G. Reinhardt

Seroprevalence of bovine viral diarrhea/mucosal disease in southern Chile

Abstract The seroprevalence of bovine viral diarrhea/mucosal disease (BVD/MD) was estimated using the serum neutralization technique on 948 cow serum samples collected from 40 large herds of the IXth and Xth Regions in southern Chile. In addition, 116 bulls were tested. The seroprevalence was found to be high, with 700 of the 948 cows testing positive (73.8%) at a titer of ⩾1:5. The herd seroprevalence was 100%, with all the herds studied containing at least one positive animal. The seroprevalence in bulls was 81.0%. The survey indicated a high seroprevalence throughout the study area, with a maximum of 87.4% in the province of Cautin, IXth Region. Furthermore, the prevalence of reactors was high in animals managed in extensive production systems and there were no differences in prevalence observed between beef, dairy and mixed farming. The results indicate that BVD/MD is widely distributed in the adult bovine population of large herds in southern Chile.

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

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.

Hepatitis aguda por virus A, E y no A-E en adultos chilenos a fines de los años 90

BACKGROUND Sanitary and socioeconomic changes and the identification of new causative virus, have changed the epidemiology of hepatitis in Chile. AIM To study the natural history of acute hepatitis caused by virus A, E and non A-E in Chilean adults. PATIENTS AND METHODS A special study protocol was followed for patients with a clinical picture of acute hepatitis. Anti HAV IgM, anti HBc IgM, anti HEV IgG and IgM and Anti HCV antibodies were determined by ELISA. RESULTS Fifty nine patients (30 male), aged 15 to 58 years old were studied. Eighty nine percent had jaundice and 50 to 70% had malaise and abdominal pain. Virus A was positive in 80%, virus E in 7%. In 14% of patients, all viral markers were negative. The evolution was typical in 78%, biphasic in 14% and cholestatic in 5%. One patient had a prolonged and one a fulminant course. Mean ALT was 1148 U/l and mean total bilirubin was 5.5 mg/dl. Seventy three percent of cases occurred during early winter and spring and 27% during summer and early autumn. CONCLUSIONS The main etiology of acute viral hepatitis in Chile is virus A and most cases occur during the rainy season. Clinical features of hepatitis non A-E are similar to enteral transmission forms.

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.

Presencia de anti-VHE en un estudio de cohorte de porcinos ¿reservorio animal de hepatitis E en Chile?

Swine hepatitis E virus (HEV) has a cross-reactionwith human anti-HEV antibodies. Therefore, pigs could be an animal reservoir, renderinghepatitis E as a zoonosis. The spread of this infection among infected pigs across countries wouldbe possible through trading. Previously, using an anti-human conjugate, we detected anti-HEVantobodies in adult pigs in Chile.BACKGROUND Swine hepatitis E virus (HEV) has a cross-reaction with human anti-HEV antibodies. Therefore, pigs could be an animal reservoir, rendering hepatitis E as a zoonosis. The spread of this infection among infected pigs across countries would be possible through trading. Previously, using an anti-human conjugate, we detected anti-HEV antobodies in adult pigs in Chile. AIM To detect anti-HEV (ELISA) in a cohort of swine at different ages. MATERIAL AND METHODS Two hundred pigs aged 42 to 360 days, divided in 20 groups of 10 animals were tested. Anti-HEV was detected by ELISA using anti-pig IgG horseradish peroxidase instead of anti-human conjugates. RESULTS Anti-HEV were detected in one animal aged 90 days, two animals aged 120 days, one animal aged 260 days and 2 animals aged 360 days, five pregnant sows and two old hogs. This represents a total of 14 animals or 7% of the sample. CONCLUSIONS There is a significant prevalence of anti-HEV in pigs from 90 days of birth, suggesting that these swine are a probable reservoir.

Estado actual de inmunidad para hepatitis por virus A en diversos grupos de adultos

Background: As sanitary and economic conditions improve, the prevalence of antibodies to hepatitis A is now significantly lower. Aim: To evaluate the prevalence of hepatitis A virus antibodies in healthy Chilean adults. Material and methods: Antibodies to hepatitis A virus were measured, using a commercial ELISA assay, in 215 voluntary blood donors (163 male, aged 19 to 30 years old) and 295 medical students and health personnel (156 male, aged 19 to 39 years old), residing in Valdivia, Chile. Results: Antibodies against hepatitis A virus were found in 68,2% of the total sample (351/510). Ninety percent of flood donors and 54% of health personnel and students were positive (p <0.01). Age specific prevalence in blood donors 19 to 22, 23 to 29 and 27 to 30 years old was 81,0%, 95,2% and 95,6% respectively. Among the same age groups in medical students, the prevalence was 47,9%, 53,2% and 61,9% respectively (p <0.01). Conclusions: This study indicates a reduction in the prevalence of hepatitis A virus antibodies among adults in Valdivia (Chile). Differences detected between individuals are probably related to different socioeconomic levels. Medical students have an increased risk for hepatitis A infections than the general population.

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

BackgroundAlthough 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 presentationIn 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.ConclusionLeptospira 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.

Plásmido de virulencia en Yersinia enterocolitica O:3 de origen murino

BACKGROUND Pathogenic strains of Yersinia enterocolitica harbor a virulence plasmid of 45-48 megadalton that can be detected using different techniques. Rodents are important reservoirs of Y enterocolitica. AIM To investigate the carrier status of Y enterocolitica in murine rodents. MATERIAL AND METHODS Two hundred sixty-one mice and rats were captured in rural and urban areas of Valdivia. Y enterocolitica was cultured from viscera and fecal homogenates. Virulence plasmids were detected using crystal violet binding. RESULTS Thirteen Y enterocolitica strains were isolated from 11 rodents. Ten strains belonged to the biotype 1 and three to the biotype 4, serotype O:3. The most frequently infected rodent species were R norvergicus (20%), followed by A longipilis (11%), A olivaceus (2%) and O longicaudatus (2%). CONCLUSIONS Rodents, and specially the domestic rat, can be an important source of Y enterocolitica infection for human and susceptible animal species.

In vitro exposure of the early mouse embryo to Herpes Simplex Virus-1 strain Wal

The causes of early embryonic death are not clearly understood, but one of them may be viral infection. To study the interaction between the virus and the undifierentiated cell, early mouse embryos in morula and blastocyst stages were exposed to Herpes Simplex Virus-1 WAL (HSV-1 WAL). In one group of a total of 167 embryos, 108 were exposed to HSV-1 WAL; the rest were maintained as controls. After washing in culture medium, these embryos were cultured on a murine fetal fibroblast monolayer for viral isolation. None showed cytopathic effects in the susceptible monolayer. In a second group, 140 empryos were exposed and 106 were maintained as controls. These embryos were cultured without a monolayer or washing to permit continuous viral contact. Eighty-seven of the exposed embryos and 74 control empryos developed normally 2 to 3 d post hatching with no morpnological differences between the two groups. No statistical differences were observed when the proportion of natched and degenerated embryos was compared. Our results indicated that the cells of early mouse embryos are not susceptible to HSV-1 WAL. We concluded that possibly the susceptibility of empryonic cells to viral agents partially depends on stage of differentiation.