Sistemas de vigilancia resultan exitosos en el seguimiento de la influenza porcina

Las preocupaciones acerca de la efectividad de los sistemas de vigilancia para la influenza durante la fase temprana de la pandemia de gripo porcina, fueron infundados de acuerdo a una investigación publicada recientemente en bmj.com

El análisis de las muestras de miembros de la población quienes llamaron al NHS Direct reportando tener catarro o síntomas similares al de la influenza durante junio del 2009, coincidieron estrechamente con las tasas de transmisión local en seis regiones de Inglaterra.

Mientras que los laboratorios confirmaban un incremento mantenido de casos de influenza pandémica H1N1 en Inglaterra durante mayo del 2009, hubo una preocupación creciente por la capacidad de los sistemas de vigilancia existentes en cuanto a su habilidad para reconocer la ‘transmisión mantenida en la comunidad’

De manera que se retomó un esquema de auto muestreo que había sido puesto en práctica durante el invierno 2003-04 para fortalecer el monitoreo de la transmisión viral local.

http://www.medicalnewstoday.com/articles/162904.php

A total of 1,385 specimens from callers to NHS Direct during June 2009 in six regions of England were tested: two regions where clinical diagnoses were increasing (London and West Midlands) and another four regions that were much less affected.

None of the participants had recently returned from an affected country, or had had contact with a confirmed case. And all were advised to self-treat their symptoms.

Pandemic influenza A (H1N1) infections were detected in 97 (7%) samples, in addition to eight influenza A H3 infections and two influenza B infections. The greatest H1N1 infection rate was in 16 to 24 year olds, in whom 20% were infected.

The results show that the change in the proportion of people infected each week closely matched the rate of increase in clinical laboratory diagnoses, giving a reliable indication of the extent to which local transmission was occurring in various parts of the country.

For example, in the regions where clinical diagnoses were low, the scheme suggested an absence of sustained community transmission, whereas in regions where clinical diagnoses were rising rapidly, the scheme provided complementary and reliable evidence of increasing community transmission compared to reported laboratory diagnoses.

The authors conclude that if the current pandemic influenza A (H1N1) intensifies through the coming autumn and winter, self-sampling of members of the public with cold or flu-like symptoms who telephone clinical advice services should enable relatively accurate monitoring of the milder flu-like illness attributable to particular flu types in different regions, as well as both the antiviral susceptibility of strains and any antigenic drift (random mutations in the genes of a virus that can lead to a loss of immunity).

Following the launch of the National Pandemic Flu Service (NPFS), the Health Protection Agency (HPA) began such a scheme from 3 August 2009 with respect to callers and internet contacts to the government service. Data from this surveillance system is routinely published in the HPA online weekly epidemiological report on pandemic influenza A (H1N1).