Peru: SENASA Reports HPAI H5 In Pelicans
WOAH: Colombia Reports Two Outbreaks of HPAI H5N1
Mexico: Senasica Orders Strategic Vaccination Of High-Risk Poultry Against HPAI H5N1
Central America: Belize Agricultural Health Authority Reports H5 Avian Flu In Commercial Poultry
While the future evolution and impact of HPAI H5 is uncertain, it is on a worrisome trajectory.
For now, HPAI H5 is primarily a threat to wild birds and poultry, but in recent weeks we've seen signs (see below) from the CDC, ECDC, and other agencies that their level of concern is increasing.
ECDC Guidance For Testing & Identification Of Zoonotic Influenza Infections In Humans In The EU/EAA
CDC On Preventive Measures to Protect Against Bird Flu Viruses
Overnight PAHO - the Pan American Health Organization - released an epidemiological alert on the growing threat from HPAI H5 in the Americas.
Epidemiological Alert - Outbreaks of avian influenza and public health implications in the Region of the Americas
19 Nov 2022
Given the increase in outbreaks of highly pathogenic avian influenza in poultry farms, backyards, and wild birds in countries of the Region of the Americas and other Regions, the Pan American Health Organization/World Health Organization (PAHO/WHO) recommends that the Member States strengthen coordination between sectors involved in alerting and responding to zoonotic events and implement the necessary measures to contain emerging pathogens that may put public health at risk. PAHO/WHO recommends monitoring the occurrence of influenza-like illness (ILI) or severe acute respiratory infection (SARI) in people exposed to birds (domestic, wild, or in captivity) infected with influenza viruses.
DOWNLOAD (816.23 KB)
Some excerpts from the 8-page document follow, but you'll want to read the report in its entirety. I'll have a brief postscript when you return.
Situation summary
According to the World Organisation for Animal Health (WOAH), the highly pathogenic avian influenza (HPAI) epidemic season continues with outbreaks in poultry and reported outbreaks in birds other than poultry, mainly in the Regions of Europe and the Americas. In the current epidemic period, H5N1 is the predominant subtype, and unusual persistence of the virus in wild birds during the summer months has been reported for the first time (1, 2).
In accordance with the seasonal pattern of HPAI 1 , the number of outbreaks is expected to increase in the coming months and WOAH recommends that countries maintain and strengthen their surveillance efforts, biosecurity measures on farms, and continue with the timely notification of avian influenza outbreaks in both birds and non-avian species. The quality of surveillance is key for the early detection and timely response to potential threats to animal health with an impact on public health (1,2).
Global context of avian influenza viruses:
Five subtypes of avian influenza A viruses capable of causing infection in humans are known (H5, H6, H7, H9, and H10 viruses). The most frequently identified subtypes causing human infections are the H5, H7, and H9 viruses. Specifically, the A(H5N1), A(H7N9), A(H5N6) (highly pathogenic avian influenza) and A(H9N2) (low pathogenic avian influenza) viruses (3). To date in the Region of the Americas, of these four, only one human case of influenza A(H5N1) virus infection has been reported. Additionally, in the Region of the Americas, cases of low pathogenicity avian influenza (LPAI) have been detected in humans (3, 4).
Avian influenza viruses are classified into low pathogenic avian influenza viruses (LPAI) and highly
pathogenic avian influenza viruses (HPAI) according to their ability to cause disease in birds.
Global context of avian influenza A(H5N1):
Since the detection of the influenza A(H5N1) virus in 1996, outbreaks were limited to Southeast Asia until 2005. After 2005, the virus spread westwards, entering Europe and Africa (5). In the Region of the Americas, in 2014, authorities in Canada and the United States of America warned of outbreaks in poultry and wild birds of a new virus genetically different from the avian influenza A(H5N1) viruses circulating in Asia, belonging to the group called "Eurasian H5 clade 2.3.4.4”, which was due to a genetic regrouping between the Eurasian A(H5N8) virus strains (introduced in 2014 in the USA), North American strains and strains resulting in turn from A(H5N2) virus regroupings detected in Canada (6) and the USA (7). In 2015, an H5N1 virus was detected in a wild bird in the United States that exhibited a new "rearrangement" with genes from highly pathogenic Asian H5 viruses and low pathogenic North American viruses (8).
Regarding infections in humans, since 2003, more than 880 confirmed cases of influenza A(H5N1) virus infection have been reported, mainly in Indonesia and Egypt until 2017, with case-fatality rates (CFR) of 46% and 25%, respectively. However, since 2018, 7 cases have been reported (1 in Nepal, 1 in Laos, 1 in India, 1 in the United Kingdom, 1 in the United States of America, and 2 in Spain) with 2 deaths (in Nepal and India) (9). The newly detected cases in the Regions of Europe and America are the first to be associated with H5N1 viruses circulating predominantly in birds and differing from previous H5N1 viruses (10).
(SNIP)
Surveillance in humans
People at risk of contracting infections are those directly or indirectly exposed to infected birds, for example, poultry keepers who maintain close and regular contact with infected birds or during slaughter or cleaning and disinfection of affected farms. For this reason, the use of adequate personal protective equipment and other protection measures is recommended to avoid zoonotic transmission in these operators.
In order to identify early transmission events at the human-animal interface, surveillance of exposed persons is recommended. In this sense, it is recommended to monitor the appearance of influenza-like illness (ILI) or severe acute respiratory infection (SARI) in people exposed to birds (domestic, wild, or in captivity) infected with influenza viruses during zoonotic events. Given the detection of an infection in humans, early notification is essential for an investigation and implementation of adequate measures that include the early isolation and treatment of the case, the active search for other cases associated with the outbreak, as well as the identification of close contacts for management and follow-up (11).
Health personnel in areas where transmission of avian influenza (HPAI or LPAI) in birds is taking place should be alerted about the possibility of infection in people exposed to these viruses. PAHO/WHO reiterates that all human infections caused by a new influenza virus subtype are mandatory and immediate notification under the International Health Regulations (IHR 2005).
Laboratory diagnosis in humans
The specific diagnosis of human infection by avian influenza is based on the detection of the viral genome by molecular methods (polymerase chain reaction, PCR) extracted from clinical swab samples (oropharyngeal or nasopharyngeal), nasopharyngeal aspirate or bronchoalveolar lavage (only in hospitalized patients), collected within the first 7 days from the onset of symptoms.
The diagnostic algorithm 9 involves an initial screening that makes it possible to define the type of virus (influenza A or B typing). If it is positive for Influenza A, it is followed by subtyping to detect the viral subtype by identifying the hemagglutinin protein gene (H1pdm and H3). If subtyping for seasonal influenza is not possible, they are tested for non-seasonal influenza, H5, H7, and H9.
All influenza A viruses that cannot be subtyped or that are defined as an avian subtype (H5, H7 or H9), must be sent immediately within 24 hours, under the appropriate conditions for the category according to International Air Transport Association (IATA) regulations, to a WHO Collaborating Center (WHO CC) which, for the Region of the Americas, is the United States Centers for Disease Control and Prevention (US CDC) for subtype identification and molecular and antigenic characterization.
In the Region of the Americas, as part of the Global Influenza Surveillance and Response System (GISRS), all National Influenza Centers (NICs) have the capacity for molecular detection of H5 and H7 influenza (some additionally for H9). Likewise, there are established mechanisms for quality control and shipment of samples for complete characterization to the US CDC, the WHO CC for the Region.
PAHO should be contacted at flu@paho.org before sending non-subtyped or avian influenza samples to the WHO CC.PAHO/WHO guidelines on surveillance, clinical management, vaccination, and risk communication are available in the Epidemiological Update on Influenza and other respiratory viruses, published on 13 November 2022, available at: https://bit.ly/3tLhAMB.
Even when a doctor is consulted - unless the illness is particularly severe, or the patient had recent live poultry exposure - rapid or laboratory testing is rarely done. In low resource settings, they may not even be available.
Recognizing these limitations, PAHO recommends that member states implement `event-based surveillance'.
PAHO/WHO recommends Member States implement event-based surveillance to accompany indicator-based surveillance. Event-based surveillance is the organized and rapid capture of information about events that may pose a potential risk to public health.
The information may come from rumors and other ad-hoc reports transmitted through formal (pre-established routine information systems) or informal -not pre-established routine information systems (i.e., media, direct communication from health care workers, or non-governmental organizations) channels. Event-based surveillance is a functional component of the early warning and response mechanism 16 .
Respiratory events that are unusual should be investigated and reported immediately.
Unusual events include influenza cases with atypical clinical progression; acute respiratory infection associated with animal disease exposure or observed in travelers to areas prone to novel influenza virus emergence; SARI among health care professionals; or clusters of influenza viral infection outside the regular circulation season.
The reality is, spillover of swine and avian flu viruses into humans probably occurs far more often than our surveillance capabilities suggest, and - as we saw in Mexico with pdmH1N1 in 2009 - a novel flu virus may circulate in humans for weeks before it is recognized.
None of this argues against enhanced surveillance (quite the opposite), only that it unlikely to provide us with much advance warning, should HPAI H5 begin spreading in humans.
Of course, we don't know if HPAI H5 is even capable of adapting well enough to human physiology to present a pandemic threat. To date, all known influenza pandemics (going back 130 years) have sprung from H1, H2, and H3 influenza viruses.
But, as COVID so aptly demonstrated in 2020, there's a first time for everything.
