January 26, 2001

Invasive Meningococcal Disease: Alberta
The Capital Health Authority (CHA) which serves a population of 827,500 in Edmonton, Alberta and surrounding counties has experienced significantly increased rates of invasive meningococcal infection (IMD) since December 1999 associated with a novel serogroup C clone. The usual incidence of IMD in the region is 0.5-1.5/100 000 annually. Between December 1999 and December 2000 inclusive 49 cases of IMD occurred in CHA (47 in 2000). All cases have been sporadic affecting all parts of the region. Routine public health follow-up including contact tracing and prophylactic antibiotics has occurred with each case. The age groups most affected were 0-4, 15-19 and 20-24 years with rates of 21.6, 27.3 and 10.6 per 100,000, respectively, in 2000. The outbreak was declared in February 2000 when the rate in the 15-19 year group reached 10/100,000 in < 3 months. A mass immunization campaign in CHA using quadrivalent vaccine was undertaken with the cooperation of Alberta Health and Wellness with 168,000 children aged 2-19 immunized over a 2-week period (an 80% coverage rate). Cases continued to occur through the spring and summer in all age groups but primarily in those 19 years or less. Vaccine effectiveness rate was 92% between February and October with 2 cases in immunized children and 6 cases in the population eligible for immunization but unimmunized. The case occurrence accelerated in the fall, 2000, resulting in a rate of 10.6/100,000 in the 20-24 year age group. In October 2000 quadrivalent vaccine was again offered to unimmunized 2-19 year olds and the vaccine campaign was expanded to all 20-24 year olds. A further 60,000 young people were immunized resulting in a coverage rate of 87% of 2-25 year-olds. The Microbiology and Public Health Laboratory of Alberta identified a novel strain of Neisseria meningitidis serogroup C through DNA characterization of involved strains. The laboratory examined the previous 4 years of meningococcal isolates in Alberta and did not find a similar strain. Isolates from other jurisdictions are currently being tested with no similar isolate being identified to date. In summary, CHA has experienced an outbreak of IMD caused by a new serogroup C clone previously unrecognized in this province. The demonstration of the disease consequences of a new clone in a community combined with timely laboratory characterization of different serogroup C clones may prove to be ground breaking in the future management of meningococcal disease.
Source: Capital Health Authority, Edmonton, Alberta

Chlamydia Trachomatis: Scandanavia
Scandanavian researchers have investigated the relationship between infection with subtypes of chlamydia and the subsequent development of invasive cervical carcinoma by conducting a longitudinal, nested case-control study within a cohort of 530,000 women who provided samples to serum banks in Finland, Norway, and Sweden. The data files were linked to respective national cancer registries. One hundred and eighty-one cases of invasive cervical carcinoma were identified. In all, 150 (82%) of the cancers were squamous cell carcinomas, and the rest were adenocarcinomas. The overall prevalence rates of serum antibodies to C. trachomatis was 27% among cancer cases and 13% in controls. Three types of chlamydia (serotypes G, I, and D) significantly increased the risk of cervical cancer: women infected with serotype G carried the highest risk, with a 6.6-fold increased incidence over uninfected cohorts, and those infected with serotypes I and D faced a risk 4 and 2.7 times greater, respectively. Moreover, the researchers found that exposure to multiple strains, or to more than one serotype, also increased the risk of squamous cell cervical cancer. Adenocarcinoma of the cervix did not seem to be associated with chlamydia. Although the study is interesting, it is unclear if chlamydia is an independent risk factor for cervical cancer or merely associated with it because it is associated with other risk factors, such as human papillomavirus and unprotected sexual activity.
Source: Journal of the American Medical Association, Vol 285, No 1, January 3, 2001

The details given are for information only and may be very provisional. Where incidents are considered of national importance and are ongoing, the initial report will be updated as new information becomes available.