The Weekly Epidemiological Record (WER) was first issued in 1926 by the Health Office of the League of Nations. It was entrusted to the World Health Organization (WHO) when it was created in 1948 and has appeared every week since then.
It serves as an essential instrument for the rapid and accurate dissemination of epidemiological information on cases and outbreaks of diseases under the IHR and on other communicable diseases of public health importance, including emerging or re-emerging infections.
An electronic version of the WER is accessible every Friday and can be downloaded free of charge.
Inside this issue
Highlighted signals and events
During epidemiological week 43 (19 to 25 October), WHO Public Health Intelligence (PHI) teams conducted digital event‑based surveillance (DEBS) to support the early detection and assessment of potential public health threats. During the reporting period, approximately 618 000 raw signals were scanned and triangulated through DEBS. From this large pool of signals, 20 signals and/or events met assessment thresholds and underwent further analysis and categorization. Of the 20 categorized signals, 19 represented unique signals. A total of 13 signals and/or events were escalated for operational attention.
In the reporting week, three new events were verified through PHI activities. One Disease Outbreak News report was published during this reporting period. A summary of identified raw signals, assessed signals, and published outputs is presented in the tables below.
| Signals screened1 | Signals categorized2 | Unique signals3 | Signals escalated4 |
|---|---|---|---|
| 618 000 | 20 | 19 | 13 |
1 Signals screened: Total volume of raw signals reviewed from across multiple sources during the reporting period.
2 Signals categorized: Number of signals categorized for further detailed WHO assessment and actions during the reporting period.
3 Unique signals: Count of distinct signals after removing duplicate or repeated entries from different sources within the same epidemiological week.
4 Signals escalated: Subset of categorized signals that triggered escalation actions.
| Region | Hazard |
|---|---|
| Africa | Cholera Dengue |
| Americas | Influenza due to identified avian or animal influenza virus |
| Eastern Mediterranean | Poliomyelitis |
| Europe | Mpox Shamonda virus infection |
| South-East Asia | No publicly available signals identified |
| Western Pacific | No publicly available signals identified |
5 The absence of listed signals indicates that no publicly available signals were identified during the reporting period and does not imply absence of signal activity overall. Signals designated as “Not yet diagnosed” refer to those with ongoing epidemiological and clinical investigations to determine the causative hazard or disease.
6 Only new events registered during the defined period are included, accordingly changes to disease/condition that occur after the data cut off of 23:59 on 25 October 2026 will not be reflected in the description. The absence of events indicates that no publicly available newly reported events were identified during the reporting period and does not imply absence of event activity overall.
| Disease Outbreak News (1) |
| Ebola disease caused by Bundibugyo virus - Democratic Republic of the Congo, Kenya and Nigeria |
Global respiratory virus activity: weekly update
The findings below are based on surveillance conducted through the WHO Global Influenza Surveillance and Response System (GISRS). More details can be found on the Global Influenza Programme’s surveillance and monitoring page.
Overview
In week 42 2026, globally, influenza positivity was below 10% and SARS-CoV-2 positivity increased slightly but remained low. Influenza positivity was below 10% in the northern hemisphere temperate and subtropical areas with a decrease in the reported specimens tested in the last four weeks. Influenza positivity decreased to around 5% in the southern hemisphere temperate and subtropical areas and remained around 15% in the tropical areas. RSV positivity also remained low globally.
Influenza
Globally, influenza detections remained low in week 42 with influenza A virus detections predominant.
In the northern hemisphere, influenza percent positivity was elevated (>10%) in some countries in Central America and the Caribbean, Western Africa, Southern, South-East and Eastern Asia and a single country in Eastern Europe. Percent positivity was over 30% in some countries in Western, Southern and South-East Asia and in single countries in Western and Eastern Africa. Increases in activity were observed in some countries in Central America and the Caribbean, Western and South-East Asia and in single countries in Northern and South West Europe, and Eastern Africa.
In the southern hemisphere, influenza percent positivity was elevated (>10%) in some countries in Tropical South America and in single countries in Temperate South America, Eastern Africa and Oceania. Percent positivity was over 30% in a single country in South-East Asia. Small increases in activity were reported in single countries in Tropical South America and Eastern Africa.
In the zones with elevated positivity, influenza A(H1N1)pdm09 was predominant in Eastern Africa, Western, Southern and South-East Asia and Oceania and influenza A(H3N2) was predominant in Eastern Asia. Influenza B was predominant in Central America and the Caribbean, Tropical and Temperate South America and in Western Africa.
SARS-CoV-2
Globally, SARS-CoV-2 positivity remained stable and low across most reporting countries, with elevated positivity (>10%) reported in some countries in South West Europe, and in single countries in Central America and the Caribbean, Northern Europe, Northern Africa, and Western and Eastern Asia. Increases in activity were observed in single countries in Tropical South America and Eastern Africa.
Respiratory Syncytial Virus (RSV)
RSV positivity was elevated (>10%) in a few countries in Central America and the Caribbean and Temperate South America and in single countries in Western Africa and Southern Asia. Percent positivity was over 30% in a single country in Southern Asia. Increases in activity were observed in some countries in Tropical South America and in single countries in Central America and the Caribbean and Southern Asia. RSV and influenza activity were both elevated in countries in Central America and the Caribbean, Temperate South America, Western Africa and Southern Asia.
Severity assessment
The severity assessments here are reported from countries, areas and territories. Assessments for transmissibility can be reported based on syndromic parameters and/or influenza-specific parameters. In the northern hemisphere temperate and subtropical areas, influenza-specific transmissibility was reported as below seasonal threshold in 14 countries, low in three countries and moderate in a single country; transmissibility using syndromic data was reported as below seasonal threshold in eight countries and low in two countries. Influenza-specific transmissibility was reported as below seasonal threshold in a single country in the tropical areas.
Current update: Global Respiratory Virus Activity: Weekly Update N° 601
All past updates: Global respiratory virus updates
Influenza at the human-animal interface summary and risk assessment, 7 Oct 2026
New human cases2: From 7 September to 7 October 2026, based on reporting date, detections of influenza A(H5N1) in one human, influenza A(H9N2) in four humans and influenza A(H1N1) variant (A(H1N1)v) in one human were officially reported.
Circulation of influenza viruses with zoonotic potential in animals: High pathogenicity avian influenza (HPAI) events in poultry and non-poultry animal species continue to be reported to the World Organisation for Animal Health (WOAH).3 The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.4 Additionally, low pathogenicity avian influenza viruses as well as swine influenza viruses continue to circulate in animal populations.
Risk assessment5: There have been no reports of sustained human-to-human transmission associated with the above-mentioned human infection events. Based on information available at the time of this update, the overall public health risk from currently known influenza A viruses detected at the human-animal interface has not changed and, at present, these viruses are not thought to be capable of sustained human-to-human transmission, although this could change as they evolve. Whilst human infections with viruses of animal origin are infrequent, they are not unexpected at the human-animal interface.
All assessments and summaries: Risk assessments and summaries of influenza at the human-animal interface
2 For epidemiological and virological features of human infections with animal influenza viruses not reported in this assessment, see the reports on human cases of influenza at the human-animal interface published in the Weekly Epidemiological Record here. ↑
3 Avian influenza. Global situation. World Organisation for Animal Health (WOAH). View source. ↑
4 Global Avian Influenza Viruses with Zoonotic Potential situation update. Food and Agriculture Organization of the United Nations (FAO). View source. ↑
5 Rapid risk assessment of acute public health events. World Health Organization; 2012. View source. ↑