Immune responses during COVID-19 breakthrough cases in vaccinated children and adolescents.

Background: Vaccine effectiveness against SARS-CoV-2 infection has been somewhat limited due to the widespread dissemination of the Omicron variant, its subvariants, and the immune response dynamics of the naturally infected with the virus. Methods: Twelve subjects between 3-17 years old (yo), vaccinated with two doses of CoronaVac®, were followed and diagnosed as breakthrough cases starting 14 days after receiving the second dose. Total IgGs against different SARS-CoV-2 proteins and the neutralizing capacity of these antibodies after infection were measured in plasma. The activation of CD4+ and CD8+ T cells was evaluated in peripheral blood mononuclear cells stimulated with peptides derived from the proteins from the wild-type (WT) virus and Omicron subvariants by flow cytometry, as well as different cytokines secretion by a Multiplex assay. Results: 2 to 8 weeks post-infection, compared to 4 weeks after 2nd dose of vaccine, there was a 146.5-fold increase in neutralizing antibody titers against Omicron and a 38.7-fold increase against WT SARS-CoV-2. Subjects showed an increase in total IgG levels against the S1, N, M, and NSP8 proteins of the WT virus. Activated CD4+ T cells showed a significant increase in response to the BA.2 subvariant (p<0.001). Finally, the secretion of IL-2 and IFN-γ cytokines showed a discreet decrease trend after infection in some subjects. Conclusion: SARS-CoV-2 infection in the pediatric population vaccinated with an inactivated SARS-CoV-2 vaccine produced an increase in neutralizing antibodies against Omicron and increased specific IgG antibodies for different SARS-CoV-2 proteins. CD4+ T cell activation was also increased, suggesting a conserved cellular response against the Omicron subvariants, whereas Th1-type cytokine secretion tended to decrease. Clinical Trial Registration: clinicaltrials.gov #NCT04992260.

Intestinal protozoa in returning travellers: a GeoSentinel analysis from 2007 to 2019.

BACKGROUND: Prolonged diarrhoea is common amongst returning travellers and is often caused by intestinal protozoa. However, the epidemiology of travel-associated illness caused by protozoal pathogens is not well described. METHODS: We analysed records of returning international travellers with illness caused by Giardia duodenalis, Cryptosporidium spp., Cyclospora cayetanensis or Cystoisospora belli, reported to the GeoSentinel Network during January 2007-December 2019. We excluded records of travellers migrating, with an unascertainable exposure country, or from GeoSentinel sites that were not located in high-income countries. RESULTS: There were 2517 cases, 82.3% giardiasis (n = 2072), 11.4% cryptosporidiosis (n = 287), 6.0% cyclosporiasis (n = 150) and 0.3% cystoisosporiasis (n = 8). Overall, most travellers were tourists (64.4%) on long trips (median durations: 18-30 days). Cryptosporidiosis more frequently affected people < 18 years (13.9%) and cyclosporiasis affected people ≥ 40 years (59.4%). Giardiasis was most frequently acquired in South Central Asia (45.8%) and sub-Saharan Africa (22.6%), cryptosporidiosis in sub-Saharan Africa (24.7%) and South-Central Asia (19.5%), cyclosporiasis in South East Asia (31.3%) and Central America (27.3%), and cystoisosporiasis in sub-Saharan Africa (62.5%). Cyclosporiasis cases were reported from countries of uncertain endemicity (e.g. Cambodia) or in countries with no previous evidence of this parasite (e.g. French Guiana). The time from symptom onset to presentation at a GeoSentinel site was the longest amongst travellers with giardiasis (median: 30 days). Over 14% of travellers with cryptosporidiosis were hospitalized. CONCLUSIONS: This analysis provides new insights into the epidemiology and clinical significance of four intestinal protozoa that can cause morbidity in international travellers. These data might help optimize pretravel advice and post-travel management of patients with travel-associated prolonged gastrointestinal illnesses. This analysis reinforces the importance of international travel-related surveillance to identify sentinel cases and areas where protozoal infections might be undetected or underreported.

Different Safety Pattern of an Inactivated SARS-CoV-2 Vaccine (CoronaVac®) According to Age Group in a Pediatric Population from 3 to 17 Years Old, in an Open-Label Study in Chile.

During the COVID-19 pandemic, the importance of vaccinating children against SARS-CoV-2 was rapidly established. This study describes the safety of CoronaVac® in children and adolescents between 3- and 17-years-old in a multicenter study in Chile with two vaccine doses in a 4-week interval. For all participants, immediate adverse events (AEs), serious AEs (SAEs), and AEs of special interest (AESIs) were registered throughout the study. In the safety subgroup, AEs were recorded 28 days after each dose. COVID-19 surveillance was performed throughout the study. A total of 1139 individuals received the first and 1102 the second dose of CoronaVac®; 835 were in the safety subgroup. The first dose showed the highest number of AEs: up to 22.2% of participants reported any local and 17.1% systemic AE. AEs were more frequent in adolescents after the first dose, were transient, and mainly mild. Pain at the inoculation site was the most frequent AE for all ages. Fever was the most frequent systemic AE for 3-5 years old and headache in 6-17 years old. No SAEs or AESIs related to vaccination occurred. Most of the COVID-19 cases were mild and managed as outpatients. CoronaVac® was safe and well tolerated in children and adolescents, with different safety patterns according to age.

Interferon ß-1a ring prophylaxis to reduce household transmission of SARS-CoV-2: a cluster randomised clinical trial.

Background: Accumulating evidence indicates that an early, robust type 1 interferon (IFN) response to SARS-CoV-2 is important in determining COVID-19 outcomes, with an inadequate IFN response associated with disease severity. Our objective was to examine the prophylactic potential of IFN administration to limit viral transmission. Methods: A cluster randomised open label clinical trial was undertaken to determine the effects of pegylated IFNß-1a administration on SARS-CoV-2 household transmission between December 3rd, 2020 and June 29th, 2021. Index cases were identified from databases of confirmed SARS-CoV-2 individuals in Santiago, Chile. Households were cluster randomised (stratified by household size and age of index cases) to receive 3 doses of 125 µg subcutaneous pegylated IFNß-1a (172 households, 607 participants), or standard care (169 households, 565 participants). The statistical team was blinded to treatment assignment until the analysis plan was finalised. Analyses were undertaken to determine effects of treatment on viral shedding and viral transmission. Safety analyses included incidence and severity of adverse events in all treatment eligible participants in the standard care arm, or in the treatment arm with at least one dose administered. Clinicaltrials.gov identifier: NCT04552379. Findings: 5154 index cases were assessed for eligibility, 1372 index cases invited to participate, and 341 index cases and their household contacts (n = 831) enrolled. 1172 participants in 341 households underwent randomisation, with 607 assigned to receive IFNß-1a and 565 to standard care. Based on intention to treat (ITT) and per protocol (PP) analyses for the primary endpoints, IFNß-1a treatment did not affect duration of viral shedding in index cases (absolute risk reduction = -0.2%, 95% CI = -8.46% to 8.06%) and transmission of SARS-CoV-2 to household contacts (absolute risk reduction = 3.87%, 95% CI = -3.6% to 11.3%). Treatment with IFNß-1a resulted in significantly more treatment-related adverse events, but no increase in overall adverse events or serious adverse events. Interpretation: Based upon the primary analyses, IFNß-1a treatment did not affect duration of viral shedding or the probability of SARS-CoV-2 transmission to uninfected contacts within a household. Funding: Biogen PTY Ltd. Supply of interferon as 'Plegridy (peginterferon beta-1a).' The study was substantially funded by BHP Holdings Pty Ltd.

Clinical and epidemiological characteristics of SARS-CoV-2 virus in ambulatory children under 2 years old.

Background: SARS-CoV-2 is an emerging virus that has mainly affected adults; hence, most clinical information has been derived from that population. Most pediatric cases are mild and with nonspecific symptoms requiring outpatient management. Children are a major source of spread for most traditional respiratory viruses. Their role in SARS-CoV-2 transmission was thought to be relevant. Children under the age of two comprise a group that is more susceptible to infection since vaccines have not been approved for them until recently. The knowledge of clinical manifestation of COVID-19 in young children is scarce. Objectives: To describe the clinical, epidemiological, and demographic characteristics of children under 2 years old with confirmed COVID-19, who did not require hospitalization. Methods: This descriptive study was performed from May, 2020 to June, 2021. Children ages 0-2 years with COVID-19, confirmed by transcriptase-polymerase chain reaction assay that were performed in laboratories of the Red de Salud UC CHRISTUS Health Network, were selected to be contacted. If the parents accepted participating and their children were not hospitalized, a survey was sent to the patients' caregivers. Results: Of the 242 cases, 159 caregivers answered the survey (65.7%). The median age of the subjects was 14 months, and 53.5% were males. Fifty percent had comorbidities, of which one third corresponded to atopy. Ninety eight percent were secondary cases. Most of them were infected within their households (81%). The most frequent sources were their parents, followed by their grandparents. The most common symptom was fever (78%) followed by irritability (67.3%), rhinorrhea (66%), and fatigue (64.8%). Infants less than 6 months old more often presented with conjunctival congestion and less loss of appetite compared to older children (p < 0.05). Conclusions: This study provides valuable insights regarding COVID-19 in ambulatory young children. Most cases of SARS-CoV-2 infection in children under 2 years old do not require hospitalization. There was a slight male predominance, and the majority had been infected within their households. SARS-CoV-2 infection should be suspected in children under 2 years old presenting with fever, irritability, fatigue, and rhinorrhea. Children with positive household contacts and fever should also be tested for COVID-19.

Evaluation of ELISA-Based Multiplex Peptides for the Detection of Human Serum Antibodies Induced by Zika Virus Infection across Various Countries.

Zika virus (ZIKV) is a mosquito-borne Flavivirus with a positive-sense RNA genome, which are generally transmitted through the bite of an infected Aedes mosquito. ZIKV infections could be associated with neurological sequelae that, and otherwise produces similar clinical symptoms as other co-circulating pathogens. Past infection with one member of the Flavivirus genus often induces cross-reactive antibodies against other flaviruses. These attributes complicate the ability to differentially diagnose ZIKV infection from other endemic mosquito-borne viruses, making it both a public health issue as well as a diagnostic challenge. We report the results from serological analyses using arbovirus-specific peptides on 339 samples that were previously collected from 6 countries. Overall, we found that our multiplexed peptide-based ELISA was highly efficient for identifying ZIKV antibodies as early as 2 weeks post infection, and that it correlates with microneutralization, plaque reduction neutralization tests (PRNTs) and commercial tests for ZIKV in previously characterized samples. We observed that seropositivity varied by patient cohort, reflecting the sampling period in relation to the 2015-2016 ZIKV outbreak. This work evaluates the accuracy, specificity, and sensitivity of our peptide-based ELISA method for detecting ZIKV antibodies from geographically diverse regions. These findings can contribute to ongoing serological methods development and can be adapted for use in future studies.

A cluster randomized trial of interferon ß-1a for the reduction of transmission of SARS-Cov-2: protocol for the Containing Coronavirus Disease 19 trial (ConCorD-19).

BACKGROUND: SARS-CoV-2 infection rapidly spreads in populations due to the high rates of community transmission. Interrupting the shedding of SARS-CoV-2 may reduce the incidence of Coronavirus Disease 19 (COVID-19). Herein we provide a protocol for a cluster randomized trial that will examine the effectiveness of treatment with interferon (IFN) ß-1a compared to standard of care in limiting the transmission of SARS-CoV-2. Co-primary objectives are to determine whether IFN therapy reduces (a) the proportion of infected cases shedding SARS-CoV-2 at day 11 post randomization and (b) the incidence of transmission of SARS-CoV-2 infection from index cases to treatment-eligible household post-exposure contacts at day 11 after randomization. Secondary objectives include assessing the impact of IFN treatment on duration of viral clearance, hospitalizations and fatalities, and evaluating the safety of IFN treatment. METHODS: Three hundred and ten households, each including an index case with a recent COVID-19 diagnosis and at least one asymptomatic treatment-eligible household contact, will be randomized to receive 3 doses of 125 µg IFN ß-1a by subcutaneous administration (days 1, 6, and 11), or standard of care. All participants will be followed until day 29. DISCUSSION: The results from this trial will identify whether IFN ß treatment of mild or moderate COVID-19 cases accelerates viral clearance and prevents disease progression and whether IFN ß treatment of post-exposure contacts of COVID-19 cases reduces transmission of infection. TRIAL REGISTRATION: This trial is registered at ClinicalTrials.gov NCT04552379; date of registration September 17, 2020.

Emergent Pneumonia in Children.

In recent decades there have been multiple pathogens, viruses and bacteria, which have emerged as causal agents of pneumonia affecting adults, albeit less frequently, to children. For the purposes of this article we have classified emerging pathogens as follows: True emerging, to pathogens identified for the very first time affecting human population (SARS-CoV-1, SARS-CoV-2, MERS-CoV, avian influenza, and hantavirus); Re-emerging, to known pathogens which circulation was controlled once, but they have reappeared (measles, tuberculosis, antimicrobial resistant bacteria such as CA-MRSA, Mycoplasma pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and new serotypes of post-vaccine pneumococcal); and finally, those that we have called old known with new presentations, including common pathogens that, in particular condition, have changed their form of presentation (rhinovirus, and non-SARS coronavirus). We will review for each of them their epidemiology, forms of presentation, therapy, and prognosis in children compared to the adult with the aim of being able to recognize them to establish appropriate therapy, prognostics, and effective control measures.

[Temporal association between the circulation of respiratory viruses and hospitalizations due to Kawasaki disease]. / Asociación temporal entre la circulación de virus respiratorios y hospitalizaciones por enfermedad de Kawasaki.

BACKGROUND: The etiology of Kawasaki disease (KD) is unknown. It is believed that viral infections could trigger the disease in susceptible patients. AIM: To study the temporal association between the circulation of respiratory viruses and KD hospitalizations in the Metropolitan Region (MR), Chile, between 2010-2017. METHODS: Ecologic study consisting of a review of KD cases in children under 18 years of age based on hospital discharges. The circulation of respiratory viruses was analyzed using the report of the metropolitan surveillance network. Moving averages for KD (MAKD) and respiratory viruses (MARV) were used. RESULTS: 14,902 cases of respiratory virus infections were recorded between 2010-2017. A direct correlation was found between MARV-respiratory syncytial virus (RSV) of one month and year and MAKD of the subsequent month (correlation coefficient (ρ) = +0.441; p < 0.001). A similar association was found for MARV-influenza A (FLU A) (ρ = + 0.362; p < 0.001). MARV-influenza B (FLU B) and MARV-metapneumovirus (MPV) had direct correlations with MAKD (ρ = +0.443; p < 0.001 and ρ = +0.412; p < 0.001, respectively), being FLU B contemporary in month and year with KD, and MPV presenting a one-month lag. CONCLUSION: There is a direct temporal correlation between RSV, FLU A, FLU B and MPV circulation and KD in children from RM, Chile.

Asociación temporal entre la circulación de virus respiratorios y hospitalizaciones por enfermedad de Kawasaki / Temporal association between the circulation of respiratory viruses and hospitalizations due to Kawasaki disease

INTRODUCCIÓN: La etiología de la enfermedad de Kawasaki (EK) es desconocida, planteándose que infecciones virales la gatillan en pacientes susceptibles. OBJETIVO: Estudiar la asociación temporal entre la circulación de virus respiratorios y hospitalizaciones por EK en la Región Metropolitana (RM), Chile, entre 2010-2017. METODOLOGÍA: Estudio ecológico retrospectivo de casos de EK en pacientes bajo 18 años de edad, en base a egresos hospitalarios. La circulación de virus se analizó mediante el reporte de la red de vigilancia metropolitana. Se utilizaron promedios móviles para EK (PMEK) y virus respiratorios (PMVR). RESULTADOS: Se registraron 14.902 casos de infecciones virales respiratorias entre 2010-2017. Se observó correlación directa entre PMVR-virus respiratorio sincicial (VRS) de un mes y año y PMEK del mes subsiguiente (coeficiente de correlación (ρ) = +0,441; p < 0,001), y una asociación similar para PMVR-influenza A (FLU A) (ρ = +0,362; p < 0,001). PMVR-influenza B (FLU B) y PMVR-metapneumovirus (MPV) presentan correlaciones directas con PMEK (ρ = +0,443; p < 0,001 y ρ = +0,412; p < 0,001, respectivamente), siendo contemporáneo en mes y año con EK para FLU B, mientras que MPV presenta un desfase de un mes entre PMVR y PMEK. CONCLUSIÓN: Existe correlación temporal directa entre la circulación de VRS, FLU A, FLU B y MPV con EK en niños de la RM, Chile.

BACKGROUND: The etiology of Kawasaki disease (KD) is unknown. It is believed that viral infections could trigger the disease in susceptible patients. AIM: To study the temporal association between the circulation of respiratory viruses and KD hospitalizations in the Metropolitan Region (MR), Chile, between 2010-2017. METHODS: Ecologic study consisting of a review of KD cases in children under 18 years of age based on hospital discharges. The circulation of respiratory viruses was analyzed using the report of the metropolitan surveillance network. Moving averages for KD (MAKD) and respiratory viruses (MARV) were used. RESULTS: 14,902 cases of respiratory virus infections were recorded between 2010-2017. A direct correlation was found between MARV-respiratory syncytial virus (RSV) of one month and year and MAKD of the subsequent month (correlation coefficient (ρ) = +0.441; p < 0.001). A similar association was found for MARV-influenza A (FLU A) (ρ = + 0.362; p < 0.001). MARV-influenza B (FLU B) and MARV-metapneumovirus (MPV) had direct correlations with MAKD (ρ = +0.443; p < 0.001 and ρ = +0.412; p < 0.001, respectively), being FLU B contemporary in month and year with KD, and MPV presenting a one-month lag. CONCLUSION: There is a direct temporal correlation between RSV, FLU A, FLU B and MPV circulation and KD in children from RM, Chile.

Infección atípica y neurorretinitis por Bartonella henselae en una unidad de hospitalización pediátrica: comunicación de tres casos / Bartonella henselae with atypical infection and neuroretinitis in a pediatric unit: report of three cases

Resumen Bartonella henselae es el agente etiológico de la enfermedad por arañazo de gato (EAG), infección endémica en Chile. Típicamente se presenta como una linfadenopatía regional autolimitada y menos frecuentemente con compromiso sistémico y manifestaciones extraganglionares: en hígado, bazo, hueso, ojo, entre otros. Se presentan tres casos de infección atípica por Bartonella henselae en las que se evidenció compromiso ocular, manifestado como una neurorretinitis. Esta revisión destaca la importancia de la búsqueda activa de complicaciones oculares en pacientes con compromiso sistémico por Bartonella henselae, implicando un cambio en el tratamiento y pronóstico de la enfermedad.

Abstract Bartonella henselae is cat scratch disease's etiological agent, which is considered an endemic infection in Chile. It typically presents as a self-limited regional lymphadenopathy and less frequently with systemic involvement and extranodal or atypical manifestations: hepatosplenic, ocular or musculoskeletal involvement, among others. We present three cases of atypical cat scratch disease with ocular compromise, as neurorretinitis. This review highlights the importance of the active search for ocular complications in patients with disseminated cat scratch disease, leading to possible change in treatment and prognosis of the disease.

[Interactive, semi-automatized and open source computational model applied to respiratory viruses surveillance]. / Modelo computacional interactivo, semi-automatizado y de código abierto aplicado a la vigilancia de virus respiratorios.

Acute respiratory infections (ARI) are an important cause of morbidity and mortality worldwide, affecting mainly children and the elderly. They are associated with a high economic burden, increased number of medical visits and hospitalizations. The surveillance of the circulation of respiratory viruses can reduce the health care associated costs, and to optimize the health response. A platform based on R and its package Shiny was designed, to create an interactive and friendly web interface for gathering, analysis and publication of the data. The data from the Chilean metropolitan respiratory viruses surveillance network, available since 2006, was uploaded into the platform. Using this platform, the researcher spends less than 1 minute to upload the data, and the analysis and publication is immediate, available to be seen by any user with a device connected to Internet, who can choose the variables to be displayed. With a very low cost, in a short time, and using the R programming language, it was possible to create a simple, and interactive platform, considerably decreasing the upload and analysis time, and increasing the impact and availability of this surveillance.

Modelo computacional interactivo, semi-automatizado y de código abierto aplicado a la vigilancia de virus respiratorios / Interactive, semi-automatized and open source computational model applied to respiratory viruses surveillance

Resumen Las infecciones respiratorias agudas (IRA) causadas por virus son una importante causa de morbilidad y mortalidad en el mundo, afectando principalmente a niños y adultos mayores. Se asocian a un alto número de consultas y hospitalizaciones, a una significativa sobrecarga del sistema de salud y a un alto costo económico. La vigilancia de virus respiratorios tiene el potencial de ayudar a optimizar la respuesta sanitaria, garantizar la disponibilidad de recursos humanos, racionalizar los recursos y disminuir los costos asociados a la atención en salud. Con el objetivo de optimizar la recolección y visualización de los datos de nuestro actual sistema de vigilancia de virus respiratorios, se diseñó una plataforma basada en R y sus paquetes Shiny, que permite la creación de una interfase web interactiva y amigable para la recolección, análisis y publicación de los datos. Se ingresaron a esta plataforma los datos de la red de vigilancia metropolitana de virus respiratorios disponibles desde 2006. En esta plataforma, el investigador demora menos de un minuto en registrar los datos. El análisis y publicación es inmediato, llegando a cualquier usuario con un dispositivo conectado a Internet, quien puede elegir las variables a consultar. Con un costo muy bajo, en poco tiempo y utilizando el lenguaje de programación R, se logró crear un sistema simple e interactivo, disminuyendo el tiempo de carga y análisis de datos de forma considerable, posiblemente aumentando el impacto y la disponibilidad de esta vigilancia.

Abstract Acute respiratory infections (ARI) are an important cause of morbidity and mortality worldwide, affecting mainly children and the elderly. They are associated with a high economic burden, increased number of medical visits and hospitalizations. The surveillance of the circulation of respiratory viruses can reduce the health care associated costs, and to optimize the health response. A platform based on R and its package Shiny was designed, to create an interactive and friendly web interface for gathering, analysis and publication of the data. The data from the Chilean metropolitan respiratory viruses surveillance network, available since 2006, was uploaded into the platform. Using this platform, the researcher spends less than 1 minute to upload the data, and the analysis and publication is immediate, available to be seen by any user with a device connected to Internet, who can choose the variables to be displayed. With a very low cost, in a short time, and using the R programming language, it was possible to create a simple, and interactive platform, considerably decreasing the upload and analysis time, and increasing the impact and availability of this surveillance.

[Bartonella henselae with atypical infection and neuroretinitis in a pediatric unit: report of three cases]. / Infección atípica y neurorretinitis por Bartonella henselae en una unidad de hospitalización pediátrica: comunicación de tres casos.

Bartonella henselae is cat scratch disease's etiological agent, which is considered an endemic infection in Chile. It typically presents as a self-limited regional lymphadenopathy and less frequently with systemic involvement and extranodal or atypical manifestations: hepatosplenic, ocular or musculoskeletal involvement, among others. We present three cases of atypical cat scratch disease with ocular compromise, as neurorretinitis. This review highlights the importance of the active search for ocular complications in patients with disseminated cat scratch disease, leading to possible change in treatment and prognosis of the disease.

[Chikungunya, emerging disease in Latin America. Description of the first cases in Chile]. / Chikungunya, enfermedad emergente en América Latina. Descripción de los primeros casos en Chile.

BACKGROUND: Chikungunya (CHIK) was introduced in The Americas in 2013, spreading rapidly. In 2014, the first imported case was diagnosed in Chile. AIM: To identify patients with clinical suspicion of CHIK and describe their clinical and laboratory characteristics. PATIENTS AND METHODS: Patients with suspected CHIK were enrolled. All were confirmed by PCR, IgM or IgG CHIK. A structured survey was applied, which included demographic questions, travel characteristics, clinical manifestations, and laboratory results. RESULTS: 21 patients were enrolled and CHIK was confirmed in 16, who were further analyzed; 12 were female (75%), average age 39 years (27-52). The Caribbean and South Americawere the most frequent sites of exposure. In 63%, the initial symptom was arthralgia. Most frequent symptoms were myalgias, malaise (both 100%), fever, and polyarthralgia (both 94%). The median duration of arthralgias was 90 days (3-262); in 53% arthralgias lasted ≥ 3 months. Main joints involved were ankles, hands, and wrists; 87% reported invalidating pain. Arthritis lasted longer in men than in women (p < 0.001). 38% of patients presented lymphopenia and one patient mild thrombocytopenia. Two patients required hospitalization, one with severe headaches, the other with acute pyelonephritis. CONCLUSIONS: Chikungunya should be suspected in returning travelers presenting with fever and severe polyarthralgia. Travelers to endemic areas should apply prevention measures to avoid mosquito bites.

Chikungunya, enfermedad emergente en América Latina. Descripción de los primeros casos en Chile / Chikungunya, emerging disease in Latin America. Description of the first cases in Chile

Resumen Introducción: Chikungunya (CHIK) se introduce en América el año 2013 diseminándose rápidamente. En 2014, se diagnosticó el primer caso importado en Chile. Objetivos: Identificar pacientes con sospecha clínica de CHIK. Describir sus características clínicas y laboratorio. Pacientes y Métodos: Se enrolaron pacientes con sospecha de CHIK. Se confirmó mediante reacción de polimerasa en cadena (RPC), IgM o IgG CHIKV. Se aplicó encuesta con preguntas demográficas, características del viaje, manifestaciones clínicas y laboratorio a pacientes y médicos tratantes. Resultados: Se enrolaron 21 pacientes, confirmando CHIK en 16 que se analizaron; 12 mujeres (75%), promedio edad 39 años (27-52). Exposición más frecuente fue el Caribe y Sudamérica. El síntoma inicial fue artralgia en 63%. Los síntomas más frecuentes fueron mialgias y malestar general (100%), fiebre y poliartralgia (94%). La mediana de duración de artralgias 90 días (3-262 días) y en 53% > 3 meses. Las articulaciones más comprometidas fueron tobillos, manos y muñecas, 87% con dolor invalidante. La artritis duró más en hombres que en mujeres (p < 0,001). El 38% de pacientes presentó linfopenia y un paciente trombocitopenia leve. Hubo dos hospitalizaciones por cefalea y pielonefritis aguda. Conclusiones: Chikungunya debe sospecharse en viajeros que regresan febriles y con poliartralgias intensas. Medidas de prevención deben ser indicadas a viajeros a zonas de riesgo.

Background: Chikungunya (CHIK) was introduced in The Americas in 2013, spreading rapidly. In 2014, the first imported case was diagnosed in Chile. Aim: To identify patients with clinical suspicion of CHIK and describe their clinical and laboratory characteristics. Patients and Methods: Patients with suspected CHIK were enrolled. All were confirmed by PCR, IgM or IgG CHIK. A structured survey was applied, which included demographic questions, travel characteristics, clinical manifestations, and laboratory results. Results: 21 patients were enrolled and CHIK was confirmed in 16, who were further analyzed; 12 were female (75%), average age 39 years (27-52). The Caribbean and South Americawere the most frequent sites of exposure. In 63%, the initial symptom was arthralgia. Most frequent symptoms were myalgias, malaise (both 100%), fever, and polyarthralgia (both 94%). The median duration of arthralgias was 90 days (3-262); in 53% arthralgias lasted ≥ 3 months. Main joints involved were ankles, hands, and wrists; 87% reported invalidating pain. Arthritis lasted longer in men than in women (p < 0.001). 38% of patients presented lymphopenia and one patient mild thrombocytopenia. Two patients required hospitalization, one with severe headaches, the other with acute pyelonephritis. Conclusions: Chikungunya should be suspected in returning travelers presenting with fever and severe polyarthralgia. Travelers to endemic areas should apply prevention measures to avoid mosquito bites.