RESUMEN
BACKGROUND: Puerto Rico began screening blood donations for Zika virus RNA with nucleic acid amplification tests (NAATs) on April 3, 2016, because of an emerging Zika virus outbreak. We followed up positive donors to assess the dynamics of viral and serological markers during the early stages of Zika virus infection and update the estimate of infection incidence in the Puerto Rican population during the outbreak. METHODS: Blood donations from volunteer donors in Puerto Rico were screened for the presence of Zika virus RNA using the cobas Zika NAAT. Positive donations were further tested to confirm infection, estimate viral load, and identify Zika virus-specific IgM antibodies. Individuals with positive blood donations were invited to attend follow-up visits. Donations with confirmed infection (defined as detection of Zika virus RNA or IgM on additional testing of index or follow-up samples) were assessed for stage of infection according to Zika virus RNA detectability in simulated minipools, viral load, and Zika virus IgM status. A three-step process was used to estimate the mean duration of NAAT reactivity of Zika virus in human plasma from individuals identified pre-seroconversion with at least one follow up visit and to update the 2016 incidence estimate of Zika virus infection. FINDINGS: Between April 3 and Dec 31, 2016, 53â112 blood donations were screened for Zika virus, of which 351 tested positive, 339 had confirmed infections, and 319 could be staged. Compared with IgM-positive index donations (n=110), IgM-negative index donations (n=209) had higher mean viral loads (1·1â×â106vs 8·3â×â104 international units per mL) and were more likely to be detected in simulated minipools (93% [n=194] vs 26% [n=29]). The proportions of donations with confirmed infections that had viral RNA detected only in individual-donation NAATs (ie, not in simulated minipools) and were IgM positive increased as the epidemic evolved. The estimated mean duration of NAAT detectability in the 140 donors included in the follow-up study was 11·70 days (95% CI 10·06-14·36). Applying this detection period to the observed proportion of donations that were confirmed NAAT positive yielded a Zika virus seasonal incidence estimate of 21·1% (95% CI 18·1-24·1); 768â101 infections in a population of 3â638â773 in 2016. INTERPRETATION: Characterisation of early Zika virus infection has implications for blood safety because infectivity of blood donations and utility of screening methods likely correlate with viral load and serological stage of infection. Our findings also have implications for diagnostic testing, public health surveillance, and epidemiology, and we estimate that around 21% of the Puerto Rican population was infected during the 2016 outbreak. FUNDING: Biomedical Advanced Research and Development Authority, National Heart, Lung, and Blood Institute.
Asunto(s)
Epidemias , ARN Viral/sangre , Infección por el Virus Zika/sangre , Virus Zika/aislamiento & purificación , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/sangre , Donantes de Sangre , Estudios de Cohortes , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Puerto Rico/epidemiología , Factores de Tiempo , Infección por el Virus Zika/virologíaRESUMEN
Puerto Rico has been heavily impacted by Zika virus, a mosquitoborne flavivirus that emerged in the Americas during 2015. Although most persons with Zika virus show no symptoms, the virus can cause neurologic and other complications, including fetal microcephaly. Local Zika virus transmission in Puerto Rico has been reported since December 2015. To prevent transfusion-associated transmission, local blood collection ceased in March 2016 but resumed in April 2016 after Zika virus screening of blood donations became available. Using data from screening of blood donations collected by the 2 largest blood centers in Puerto Rico during April 3-August 12, 2016, and assuming a 9.9-day duration of viremia, we estimated that 469,321 persons in Puerto Rico were infected during this period, for an estimated cumulative incidence of 12.9%. Results from blood donation screening during arboviral outbreaks can supplement routine clinical and surveillance data for improved targeting of prevention efforts.
Asunto(s)
Donantes de Sangre , Infección por el Virus Zika/epidemiología , Virus Zika , Adolescente , Adulto , Femenino , Historia del Siglo XXI , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Vigilancia de la Población , Puerto Rico/epidemiología , Estaciones del Año , Adulto Joven , Virus Zika/inmunologíaRESUMEN
BACKGROUND: Zika virus (ZIKV) is transmitted by Aedes mosquitos and can result in severe congenital and adult neurologic abnormalities. ZIKV has rapidly spread northward through Central America and the Caribbean and autochthonous cases have been identified in the continental United States. High rates of ZIKA RNA positivity were detected in blood donors during previous epidemics. ZIKV transmission by transfused blood from healthy donor components has been a growing concern. STUDY DESIGN AND METHODS: Individual-donation aliquots of plasma from volunteer blood donors were tested individually with an investigational Procleix ZIKV assay. Initially reactive samples were tested for ZIKV RNA in plasma and red blood cells (RBCs) and for ZIKV-specific antibodies in serum. A confirmed positive classification required confirmation of RNA and/or detection of ZIKV antibodies in index and/or follow-up samples. RESULTS: Between September 19 and November 30, 2016, a total of 466,834 donations were screened for ZIKV RNA. Five donors (one in approx. 93,000) were reactive for ZIKV RNA by both the Procleix ZIKV assay and supplemental testing. The donations were collected outside areas considered as having active transmission, and all five donors had travel exposures. A lookback case demonstrated no infection despite transfusion of a Zika IgG-positive platelet (PLT) component with probable low levels of ZIKV RNA. CONCLUSIONS: This report describes the first ZIKV-positive donors detected outside areas with active transmission. These donors most likely represent travel-acquired "tail-end infections" with prolonged RBC-associated ZIKV RNA. The lack of transmission to the recipient of an apheresis PLT may suggest that these units are not infectious.
Asunto(s)
Donantes de Sangre , ARN Viral/sangre , Infección por el Virus Zika , Virus Zika , Adulto , Región del Caribe/epidemiología , América Central/epidemiología , Femenino , Humanos , Masculino , Infección por el Virus Zika/sangre , Infección por el Virus Zika/etnología , Infección por el Virus Zika/transmisiónRESUMEN
Transfusion-transmitted infections have been documented for several arboviruses, including West Nile and dengue viruses (1). Zika virus, a flavivirus transmitted primarily by Aedes aegypti mosquitoes that has been identified as a cause of congenital microcephaly and other serious brain defects (2), became recognized as a potential threat to blood safety after reports from a 2013-2014 outbreak in French Polynesia. Blood safety concerns were based on very high infection incidence in the population at large during epidemics, the high percentage of persons with asymptomatic infection, the high proportion of blood donations with evidence of Zika virus nucleic acid upon retrospective testing, and an estimated 7-10-day period of viremia (3). At least one instance of transfusion transmission of Zika virus has been documented in Brazil after the virus emerged there, likely in 2014 (4). Rapid epidemic spread has followed to other areas of the Americas, including Puerto Rico.
Asunto(s)
Seguridad de la Sangre/métodos , Brotes de Enfermedades/prevención & control , Tamizaje Masivo , Infección por el Virus Zika/prevención & control , Humanos , Puerto Rico/epidemiologíaRESUMEN
Chikungunya virus (CHIKV) caused large epidemics throughout the Caribbean in 2014. We conducted nucleic acid amplification testing (NAAT) for CHIKV RNA (n = 29,695) and serologic testing for IgG against CHIKV (n = 1,232) in archived blood donor samples collected during and after an epidemic in Puerto Rico in 2014. NAAT yields peaked in October with 2.1% of donations positive for CHIKV RNA. A total of 14% of NAAT-reactive donations posed a high risk for virus transmission by transfusion because of high virus RNA copy numbers (10 (4) -10 (9) RNA copies/mL) and a lack of specific IgM and IgG responses. Testing of minipools of 16 donations would not have detected 62.5% of RNA-positive donations detectable by individual donor testing, including individual donations without IgM and IgG. Serosurveys before and after the epidemic demonstrated that nearly 25% of blood donors in Puerto Rico acquired CHIKV infections and seroconverted during the epidemic.
Asunto(s)
Fiebre Chikungunya/epidemiología , Fiebre Chikungunya/virología , Virus Chikungunya/aislamiento & purificación , Viremia/epidemiología , Donantes de Sangre , Epidemias , Humanos , Incidencia , Técnicas de Amplificación de Ácido Nucleico , Puerto Rico , Pruebas SerológicasRESUMEN
Species distribution models were constructed for ten Ixodes species and Amblyomma cajennense for a region including Mexico and Texas. The model was based on a maximum entropy algorithm that used environmental layers to predict the relative probability of presence for each taxon. For Mexico, species geographic ranges were predicted by restricting the models to cells which have a higher probability than the lowest probability of the cells in which a presence record was located. There was spatial nonconcordance between the distributions of Amblyomma cajennense and the Ixodes group with the former restricted to lowlands and mainly the eastern coast of Mexico and the latter to montane regions with lower temperature. The risk of Lyme disease is, therefore, mainly present in the highlands where some Ixodes species are known vectors; if Amblyomma cajennense turns out to be a competent vector, the area of risk also extends to the lowlands and the east coast.
RESUMEN
A molecular epidemiologic investigation in two Brazilian states (Rondônia and São Paulo) was undertaken to determine if Ehrlichia species responsible for human and animal ehrlichioses in North America could be found in Brazilian vectors, potential natural mammalian reservoirs and febrile human patients with a tick bite history. Samples, including 376 ticks comprising 9 Amblyomma species, 29 capybara (Hydrochaeris hydrochaeris) spleens, 5 canine blood, and 75 human blood samples from febrile patients with history of tick bites were tested by a real-time PCR assay targeting a fragment of the Ehrlichia dsb gene. Ehrlichia DNA was not detected in any tick, capybara or human samples. In contrast, 4 out of 5 dogs contained Ehrlichia canis DNA in their blood, which were sequenced, representing the first report of E. canis infecting dogs in the Amazon region of Brazil. Further studies are needed to evaluate the presence of other agents of human and animal ehrlichioses in Brazil.