Virus emergentes de importancia en medicina transfusional: paradigmas, hitos, aprendizajes / Emergent virus with importance in transfusional medicine: paradigms, milestones, learnings

Las infecciones emergentes juegan un papel importantísimo en medicina transfusional. La experiencia con HIV puso en evidencia la necesidad de actuar rápidamente. La lentitud en la respuesta de los Bancos de Sangre y la falta de un liderazgo en la adopción de medidas preventivas dieron lugar a una transmisión importante por vía transfusional. En cuanto a las hepatitis postransfusionales NANB, aprendimos las lecciones acerca de las pruebas subrogantes. Sin embargo, la respuesta para prevenir la transmisión de HCV fue lenta porque la comunidad científica estaba focalizada en la transmisión de HIV. En el caso del XMRV, la presión ejercida por la comunidad fue muy importante. Se formaron grupos multidisciplinarios de expertos que realizaron gran cantidad de estudios y la respuesta ocurrió rápidamente, aunque al poco tiempo se demostró que este patógeno no era relevante para la Medicina Transfusional. Con respecto al WNV, la familiaridad con los modelos desarrollados por el CDC para estimar los riesgos y las lecciones aprendidas por las experiencias con HIV y HCV facilitaron una respuesta rápida y se implementaron medidas rápidamente para minimizar el riesgo de transmisión por vía transfusional. Se abrió un nuevo paradigma: la importancia de considerar los riesgos de transfusión que pueden derivar de agentes que causan viremias breves, usualmente asintomáticas, pero con el potencial de generar brotes estacionales de alta incidencia. La respuesta a la amenaza con WNV fue rápida, apropiada y exitosa. Las nuevas herramientas de biología molecular han permitido el aislamiento de numerosos gérmenes emergentes y lo seguirán haciendo en el futuro. Estar alertas ante nuevos patógenos de potencial importancia es nuestra responsabilidad.

Emerging infections play an extremely important role in transfusion medicine. Experience with HIV highlighted the necessity to act quickly. The slow Blood Banks response and the lack of leadership in the adoption of preventive measures resulted in a significant transfusional transmission. Regarding the post-transfusion NANB hepatitis, we have learned the lessons about the surrogate tests. However, the response to prevent HCV transmission was slow given that the scientific community was focused on HIV transmission. In the case of XMRV, pressure from the community was extremely important. Multidisciplinary groups of experts who conducted many studies were formed and the answer came quickly, but soon it was proved that this pathogen was not relevant to Transfusion Medicine. With respect to WNV, familiarity with the models developed by the CDC to estimate the risks and lessons learned from experiences with HIV and HCV facilitated a quick response, and measures were quickly implemented to minimize the risk of transmission by transfusion. A new paradigm came up: the importance of con­sidering the risks of transfusion that may result from agents that cause brief, usually asymptomatic viremia, but with the potential to generate high incidence seasonal outbreaks of viralloads. The response to the threat with WNV was rapid, appropriate and successful. The new tools of molecular biology have allowed the isolation of many emerging germs and will continue to do so in the future. Being alert to new pathogens of potential importance is our responsibility.

Emergence of dengue virus type-3 in northern India.

During the last few decades dengue has reemerged in several parts of Southeast Asia, including India. A major outbreak of dengue infection occurred in northern India during October to December 2003. To determine the etiology, we carried out serological, virological and molecular investigations of this outbreak. A total of 76 dengue suspected patient blood samples were collected from Gwalior, Madhya Pradesh and Delhi, India. Serological investigations carried out using an in-house Dipstick ELISA protocol revealed the presence of anti-dengue antibodies in 53 patients. Twelve of them (22%) had a positive IgM response, indicative of primary infection, and 22 of them (42%) revealed only IgG antibodies, indicative of secondary infection. RT-PCR analysis employing dengue group specific amplimer revealed the presence of dengue specific RNA in four acute phase samples. These four RT-PCR positive samples were further processed for virus isolation in C6/36 cells and suckling mice, yielding four dengue virus isolates. The Nested PCR analysis employing serotype specific amplimer revealed the presence of dengue-3 specific 389 bp amplicon. This study confirmed the reemergence of dengue virus type-3 in a dominant form in India after a gap of nine years. Earlier, dengue virus type-2 was implicated as the etiology of a major dengue epidemic in Delhi in 1996 and Gwalior in 2001. The implication of dengue type-3 as etiology of a DHF epidemic in neighboring Sri Lanka and Bangladesh recently confirms the reemergence of dengue type-3 as the dominant form on the Indian subcontinent.