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Objective: This work sought to estimate population measles seroprevalence and heterogeneity in the antibody concentration distribution that could be explained by the birth-year cohort according to the opportunity of viral and vaccine exposure, applied to data from Medellín, Colombia. Methods: Prevalence of IgG antibodies was analyzed for measles based on a population study with a random sample of 2098 individuals from 6 to 64 years of age. Finite mixture models were used to estimate global seroprevalence and that of three birth-year cohorts (I: born up to 1982; II: 1983-1994; III: born since 1995). Multiple linear regression permitted adjusting the concentration of antibodies by cohort, zone, and sex. Results: Globally, seronegativity was 6.5% (95% CI 4.9- 8.6), seropositivity of 78.4% (95% CI 75.1-81.4), and equivocal of 15.1% (95% CI 12.5-18.1). Two components were found with skewed normal distribution, which reclassified those equivocal as seropositive. Differences were observed by cohort in the geometric mean of antibodies [Cohort I: 1704.6; II: 562.2; III: 802.1 milli-international units per milliliter (mIU/mL] and seronegativity (Cohort I: 4%; II:13.3%; III: 8.9%). Antibody concentration increased by 1.26 mIU/mL in residents in the rural area, while diminishing in individuals from cohort II (by 3.02 mIU/mL) and cohort III (by 2.14 mIU/mL). Conclusion: The younger cohorts (II and III) had a lower antibody concentration (higher seronegativity), indicating the need to monitor periodically seroprevalence and an eventual reestablishment of the transmission in these groups with higher risk of infection.

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Background: COVID-19 requires an early diagnosis to optimize management and limit transmission. SARS-CoV-2 is able to spread effectively. Infected asymptomatic individuals have been found to be contagious. RT-qPCR is the currently recommended laboratory method for diagnosing acute infection. However, rapid antigen detection (RAD) tests are not only fast, but require less specialized training. The possibility of using RAD tests to identify asymptomatic patients is attractive, as it could effectively contribute to minimizing the hospital spread of SARS-CoV-2. The objective of the study was to determine the performance of RAD vs. RT-qPCR for the detection of asymptomatic cases in INER health personnel. Methods: In order to follow WHO guidelines, generalized tests, a test station for health care workers was implemented on demand. A rapid test was carried out and a second sample was taken to be processed by RT-qPCR. With the results of both tests we conducted a retrospective study. Sensitivity, specificity, positive predictive value, negative predictive value and negative likelihood ratios were calculated. Results: A total of 1640 RAD tests were performed in health care workers (mean age was 39, 69, 47% with a self-reported comorbidity). Participants provided 1,640 valid RAD/RT-qPCR test pairs with 2% testing positive via RT-qPCR. 12 RAD samples were positive for SARS-CoV-2. Overall sensitivity of the PANBIO ™ COVID-19 Ag Rapid Test test was 35.2%. Conclusions: RADs are not recommended for the detection of asymptomatic cases due to low performance.

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Multi-drug resistant (MDR) bacteria have gained importance as a health problem worldwide, and novel antibacterial agents are needed to combat them. Silver nanoparticles (AgNPs) have been studied as a potent antimicrobial agent, capable of countering MDR bacteria; nevertheless, their conventional synthesis methods can produce cytotoxicity and environmental hazards. Biosynthesis of silver nanoparticles has emerged as an alternative to reduce the cytotoxic and environmental problems derived from their chemical synthesis, using natural products as a reducing and stabilizing agent. Sonoran Desert propolis (SP) is a poplar-type propolis rich in polyphenolic compounds with remarkable biological activities, such as being antioxidant, antiproliferative, and antimicrobial, and is a suitable candidate for synthesis of AgNPs. In this study, we synthesized AgNPs using SP methanolic extract (SP-AgNPs) and evaluated the reduction capacity of their seasonal samples and main chemical constituents. Their cytotoxicity against mammalian cell lines and antibacterial activity against multi-drug resistant bacteria were assessed. Quercetin and galangin showed the best-reduction capacity for synthesizing AgNPs, as well as the seasonal sample from winter (SPw-AgNPs). The SPw-AgNPs had a mean size of around 16.5 ± 5.3 nm, were stable in different culture media, and the presence of propolis constituents was confirmed by FT-IR and HPLC assays. The SPw-AgNPs were non-cytotoxic to ARPE-19 and HeLa cell lines and presented remarkable antibacterial and antibiofilm activity against multi-drug resistant clinical isolates, with E. coli 34 and ATCC 25922 being the most susceptible (MBC = 25 µg/mL), followed by E. coli 2, 29, 37 and PNG (MBC = 50 µg/mL), and finally E. coli 37 and S. aureus ATCC 25923 (MBC = 100 µg/mL). These results demonstrated the efficacy of SP as a reducing and stabilizing agent for synthesis of AgNPs and their capacity as an antibacterial agent.

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Background: COVID-19 cases in Medellín, the second largest city in Colombia, were monitored during the first year of the pandemic using both mathematical models based on transmission theory and surveillance from each observed epidemic phase. Design and Methods: Expected cases were estimated using mandatory reporting data from Colombia's national epidemiological surveillance system from March 7, 2020 to March 7, 2021. Initially, the range of daily expected cases was estimated using a Borel-Tanner stochastic model and a deterministic Susceptible-Infected-Removed (SIR) model. A subsequent expanded version of the SIR model was used to include asymptomatic cases, severe cases and deaths. The moving average, standard deviation, and goodness of fit of estimated cases relative to confirmed reported cases were assessed, and local transmission in Medellin was contrasted with national transmission in Colombia. Results: The initial phase was characterized by imported case detection and the later phase by community transmission and increases in case magnitude and severity. In the initial phase, a maximum range of expected cases was obtained based on the stochastic model, which even accounted for the reduction of new imported cases following the closure of international airports. The deterministic estimate achieved an adequate fit with respect to accumulated cases until the conclusion of the mandatory national quarantine and gradual reopening, when reported cases increased. The estimated new cases were reasonably fit with the maximum reported incidence. Conclusion: Adequate model fit was obtained with the reported data. This experience of monitoring epidemic trajectory can be extended using models adapted to local conditions.

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BACKGROUND: Stigma towards tuberculosis (TB) delays diagnosis and compromises adherence to treatment. We measured the degree of stigma and identified the sociodemographic and clinical characteristics that were associated with a higher degree of stigma in patients with pulmonary and extrapulmonary TB in Colombia. METHODS: We conducted a cross-sectional study with 232 participants included in the TB control program in 2017. Sociodemographic and clinical variables were measured. The stigma component was measured through a validated scale and a multiple linear regression was used. RESULTS: The study analysed 232 patients, of which 52.2% were men, 53.5% were between 27 and 59 y of age and 66.8% had a basic-medium education level. Two characteristics were significantly related to a higher stigma score: the basic-medium education level and homeless status. Homeless status increased the stigma score by 0.27. In contrast, the adjusted stigma score decreased by 0.07 if the patient's health status was perceived as 'healthy'. CONCLUSION: Stigma is maximized in homeless patients and patients with a low education level. It is minimized in patients who perceive their state of health as 'healthy'.

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The tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine is recommended during pregnancy for neonatal protection against pertussis, although little is known of the protection it provides against diphtheria. The work used a cross-sectional design to estimate seroprevalence against diphtheria in 805 pregnant women with ≥37 gestation weeks and their newborns whose deliveries were attended in eight hospitals randomly chosen from a subregion of Antioquia, Colombia and to explore factors related with maternal protection. Levels of IgG antibodies were determined by using a commercial enzyme-linked immunosorbent assay test. Placental transfer of antibodies and crude and adjusted prevalence ratio (aPR) were analyzed to describe factors related with maternal protection against diphtheria. Protection against diphtheria was observed in 91.7% (95% CI 90.3-93.0) of the pregnant women and 93.1% (95% CI 91.7-94.4) of newborns, whose antibody levels were positively correlated (Spearman's r = 0.769; p = 0.000). Maternal protection could be influenced by having been vaccinated during the current pregnancy (aPR 0.85, 95% CI: 0.82-0.93). The protective effect of vaccination during pregnancy and the efficiency of maternal antibody transfers were detected. Public health efforts should focus on increasing Tdap vaccination during each pregnancy to protect mothers and newborns against diphtheria.

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PURPOSE: This study aims to compare protection against diphtheria and tetanus conferred on the mother and the neonate before and after maternal vaccination against tetanus, diphtheria, and acellular pertussis (Tdap), transfer of antibodies, and the variables that could impact on the protection. MATERIALS AND METHODS: The study followed a cohort of 200 pregnant women from a region in Colombia, contacted during prenatal control before vaccination and upon delivery. The work determined immunoglobulin G antibodies against diphtheria and tetanus of pregnant women and umbilical cord. The proportion of protection, the geometric mean of the concentration, and the transfer of maternal antibodies were calculated. The protection profile of the pregnant women was explored by using multiple correspondence analysis. RESULTS: The concentration of antibodies against diphtheria was significant before and after vaccination of the pregnant women (p=0.000) with proportions of 85.0% and 97.5%, respectively, and of 98.6% in the umbilical cord, with significant antibody correlation (Spearman's coefficient=0.668, p=0.01). Sero-protection against tetanus before vaccination was at 71.0%, after at 92.6%, and in the umbilical cord at 95.9%, with significant antibody concentration before and after vaccination (p=0.000) and antibody correlation (Spearman's coefficient=0.936, p=0.01). Sero-protection was higher when the pregnant women were vaccine 8 to 11 weeks before delivery. Unprotected pregnant women were those not vaccinated during pregnancy. CONCLUSION: The high proportion of protection against diphtheria and tetanus and the placental transfer support the need to promote maternal immunization with Tdap.

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BACKGROUND: In Latin America, there are few studies of the impact of vaccination against diphtheria, tetanus, and pertussis. We estimate the impact of infant and maternal vaccination on the incidence of these diseases in Colombia. DESIGN AND METHODS: an interrupted time series study analyzing the incidence before and after of vaccination with DwPT (1975-2018) and with Tdap in pregnant women (2008-2018). A segmented regression model with negative binomial distribution estimated the change in level and trend of the predicted incidence ratio after vaccination in relation to the incidence if vaccination had not been started (IRR), using a Prais Winsten regression. RESULTS: The pertussis IRR decreased immediately after the start of childhood vaccination (0.91, p=0.51), but this was only significant (1.01, p<0.001) along with the trend per year, after the start of maternal vaccination (0.98, p<0.001). In the absence of vaccination, the incidence would not have been reduced. Neonatal tetanus had the highest rate of change with significant reduction -1.69 - CI 95%: -2.91, -0.48). The trend after vaccination was the highest with an annual reduction of 19% (0.81, p=0.001). The change in incidence of diphtheria was significant, although slow (-0.02 - CI 95%: -0.04, -0.004). The sustained effect in the post-vaccination period was smaller (0.95, p=0.79). CONCLUSIONS: Childhood and maternal vaccination markedly reduced the incidence of pertussis and neonatal tetanus. It is necessary to maintain optimal vaccination coverage and surveillance, within an integrated elimination plan, which prevents the resurgence of these diseases.

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We estimate the seroprevalence of IgG antibodies to varicella zoster virus (VZV) based on the first serological study in a cohort of pregnant women and newborns from the Aburrá Valley (Antioquia-Colombia) who attended delivery in eight randomly chosen hospitals. An indirect enzyme immunoassay was used to determine anti-VZV IgG antibodies. Generalized linear models were constructed to identify variables that modify seropositivity. In pregnant women, seropositivity was 85.8% (95% CI: 83.4-85.9), seronegativity was 12.6% (95% CI: 10.8-14.6), and concordance with umbilical cord titers was 90.0% (95% CI: 89-91). The seropositivity of pregnant women was lower in those who lived in rural areas (IRR: 0.4, 95% CI: 0.2-0.7), belonged to the high socioeconomic status (IRR: 0.4, 95% CI: 0.2-0.7), and had studied 11 years or more (IRR: 0.6, 95% CI: 0.4-0.8). Among newborns, seropositivity was lower in those who weighed less than 3000 g (IRR: 0.8, 95% CI: 0.6-1.0). The high seropositivity and seronegativity pattern indicates the urgent need to design preconception consultation and vaccination reinforcement for women of childbearing age according to their sociodemographic conditions, to prevent infection and complications in the mother and newborn.

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BACKGROUND: Delay in tuberculosis (TB) diagnosis is one of the first obstacles for controlling the disease. Delays generate greater deterioration of the health of the patients and increase the possibilities of transmission and infection at home and in the community. The aim of the study was to identify profiles and individual variables associated with patient delays and health care system delays in patients with pulmonary tuberculosis (PTB) in Medellín, Colombia, a city that notifies 1400 new cases per year. METHODS: A retrospective cohort study in adults with PTB was conducted from May to September of 2017. Sociodemographic, health care-seeking behaviour, and clinical variables were measured. The outcomes were patient delay and health care system delay. The data were obtained from records of the local TB program, and a questionnaire was applied by the health care team that performs routine field visits. Simple correspondence analysis was used to identify groups (profiles), and their characteristics. Cox's proportional hazards model was carried out to identify the variables associated with the delays. RESULTS: The study included 183 patients. The total delay median was 101 days (IQR: 64-163). Patient delay was of 35 days (IQR: 14-84), the profile with greater delay belonged to consumers of psychoactive substances. The health care system delay was of 27 days (IQR: 7-89), the attributes of the profile with greater delay were being a female, having more than two consultations before the diagnosis, and having prescribed antibiotics. Basic-medium educational level [HRa = 0.69; 95% CI (0.49-0.97)] and having a TB home contact [HRa = 0.68; 95% CI (0.48-0.96)] were associated with greater patient delay. Having negative acid-fast bacilli (AFB) smear [HRa = 0.64; 95% CI (0.45-0.92)] and more than two consultations before the diagnosis [HRa = 0.33; 95% CI (0.22-0.49)] was associated with greater health care system delay. CONCLUSIONS: Data from epidemiological surveillance allowed locating risk groups with delays in TB diagnosis which requires the prioritisation of the local TB control program to promote early detection and prevention of adverse outcomes.

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