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New information is emerging about SARS-CoV-2 epidemiology and immunity, but little of this information comes from low- and middle-income countries or from patients receiving care in the outpatient setting. The current study investigated the SARS-CoV-2 infection status and antibody responses in 157 patients seeking care for a respiratory disease suggestive of COVID-19 in private healthcare clinics during the first wave (June-October 2020) of infections in Nicaragua. We examined nasal swabs for the presence of viral RNA via RT-PCR and longitudinally collected sera for the changes in SARS-CoV-2 Spike antibody levels over six months. Among patients with confirmed SARS-CoV-2 infections, we evaluated if clinical symptoms were associated with age, hematological parameters and co-morbidities. The combination of PCR and paired serology identified 60 (38%) of the 157 outpatients as acute COVID-19. While both PCR and serology identified the majority (n = 38, 64%) of the acute infections, a notable number of outpatients were identified by RT-qPCR (n = 13, 22%) or by serology (n = 9, 14%) only. During the longitudinal study, we identified 6 new infections by serology among the 97 non-COVID-19 subjects. In conclusion, this study report that more than one third of the outpatients seeking care for acute respiratory disease during the first epidemic wave of SARS-CoV-2 in Nicaragua had an acute mild COVID-19 infection that correlate with prolonged humoral response. This immune response to the RBD antigen, more likely IgG dependent, significantly increased between the acute to convalescent and decay in the late convalescent but still remained seropositive.
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BACKGROUND: Rickettsial infections and Q fever present similarly to other acute febrile illnesses, but are infrequently diagnosed because of limited diagnostic tools. Despite sporadic reports, rickettsial infections and Q fever have not been prospectively studied in Central America. METHODOLOGY/PRINCIPAL FINDINGS: We enrolled consecutive patients presenting with undifferentiated fever in western Nicaragua and collected epidemiologic and clinical data and acute and convalescent sera. We used ELISA for screening and paired sera to confirm acute (≥4-fold rise in titer) spotted fever and typhus group rickettsial infections and Q fever as well as past (stable titer) infections. Characteristics associated with both acute and past infection were assessed. CONCLUSIONS/SIGNIFICANCE: We enrolled 825 patients and identified acute rickettsial infections and acute Q fever in 0.9% and 1.3%, respectively. Clinical features were non-specific and neither rickettsial infections nor Q fever were considered or treated. Further study is warranted to define the burden of these infections in Central America.
Assuntos
Febre/etiologia , Febre Q/diagnóstico , Febre Q/epidemiologia , Infecções por Rickettsia/diagnóstico , Infecções por Rickettsia/epidemiologia , Doença Aguda , Adolescente , Anticorpos Antibacterianos/sangue , Criança , Ensaio de Imunoadsorção Enzimática , Feminino , Febre/microbiologia , Hospitalização , Humanos , Masculino , Nicarágua/epidemiologia , Febre Q/microbiologia , Infecções por Rickettsia/imunologia , Infecções por Rickettsia/microbiologia , Tifo por Ácaros/sangue , Tifo por Ácaros/diagnóstico , Tifo por Ácaros/microbiologia , Testes SorológicosRESUMO
BACKGROUND: Dengue is an emerging infectious disease of global significance. Suspected dengue, especially in children in Nicaragua's heavily-urbanized capital of Managua, has been well documented, but unsuspected dengue among children and adults with undifferentitated fever has not. METHODOLOGY/PRINCIPAL FINDINGS: To prospectively study dengue in semi-urban and rural western Nicaragua, we obtained epidemiologic and clinical data as well as acute and convalescent sera (2 to 4 weeks after onset of illness) from a convenience sample (enrollment Monday to Saturday daytime to early evening) of consecutively enrolled patients (n = 740) aged ≥ 1 years presenting with acute febrile illness. We tested paired sera for dengue IgG and IgM and serotyped dengue virus using reverse transcriptase-PCR. Among 740 febrile patients enrolled, 90% had paired sera. We found 470 (63.5%) were seropositive for dengue at enrollment. The dengue seroprevalance increased with age and reached >90% in people over the age of 20 years. We identified acute dengue (serotypes 1 and 2) in 38 (5.1%) patients. Only 8.1% (3/37) of confirmed cases were suspected clinically. CONCLUSIONS/SIGNIFICANCE: Dengue is an important and largely unrecognized cause of fever in rural western Nicaragua. Since Zika virus is transmitted by the same vector and has been associated with severe congenital infections, the population we studied is at particular risk for being devastated by the Zika epidemic that has now reached Central America.
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Dengue/diagnóstico , Febre/diagnóstico , Adolescente , Adulto , Anticorpos Antivirais/sangue , Criança , Pré-Escolar , Dengue/sangue , Dengue/epidemiologia , Dengue/virologia , Vírus da Dengue/imunologia , Vírus da Dengue/isolamento & purificação , Feminino , Febre/sangue , Febre/epidemiologia , Febre/virologia , Humanos , Masculino , Pessoa de Meia-Idade , Nicarágua/epidemiologia , Estudos Prospectivos , Adulto JovemRESUMO
Ehrlichia chaffeensis, the etiologic agent of human monocytic ehrlichiosis (HME), has been extensively studied as a cause of acute febrile illness and an emerging tick-borne zoonosis in the United States. Limited data suggest its presence in other regions, including Central and South America but not Nicaragua to date. Diagnosis of E. chaffeensis infection by indirect immunofluorescence assay (IFA) is the reference standard due to its presumed high sensitivity and specificity, but IFA is impractical, variably reproducible, and cumbersome for large epidemiologic studies and for clinical diagnosis in resource-poor regions. We evaluated a high-throughput, objective peptide-based enzyme-linked immunosorbent assay (ELISA) for use alone or in combination with IFA. We found that it performed best as a screening test (sensitivity, 100%; specificity, 84%) to reduce the proportion of serum samples that were required by the more cumbersome and subjective IFA testing to <20%. Using a two-step diagnostic approach (IFA is performed if the ELISA is positive), we identified E. chaffeensis or a serologically and antigenically similar organism as a heretofore unrecognized cause of acute febrile illness in humans in Nicaragua and demonstrated the utility of the peptide ELISA as a screening tool for large-scale clinical studies.
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Anticorpos Antibacterianos/sangue , Ehrlichia chaffeensis/imunologia , Ehrlichiose/diagnóstico , Ensaio de Imunoadsorção Enzimática/métodos , Técnica Indireta de Fluorescência para Anticorpo/métodos , Doenças Transmitidas por Carrapatos/diagnóstico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Nicarágua , Sensibilidade e Especificidade , Adulto JovemRESUMO
BACKGROUND: Epidemic severe leptospirosis was recognized in Nicaragua in 1995, but unrecognized epidemic and endemic disease remains unstudied. METHODOLOGY/PRINCIPAL FINDINGS: To determine the burden of and risk factors associated with symptomatic leptospirosis in Nicaragua, we prospectively studied patients presenting with fever at a large teaching hospital. Epidemiologic and clinical features were systematically recorded, and paired sera tested by IgM-ELISA to identify patients with probable and possible acute leptospirosis. Microscopic Agglutination Test and PCR were used to confirm acute leptospirosis. Among 704 patients with paired sera tested by MAT, 44 had acute leptospirosis. Patients with acute leptospirosis were more likely to present during rainy months and to report rural residence and fresh water exposure. The sensitivity of clinical impression and acute-phase IgM detected by ELISA were poor. CONCLUSIONS/SIGNIFICANCE: Leptospirosis is a common (6.3%) but unrecognized cause of acute febrile illness in Nicaragua. Rapid point-of-care tests to support early diagnosis and treatment as well as tests to support population-based studies to delineate the epidemiology, incidence, and clinical spectrum of leptospirosis, both ideally pathogen-based, are needed.
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Febre/microbiologia , Leptospirose , Doença Aguda , Adolescente , Adulto , Anticorpos Antibacterianos/sangue , Técnicas Bacteriológicas , Criança , Pré-Escolar , Feminino , Humanos , Leptospirose/diagnóstico , Leptospirose/epidemiologia , Leptospirose/imunologia , Leptospirose/microbiologia , Masculino , Nicarágua/epidemiologia , Adulto JovemRESUMO
The objective of this study was to determine the prevalence of HIV and syphilis and to identify risk factors among pregnant women visiting antenatal clinics in León, Nicaragua. During February to April 2004, blood samples from pregnant women were collected after written consent had been obtained. The samples were tested for antibodies against HIV and Treponema pallidum. A questionnaire was also completed. In total, 1,059 women were included. Antibodies against HIV were not detected in any of the women, whereas antibodies against T. pallidum were detected in 16 (1.5%). Risk factors for syphilis included illiteracy, lower education, and two or more pregnancies. HIV does not seem to be highly prevalent among pregnant women in León (prevalence, 0%; 95% CI, 0.0-0.3). The higher proportion of women infected with syphilis than found in earlier studies suggests that sexually transmitted diseases are circulating in the general population and highlights the increasing importance of HIV prevention.