Invasive bacterial infections following influenza: a time-series analysis in Montréal, Canada, 1996-2008

BACKGROUND

Shared seasonal patterns, such as between influenza and some respiratory bacterial infections, can create associations between phenomena not causally related.

OBJECTIVES

To estimate the association of influenza with subsequent bacterial infections after full adjustment for confounding by seasonal and long-term trends.

METHODS

Time series of weekly counts of notified cases of invasive infections with Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae and Streptococcus pyogenes, in Montréal, Canada, 1996-2008, were modelled by negative binomial regression, with terms representing seasonal and long-term trends and terms for numbers of positive laboratory tests for influenza A and B.

RESULTS

The associations of S. pneumoniae, H. influenzae and N. meningitidis with influenza disappeared after seasonal terms were added to the model. However, the influenza B count remained associated with the S. pyogenes counts for the same week and the following week: S. pyogenes incidence rate ratios were 1.0376 (95% CI: 1.0009-1.0757) and 1.0354 (0.9958-1.0766), respectively, for each increase of 1 in the influenza count.

CONCLUSIONS

Influenza B accounts for about 8 percnt; of the incidence of invasive S. pyogenes infections, over and above any effect associated with modellable seasonal and long-term trends. This association of influenza B with S. pyogenes infections can be attributed largely to the years 1997, 2001, 2007 and 2008, when late peaks in influenza B counts were followed by peaks in S. pyogenes notifications. This finding reinforces the case for universal immunization against influenza, as partial protection against the 'flesh eating disease'.

Ion mobility spectrometry of drugs of abuse in customs scenarios: concentration and temperature study

A custom-built ion mobility spectrometer has been used to obtain the IMS spectra of cocaine, heroin, amphetamine sulfate and LSD at different drug concentrations and desorption temperatures. Practical detection limits for these four drugs were obtained as a function of desorber temperature and for heroin as a function of analysis time. Spectral and ionization interferences for each of the four drugs of interest were determined. Spectral interferences by innocuous materials are few; ionization interferences occur only at very high ratios of the mass of innocuous material to that of the drug of interest.

Preliminary report on the observation of a coronavirus in the intestine of the laboratory rabbit

Intestinal infections are a major cause of mortality in domestic rabbits. Although a few pathogenic organisms have been associated with this type of infection, it is often impossible to demonstrate the presence of any etiologic agents. Recently viral particles were observed in the intestine of diseased rabbits submitted to our laboratory for diagnosis. A study was then initiated to evaluate the presence of viral agents in the intestine of rabbits showing clinical signs of enteritis. Viral particles with morphological characteristics of the Coronaviridae family were observed by electron microscopy in most specimens of fecal material obtained from sick rabbits. Such particles were not seen in the feces of healthy animals. These particles, which have a density of 1.07-1.18g/cm3 on sucrose gradient, hemagglutinate rabbit red blood cells. Furthermore this virus has some antigenic relationship with the human coronavirus 229-E since immune serum to this virus blocks the hemagglutination of the rabbit erythrocytes. Antibody titers to this virus were detected in rabbit sera obtained from colonies with a high incidence of intestinal infections. When fecal material containing coronavirus particles were inoculated on various tissue culture systems, no cytopathic effects were observed.