Update on Influenza in the Americas

United States (USA): Influenza activity in the USA continued to increase during Epidemiological Week (EW) 45 (2–8 November 2003). WHO (World Health Organization) and NSSREV (National Surveillance System of Respiratory and Enteric Viruses) collaborating laboratories tested 1,056 samples for influenza, of which 203 (19.2%) were positive: 170 for unsubtyped Influenza A, 30 for Influenza A Subtype H3N2, 3 for Influenza B. The percentage of positive samples increased from 7.9% during EW 44 to 19.2% for this week. A review of national virological surveillance data from the 1976–1977 season to the present shows this to be the earliest week in which the percentage of positive specimens has exceeded 10% nationally; the South Central and the Mountain regions presented the greatest percentage of positive specimens, with 46.5% and 34.7%, respectively. The proportion of deaths attributed to pneumonia and influenza was 6.2%, below epidemic threshold for this week.

Source: Influenza Summary Update, Week Ending November 8, 2003-Week 45, Influenza: Reports & Surveillance Methods in the United States. Centers for Disease Control and Prevention of the United States (CDC), National Center for Infectious Diseases (NCID).

The Department of Health and Human Services of the United States (DHHS) is engaged in an intense public-information campaign, urging people to get their flu shot. Health authorities have noticed that this flu season is expected to be much more severe that the previous one. In a press release published on 17 November 2003, Dr. Gerberding announced a new strain of the Influenza A virus, Subtype H3N2 Fujian, that is not included in this year’s vaccine for the northern hemisphere. The vaccine protects against three strains of flu: H3N2 Panama, H1N1 New Caledonia, and Influenza B Hong Kong. However, experiments with animals suggest that the vaccine will provide cross-protection against the Fujian strain. For more information, consult the source below.

Source: CDC News Conference Transcript: Update on Current Influenza Season. Centers for Disease Control and Prevention of the United States (CDC).

Canada: During EW 45 (2–8 November 2003), widespread influenza activity was reported in all regions in Saskatchewan. Localized activity was reported throughout all of Alberta and the Northwest Territories, as well as in two regions of Ontario and one region of British Columbia. For this week, Health Canada received 1,954 reports of laboratory tests for influenza, of which 381 (19.5%) were positive for Influenza A. From the beginning of this year’s season (beginning on 24 August 2003) to date, the National Microbiology Laboratory has antigenically characterized 14 specimens, all of them A/Panama/2007/99-like, which is included in the vaccine for the current season.

Source: FluWatch: November 2 to November 8, 2003 (Week 45). Health Canada: English   |   français

Hepatitis A Outbreak in the United States

USA, 15 November 2003: The Food and Drug Administration of the United States (FDA) is warning the public that several of the recent Hepatitis A outbreaks have been associated with the consumption of raw or semi-cooked green onions (scallions). The outbreaks associated with this vegetable being served in restaurants occurred in Tennessee, North Carolina, and Georgia last September.

Another outbreak during late October and early November of this year occurred among customers at a restaurant in Pennsylvania, though its source has not been established. Pennsylvania health authorities, the CDC, and the FDA are investigating whether a specific food is associated to with the Pennsylvania outbreak and, if so, its source. More than 500 cases have been reported to the Pennsylvania Department of Health.

Sources

• FDA Talk Paper: Consumers Advised That Recent Hepatitis A Outbreaks Have Been Associated With Green Onions. Food and Drug Administration of the United States (FDA).
• Response by Dr. Gerberding made during CDC News Conference Transcript: Update on Current Influenza Season, op. cit. CDC.

Update on West Nile Virus (WNV) in the Americas

USA: During EW 45, 12 states reported a total of 176 human WNV cases (Arizona, Georgia, Kansas, Louisiana, Maryland, Nebraska, New Jersey, New Mexico, Pennsylvania, South Dakota, Tennessee, and Virginia), including 2 fatalities in Louisiana. During the same period, infections were reported in 39 dead birds, 12 mosquito pools, 93 horses, 1 cat, and 5 dogs.

Source: West Nile Virus Activity-United States, November 6–12, 2003. Morbidity and Mortality Weekly Reports (MMWR), November 14, 2003 / 52 (45); 1105-1106. Centers for Disease Control and Prevention of the United States (CDC).

Mexico: The CDC journal Emerging Infectious Diseases (EID) published an article presenting evidence of the spread of WNV in Mexico since 2002. This article can be consulted via the source below.

Source: Dispatch: West Nile Virus in Mexico: Evidence of Widespread Circulation since July 2002 (Estrada-Franco et al.). Emerging Infectious Diseases (EID). Centers for Disease Prevention and Control of the United States (CDC).

Electronic Information Sources on the Occurrence and Distribution of Communicable Diseases in the Countries of Americas

(Sources provided in language of country; EW = Epidemiological Week; CAREC = Caribbean Epidemiology Centre, serving the English-speaking Caribbean.)

Erratum: In Table 1 on yellow fever in last week’s updates (No. 19, 12 November 2003), the total number of deaths should have been 96, not 99. The error in last week's issue has been corrected.