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The main objective of this study was to estimate the performance, under local epidemiological conditions, of two in-house ELISA assays for the combined detection of anti-SARS-CoV-2 IgA, IgM, and IgG immunoglobulins. A total of 94 serum samples were used for the assessment, where 44 corresponded to sera collected before the pandemic (free of SARS-CoV-2 antibodies), and 50 sera were collected from confirmed COVID-19 patients admitted to the main public hospital in the city of Valdivia, southern Chile. The Nucleocapsid (Np) and the receptor-binding domain (RBD) proteins were separately used as antigens (Np and RBD ELISA, respectively) to assess their diagnostic performance. A receiver operating characteristic (ROC) analysis was performed to estimate the optical density (OD) cut-off that maximized the sensitivity (Se) and specificity (Sp) of the ELISA assays. Np ELISA had a mean Se of 94% (95% CI = 83.5-98.8%) and a mean Sp of 100% (95% CI = 92.0-100%), with an OD 450 nm positive cut-off value of 0.88. On the other hand, RBD ELISA presented a mean Se of 96% (95% CI = 86.3-99.5%) and a mean Sp of 90% (95% CI = 78.3-97.5%), with an OD 450 nm positive cut off value of 0.996. Non-significant differences were observed between the Se distributions of Np and RBD ELISAs, but the latter presented a significant lower Sp than Np ELISA. In parallel, collected sera were also analyzed using a commercial lateral flow chromatographic immunoassay (LFCI), to compare the performance of the in-house ELISA assays against a commercial test. The LFCI had a mean sensitivity of 94% (95% CI = 87.4-100%) and a mean specificity of 100% (95% CI = 100-100%). When compared to Np ELISA, non-significant differences were observed on the performance distributions. Conversely, RBD ELISA had a significant lower Sp than the LFCI. Although, Np ELISA presented a similar performance to the commercial test, this was 2.5 times cheaper than the LFCI assay (labor cost not considered). Thus, the in-house Np ELISA could be a suitable alternative tool, in resource limited environments, for the surveillance of SARS-CoV-2 infection, supporting further epidemiological studies.

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The objective was to evaluate the association between the severity of histopathological lesions caused by Mycobacterium avium subspecies paratuberculosis (MAP) infection and the molecular diversity of this pathogen. Blood, ileum, and mesenteric lymph node samples were collected at slaughter, from 1,352 adult cattle [source population 1 (SP1)]. In addition, 42 dairy herds (n = 4,963 cows) were followed for 2 years, and samples from compatible paratuberculosis clinical cases [source population 2 (SP2)] were collected. MAP infection was confirmed using an ELISA test, liquid media culture, and PCR. Isolates were genotyped using five MIRU-VNTR markers. Tissues from confirmed samples were subjected to a histopathological examination. A histopathological severity score (HSS) system was developed and used to grade (0 to 5) the magnitude of lesions caused by MAP. In general, the HSS system assesses the number of foci and degree of macrophage infiltration, together with the presence of multinucleated giant cells (MGCs) and acid-fast bacilli (AFB), in addition to the fusion of the intestinal villi and hyperplasia of the crypts. Despite the large sampling effort, only 79 MAP isolates were successfully genotyped, where 19 different haplotypes were described. A mixed-effect Poisson regression model was used to assess the relationship between haplotypes and HSS values. The model was controlled by animal age, and the farm was used as a random effect. Haplotypes were grouped based on their relative frequency: the most frequent haplotype (group i, 49.4%), the second most frequent haplotype (group ii, 12.7%), and all other haplotypes (group iii, 37.9%). Model outputs indicated that group i had significantly higher HSS values than group iii. In addition, group i was also associated with higher optical density (OD) values of the ELISA test. These results support the existence of differences in pathogenicity between MAP haplotypes. However, results were based on a relatively small sample size; thus, these should be taken with caution. Despite this, study findings suggest that haplotypes would be associated with differences in disease progression, where the dominant haplotype tends to generate more severe lesions, which could be linked to a greater shed of MAP cells than non-dominant haplotypes, increasing their chances of transmission.

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One of the important routes of Mycobacterium avium subsp. paratuberculosis (MAP) transmission in dairy calves is milk. The aim of the present study was to assess the efficacy of milk treatments to prevent MAP infection transmission to calves. A one-year longitudinal study was carried out. Newborn calves were assigned to one of four experimental groups: 5 calves received naturally MAP-contaminated milk, 5 calves received copper treated milk, 4 calves were fed calf milk replacer, and 3 were fed UHT pasteurized milk. MAP load in milk was estimated. Infection progression was monitored monthly. After one year, calves were euthanized, and tissue samples were cultured and visually examined. MAP was undetectable in milk replacer and UHT milk. Copper ion treatment significantly reduced the number of viable MAP in naturally contaminated milk. Fecal shedding of MAP was observed in all study groups but began earlier in calves fed naturally contaminated milk. Paratuberculosis control programs must place multiple hurdles between the infection source, MAP-infected adult cows, and the most susceptible animals on the farm, young calves. As our study shows, strict dependence on a single intervention to block infection transmission, no matter how important, fails to control this insidious infection on dairy farms.

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Vibrio parahaemolyticus is the leading cause of seafood-associated bacterial gastroenteritis worldwide. Although different studies have focused on its pattern of variation over time, knowledge about the environmental factors driving the dynamics of this pathogen, within the Chilean territory, is still lacking. This study determined the prevalence of total and pathogenic V. parahaemolyticus strains (tdh and/or trh genes) in mussels (Mytilus chilensis) collected from two natural growing areas between 2017 and 2018, using selective agar and PCR analysis. V. parahaemolyticus was detected in 45.6% (93/204) of pooled samples from the Valdivia River Estuary. The pathogenic strains carrying the tdh and/or trh gene were detected in 11.8% (24/204): tdh in 9.8% (20/204), trh in 0.5% (1/204), and 1.5% (3/204) presented both genes. In Reloncaví Fjord, V. parahaemolyticus was detected in 14.4% (30/209) of the samples, pathogenic V. parahaemolyticus carrying the trh gene was detected in 0.5% (1/209) of the samples, while the tdh gene was not detected in the samples from this area. The total count of mauve-purple colonies typical of V. parahaemolyticus on CHROMagar was positively associated by multivariate analysis with area, water temperature, and salinity. Similarly, V. parahaemolyticus detection rates by PCR had a positive correlation with the area and water temperature. The chances of detecting total V. parahaemolyticus in the Valdivia River Estuary are significantly higher than in the Reloncaví Fjord, but inversely, during spring-summer months, the interaction factor between the area and temperature indicated that the chances of detecting V. parahaemolyticus are higher in the Reloncaví Fjord. Interestingly, this period coincides with the season when commercial and natural-growing shellfish are harvested. On the other hand, pathogenic V. parahaemolyticus tdh+ was significantly correlated with an increase of water temperature. These environmental parameters could be used to trigger a warning on potential hazard, which would influence human health and economic losses in aquaculture systems.

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RESUMEN: El coronavirus tipo 2, SARS-CoV-2, que causa la enfermedad denominada por la OMS como COVID-19, se ha expandido provocando una pandemia desde 2019, sin cura hasta la fecha. El mecanismo de transmisión del SARS-CoV-2 entre humanos es mediante las secreciones generadas durante la respiración y estornudos, presentándose con un período de incubación desde 1 a 14 días. Se describen fiebre, tos y astenia como los síntomas más habituales. El diagnóstico definitivo se logra a través de la correlación entre la presentación clínica y exámenes complementarios, pero en la actualidad, el método de muestreo de preferencia para el diagnóstico de SARS-CoV-2 es mediante una muestra de nasofaringe, en donde se analiza la presencia de material genético viral por medio de RT-PCR. Debido a las complicaciones en la obtención de la muestra, tanto para el personal sanitario como para el paciente, se ha implementado la muestra de saliva con finalidad diagnóstica, como un método que proporciona una detección rápida, simple y no invasiva de la infección viral. Esta alternativa diagnóstica podría entregar información respecto a la patogenia de la enfermedad, permitiendo el manejo y control de pacientes positivos. El siguiente artículo, tiene por objetivo realizar una comparación entre las tomas de muestra de saliva y de nasofaringe para el diagnóstico de SARS-CoV-2, mediante la prueba de reacción en cadena de la polimerasa con transcriptasa inversa (RT-PCR).

SUMMARY: The type 2 coronavirus, SARS-CoV-2, named by the WHO like COVID-19, has expanded causing a pandemic since 2019, with no cure to date. The mechanism of transmission of SARS-CoV-2 between humans is through secretions generated during breathing and sneezing, presenting with an incubation period range from 1 - 14 days. Fever, cough, and fatigue are described as the most common symptoms. The definitive diagnosis is achieved through the correlation between the clinical presentation and the complementary exams, but at present, the preferred sampling method for the diagnosis of SARS-CoV-2 is through a nasopharyngeal swab specimen, where it is analyzed the presence of viral genetic material by the RT-PCR. Due to the complications in obtaining the sample, both for health personnel and for the patient, the saliva sample has been implemented, as a method that provides rapid, simple and non-invasive detection of viral infection. This diagnostic alternative could provide information on the pathogenesis of the disease, the management and control of positive patients. The following article aims to make a comparison between the saliva and nasopharyngeal samples taken for the diagnosis of SARS-CoV-2, using the reverse transcription polymerase chain reaction test (RT-PCR).

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RESUMEN: La enfermedad originada por el nuevo tipo de coronavirus, SARS-CoV-2, se ha convertido en un problema de Salud Pública a nivel mundial. Esto ha llevado a posponer las atenciones clínicas electivas de pacientes, exceptuando las atenciones de urgencia o emergencia. Las urgencias odontológicas han continuado con alta demanda en el Sistema Público de Salud durante la pandemia COVID-19, e incluso han aumentado en severidad de los cuadros. Las restricciones de horario y las medidas implementadas a nivel país, llevan a que los pacientes consulten en el Centro de Salud más cercano a su domicilio, es decir, Centro de Salud Familiar (CESFAM) o en los Servicios de Atención Primaria de Urgencia (SAPU). Como Cirujanos Dentistas somos parte de un equipo multidisciplinario de salud, por lo que debemos conocer la enfermedad de COVID-19, sus principales signo s, síntomas y riesgos asociados. El Cirujano Dentista es indispensable en el diagnóstico, tratamiento y derivación oportuna de enfermedades buco-maxilofaciales, las cuales pueden afectar de forma física y psicológica a los pacientes, llegando a producir complicaciones sistémicas graves si no son tratadas oportunamente. La atención odontológica actual debe incluir el manejo previo, durante y posterior al tratamiento del paciente de APS. Debemos considerar que el personal odontológico tiene un elevado riesgo de transmisión viral, debido a la cercanía con fluidos desde la cavidad oral del paciente. En este artículo se entregaran recomendaciones, basadas en la mejor evidencia disponible y la experiencia clínica actual para la atención odontológica de urgencias enfocadas en la Atención Primaria de Salud.

ABSTRACT: The disease caused by the new coronavirus, SARS-CoV-2 has become a world wide public health problem. This has lead to pospone elective clinical care, maintaining urgent and emergency care. Dental emergency maintains high demand, even more severe clinical situations, at the public health system during the pandemic COVID-19. The local restrictions implemented makes patients to consult at the closest health center, like the Family health centers (CESFAM) or at primary health urgency centers (SAPU). As dental surgeons, part of the multidisciplinary health team, it is a duty to know the COVID-19, signs, simptoms and associated risks. The dental surgeon it is essential in the diagnosis, traetment and timely referral of maxilofacial diseases, wich can affect patients physically and psychologically, even leading to serious systemic complications if not treated promptly. Dental care should have previous, during and posterior considerations in pandemic situations. Dental staff has high viral transmisión risk, due to closeness with oral cavity fluids. This article will provide evidence based recommendations and current clinical experience for dental emergency care at primary health centers.

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The objective of this study was to estimate the performance of the peptide magnetic separation PCR test (PMS-PCR) for the diagnosis of Mycobacterium avium subsp. paratuberculosis (MAP) in sub-clinically infected dairy cattle. Twenty-one herds were randomly selected from a source population of 131 commercial dairy herds with a known history of MAP infection, located in the De Los Rios and De Los Lagos regions, in southern Chile. In the selected herds, all milking cows with ≥2 parities and without any clinical signs were sampled, collecting feces and blood-serum samples. The PMS-PCR test was used to analyze the fecal samples, while serum samples were analyzed using a commercial ELISA kit. A Bayesian latent class model was used to estimate the sensitivity (Se) and specificity (Sp) of the diagnostic tests. A total of 1381 animals were sampled in the 21 selected dairy herds, with an average sample size of 65 animals per herd (range 10-721). The PMS-PCR test had a greater Se than the ELISA test, with a median of 85.5 % (posterior probability interval (PPI) 95 %: 79.3-91.0%), while the ELISA test presented a median of 21.7 % (95 % PPI: 18.3-25.4%). On the other hand, the ELISA test had a better Sp than the PMS-PCR test, with a median of 97.7 % (95 % PPI: 96.6-98.5%), whereas PMS-PCR presented a median of 90.8 % (95 % PPI: 88.3-93.9%). Model results showed that PMS-PCR has a better Se than all available tests for MAP diagnosis in subclinical animals. However, this test should be used with care in herds with high infection rates, where a high MAP environmental load is expected, potentially increasing the frequency of false positive cases due to the pass-through phenomenon.

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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.

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Los Coronavirus son una familia de virus de amplia distribución en la naturaleza presentes principalmente en los animales. El Covid-19 es la enfermedad causada por el coronavirus (SARS-CoV-2), que fue identificado y caracterizado en enero de 2020 en China. Los profesionales del área odontológica deben tomar todas las medidas de protección al tener que realizar una atención de urgencia, lavado de manos y utilización de equipos de protección personal. Para cada una de las urgencias odontológicas consideradas en la guía del Ministerio de Salud de Chile se dan recomendaciones para el actuar y posterior desechos e higienización de materiales. El objetivo de este artículo de revisión es entregar recomendaciones actualizadas y atingentes a nuestra realidad nacional a fin de disminuir las posibilidades de contagio ante la exposición inminente de pacientes sospechosos o que pudiesen presentar Covid-19.

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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.

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PCR is a highly accurate technique for confirming the presence of Mycobacterium avium subsp. paratuberculosis (Map) in broth culture. In this study, a simple, efficient, and low-cost method of harvesting DNA from Map cultured in liquid medium was developed. The proposed protocol (Universidad Austral de Chile [UACH]) was evaluated by comparing its performance to that of two traditional techniques (a QIAamp DNA Stool Mini Kit and cethyltrimethylammonium bromide [CTAB] method). The results were statistically assessed by agreement analysis for which differences in the number of cycles to positive (CP) were compared by Student's t-test for paired samples and regression analysis. Twelve out of 104 fecal pools cultured were positive. The final PCR results for 11 samples analyzed with the QIAamp and UACH methods or ones examined with the QIAamp and CTAB methods were in agreement. Complete (100%) agreement was observed between data from the CTAB and UACH methods. CP values for the UACH and CTAB techniques were not significantly different, while the UACH method yielded significantly lower CP values compared to the QIAamp kit. The proposed extraction method combines reliability and efficiency with simplicity and lower cost.

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The placement of sentinel birds in a commercial poultry flock infected with low pathogenic avian influenza virus (LPAIV) may be an effective way of detecting subsequent change in the isolate to a high pathogenic avian influenza virus (HPAIV). Data collected from the 2002 Chilean HPAIV outbreak, along with information from a literature review of laboratory studies involving A/chicken/Chile/176822/02 (H7N3/LP) and A/chicken/Chile/184240-1/02 (H7N3/HP) viruses, were used to construct a computer simulation model. Mortality rates of the original LPAIV-infected population and the sentinel population were compared to detect the presence of HPAIV. A total of 12 increased mortality threshold scenarios were examined, using one-day absolute (2, 3, or 4 birds) or relative (0.5, 1.0, or 1.5%) mortality thresholds, and two-day absolute (1, 2, or 3 birds) or relative (0.25, 0.50, or 1.00%) mortality thresholds, to indicate the change from LPAIV to HPAIV in the sentinel and original populations, respectively. Results showed that following a one-day approach, threshold mortalities occurred on average at 7.35, 7.82, and 8.17 (0.5, 1.0, or 1.5%) and 6.21, 6.38, and 6.45 (2, 3, or 4 birds) days after the first infectious case for the original and sentinel populations, respectively. The two-day approach delayed the occurrence of threshold mortalities, on average, to 7.64, 8.05, and 8.62 (0.25, 0.50, or 1.00%) and 6.86, 6.78, and 7.23 (1, 2, or 3 birds) days after the first infectious case for the original and sentinel populations, respectively. Although, significant (p<0.10) differences were observed among different combinations of detection times for the original and sentinel populations, the use of sentinel birds has a maximum mean advantage, over monitoring mortality exclusively in the original population, of 1.96 and 1.84 days for one- and two-day threshold moralities, respectively. Additionally, the early warning system based on a sentinel vs. original population presented a decrease of the probabilities of a false alarm, from 0.04-0.45 to <0.01-0.10%. These findings may be used by decision makers to evaluate the risk of not depopulating a flock infected with a H5 or H7 LPAIV strain and the benefit of using sentinel birds as an early warning system of a change to HPAIV.

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