Giuseppe
Emeritus
[Source: World Health Organization, full PDF document: (LINK). Edited.]
Influenza Update N? 168 - 14 September 2012
Summary
Countries in the temperate zone of the northern hemisphere
Influenza transmission in all reporting countries in the temperate regions of the northern hemisphere is minimal, that is, at inter-seasonal levels.
In the United States of America, laboratory-confirmed human cases of swine-origin influenza A(H3N2) virus, also known as (H3N2)v, continues to be reported. New cases have been discovered primarily as a result of active case finding in animal fairs and around reported cases .
Sixteen cases have been hospitalized and one H3N2v-associated death has been reported in in a person with underlying medical conditions. The large majority of cases have been associated with swine exposure though some instances of likely human-to-human transmission have been identified. However despite intense surveillance no sustained human-to-human transmission has been reported.
As a result of enhanced surveillance activities for H3N2v, three infections with influenza A(H1N2) variant virus (H1N2)v have been detected in Minnesota in the patients who became ill after contact with swine. One patient was hospitalized, but all have recovered from their illness. More information can be found at: http://www.cdc.gov/flu/swineflu/variant.htm
In the Netherland, influenza A(H1N1)pdm09 viruses with the mutation which confers high-level oseltamivir-resistant were detected in two travelers returning from Spain. For more information, see the full report published in Eurosurveillance and ECDC comment.
Countries in the tropical zone
Tropical countries of the Americas
Transmission in Central America, the Caribbean, and tropical South America continues to be at low levels in reporting countries.
Across Central America, influenza B continues to be commonly detected.
Costa Rica and El Salvador continue to report low levels of influenza B virus, while Honduras has reported low levels of A(H1N1)pdm09. Panama has reported a sustained decrease in influenza B levels since the mid-August, indicating that their influenza season is over. On the other hand, Nicaragua has reported a notable increase in both influenza B and A(H3N2) virus strains in the past two weeks.
In the Caribbean, Cuba continues to report persistent levels of influenza B virus activity.
In the tropical zone of South America, recently reported transmission of influenza has been noted primarily in Brazil and Peru.
In Brazil, the levels of influenza activity continue to decrease. In 2012, influenza viruses were detected in 22% (3541/16373) of Severe Acute Respiratory Infection (SARI) cases. Of these, 69% (2459/3541) were influenza A(H1N1)pdm09. In 2012, 1349 SARI deaths were reported, of which 378 (28%) were positive for an influenza virus. Of these, 316 (84%) were positive for influenza A(H1N1)pdm09. Of the total deaths from SARI, 51% (638/1349) were male and the median age was 46 years (range 0-99 years); 60% were reported to have at least one comorbidity.
Peru in contrast to Brazil, primarily reported influenza type B detections in recent weeks, at low level and in decreasing number.
Sub-Saharan Africa
Of countries in Sub-Saharan Africa that have reported influenza data, Kenya and Zambia reported recent low level co-circulation of influenza A(H3N2) and type B. Whereas Ghana has reported notable virus circulation; primarily type B. Detections in Madagascar have continued to decline to almost undetectable levels, after a peak of predominantly influenza A(H3N2) transmission in mid-June.
Tropical Asia
A few areas of tropical Asia have experienced recent significant influenza virus circulation most notably in Thailand.
Thailand has reported circulation of mainly influenza A(H1N1)pdm09 and influenza type B, with some detections of influenza A(H3N2). Virus transmission in Viet Nam has decreased, after experiencing a peak in levels in the previous two months, with both influenza B and A(H3N2) reported.
India and Sri Lanka, detect persistent transmission of influenza A(H1N1)pdm09 and influenza type B, in approximately equal numbers. Bangladesh continues to report mainly influenza B activity. The Philippines has reported some influenza A activity, after a peak of transmission of influenza A and influenza A(H3N2) in the previous month.
In southern China influenza activity remained at low levels. The percentage of outpatient visits that were due to ILI at sentinel sites was 2.7% during the most recent reporting week, which was the same as the previous week. Of ILI specimens tested, 19.3% (188/976) were positive for influenza and 91.2% (165/188) of the southern China subtyped influenza viruses were A(H3N2).
In Singapore, acute respiratory infection (ARI) activity decreased and has been below the warning level for the last four reporting weeks. The overall prevalence of influenza among ILI samples (n=95) in the community was 37.9% in the past four weeks. Of all the positive samples tested in August 2012, influenza A(H3N2) constituted 43%, whilst influenza A(H1N1)pdm09 and influenza B constituted 31% and 26%, respectively.
Countries in the temperate zone of the southern hemisphere
Influenza activity has continued to decline in all temperate countries of the southern hemisphere.
Temperate countries of South America
Influenza activity in the southern cone of South America appears to have peaked and is decreasing in Argentina, Chile, Paraguay and Uruguay.
Chile reported an ILI consultation rate of 7.2 per 100 000 which represents a slight decrease from the previous reporting week (11.7 per 100 000) and continues a declining trend since late June. Of all influenza viruses detected in the most recent reporting week, 60% (42/70) were influenza A(H3N2), 26% (18/70) influenza B and 14% (10/70) influenza A(not subtyped). Of the 16 SARI samples positive for an influenza virus in the most recent reporting week, 88% (n=14) were influenza A(H3N2) and two (12%) influenza B. This represents a continued decrease in the number of influenza virus detections in cases of SARI, after a peak in early August. Since the beginning of 2012, the distribution of influenza A(H3N2) has occurred largely in the age strata 60 years and above and 2 years and below, accounting for 37% and 24% of all A(H3N2) respectively. Of the 92 SARI deaths reported in 2012, fourteen were confirmed with some respiratory virus. Of these, 64% (n=9) were influenza A(H3N2).
Argentina continued to report only small numbers of influenza virus detections. Of those detected, both influenza A(H1N1)pdm09 and influenza B were found. ILI and SARI cases continued a decreasing trend since the first week of June, which is concurrent with the decrease of respiratory syncytial virus (RSV) detections.
In Paraguay, the total number of influenza detections decreased to almost undetectable levels since a peak in mid-July. SARI hospitalization rates continued to decrease, which has been the trend since early August, coinciding with a decrease in both influenza and RSV detections.
Of the 2012 SARI fatalities with laboratory confirmed respiratory viruses (n=30), eighteen (60%) were confirmed influenza A(H1N1)pdm09.
In Uruguay, virus detections decreased to almost undetectable levels after experiencing co-circulation of influenza A(H3N2) and type B since early July.
Temperate countries of southern Africa
In South Africa, a decrease in the number of influenza virus detections was reported in the last two reporting weeks, after an apparent peak in late July. Co-circulation of both influenza A(H3N2) and influenza B continued to be reported in approximate equal numbers. In SARI samples positive for influenza, A(H3N2) makes up the majority of detections.
Oceania, Melanesia and Polynesia
Australia continued to report a decrease in most influenza indicators in the recent reporting period, New Zealand continued to report a decrease in ILI consultations, representing the first time that ILI consultation rates were below the threshold of 50/100 000 population since late July.
In Australia in the week of 26 August to 1 September 2012, 936 ILI samples were received with 24% (n=220) positive for an influenza virus, which is a decrease in the percent positive from the previous reporting week (32%). Of all influenza viruses with sub-typing, 59% (n=129) were influenza A(H3N2), 40% (n=87) influenza B and 1% (n=3) A(H1N1)pdm09.
Most jurisdictions continued to report a decrease in ILI activity compared to the previous reporting period, which represents a four week period of sustained decrease in influenza activity. Nationally, for the period 1 to 8 September 2012, there were 684 laboratory confirmed notifications of influenza, with 74% coming from Queensland, where they have recently reported the first decline in influenza activity since early June. All states and territories have reported decreasing trends in influenza activity in the most recent reporting period.
Nationally, influenza A(H3N2) continues to be the predominant circulating virus with some co-circulation of influenza B. The distribution of types and subtypes is not uniform across all areas of the country. Influenza A(H3N2) is predominant across most states and territories, however influenza B represents approximately half of notifications in Western Australia.
In New Zealand, ILI consultation rates continued to decrease and are now below baseline activity levels. A weekly ILI consultation rate of 36.7 per 100 000 was reported.
Nationally, of the 391 ILI samples received, 29% (n=113) were positive for an influenza virus. Of these, influenza A(H3N2) accounted for 62% (n=70), influenza A not subtyped for 21% (n=24), influenza B for 13% (n=15) and influenza A(H1N1)pdm09 for 4% (n=4).
The number of SARI cases and incidence per 100 000 population has decreased in New Zealand. Nationally, of the 55 SARI specimens tested between 27 August to 2 September 2012 by The Southern Hemisphere Influenza and Vaccine Effectiveness Research and Surveillance (SHIVERS) Project, 13 (24%) were positive for influenza viruses with influenza A(not subtyped) accounting for 15% (n=2), influenza A(H3N2) for 54% (n=7) and influenza B for 31% (n=4). Of the 1410 SARI specimens collected since 30 April 2012, 22% (311) were positive for influenza viruses.
Source of data
The Global Influenza Programme monitors influenza activity worldwide and publishes an update every two weeks.
The updates are based on available epidemiological and virological data sources, including FluNet (reported by the Global Influenza Surveillance and Response System) and influenza reports from WHO Regional Offices and Member States. Completeness can vary among updates due to availability and quality of data available at the time when the update is developed.
Link to web pages
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Influenza Update N? 168 - 14 September 2012
Summary
- Most countries in the northern temperate zone have either shifted to out of season surveillance schedules or not yet started seasonal reporting. But from available data, seasonal influenza transmission has not been picked up yet in the northern temperate zone.
- The United States of America is continuing to detect cases of influenza A(H3N2)v in humans and reported three human cases of influenza A(H1N2) variant virus infection. Investigation around the cases indicates no evidence of sustained human-to-human transmission.
- In the tropical areas of most countries are reporting low or decreasing trends of influenza detections. The exceptions are Nicaragua in the Americas where mainly influenza B is detected and in Asia, India and Thailand are both reporting influenza A(H1N1)pdm09 and B circulation.
- Influenza activity decreased in most of the temperate countries of the southern hemisphere. Australia, Chile, New Zealand, Paraguay and South Africa, continue to report declines in influenza indicators. Argentina continues to report very low numbers of detections compared to previous seasons.
Countries in the temperate zone of the northern hemisphere
Influenza transmission in all reporting countries in the temperate regions of the northern hemisphere is minimal, that is, at inter-seasonal levels.
In the United States of America, laboratory-confirmed human cases of swine-origin influenza A(H3N2) virus, also known as (H3N2)v, continues to be reported. New cases have been discovered primarily as a result of active case finding in animal fairs and around reported cases .
Sixteen cases have been hospitalized and one H3N2v-associated death has been reported in in a person with underlying medical conditions. The large majority of cases have been associated with swine exposure though some instances of likely human-to-human transmission have been identified. However despite intense surveillance no sustained human-to-human transmission has been reported.
As a result of enhanced surveillance activities for H3N2v, three infections with influenza A(H1N2) variant virus (H1N2)v have been detected in Minnesota in the patients who became ill after contact with swine. One patient was hospitalized, but all have recovered from their illness. More information can be found at: http://www.cdc.gov/flu/swineflu/variant.htm
In the Netherland, influenza A(H1N1)pdm09 viruses with the mutation which confers high-level oseltamivir-resistant were detected in two travelers returning from Spain. For more information, see the full report published in Eurosurveillance and ECDC comment.
Countries in the tropical zone
Tropical countries of the Americas
Transmission in Central America, the Caribbean, and tropical South America continues to be at low levels in reporting countries.
Across Central America, influenza B continues to be commonly detected.
Costa Rica and El Salvador continue to report low levels of influenza B virus, while Honduras has reported low levels of A(H1N1)pdm09. Panama has reported a sustained decrease in influenza B levels since the mid-August, indicating that their influenza season is over. On the other hand, Nicaragua has reported a notable increase in both influenza B and A(H3N2) virus strains in the past two weeks.
In the Caribbean, Cuba continues to report persistent levels of influenza B virus activity.
In the tropical zone of South America, recently reported transmission of influenza has been noted primarily in Brazil and Peru.
In Brazil, the levels of influenza activity continue to decrease. In 2012, influenza viruses were detected in 22% (3541/16373) of Severe Acute Respiratory Infection (SARI) cases. Of these, 69% (2459/3541) were influenza A(H1N1)pdm09. In 2012, 1349 SARI deaths were reported, of which 378 (28%) were positive for an influenza virus. Of these, 316 (84%) were positive for influenza A(H1N1)pdm09. Of the total deaths from SARI, 51% (638/1349) were male and the median age was 46 years (range 0-99 years); 60% were reported to have at least one comorbidity.
Peru in contrast to Brazil, primarily reported influenza type B detections in recent weeks, at low level and in decreasing number.
Sub-Saharan Africa
Of countries in Sub-Saharan Africa that have reported influenza data, Kenya and Zambia reported recent low level co-circulation of influenza A(H3N2) and type B. Whereas Ghana has reported notable virus circulation; primarily type B. Detections in Madagascar have continued to decline to almost undetectable levels, after a peak of predominantly influenza A(H3N2) transmission in mid-June.
Tropical Asia
A few areas of tropical Asia have experienced recent significant influenza virus circulation most notably in Thailand.
Thailand has reported circulation of mainly influenza A(H1N1)pdm09 and influenza type B, with some detections of influenza A(H3N2). Virus transmission in Viet Nam has decreased, after experiencing a peak in levels in the previous two months, with both influenza B and A(H3N2) reported.
India and Sri Lanka, detect persistent transmission of influenza A(H1N1)pdm09 and influenza type B, in approximately equal numbers. Bangladesh continues to report mainly influenza B activity. The Philippines has reported some influenza A activity, after a peak of transmission of influenza A and influenza A(H3N2) in the previous month.
In southern China influenza activity remained at low levels. The percentage of outpatient visits that were due to ILI at sentinel sites was 2.7% during the most recent reporting week, which was the same as the previous week. Of ILI specimens tested, 19.3% (188/976) were positive for influenza and 91.2% (165/188) of the southern China subtyped influenza viruses were A(H3N2).
In Singapore, acute respiratory infection (ARI) activity decreased and has been below the warning level for the last four reporting weeks. The overall prevalence of influenza among ILI samples (n=95) in the community was 37.9% in the past four weeks. Of all the positive samples tested in August 2012, influenza A(H3N2) constituted 43%, whilst influenza A(H1N1)pdm09 and influenza B constituted 31% and 26%, respectively.
Countries in the temperate zone of the southern hemisphere
Influenza activity has continued to decline in all temperate countries of the southern hemisphere.
Temperate countries of South America
Influenza activity in the southern cone of South America appears to have peaked and is decreasing in Argentina, Chile, Paraguay and Uruguay.
Chile reported an ILI consultation rate of 7.2 per 100 000 which represents a slight decrease from the previous reporting week (11.7 per 100 000) and continues a declining trend since late June. Of all influenza viruses detected in the most recent reporting week, 60% (42/70) were influenza A(H3N2), 26% (18/70) influenza B and 14% (10/70) influenza A(not subtyped). Of the 16 SARI samples positive for an influenza virus in the most recent reporting week, 88% (n=14) were influenza A(H3N2) and two (12%) influenza B. This represents a continued decrease in the number of influenza virus detections in cases of SARI, after a peak in early August. Since the beginning of 2012, the distribution of influenza A(H3N2) has occurred largely in the age strata 60 years and above and 2 years and below, accounting for 37% and 24% of all A(H3N2) respectively. Of the 92 SARI deaths reported in 2012, fourteen were confirmed with some respiratory virus. Of these, 64% (n=9) were influenza A(H3N2).
Argentina continued to report only small numbers of influenza virus detections. Of those detected, both influenza A(H1N1)pdm09 and influenza B were found. ILI and SARI cases continued a decreasing trend since the first week of June, which is concurrent with the decrease of respiratory syncytial virus (RSV) detections.
In Paraguay, the total number of influenza detections decreased to almost undetectable levels since a peak in mid-July. SARI hospitalization rates continued to decrease, which has been the trend since early August, coinciding with a decrease in both influenza and RSV detections.
Of the 2012 SARI fatalities with laboratory confirmed respiratory viruses (n=30), eighteen (60%) were confirmed influenza A(H1N1)pdm09.
In Uruguay, virus detections decreased to almost undetectable levels after experiencing co-circulation of influenza A(H3N2) and type B since early July.
Temperate countries of southern Africa
In South Africa, a decrease in the number of influenza virus detections was reported in the last two reporting weeks, after an apparent peak in late July. Co-circulation of both influenza A(H3N2) and influenza B continued to be reported in approximate equal numbers. In SARI samples positive for influenza, A(H3N2) makes up the majority of detections.
Oceania, Melanesia and Polynesia
Australia continued to report a decrease in most influenza indicators in the recent reporting period, New Zealand continued to report a decrease in ILI consultations, representing the first time that ILI consultation rates were below the threshold of 50/100 000 population since late July.
In Australia in the week of 26 August to 1 September 2012, 936 ILI samples were received with 24% (n=220) positive for an influenza virus, which is a decrease in the percent positive from the previous reporting week (32%). Of all influenza viruses with sub-typing, 59% (n=129) were influenza A(H3N2), 40% (n=87) influenza B and 1% (n=3) A(H1N1)pdm09.
Most jurisdictions continued to report a decrease in ILI activity compared to the previous reporting period, which represents a four week period of sustained decrease in influenza activity. Nationally, for the period 1 to 8 September 2012, there were 684 laboratory confirmed notifications of influenza, with 74% coming from Queensland, where they have recently reported the first decline in influenza activity since early June. All states and territories have reported decreasing trends in influenza activity in the most recent reporting period.
Nationally, influenza A(H3N2) continues to be the predominant circulating virus with some co-circulation of influenza B. The distribution of types and subtypes is not uniform across all areas of the country. Influenza A(H3N2) is predominant across most states and territories, however influenza B represents approximately half of notifications in Western Australia.
In New Zealand, ILI consultation rates continued to decrease and are now below baseline activity levels. A weekly ILI consultation rate of 36.7 per 100 000 was reported.
Nationally, of the 391 ILI samples received, 29% (n=113) were positive for an influenza virus. Of these, influenza A(H3N2) accounted for 62% (n=70), influenza A not subtyped for 21% (n=24), influenza B for 13% (n=15) and influenza A(H1N1)pdm09 for 4% (n=4).
The number of SARI cases and incidence per 100 000 population has decreased in New Zealand. Nationally, of the 55 SARI specimens tested between 27 August to 2 September 2012 by The Southern Hemisphere Influenza and Vaccine Effectiveness Research and Surveillance (SHIVERS) Project, 13 (24%) were positive for influenza viruses with influenza A(not subtyped) accounting for 15% (n=2), influenza A(H3N2) for 54% (n=7) and influenza B for 31% (n=4). Of the 1410 SARI specimens collected since 30 April 2012, 22% (311) were positive for influenza viruses.
Source of data
The Global Influenza Programme monitors influenza activity worldwide and publishes an update every two weeks.
The updates are based on available epidemiological and virological data sources, including FluNet (reported by the Global Influenza Surveillance and Response System) and influenza reports from WHO Regional Offices and Member States. Completeness can vary among updates due to availability and quality of data available at the time when the update is developed.
Link to web pages
- Epidemiological Influenza updates: http://www.who.int/influenza/surveillance_monitoring/updates/latest_update_GIP_surveillance
- Epidemiological Influenza updates archives 2012: http://www.who.int/influenza/surveillance_monitoring/updates/GIP_surveillance_2012_archives
- Virological surveillance updates : http://www.who.int/influenza/gisrs_laboratory/updates/summaryreport
- Virological surveillance updates archives : http://www.who.int/influenza/gisrs_laboratory/updates/en/index.html
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