Caracterización de los resultados correspondientes al brote de sarampión de Madrid de 2019 en las muestras clínicas procesadas en el Laboratorio Regional de Salud Pública

In the spring of 2019 an increase of cases of measles have been detected in Madrid. The aims of this study is to describe the type of studied clinical samples and the results obtained in this outbreak. Between April 1 and June 25 of 2019 one hundred ninety three biological samples corresponding to 109 clinical suspicions of measles were processed. The serological determinations (IgM and IgG against measles and rubella) were carried out by ELISA. The ARN amplification of measles and rubella virus were performed by RT-PCR.   Forty four cases of measles were confirmed. Two cases have been vaccinated recently and both presented the vaccine genotype A. All wild strains amplified (21) were D8. In Thirty two confirmed cases both samples of pharyngeal exudate and blood were available for RT-PCR for serology respectively. In all 32 the RT-PCR resulted positive (sensitivity 100%, CI95% 86.7- 99.7) while in 22 the IgM was positive (sensitivity 68.8%, CI95% 49.9- 83.3). Inversely, in 49 discarded measles suspicions samples of pharyngeal exudate and blood were available and in all 49 the RT-PCR was negative (specificity 100%, CI95% 90.9- 99.8). In one sample corresponding to a discarded measles suspicion the IgM was positive (specificity 98.0%, CI95% 87.8- 99.9). In the measles and rubella elimination era the standards of surveillance must go directed to detect all possible cases. For this motive is precise the correct timely obtaining of adequate biological samples (sera and especially pharyngeal exudate).