTR showed that all 25 strains belonged to genotype 1. Twenty-three of the strains could further be subdivided into subtype 1b, and two out of ten Chilean strains into subtype 1a. In conclusion, in total 23 out of 25 strains analyzed were of genotype 1, subtype 1b. This is the predominant BVDV subtype in many countries all over the world, including USA. The close homology with previously described strains reflects the influence of livestock trade on the diversity of BVDV circulating within and between countries and continents. Peru and Chile have imported large numbers of cattle from USA and Europe, mostly with insufficient or lacking health documentation.

Um total de 25 isolados do vírus da diarréia viral bovina (BVDV), sendo 15 originarias do Peru e 10 do Chile foram sujeitas a caracterização genética. A árvore filogenética baseada na análise da região proximal não-codificante (5'UTR) do genoma viral demonstrou que as 25 estirpes pertencem ao genótipo 1 do vírus BVD. Vinte e três destas estirpes puderam adicionalmente ser subdivididas no subtipo 1b, enquanto duas das 10 estirpes isolados provenientes do Chile foram identificadas como pertencentes ao subtipo 1a. Em conclusão, 23 de um total de 25 isolados analisados pertencem ao genótipo 1, subtipo 1b. Este é o subtipo de BVDV predominante em muitos países do mundo, incluindo os EUA. A elevada similaridade genética com isolados descritos anteriormente em outras regiões do mundo realça o papel do comércio internacional de gado no estabelecimento de diversidade genética do vírus BVD. Tanto o Peru como o Chile têm historia de importação de grandes quantidades de gado dos Estados Unidos e da Europa, no entanto sem suficiente documentação comprovativa do estado sanitário no que concerne a esta virose.

Immunogenicity and reactogenicity of combined versus separately administered DTPw-HBV and Hib vaccines given to healthy infants at 2, 4 and 6 months of age, with a booster at 18 months.

OBJECTIVES: To determine the immunogenicity and reactogenicity of a combined DTPw-HBV/Hib vaccine, in comparison with DTPw-HBV and Hib vaccines given as separate concomitant injections. METHODS: In an open, randomized study, healthy infants were injected with either DTPw-HBV/Hib vaccine or separate DTPw-HBV and Hib vaccines at 2, 4 and 6 months of age, with a booster at 18 months. RESULTS: Both vaccination regimens were immunogenic, with seropositivity rates of 100% after the booster vaccination for all vaccine components. Even as early as 2 months after the second dose of the primary vaccination, most patients had seroprotective antibody titers, the proportion of seropositive subjects approaching 100% for tetanus, hepatitis B, and Hib. Post-primary and post-booster geometric mean titers (GMTs) were well above seroprotective thresholds for each vaccine antigen in both groups, with no clinically relevant differences in the groups. The separate and combined administrations showed comparable reactogenicity profiles, and neither showed a significant increase in reactogenicity with successive doses. CONCLUSIONS: The results of this study support the combination of Hib and DTPw-HBV vaccination in routine infant immunization at 2, 4 and 6 months of age with a booster at 18 months. Maximum benefit is obtained from compliance with the full course, but substantial benefit is likely to be achieved even in partially compliant patients, provided they receive at least two doses. Furthermore, these results demonstrate the tolerability of a fourth (booster) administration, where the addition of the Hib vaccine to DTPw-HBV did not lead to an increase in the overall reactogenicity.