Mother-to-Child Transmission of Andes Virus through Breast Milk, Chile1.

Andes virus (ANDV) is the only hantavirus transmitted between humans through close contact. We detected the genome and proteins of ANDV in breast milk cells from an infected mother in Chile who transmitted the virus to her child, suggesting gastrointestinal infection through breast milk as a route of ANDV person-to-person transmission.

Herd level risk factors for Mycobacterium avium subsp. paratuberculosis infection and clinical incidence in dairy herds in Chile.

The study objective was to identify risk factors associated to: i) the infection by Mycobacterium avium subsp. paratuberculosis (MAP), and ii) paratuberculosis clinical incidence in Chilean dairy herds. A random sample of forty herds with previous history of MAP infection was selected. At herd level, all lactating cows were tested using a commercial ELISA kit. On the sampling date, a questionnaire gathering information on herd demographics, husbandry practices, and biosecurity measures was applied. Additionally, the farm manager/owner was surveyed regarding the number of paratuberculosis compatible clinical cases (CCC) in the last 12 months. Two Bayesian generalized linear mixed effect models were used to evaluate the association between the questionnaire data, and the proportion of truly infected animals (model 1) or the number of CCC (model 2). A total of 4963 animals were sampled with an average apparent prevalence of 6.3 % (95 % confidence interval (4.0-8.0%). All sampled herds presented seropositive animals. Forty eight percent of the herds did not observe any CCC in the last year. Although, among those herd that did report CCC, a median of two cases per year was estimated. Model outputs showed that the proportion of truly infected animals and CCC reporting rates are associated to management practices. Specifically, positive associations were observed for feeding of calves exclusively with milk replacer, and the distance between the milking parlor and the calves' barn. Additionally, CCC reporting rates were higher in farms that recently purchased animals, and where the distance between the milking parlor and the calves' barn was less than 30 m.

Within-herd prevalence and clinical incidence distributions of Mycobacterium avium subspecies paratuberculosis infection on dairy herds in Chile.

This study aimed to estimate the distributions of the within-herd true prevalence (TP) and the annual clinical incidence proportion (CIp) of Mycobacterium avium subsp. paratuberculosis (MAP) infection in dairy cattle herds in Chile. Forty two commercial herds with antecedents of MAP infection were randomly selected to participate in the study. In small herds (≤30 cows), serum samples were collected from all animals present. Whereas, in larger herds, milk or serum samples were collected from all milking cows with 2 or more parities. Samples were analysed using the Pourquier® ELISA PARATUBERCULOSIS (Insitute Pourquier, France) test. Moreover, a questionnaire gathering information on management practices and the frequency of clinical cases, compatible with paratuberculosis (in the previous 12 months), was applied on the sampling date. A Bayesian latent class analysis was used to obtain TP and clinical incidence posterior distributions. The model adjusts for uncertainty in test sensitivity (serum or milk) and specificity, and prior TP & CIp estimates. A total of 4963 animals were tested, with an average contribution of 124 samples per herd. A mean apparent prevalence of 6.3% (95% confidence interval: 4.0-8.0%) was observed. Model outputs indicated an overall TP posterior distribution, across herds, with a median of 13.1% (95% posterior probability interval (PPI); 3.2-38.1%). A high TP variability was observed between herds. CIp presented a posterior median of 1.1% (95% PPI; 0.2-4.6%). Model results complement information missing from previously conducted epidemiological studies in the sector, and they could be used for further assessment of the disease impact and planning of control programs.