Update on Influenza in the Americas

United States: During Epidemiological Week (EW) 43 (19–25 October 2003), 1.8% of all patient visits to sentinel providers was for influenza-like illness (ILI), a figure below the national baseline of 2.5%. The proportion of deaths attributed to pneumonias and influenza was 6.1%.

For this week, WHO and the US National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories examined 707 samples to detect influenza virus, of which 48 (6.8%) came out positive. Of these positive samples, the Influenza A Subtype H3N2 virus was identified in 32 of them; unsubtyped Influenza A, in 15; and Influenza B, in 1. Since 28 September, a total of 3,115 samples have been examined, with 121 of them (3.9%) positive. Of the 121 viruses identified, 119 (98%) were Influenza A, of which 47 (39%) were subtyped as H3N3; and 2 (2%) were Influenza B. Of the isolates, 110 (91%) came from the West South Central region.

Source: Influenza, Reports and Surveillance Methods in the United States: Influenza Summary Update, Week ending October 25, 2003-Week 43. Centers for Disease Control and Prevention of the United States (CDC), National Center for Infectious Diseases (NCID).

Canada: During the Epidemiological Week ending on 25 October 2003 (EW 43), sentinel providers reported 33 cases of influenza-like illness (ILI) per every 1,000 patient visits, which for this week exceeded the national baseline calculated by doubling the number of reports from the preceding week. This week, Health Canada received 1,416 reports of laboratory tests for influenza, 165 (11.65%) of which detected Influenza A (in Saskatchewan and Alberta). The National Microbiology Laboratory has antigenetically characterized 14 influenza viruses to date, all of which were similar to the A/Panamá/2007/99 strain included in the vaccine for the 2003–2004 season. During EW 43, Alberta reported 3 influenza outbreaks in schools and 2 outbreaks in long-term care (LTC) facilities. For 2003, a total of 7,179 tests have been conducted, of which 340 were positive (339 with Influenza A and 1 with Influenza B).

Source: FluWatch, October 19 to October 25, 2003 (Week 43), Health Canada website: English   |   français.

Chile: For the moment, numerous cases of Influenza A have been characterized that are similar to the A/Panama/2007/99 (H3N2) strain included in the 2003 vaccine, along with one Influenza B case. For the week of 19–25 October 2003, sporadic activity has been detected, with 2 cases of Influenza A in Talcahuano and 1 in Concepción.

Source: FluNet: Country Reports for 2003-2004 Season, World Health Organization (WHO).

Caribbean: Influenza activity, was detected in Suriname during the months of June and July 2003. An influenza virus strain was isolated and typed similar to A/Panamá/2007/99 (H3N2), which was probably associated with the influenza season in the Southern Hemisphere. However, during the last week of October, CAREC has also been receiving laboratory requests from patients clinically presenting Acute Respiratory Syndrome, which may be an indication of influenza virus activity in the Caribbean.

Source: Caribbean Surveillance Network (CariSurvNet), Caribbean Epidemiology Centre (CAREC).

Update on SARS

On 6 November 2003, to follow up on its recent meeting, the World Health Organization (WHO) published via its website the Summary of the Discussion and Recommendations of the SARS Laboratory Workshop, 22 October 2003 (6 pp, PDF).

III^rd Biannual Meeting of Subregional Emerging-Disease Surveillance Networks

Since 2000, the Initiative on Subregional Emerging-Disease Surveillance Networks has been holding biannual meetings to coincide with the International Conference on Emerging Infectious Diseases. We are pleased to announce next year's meeting will be held from 27–29 February 2004 in Atlanta, Georgia, USA, immediately before the EID Conference (held on 29 February–3 March 2004). The PAHO/WHO Country Offices will be providing the national Ministries of Health with detailed information on a regular basis.

Erratum: In the EID Weekly Updates for 30 October 2003, an error occurred in the section on “Update on Influenza in the Americas,” second paragraph, first sentence, which should be “WHO and US National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories.”