Highly pathogenic avian influenza A(H5N1) virus of clade 2.3.4.4b isolated from a human case in Chile causes fatal disease and transmits between co-housed ferrets

Clade 2.3.4.4b highly pathogenic avian influenza A(H5N1) viruses have caused large outbreaks within avian populations on five continents, with concurrent spillover into a variety of mammalian species. Mutations associated with mammalian adaptation have been sporadically identified in avian isolates, and more frequently among mammalian isolates following infection. Reports of human infection with A(H5N1) viruses following contact with infected wildlife have been reported on multiple continents, highlighting the need for pandemic risk assessment of these viruses. In this study, the pathogenicity and transmissibility of A/Chile/25945/2023 HPAI A(H5N1) virus, a novel reassortment with four gene segments (PB1, PB2, NP, MP) from North America lineage, isolated from a severe human case in Chile, was evaluated in vitro and using the ferret model. This virus possessed a high capacity to cause fatal disease, characterized by high morbidity and extrapulmonary spread in virus-inoculated ferrets. The virus was capable of transmission to naïve contacts in a direct contact setting, with contact animals similarly exhibiting severe disease, but did not exhibit productive transmission in respiratory droplet or fomite transmission models. Our results indicate that the virus would need to acquire an airborne transmissible phenotype in mammals to potentially cause a pandemic. Nonetheless, this work warrants continuous monitoring of mammalian adaptations in avian viruses, especially in strains isolated from humans, to aid pandemic preparedness efforts.

The first case of human infection with H5N1 avian Influenza A virus in Chile

Highlights Here we present the first human case of Influenza A H5N1 infection in Chile, and the fifth worldwide in 2023.The patient is a 53-year-old man who lives in the north region of Chile, near the seashore.The Chilean sample was subtyped in the clade 2.3.4.4b.

Cross-species transmission and PB2 mammalian adaptations of highly pathogenic avian influenza A/H5N1 viruses in Chile

H5N1 highly pathogenic avian influenza viruses (HPAIV) emerged in wild birds in Chile in December 2022 and spilled over into poultry, marine mammals, and one human. Between December 9, 2022 - March 14, 2023, a coordinated government/academic response detected HPAIV by real-time RT-PCR in 8.5% (412/4735) of samples from 23 avian and 3 mammal orders. Whole-genome sequences obtained from 77 birds and 8 marine mammals revealed that all Chilean H5N1 viruses belong to lineage 2.3.4.4b and cluster monophyletically with viruses from Peru, indicating a single introduction from North America into Peru/Chile. Mammalian adaptations were identified in the PB2 segment: D701N in two sea lions, one human, and one shorebird, and Q591K in the human and one sea lion. Minor variant analysis revealed that D701N was present in 52.9 - 70.9% of sequence reads, indicating the presence of both genotypes within hosts. Further surveillance of spillover events is warranted to assess the emergence and potential onward transmission of mammalian adapted H5N1 HPAIV in South America.

Severity of influenza illness by seasonal influenza vaccination status among hospitalised patients in four South American countries, 2013-19: a surveillance-based cohort study

BACKGROUND

Although several studies have reported attenuated influenza illness following influenza vaccination, results have been inconsistent and have focused predominantly on adults in the USA. This study aimed to evaluate the severity of influenza illness by vaccination status in a broad range of influenza vaccine target groups across multiple South American countries.

METHODS

We analysed data from four South American countries (Argentina, Brazil, Chile, and Paraguay) participating in REVELAC-i, a multicentre, test-negative design, vaccine effectiveness network including 41 sentinel hospitals. Individuals hospitalised at one of these centres with severe acute respiratory infection were tested for influenza by real-time RT-PCR, and were included in the analysis if they had complete information about their vaccination status and outcomes of their hospital stay. We used multivariable logistic regression weighted by inverse probability of vaccination and adjusted for antiviral use, duration of illness before admission, and calendar week, to calculate the adjusted odds ratios (aORs) of intensive care unit (ICU) admission and in-hospital death (and combinations of these outcomes) among influenza-positive patients by vaccination status for three target groups: young children (aged 6-24 months), adults (aged 18-64 years) with pre-existing health conditions, and older adults (aged ≥65 years). Survival curves were used to compare length of hospital stay by vaccination status in each target group.

FINDINGS

2747 patients hospitalised with PCR-confirmed influenza virus infection between Jan 1, 2013, and Dec 8, 2019, were included in the study: 649 children (70 [10·8%] fully vaccinated, 193 [29·7%] partially vaccinated) of whom 87 (13·4%) were admitted to ICU and 12 (1·8%) died in hospital; 520 adults with pre-existing medical conditions (118 [22·7%] vaccinated), of whom 139 (26·7%) were admitted to ICU and 55 (10·6%) died in hospital; and 1578 older adults (609 [38·6%] vaccinated), of whom 271 (17·2%) were admitted to ICU and 220 (13·9%) died in hospital. We observed earlier discharge among partially vaccinated children (adjusted hazard ratio 1·14 [95% CI 1·01-1·29]), fully vaccinated children (1·24 [1·04-1·47]), and vaccinated adults with pre-existing medical conditions (1·78 [1·18-2·69]) compared with their unvaccinated counterparts, but not among vaccinated older adults (0·82 [0·65-1·04]). Compared with unvaccinated individuals, lower odds of ICU admission were found for partially vaccinated children (aOR 0·64 [95% CI 0·44-0·92]) and fully vaccinated children (0·52 [0·28-0·98]), but not for adults with pre-existing conditions (1·25 [0·93-1·67]) or older adults (0·88 [0·72-1·08]). Lower odds of in-hospital death (0·62 [0·50-0·78]) were found in vaccinated versus unvaccinated older adults, with or without ICU admission, but did not differ significantly in partially vaccinated (1·35 [0·57-3·20]) or fully vaccinated young children (0·88 [0·16-4·82]) or adults with pre-existing medical conditions (1·09 [0·73-1·63]) compared with the respective unvaccinated patient groups.

INTERPRETATION

Influenza vaccination was associated with illness attenuation among those hospitalised with influenza, although results differed by vaccine target group. These findings might suggest that attenuation of disease severity might be specific to certain target groups, seasons, or settings.

FUNDING

US Centers for Disease Control and Prevention.

TRANSLATIONS

For the Spanish and Portuguese translations of the abstract see Supplementary Materials section.

Differences in the immune response elicited by two immunization schedules with an inactivated SARS-CoV-2 vaccine in a randomized phase 3 clinical trial

Background:

The development of vaccines to control the coronavirus disease 2019 (COVID-19) pandemic progression is a worldwide priority. CoronaVac is an inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine approved for emergency use with robust efficacy and immunogenicity data reported in trials in China, Brazil, Indonesia, Turkey, and Chile.

Methods:

This study is a randomized, multicenter, and controlled phase 3 trial in healthy Chilean adults aged ≥18 years. Volunteers received two doses of CoronaVac separated by 2 (0–14 schedule) or 4 weeks (0–28 schedule); 2302 volunteers were enrolled, 440 were part of the immunogenicity arm, and blood samples were obtained at different times. Samples from a single center are reported. Humoral immune responses were evaluated by measuring the neutralizing capacities of circulating antibodies. Cellular immune responses were assessed by ELISPOT and flow cytometry. Correlation matrixes were performed to evaluate correlations in the data measured.

Results:

Both schedules exhibited robust neutralizing capacities with the response induced by the 0–28 schedule being better. No differences were found in the concentration of antibodies against the virus and different variants of concern (VOCs) between schedules. Stimulation of peripheral blood mononuclear cells (PBMCs) with Mega pools of Peptides (MPs) induced the secretion of interferon (IFN)-γ and the expression of activation induced markers in CD4⁺ T cells for both schedules. Correlation matrixes showed strong correlations between neutralizing antibodies and IFN-γ secretion.

Conclusions:

Immunization with CoronaVac in Chilean adults promotes robust cellular and humoral immune responses. The 0–28 schedule induced a stronger humoral immune response than the 0–14 schedule.

Funding:

Ministry of Health, Government of Chile, Confederation of Production and Commerce & Millennium Institute on Immunology and Immunotherapy, Chile.

Clinical trial number:

NCT04651790

Implementation of a COVID-19 Genomic Surveillance Regional Network for Latin America and Caribbean region

The timely release of SARS-CoV-2 first genomic sequences allowed the identification of the etiologic agent and development of diagnostic protocols. Genomic sequencing was a crucial step in generating data for driving laboratory response and detections of SARS-CoV-2 since the start of the COVID-19 pandemic. Because of all the progression and achievements that timely release of genetic sequence data represents in the public health response, the Pan American Health Organization (PAHO) in collaboration with countries' public health laboratories, started implementation of a network for strengthening the Latin America and Caribbean (LAC) region on timely generation of SARS-CoV-2 genomic data. Here we describe the implementation of the COVID-19 Genomic Surveillance Regional Network in the Americas region during the beginning of the pandemic. The establishment of this network has strengthened laboratory response capacity at the country level, as well as facilitated timely release of SARS-CoV-2 genomic information to be used to complement the multiple response strategies for COVID-19 pandemic mitigation. As genomic epidemiology is useful for guiding public health decisions on outbreak and response, we also analysed the first SARS-CoV-2 genomic sequence data from countries of the Latin America and Caribbean Region.

A booster dose of an inactivated SARS-CoV-2 vaccine increases neutralizing antibodies and T cells that recognize Delta and Omicron variants of concern

Background

CoronaVac ^® is an inactivated SARS-CoV-2 vaccine approved by the World Health Organization. Previous studies reported increased levels of neutralizing antibodies and specific T cells two- and four-weeks after two doses of CoronaVac ^® , but the levels of neutralizing antibodies are reduced at six to eight months after two doses. Here we report the effect of a booster dose of CoronaVac ^® on the anti-SARS-CoV-2 immune response generated against variants of concern (VOC) Delta and Omicron in adults participating in a phase 3 clinical trial in Chile.

Methods

Volunteers immunized with two doses of CoronaVac ^® in a four-week interval received a booster dose of the same vaccine between twenty-four and thirty weeks after the 2nd dose. Four weeks after the booster dose, neutralizing antibodies and T cell responses were measured. Neutralization capacities and T cell activation against VOC Delta and Omicron were detected at four weeks after the booster dose.

Findings

We observed a significant increase in neutralizing antibodies at four weeks after the booster dose. We also observed an increase in CD4 ⁺ T cells numbers over time, reaching a peak at four weeks after the booster dose. Furthermore, neutralizing antibodies and SARS-CoV-2 specific T cells induced by the booster showed activity against VOC Delta and Omicron.

Interpretation

Our results show that a booster dose of CoronaVac ^® increases the anti-SARS-CoV-2 humoral and cellular immune responses in adults. Immunity induced by a booster dose of CoronaVac ^® is active against VOC, suggesting an effective protection.

Neutralization of alpha, gamma, and D614G SARS-CoV-2 variants by CoronaVac vaccine-induced antibodies

Vaccination generates a neutralizing immune response against SARS‐CoV‐2. The genomic surveillance is showing the emergence of variants with mutations in spike, the main target of neutralizing antibodies. To understand the impact of these variants, we report the neutralization potency against alpha, gamma, and D614G SARS‐CoV‐2 variants in 44 individuals that received two doses of CoronaVac vaccine, an inactivated SARS‐CoV‐2 vaccine. Plasma samples collected at 60 days after the second dose of CoronaVac were analyzed by the reduction of cytopathic effect in Vero E6 cells with the three infectious variants of SARS‐CoV‐2. Plasma showed lower neutralization with alpha (geometric mean titer [GMT] = 18.5) and gamma (GMT = 10.0) variants than with D614G (GMT = 75.1) variant. Efficient neutralization against the alpha and gamma variants was not detected in 31.8% and 59.1% of plasma, respectively. These findings suggest the alpha and gamma variants could escape from neutralization by antibodies elicited by vaccination. Robust genomic and biological surveillance of viral variants could help to develop effective strategies for the control of SARS‐CoV‐2.

Inactivation of SARS-CoV-2 isolates from lineages B.1.1.7 (Alpha), P.1 (Gamma) and B.1.110 by heating and UV irradiation

Currently, the rapid global spread of SARS-CoV-2 is related to G clade (including GH, GR, GRY and GV clades), which are associated with more than 98 % of sequenced viral isolates worldwide. The unprecedented velocity of spread of SARS-CoV-2 outbreak represents a critical need for prevention strategies. Vaccines are recently being available and antiviral drugs have shown limited efficacy in COVID-19 patients. Thus, it is needed to know how to reduce the infectivity of the virus by different physicochemical conditions in order to prevent exposure to contaminated material.

This work describes heating and irradiating UV-C light procedures to reduce the infectivity of SARS-CoV-2 belonging to different three lineages. Results of physicochemical treatment showed no differences among viral lineages. Analytical conditions for efficient inactivation of SARS-CoV-2 were determined.

Interim report: Safety and immunogenicity of an inactivated vaccine against SARS-CoV-2 in healthy chilean adults in a phase 3 clinical trial

BACKGROUND

The ongoing COVID-19 pandemic has had a significant impact worldwide, with an incommensurable social and economic burden. The rapid development of safe and protective vaccines against this disease is a global priority. CoronaVac is a vaccine prototype based on inactivated SARS-CoV-2, which has shown promising safety and immunogenicity profiles in pre-clinical studies and phase 1/2 trials in China. To this day, four phase 3 clinical trials are ongoing with CoronaVac in Brazil, Indonesia, Turkey, and Chile. This article reports the safety and immunogenicity results obtained in a subgroup of participants aged 18 years and older enrolled in the phase 3 Clinical Trial held in Chile.

METHODS

This is a multicenter phase 3 clinical trial. Healthcare workers aged 18 years and older were randomly assigned to receive two doses of CoronaVac or placebo separated by two weeks (0-14). We report preliminary safety results obtained for a subset of 434 participants, and antibody and cell-mediated immunity results obtained in a subset of participants assigned to the immunogenicity arm. The primary and secondary aims of the study include the evaluation of safety parameters and immunogenicity against SARS-CoV-2 after immunization, respectively. This trial is registered at clinicaltrials.gov ( NCT04651790 ).

FINDINGS

The recruitment of participants occurred between November 27 ^th , 2020, until January 9 ^th , 2021. 434 participants were enrolled, 397 were 18-59 years old, and 37 were ≥60 years old. Of these, 270 were immunized with CoronaVac, and the remaining 164 participants were inoculated with the corresponding placebo. The primary adverse reaction was pain at the injection site, with a higher incidence in the vaccine arm (55.6%) than in the placebo arm (40.0%). Moreover, the incidence of pain at the injection site in the 18-59 years old group was 58.4% as compared to 32.0% in the ≥60 years old group. The seroconversion rate for specific anti-S1-RBD IgG was 47.8% for the 18-59 years old group 14 days post immunization (p.i.) and 95.6% 28 and 42 days p.i. For the ≥60 years old group, the seroconversion rate was 18.1%, 100%, and 87.5% at 14, 28, and 42 days p.i., respectively. Importantly, we observed a 95.7% seroconversion rate in neutralizing antibodies for the 18-59 years old group 28 and 42 days p.i. The ≥60 years old group exhibited seroconversion rates of 90.0% and 100% at 28 and 42 days p.i. Interestingly, we did not observe a significant seroconversion rate of anti-N-SARS-CoV-2 IgG for the 18-59 years old group. For the participants ≥60 years old, a modest rate of seroconversion at 42 days p.i. was observed (37.5%). We observed a significant induction of a T cell response characterized by the secretion of IFN-γ upon stimulation with Mega Pools of peptides derived from SARS-CoV-2 proteins. No significant differences between the two age groups were observed for cell-mediated immunity.

INTERPRETATION

Immunization with CoronaVac in a 0-14 schedule in adults of 18 years and older in the Chilean population is safe and induces specific IgG production against the S1-RBD with neutralizing capacity, as well as the activation of T cells secreting IFN-γ, upon recognition of SARS-CoV-2 antigens.

FUNDING

Ministry of Health of the Chilean Government; Confederation of Production and Commerce, Chile; Consortium of Universities for Vaccines and Therapies against COVID-19, Chile; Millennium Institute on Immunology and Immunotherapy.

Quantitative detection of SARS-CoV-2 RNA in nasopharyngeal samples from infected patients with mild disease

Diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) cases is based on the count of real-time reverse transcription-plymerase chain reaction (RT-PCR) positive people. Viral load by real-time RT-PCR has been suggested as a biomarker of the SARS-CoV-2 infection. However, the association of viral load and severity of the disease is not yet resolved. Nasopharyngeal samples from 458 patients were tested by RT-PCR for SARS-CoV-2 diagnosis. Relative quantitation was made by the comparative threshold cycle (ΔΔC_t ) formula between ORF1ab viral and RNase P housekeeping genes. Absolute viral load was calculate using a reference positive control. Most prevalent clinical signs were cough (75.8%), myalgia (66.7%), and fever (48.5%). Hypertension (18.2%), neurological diseases (15.1%), and asthma and hypothyroidism (12.1%) were most frequent comorbidities. Fever, either as an exclusive symptom or combined with others, was associated with high viral loads ( 2 - ∆ ∆ C t range, 35.65-155.16; 4.25-4.89 log₁₀ RNA copies/test]). During the first week after onset of symptoms in mild patients up to 60 years-old was detected the peak of viral load. Children under 10 years old have a high viral load (313.84; 2.50) in the first 2 days postinfection with a sharp decline thereafter. Cases between 10 and 49 years old mostly showed low and moderate viral load during the first 2 days postinfection (range, 0.03 to 17.24; -1.50 to 1.24). Patients over 60 years old have high viral load up to the second week after the onset of symptoms (range, 25.32-155.42; 1.40-2.19), indicating the longer presence of the virus in them. These findings suggest the viral load in nasopharyngeal swabs would help to monitor the SARS-CoV-2 infection in mild coronavirus disease 2019 cases.

Geographical Distribution of Genetic Variants and Lineages of SARS-CoV-2 in Chile

The pandemic caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a worldwide public health concern. First confined in China and then disseminated widely across Europe and America, SARS-CoV-2 has impacted and moved the scientific community around the world to working in a fast and coordinated way to collect all possible information about this virus and generate new strategies and protocols to try to stop the infection. During March 2020, more than 16,000 full viral genomes have been shared in public databases that allow the construction of genetic landscapes for tracking and monitoring the viral advances over time and study the genomic variations present in geographic regions. In this work, we present the occurrence of genetic variants and lineages of SARS-CoV-2 in Chile during March to April 2020. Complete genome analysis of 141 viral samples from different regions of Chile revealed a predominance of variant D614G like in Europe and the USA and the major presence of lineage B.1. These findings could help take control measures due to the similarity of the viral variants present in Chile, compared with other countries, and monitor the dynamic change of virus variants in the country.

A simple method for SARS-CoV-2 detection by rRT-PCR without the use of a commercial RNA extraction kit

The World Health Organization (WHO) has declared a pandemic caused by a new coronavirus named SARS-CoV-2. The growing demand for commercial kits used for automated extraction of SARS-CoV-2 RNA, a key step before rRT-PCR diagnosis, could cause a shortage of stocks that hinders the rapid processing of samples.

Although the recommendation is to use automated methods for nucleic acid extraction, alternatives are necessary to replace commercial kits. However, these alternatives should be as reliable as automated methods.

This work describes a simple method to detect SARS-CoV-2 from specimens collected in different preservation media. Samples were previously inactivated by heating and precipitating with a PEG/NaCl solution before rRT-PCR assays for Orf1ab, N and S genes. The new method was compared with an automated protocol of nucleic acid extraction. Both procedures showed similar analytical results. Consequently, this simple and inexpensive method is a suitable procedure for laboratory diagnosis of SARS-CoV-2 infection.

Results from the WHO external quality assessment for the respiratory syncytial virus pilot, 2016-17

Background

External quality assessments (EQAs) for the molecular detection of respiratory syncytial virus (RSV) are necessary to ensure the provision of reliable and accurate results. One of the objectives of the pilot of the World Health Organization (WHO) Global RSV Surveillance, 2016‐2017, was to evaluate and standardize RSV molecular tests used by participating countries. This paper describes the first WHO RSV EQA for the molecular detection of RSV.

Methods

The WHO implemented the pilot of Global RSV Surveillance based on the WHO Global Influenza Surveillance and Response System (GISRS) from 2016 to 2018 in 14 countries. To ensure standardization of tests, 13 participating laboratories were required to complete a 12 panel RSV EQA prepared and distributed by the Centers for Disease Control and Prevention (CDC), USA. The 14th laboratory joined the pilot late and participated in a separate EQA. Laboratories evaluated a RSV rRT‐PCR assay developed by CDC and compared where applicable, other Laboratory Developed Tests (LDTs) or commercial assays already in use at their laboratories.

Results

Laboratories performed well using the CDC RSV rRT‐PCR in comparison with LDTs and commercial assays. Using the CDC assay, 11 of 13 laboratories reported correct results. Two laboratories each reported one false‐positive finding. Of the laboratories using LDTs or commercial assays, results as assessed by Ct values were 100% correct for 1/5 (20%). With corrective actions, all laboratories achieved satisfactory outputs.

Conclusions

These findings indicate that reliable results can be expected from this pilot. Continued participation in EQAs for the molecular detection of RSV is recommended.

Phylogenetic analysis of the first four SARS-CoV-2 cases in Chile

The current pandemic caused by the new coronavirus is a worldwide public health concern. To aboard this emergency, and like never before, scientific groups around the world have been working in a fast and coordinated way to get the maximum of information about this virus when it has been almost 3 months since the first cases were detected in Wuhan province in China. The complete genome sequences of around 450 isolates are available, and studies about similarities and differences among them and with the close related viruses that caused similar epidemics in this century. In this work, we studied the complete genome of the first four cases of the new coronavirus disease in Chile, from patients who traveled to Europe and Southeast Asia. Our findings reveal at least two different viral variants entries to Chilean territory, coming from Europe and Asia. We also sub‐classified the isolates into variants according to punctual mutations in the genome. Our work contributes to global information about transmission dynamics and the importance to take control measures to stop the spread of the infection.

First genetic study of the SARS‐CoV‐2 isolates in Chile.

At least two different viral variants were identified from Chilean travelers.

S and G Chilean variants are associated to European and Asian viral isolates.

Human respiratory syncytial virus and influenza seasonality patterns-Early findings from the WHO global respiratory syncytial virus surveillance

Background

Human respiratory syncytial virus (RSV) causes illnesses among all age groups and presents a burden to healthcare services. To better understand the epidemiology and seasonality of RSV in different geographical areas, the World Health Organization (WHO) coordinated a pilot initiative to access the feasibility of establishing RSV surveillance using the existing Global Influenza Surveillance and Response System (GISRS) platform.

Objectives

To describe and compare RSV and influenza seasonality in countries in the northern andsouthern temperate, and tropics during the period January 2017 to April 2019.

Methods

Fourteen countries in six WHO regions participating in the GISRS were invited for the pilot. Hospitalized patients presenting with severe acute respiratory illness (SARI), SARI without fever and outpatients presenting with acute respiratory illness (ARI) were enrolled from January 2017 to April 2019. The expected minimum sample size was 20 samples per week, year‐round, per country. Real‐time RT‐PCR was used to detect RSV and influenza viruses. Results were uploaded to the WHO FluMart platform.

Results

Annual seasonality of RSV was observed in all countries, which overlapped to a large extent with the influenza activity. In countries, in temperate regions RSV peaked in the autumn/winter months. In Egypt, a subtropical country, RSV activity peaked in the cooler season. In the tropical regions, RSV peaked during the rainy seasons.

Conclusion

Early findings from the WHO RSV surveillance pilot based on the GISRS suggest annual seasonal patterns for of RSV circulation that overlap with influenza. RSV surveillance needs to be continued for several more seasons to establish seasonality patterns to inform prevention and control strategies.

Genetic evolution of influenza viruses among selected countries in Latin America, 2017-2018

OBJECTIVE

Since the 2009 influenza pandemic, Latin American (LA) countries have strengthened their influenza surveillance systems. We analyzed influenza genetic sequence data from the 2017 through 2018 Southern Hemisphere (SH) influenza season from selected LA countries, to map the availability of influenza genetic sequence data from, and to describe, the 2017 through 2018 SH influenza seasons in LA.

METHODS

We analyzed influenza A/H1pdm09, A/H3, B/Victoria and B/Yamagata hemagglutinin sequences from clinical samples from 12 National Influenza Centers (NICs) in ten countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Mexico, Paraguay, Peru and Uruguay) with a collection date from epidemiologic week (EW) 18, 2017 through EW 43, 2018. These sequences were generated by the NIC or the WHO Collaborating Center (CC) at the U.S Centers for Disease Control and Prevention, uploaded to the Global Initiative on Sharing All Influenza Data (GISAID) platform, and used for phylogenetic reconstruction.

FINDINGS

Influenza hemagglutinin sequences from the participating countries (A/H1pdm09 n = 326, A/H3 n = 636, B n = 433) were highly concordant with the genetic groups of the influenza vaccine-recommended viruses for influenza A/H1pdm09 and influenza B. For influenza A/H3, the concordance was variable.

CONCLUSIONS

Considering the constant evolution of influenza viruses, high-quality surveillance data-specifically genetic sequence data, are important to allow public health decision makers to make informed decisions about prevention and control strategies, such as influenza vaccine composition. Countries that conduct influenza genetic sequencing for surveillance in LA should continue to work with the WHO CCs to produce high-quality genetic sequence data and upload those sequences to open-access databases.

Host characteristics predict outcome among adult patients admitted by severe acute respiratory infection

BACKGROUND

Except for influenza pandemics, different observational studies have failed to demonstrate differences in mortality between various etiologies in adult patients hospitalized for respiratory infections.

AIM

To compare clinical and mortality differences between different viral pathogens associated with severe acute respiratory infections (SARI) in hospitalized adults.

MATERIAL AND METHODS

One-year prospective study in a sentinel center. We included 132 patients with SARI hospitalized for any of the nine viruses under study by PCR. Clinical variables were compared, excluding cases of coinfection.

RESULTS

A viral coinfection was identified in 12% and influenza infection in 56% of cases. Eighty percent of patients were aged ≥ 65 years, with a high frequency of comorbidities, 27% were bedridden. Twenty four percent were admitted to critical care units, 20% required ventilatory assistance and 16% died. Cases occurred throughout the year, with an expected seasonal peak between autumn and spring and a predominance of infections not associated with influenza during summer months. In the multivariate analysis, only being bedridden was significantly associated with mortality at discharge (Odds ratio 23.46; 95% confidence intervals 3.33-165.12, p < 0.01), without association with age, comorbidity, viral pathogen involved, laboratory parameters, clinical presentation or CURB65 score. No major clinical dissimilarities were found between different viral pathogens.

CONCLUSIONS

In our series of patients, mostly elderly, only bedridden status was significantly associated with mortality at discharge in patients hospitalized for SARI. Viral pathogens were not relevant.

Burden of influenza-associated respiratory hospitalizations in the Americas, 2010-2015

BACKGROUND

Despite having influenza vaccination policies and programs, countries in the Americas underutilize seasonal influenza vaccine, in part because of insufficient evidence about severe influenza burden. We aimed to estimate the annual burden of influenza-associated respiratory hospitalizations in the Americas.

METHODS

Thirty-five countries in the Americas with national influenza surveillance were invited to provide monthly laboratory data and hospital discharges for respiratory illness (International Classification of Diseases 10th edition J codes 0-99) during 2010-2015. In three age-strata (<5, 5-64, and ≥65 years), we estimated the influenza-associated hospitalizations rate by multiplying the monthly number of respiratory hospitalizations by the monthly proportion of influenza-positive samples and dividing by the census population. We used random effects meta-analyses to pool age-group specific rates and extrapolated to countries that did not contribute data, using pooled rates stratified by age group and country characteristics found to be associated with rates.

RESULTS

Sixteen of 35 countries (46%) contributed primary data to the analyses, representing 79% of the America's population. The average pooled rate of influenza-associated respiratory hospitalization was 90/100,000 population (95% confidence interval 61-132) among children aged <5 years, 21/100,000 population (13-32) among persons aged 5-64 years, and 141/100,000 population (95-211) among persons aged ≥65 years. We estimated the average annual number of influenza-associated respiratory hospitalizations in the Americas to be 772,000 (95% credible interval 716,000-829,000).

CONCLUSIONS

Influenza-associated respiratory hospitalizations impose a heavy burden on health systems in the Americas. Countries in the Americas should use this information to justify investments in seasonal influenza vaccination-especially among young children and the elderly.

Severe acute respiratory infections (SARI) from influenza in adult patients in Chile: the experience of a sentinel hospital

Objective

To 1) describe clinical characteristics of adult patients in Chile with severe acute respiratory infections (SARI) associated with influenza viruses, and 2) analyze virus subtypes identified in specimens collected from those patients, hospital resources used in clinical management, clinical evolution, and risk factors associated with a fatal outcome, using observational data from the SARI surveillance network (SARInet).

Methods

Adults hospitalized from 1 July 2011 to 31 December 2015 with influenza-associated SARI at a SARI sentinel surveillance hospital in Santiago were identified and the presence of influenza in all cases confirmed by reverse transcription polymerase chain reaction (RT-PCR), using respiratory samples.

Results

A total of 221 patients (mean age: 74.1 years) were hospitalized with influenza-associated SARI during the study period. Of this study cohort, 91.4% had risk factors for complications and 34.3% had been vaccinated during the most recent campaign. Pneumonia was the most frequent clinical manifestation, occurring in 57.0% of the cohort; other manifestations included influenza-like illness, exacerbated chronic bronchitis, decompensated heart failure, and asthmatic crisis. Cases occurred year-round, with an epidemic peak during autumn–winter. Both influenza A (H1N1pdm09 and H3N2) and B virus co-circulated. Critical care beds were required for 26.7% of the cohort, and 19.5% needed ventilatory assistance. Multivariate analysis identified four significant factors associated with in-hospital mortality: 1) being bedridden (adjusted odds ratio (aOR): 22.3; 95% confidence interval (CI): 3.0–164); 2) admission to critical care unit (aOR: 8.9; CI: 1.44–55); 3) Pa0₂/Fi0₂ ratio < 250 (aOR: 5.8; CI: 1.02–33); and 4) increased serum creatinine concentration (> 1 mg/dL) (aOR: 5.47; CI: 1.20–24). Seasonal influenza vaccine was identified as a significant protective factor (aOR: 0.14; CI: 0.021–0.90).

Conclusions

Influenza-associated SARI affected mainly elderly patients with underlying conditions. Most patients evolved to respiratory failure and more than one-quarter required critical care beds. Clinical presentation was variable. Death was associated with host characteristics and disease-associated conditions, and vaccine was protective. Virus type did not influence outcome.

[Acute glomerulonephritis with hemodialysis requirement secondary to influenza A H1N1pdm09 infection: Report of two cases]

Acute renal failure (ARF) requiring hemodialysis is not common among patients affected by influenza. We report two unvaccinated adult patients with smoking habit, which were admitted with severe influenza A H1N1pdm09 that evolved with shock and required mechanical ventilation. Both patients developed progressive renal failure with oliguria/anuria, associated with urinary of inflammatory sediment with proteinuria, microhematuria and in one case also with hypocomplementemia, suggesting acute glomerulonephritis. Renal replacement therapy (RRT) was required in both cases. In one patient, who died of late complications, sequencing of the HA1 segment revealed the previously described D222N mutation associated to severe cases. ARF with RRT appears to be an uncommon complication of patients hospitalized for influenza A H1N1pdm09 and may be secondary to acute glomerulonephritis.

Novel nonsense mutation in the katA gene of a catalase-negative Staphylococcus aureus strain

We report the first description of a rare catalase-negative strain of Staphylococcus aureus in Chile. This new variant was isolated from blood and synovial tissue samples of a pediatric patient. Sequencing analysis revealed that this catalase-negative strain is related to ST10 strain, which has earlier been described in relation to S. aureus carriers. Interestingly, sequence analysis of the catalase gene katA revealed presence of a novel nonsense mutation that causes premature translational truncation of the C-terminus of the enzyme leading to a loss of 222 amino acids. Our study suggests that loss of catalase activity in this rare catalase-negative Chilean strain is due to this novel nonsense mutation in the katA gene, which truncates the enzyme to just 283 amino acids.

A report on the outbreak of Zika virus on Easter Island, South Pacific, 2014

Zika virus (ZIKV) is an emerging mosquito-borne flavivirus circulating in Asia and Africa. In 2013, a large outbreak was reported on the archipelago of French Polynesia. In this study, we report the detection and molecular characterization of Zika virus for the first time in Chile from an outbreak among the inhabitants of Easter Island. A total of 89 samples from patients suspected of having ZIKV infection were collected between the period from January to May, 2014. Molecular diagnosis of the virus was performed by RT-PCR followed by the sequencing of the region containing the NS5 gene. A comparison of the viral nucleic acid sequence with those of other strains of ZIKA virus was performed using the MEGA software. Fifty-one samples were found positive for ZIKV by RT-PCR analysis. Further analysis of the NS5 gene revealed that the ZIKV strains identified in Easter Island were most closely related to those found in French Polynesia (99.8 to 99.9% nt and 100% aa sequence identity). These results strongly suggest that the transmission pathway leading to the introduction of Zika virus on Easter Island has its origin in French Polynesia.

Many respiratory viruses have temporal association with meningococcal disease

BACKGROUND

Previous ecological studies have shown a temporal and spatial association between influenza epidemics and meningococcal disease (MNG); however, none have examined more than two respiratory viruses.

METHODS

Data were obtained in Chile between 2000 and 2005 on confirmed cases of MNG and all confirmed cases of respiratory viruses (influenza A and B; parainfluenza; adenovirus; and respiratory syncytial virus [RSV]). Both variables were divided by epidemiological weeks, age range, and regions. Models of transference functions were run for rates of MNG.

RESULTS

In this period, 1022 reported cases of MNG and 34,737 cases of respiratory virus were identified (25,137 RSV; 4300 parainfluenza; 2527 influenza-A; 356 influenza-B; and 2417 adenovirus). RSV was the major independent virus temporally associated to MNG (it appears one week before MNG), followed by parainfluenza, influenza-B, adenovirus, and influenza-A.

CONCLUSIONS

The rate of MNG in Chile is temporally associated to all of the respiratory viruses studied, but with variability according age range, and regions.

Strengthening the influenza vaccine virus selection and development process: Report of the 3rd WHO Informal Consultation for Improving Influenza Vaccine Virus Selection held at WHO headquarters, Geneva, Switzerland, 1-3 April 2014

Despite long-recognized challenges and constraints associated with their updating and manufacture, influenza vaccines remain at the heart of public health preparedness and response efforts against both seasonal and potentially pandemic influenza viruses. Globally coordinated virological and epidemiological surveillance is the foundation of the influenza vaccine virus selection and development process. Although national influenza surveillance and reporting capabilities are being strengthened and expanded, sustaining and building upon recent gains has become a major challenge. Strengthening the vaccine virus selection process additionally requires the continuation of initiatives to improve the timeliness and representativeness of influenza viruses shared by countries for detailed analysis by the WHO Global Influenza Surveillance and Response System (GISRS). Efforts are also continuing at the national, regional, and global levels to better understand the dynamics of influenza transmission in both temperate and tropical regions. Improved understanding of the degree of influenza seasonality in tropical countries of the world should allow for the strengthening of national vaccination policies and use of the most appropriate available vaccines. There remain a number of limitations and difficulties associated with the use of HAI assays for the antigenic characterization and selection of influenza vaccine viruses by WHOCCs. Current approaches to improving the situation include the more-optimal use of HAI and other assays; improved understanding of the data produced by neutralization assays; and increased standardization of serological testing methods. A number of new technologies and associated tools have the potential to revolutionize influenza surveillance and response activities. These include the increasingly routine use of whole genome next-generation sequencing and other high-throughput approaches. Such approaches could not only become key elements in outbreak investigations but could drive a new surveillance paradigm. However, despite the advances made, significant challenges will need to be addressed before next-generation technologies become routine, particularly in low-resource settings. Emerging approaches and techniques such as synthetic genomics, systems genetics, systems biology and mathematical modelling are capable of generating potentially huge volumes of highly complex and diverse datasets. Harnessing the currently theoretical benefits of such bioinformatics ("big data") concepts for the influenza vaccine virus selection and development process will depend upon further advances in data generation, integration, analysis and dissemination. Over the last decade, growing awareness of influenza as an important global public health issue has been coupled to ever-increasing demands from the global community for more-equitable access to effective and affordable influenza vaccines. The current influenza vaccine landscape continues to be dominated by egg-based inactivated and live attenuated vaccines, with a small number of cell-based and recombinant vaccines. Successfully completing each step in the annual influenza vaccine manufacturing cycle will continue to rely upon timely and regular communication between the WHO GISRS, manufacturers and regulatory authorities. While the pipeline of influenza vaccines appears to be moving towards a variety of niche products in the near term, it is apparent that the ultimate aim remains the development of effective "universal" influenza vaccines that offer longer-lasting immunity against a broad range of influenza A subtypes.

Clinical relevance of rhinovirus infections among adult hospitalized patients

Human rhinovirus (HRV) is an emerging viral pathogen.

Aim

To characterize a group of patients admitted due to infection by this agent in a general hospital in Chile.

Methods

Cases were identified by RT-PCR for 1 year through active surveillance of patients admitted with severe respiratory illness. Diagnosis was not available during hospitalization. Thirty-two cases were identified, 90% were ≥60 years old or had co-morbid conditions. Human rhinovirus-related admissions represented 23.7% of hospitalization due to severe acute respiratory infections among adults and ranked second to influenza (37.8%). Patients presented with pneumonia (68.8%), decompensated chronic lung conditions (21.9%), heart failure or influenza-like illness (6.3% each). Admission to intensive or intermediate care units was required by 31.2% and in-hospital mortality reached 12.5%. A CURB-65 score ≥3 was significantly associated to in-hospital mortality (p < 0.05). Most patients received antibiotics (90%).

Conclusions

Human rhinovirus infections in elderly patients with co-morbid conditions are associated with hospitalizations, requiring critical or semi-critical antibiotics use. A high CURB-65 score was associated to in-hospital mortality.

[Morbidity and mortality associated to influenza A (H1N1) 2009 admissions in two hospitals of the Metropolitan area and analysis of its economic impact]

Influenza A (H1N1) 2009 infection was an important cause of morbidity and mortality in Chile.

AIM

To characterize the clinical pattern of hospitalized patients, identify risk factors associated with ICU admission or death, and evaluate its economic impact.

PATIENTS AND METHODS

Twenty five adult patients admitted to 2 hospitals in the Metropolitan Area from May 2009 to December 2010 with PCR confirmed H1N1 infection were analyzed. Total hospital charges were obtained and, using data of registered cases, expenses for the whole country during the first epidemic wave were estimated.

RESULTS

Aill cases presented a risk factor: age over 60 years old (n = 13, 52%), co-morbid conditions (n = 24, 96%) or pregnancy (n = 1, 4%). Pneumonia was present in 64% (n = 16) and 16% (n = 4) had hypotension. Only 6 patients (24%) had a CURB-65 score ≥ 2 and 36% (n = 9) requiring ICU admission. Case fatality rate was 16% (n = 4). By multivariate analysis, diabetes mellitus type 2 was independently associated with ICU admission or death (OR 8.12; IC95 1.11-59.2, p < 0.05). Hospital charges for those admitted to ICU or the intermediate care unit reached US$ 20,304, and US$ 1,262 for those admitted in general wards. We estimated US$ 20 million in hospital charges for influenza related hospitalizations during the first wave for the whole country.

CONCLUSIONS

A high proportion of patients affected by influenza A (H1N1) 2009 infection required ICU admission during 2009-2010. Case fatality rate associated to this infection was high, and diabetes mellitus type 2 was a risk factor for ICU admission or death. Hospital charges were higher for those admitted in critical care units and represented an important expenditure for Chile during the first wave. The CURB-65 score was inappropriate to recognize patients at risk of hospitalization or ICU admission.

Age as risk factor for death from pandemic (H1N1) 2009, Chile

Pandemic (H1N1) 2009 affected Chile during the winter of 2009. The hospitalization rate was 0.56% overall and 3.47% for persons >60 years of age at risk for severe disease and death independent of concurrent conditions. Age >60 years was the major risk factor for death from pandemic (H1N1) 2009.

Role of neutralizing antibodies in adults with community-acquired pneumonia by respiratory syncytial virus

Background. Respiratory syncytial virus (RSV) has been implicated in the etiology of adult community-acquired pneumonia (CAP). We investigated RSV infection in Chilean adults with CAP using direct viral detection, real-time reverse-transcription polymerase chain reaction (rtRT-PCR), and serology (microneutralization assay).

Methods. RSV, other respiratory viruses, and bacteria were studied by conventional and molecular techniques in adults aged ≥18 years presenting with CAP to the healthcare facilities in Santiago, Chile from February 2005 through December 2007.

Results. All 356 adults with CAP enrolled had an acute blood sample collected at enrollment, and 184 had a convalescent blood sample. RSV was detected in 48 cases (13.4%). Immunofluorescence assay and viral isolation each detected only 1 infection (0.2%), whereas rtRT-PCR was positive in 32 (8.9%) cases and serology was positive in 20 (10.8%) cases. CAP clinical characteristics were similar in RSV-infected and non-RSV-infected cases. RSV-specific geometric mean serum-neutralizing antibody titer (GMST) was significantly lower at admission in the 48 RSV-infected cases compared with 308 non-RSV-infected adults (GMST in log₂: RSV/A 8.1 vs 8.9, and RSV/B 9.3 vs 10.4; P < .02).

Conclusions. RSV infection is frequent in Chilean adults with CAP. Microneutralization assay was as sensitive as rtRT-PCR in detecting RSV infection and is a good adjunct assay for diagnostic research. High RSV-specific serum-neutralizing antibody levels were associated with protection against common and severe infection. The development of a vaccine could prevent RSV-related CAP in adults.

Epidemiologic and virologic assessment of the 2009 influenza A (H1N1) pandemic on selected temperate countries in the Southern Hemisphere: Argentina, Australia, Chile, New Zealand and South Africa

Please cite this paper as: Van Kerkhove et al. (2011) Epidemiologic and virologic assessment of the 2009 influenza A (H1N1) pandemic on selected temperate countries in the Southern Hemisphere: Argentina, Australia, Chile, New Zealand and South Africa. Influenza and Other Respiratory Viruses 5(6), e487–e498.

Introduction and Setting  Our analysis compares the most comprehensive epidemiologic and virologic surveillance data compiled to date for laboratory‐confirmed H1N1pdm patients between 1 April 2009 ‐ 31 January 2010 from five temperate countries in the Southern Hemisphere–Argentina, Australia, Chile, New Zealand, and South Africa.

Objective  We evaluate transmission dynamics, indicators of severity, and describe the co‐circulation of H1N1pdm with seasonal influenza viruses.

Results  In the five countries, H1N1pdm became the predominant influenza strain within weeks of initial detection. South Africa was unique, first experiencing a seasonal H3N2 wave, followed by a distinct H1N1pdm wave. Compared with the 2007 and 2008 influenza seasons, the peak of influenza‐like illness (ILI) activity in four of the five countries was 3‐6 times higher with peak ILI consultation rates ranging from 35/1,000 consultations/week in Australia to 275/100,000 population/week in New Zealand. Transmission was similar in all countries with the reproductive rate ranging from 1.2–1.6. The median age of patients in all countries increased with increasing severity of disease, 4–14% of all hospitalized cases required critical care, and 26–68% of fatal patients were reported to have ≥1 chronic medical condition. Compared with seasonal influenza, there was a notable downward shift in age among severe cases with the highest population‐based hospitalization rates among children <5 years old. National population‐based mortality rates ranged from 0.8–1.5/100,000.

Conclusions  The difficulty experienced in tracking the progress of the pandemic globally, estimating its severity early on, and comparing information across countries argues for improved routine surveillance and standardization of investigative approaches and data reporting methods.

Influenza pneumonia: a comparison between seasonal influenza virus and the H1N1 pandemic

We compared clinical presentation, complications and outcome in patients with influenza A (H1N1) and seasonal influenza pneumonia. The group of patients with influenza A (H1N1) pneumonia consisted of 75 patients. 52 patients with pneumonia associated with seasonal influenza were included for comparison. Patients with pneumonia associated with novel H1N1 influenza were younger (mean age 39.7 yrs versus 69.6 yrs) and had fewer chronic comorbidities and less alcoholism. Infiltrates were more extensive and frequently interstitial. Respiratory failure was more frequent (those with an arterial oxygen tension/inspiratory oxygen fraction ratio <200 28% versus 12%, p = 0.042), leading to a higher rate of intensive care unit (ICU) admission and mechanical ventilation (29.3% versus 7.7% (p<0.0030) and 18.7% versus 2% (p<0.0045)). Mortality was twice as high in patients with novel H1N1 (12% versus 5.8%; p = 0.238), although this was not significant, and was attributable to pneumonia in most instances (77.8% versus 0%; p = 0.046). Younger age, fewer comorbidities, more extensive radiographic extension and more severe respiratory compromise, and ICU admissions are key features of the clinical presentation of patients with novel H1N1-associated pneumonia compared with seasonal influenza pneumonia.

Pandemic (H1N1) 2009 in breeding turkeys, Valparaiso, Chile

Pandemic (H1N1) 2009 virus was detected in breeding turkeys on 2 farms in Valparaiso, Chile. Infection was associated with measurable declines in egg production and shell quality. Although the source of infection is not yet known, the outbreak was controlled, and the virus was eliminated from the birds.

Impact of limited cephalosporin use on prevalence of methicillin-resistant Staphylococcus aureus in the intensive care unit

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a leading pathogen causing nosocomial infections. Many studies have shown that the restricted use of antibacterials is associated with a decline in resistance. To establish whether an intervention protocol designed to limit the use of cephalosporins can lower mRSA infection rates and impact on Gram-negative bacteria susceptibility in an intensive Care Unit (ICU), we conducted a prospective, non-randomized, before-after intervention study in an 18-bed ICU in Genoa, Italy. The intervention was a hospital antibiotic control policy and the observation was routine monitoring for nosocomial infections and antibiotic use, recording periodically the incidence density and MRSA prevalence. The intervention included a new antibiotic guideline that restricted the use of cephalosporins for all ICU inpatients. The analysis showed that the intervention determined a significant reduction in cephalosporin usage (-70.3%), while fluoroquinolones, mainly ciprofloxacin, increased after introduction of the antibiotic policy (+46.5%). A significant reduction in the percentage of MRSA infections (-30%) and heterogeneous susceptibility patterns in Klebsiella pneumoniae and Pseudomonas aeruginosa were noted.

Antimicrobial use and resistance among Gram-negative bacilli in an Italian intensive care unit (ICU)

Gram-negative bacilli antimicrobial resistance remains a significant problem for patients in the intensive care unit (ICU). We performed a retrospective analysis of microbiological data and antibiotic consumption over a 4-year period (2000-2003) in an Italian ICU. Pseudomonas aeruginosa and Klebsiella pneumoniae represented approximately 40% of all isolates. The most significant trend in antimicrobial use was an increase in use of 3(rd )generation cephalosporins, imipenem, and ciprofloxacin. A significant trend toward an increase in resistance rates to piperacillin, 3( rd )generation cephalosporins and ciprofloxacin was observed for K. pneumoniae and a positive correlation between resistance and drug-usage was evident for K. pneumoniae and piperacillin, cefotaxime, ceftazidime, cefepime, and ciprofloxacin, but not for piperacillin/tazobactam. No statistically significant correlations were evidenced for P. aeruginosa. Trends in resistances were studied also for Serratia spp and Proteus spp. Isolation rates of extended-spectrum beta-lactamase (ESBL)-producing strains in pathogens studied were high, especially for K. pneumoniae (72%, 160/222) and Proteus spp (41%, 18/43). In conclusion, the study showed high resistance among Gram-negative organisms isolated in the ICU and significant ESBL production. A significant correlation between antibiotic consumption and increasing resistance was evident for K. pneumoniae.

Efficacy of the combination of levofloxacin plus ceftazidime in the treatment of hospital-acquired pneumonia in the Intensive Care Unit

To investigate the efficacy and tolerability of treatment with a combination of levofloxacin and ceftazidime in Gram-negative hospital-acquired pneumonia (HAP) in the Intensive Care Unit (ICU), we performed a prospective, open-label, non-comparative, 1-year study in an Italian ICU. Patients received levofloxacin 500 mg twice a day intravenously plus ceftazidime 2 g three times a day intravenously for 7-14 days. Primary efficacy variables were clinical and microbiological responses at test-of-cure visit. Twenty-one patients were enrolled. Pseudomonas aeruginosa and Klebsiella pneumoniae were the most frequently identified pathogens. Clinical success was achieved in 17/21 clinically evaluable patients (81%) and in 12/15 microbiologically evaluable patients (80%). Regarding only the group with ventilator-associated pneumonia, cure was achieved in 10/14 clinically evaluable patients (71%) and in 11/14 microbiologically evaluable patients (79%). Therapy was well tolerated. We conclude that this combination regimen is safe and clinically and microbiologically efficacious in the treatment of Gram-negative HAP.

[Immune status against measles and rubella among 4 Chilean groups of different ages]

BACKGROUND

Results of clinical and epidemiological studies confirm that no cases of measles have occurred in Chile since 1993. However, since covering of vaccination programs do not exceed 95%, an immunological surveillance for this disease is warranted.

AIM

To know the immune status against measles and rubella in the Chilean population.

MATERIAL AND METHODS

A serological census of a representative sample of communities with high (90% or more) or low immunization coverings was performed. Four sub samples along the country were selected: 122 children aged 18 months of age (stratum A), 1,276 children attending the first years of basic school (stratum B), 899 teenagers in their last high school year (stratum C) and 399 women attending a family planning clinic (stratum D). IgG antibodies against measles and rubella were measured using ELISA and hemagglutination inhibition techniques, respectively.

RESULTS

Antibodies against measles and rubella were found in 96% and 94% of study subjects. No differences in these titres were found between different strata or communities with high or low vaccination covering. There is a high percentage of positive antibodies against measles among children of 18 months of age and a high percentage of antibodies against rubella among teenagers and women in family planning. Only 3% of the sample had not received any vaccine at the moment of the study.

CONCLUSIONS

The high prevalence of antibodies against rubella allows to conclude that it is not necessary to consider this antigen in the next vaccination campaign. Due to the high prevalence of antibodies against measles, only the population older than 20 years old should be affected by the disease if this virus enters the country.

[Laboratory surveillance of measles. Chile, 1992-1995]

BACKGROUND

The first massive national measles vaccination campaign in Chile was done in 1992. Since then a laboratory surveillance of the disease has been undertaken at the Instituto de Salud Pública.

AIM

To report the results of laboratory surveillance of measles between 1992 and 1995.

MATERIAL AND METHODS

Paired serum samples from suspected cases of measles were received at the Institute. Measles specific IgG was determined with indirect immunofluorescence methods. IgG and IgM immunoenzymatic methods were used as complementary techniques, and rubella infections were ruled out by hemmaglutination inhibition tests.

RESULTS

Sera from 1087 presumptive cases (489 in 1992, 196 in 1993, 180 in 1994 and 222 in 1995) were analyzed. Only two cases of wild imported measles were confirmed, one in Arica in 1992 and the other in Santiago in 1993. Five additional post vaccine cases were detected. Eighty eight percent of samples in 1992 and 75% in 1994 were seropositive. A high percentage of cases were confirmed as rubella (55% in 1992 and 19% in 1994).

CONCLUSIONS

Absence of wild measles virus circulation in Chile from 1992 to 1995 emphasizes the importance of laboratory surveillance of the disease.

Treatment of allergic diseases during pregnancy

Pregnancy may variously modify the natural history of allergic disorders through occurring endocrinologic, functional and immunological changes. A pharmacologic treatment of allergic diseases (mainly asthma) is often necessary during pregnancy. On the other hand, a drug should be not potentially teratogenic and should not have serious side effects, both for the mother and the fetus. This paper reviews current knowledge about allergic diseases during pregnancy, considering the points of view of the different specialists involved in their management. Topical mucosal agents seem to be the safest, due to their minimal or absent absorption which should reflect reduced side effects. Preferred agents should be topical antihistamines (for rhinitis and conjunctivitis), and cromones and topical steroids (for asthma), as they are both safe and effective.

[Molecular study of 6 episodes of nosocomial infections produced by methicillin resistant Staphylococcus aureus]

A critical step in any epidemiologic research concerning nosocomial infections is the precise identification of the responsible pathogen. The present work utilized a molecular approach -plasmids identification, restriction length polymorphism DNA analysis, and random amplified polymorphic DNA- for the characterization of 6 nosocomial outbreaks due to 52 strains of methicillin-resistant Staphylococcus aureus (MRSA). In these episodes, the clinic-epidemiologic and phenotypic analysis (antibiotype) pointed to a nosocomial infection. Through molecular analysis it was possible to establish, in a very precise way, clonality due to MRSA strains in 2 of the studied outbreaks; the same type of analysis allowed to eliminate a MRSA clonal origin in the remainder 4 episodes. The antibiogram was not an useful analytic tool due to its poor discriminatory power. Also, through a PCR procedure, it was possible to identify the presence of the gen mecA in every of the 52 MRSA strains studied.