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HEALTH AND CONSUMPTION
GENERAL DIRECTORATE OF
PUBLIC HEALTH, QUALITY AND
INNOVATION
Alert Coordination Center and
Health Emergencies
RAPID RISK ASSESSMENT
Avian influenza A(H5N1) in Spain
2nd update: February 2, 2023
Summary of the situation and conclusions
Throughout 2022 there has been a high number of outbreaks of high-risk avian influenza
pathogenicity (HPAI) A(H5N1) of clade 2.3.4.4b in birds in Spain. In connection with the work of
control around an outbreak on a poultry farm in Guadalajara, there were two detections
in nasopharyngeal swabs from farm workers on September 23 and 13 October 2022.
However, the absence of symptoms and the low viral load in both cases together
with the negative results of the serological tests in the first of them suggest that he was treated
of environmental contamination in the context of a high presence of the virus on the farm
affected. However, given the pandemic potential of avian influenza viruses, precautions were taken
appropriate public health measures to prevent possible transmission to others.
On the other hand, on October 13, 2022, an outbreak of HPAI A(H5N1) was confirmed on a farm in
minks in La Coruña that produced a high mortality among the animals. carried out the
control measures and early detection around said focus, there was no detection
among exposed workers.
Avian influenza A(H5N1) is an infection with a high lethality in birds and with important
economic repercussions. Human cases can be serious, but are rare
because bird-to-human transmission is rare and transmission between
people is extremely rare. Despite the magnitude of the current epizootic, the largest
of those registered so far worldwide, only four other detections have been reported
confirmed and one pending confirmation in humans since 2021.
In Spain there are protocols for the surveillance and control of avian influenza that include the
Surveillance of possible human cases related to outbreaks in animals.
Despite the fact that cases can become serious, the low capacity to transmit between
individuals causes the risk to be considered very low for the general population. Also, the risk
continues to be considered low for workers with occupational exposure in the
Affected farms with sick animals. The risk associated with the consumption of poultry meat or
eggs is virtually non-existent.
Rationale for updating the risk assessment
Since the last risk assessment, there has been a second detection of the influenza virus
avian A(H5N1) in humans. Both this and the first have been produced in samples of
workers exposed to the same outbreak on a poultry farm and are the result of RTPCR screening
of exposed asymptomatic workers. The low viral load, the absence of symptoms and the
Negative serology results suggest that these events correspond to contaminations
environmental rather than true infections.
On the other hand, an outbreak of HPAI A(H5N1) has been confirmed in a mink farm.
This event does evaluation of a possible adaptation of the virus to mammals is necessary.
Both the new data on detections in samples of exposed workers and the
confirmation of the outbreak on the mink farm justify this new risk assessment.
Contributions from previous updates of this
Risk evaluation
01.31.2022 Detection of the first foci of avian flu or High Avian Influenza
Pathogenicity (HPAI) A(H5N1) in wild birds and in a poultry farm in
Spain.
04.10.2022 First detection of the HPAI A(H5N1) virus in an asymptomatic worker
exposed to a focus of birds on a farm in Spain.
...
Description of events
On September 27 and October 21, two HPAI A(H5N1) detections were confirmed in
Samples from asymptomatic workers from a poultry farm in Guadalajara, Castilla-La Mancha.
The two detections occurred in the context of control and early detection of
possible cases in exposed humans carried out around the animal outbreak confirmed in said
exploitation on September 20. The farm was less than 10 kilometers away
from another previously affected farm, within the surveillance zone established around it, and the
September 17, the suspected focus had been reported due to an increase in mortality
of the birds.
In accordance with the prevention, early detection and control protocol, on September 23
performed tests for the detection of the virus by means of RT-PCR in nasopharyngeal exudate at 12
workers, all of them asymptomatic. On September 27, the National Center for Microbiology
(CNM) confirmed that one of the samples, corresponding to a 19-year-old male, was positive for
influenza A(H5N1). The RT-PCR result indicated a high Ct value, which corresponded to
a low viral load. Subsequently, the H5N1 subtype could be confirmed by sequencing. The
Comparative sequence analysis with those of two of the affected birds on the farm confirmed that
they were closely related. In addition, a serum sample was obtained from worker 13
days after the positive result of the RT-PCR and serology tests were carried out in the laboratory of
reference of the World Health Organization (WHO) that demonstrated the absence of antibodies
specific against the virus.
On October 13, the day the birds were slaughtered on the farm, they underwent
workers to a new screening by RT-PCR in which the second detection occurred.
In this case, the sample belonged to a 27-year-old man, equally asymptomatic. On the 21st of
In October, the characterization of the virus as influenza A(H5N1) was confirmed at the CNM, again with
high Ct values indicating a low viral load. The serological tests in this case are still
pending results.
Both the absence of symptoms and the low viral load in both cases and the negative results of
serological tests in the first of them suggest that these isolated findings possibly
they correspond to environmental contamination of the nasal or pharyngeal mucosa and not to an infection. Not
However, as established in the case definition reflected in Decision 2018/945 of June 22,
2018 from the European Commission, anyone with a positive test for influenza A(H5) or A(H5N1)
carried out by a National Reference Laboratory that participates in the Community Network of
Reference Laboratories for human influenza is considered a confirmed case, without it being
the presence of symptoms is necessary to establish this confirmation (1). Likewise, following the
precautionary principle, control measures should be taken around these detections in people
asymptomatic Both workers were isolated in their homes until obtaining a
sample with negative result by RT-PCR. Contact studies were carried out
they located a single close contact in the first case and two in the second. Both these contacts
Like the rest of the workers, they remained asymptomatic during the established period of seven
follow-up days. In addition, RT-PCR tests were performed on close contacts who also
they turned out negative.
On the other hand, on October 13, an outbreak of HPAI A(H5N1) was confirmed in a mink farm in La
Coruña that produced a high mortality among the animals. The confirmation was made in the
Central Veterinary Laboratory using RT-PCR on samples from two of the deceased animals.
The viruses have been characterized in the European reference laboratory for avian influenza. Even though
do not present known mutations of adaptation to mammals, it has been possible to identify a
mutation in the PB2 protein that is associated with increased polymerase activity in cells of
mammals (2,3). All the farm animals were slaughtered and their carcasses destroyed, after
which proceeded to the cleaning and disinfection of the facilities. There have been no detections in the
exposed workers related to this outbreak.
Public health actions
The pertinent focus control measures established in the Practical Manual of
operations of the Ministry of Agriculture, Fisheries and Food (4). Among them, around the farm
poultry farm in Guadalajara, protection and surveillance zones were delimited with a radius of 3 and 10 km
respectively, in which inspection visits were carried out by the Veterinary Services
Officials, to verify the absence of infection in birds and compliance with safety measures.
adequate biosecurity. The birds were sacrificed in situ, the destruction of materials
stubborn people who could carry the virus and the cleaning and disinfection of the facilities.
The measures aimed at detecting cases in humans were established in accordance with the
Protocol for the prevention, early detection and control of avian influenza approved on March 4,
2022 (5). This protocol updates the "Protocol of action for workers and people
asymptomatic exposed to animals infected with influenza viruses with pandemic potential” of 2017
(6) and adds to the passive surveillance of the appearance of infection symptoms, which already contemplated the
original protocol, screening by RT-PCR in asymptomatic people exposed to foci of influenza
avian. Since the publication of the new protocol, workers have been screened in all
of the farms affected, which have been a total of twelve. All tests performed on people
exposed were negative, with the exception of the two detections in workers exposed to the focus
from the Guadalajara farm.
After the first positive result, additional screenings were established. In total they were carried out
three rounds of screening on September 23, September 29 and October 13. In the first
the twelve farm workers were included and in the second and third 9 were added
workers involved in control tasks and 5 veterinarians.
After the positive RT-PCR results in the two asymptomatic workers, one in the screening of the
on September 23 and another on October 13, a contact study was carried out and
home isolation of both until a negative sample is obtained (September 28
in the first of them and October 22 in the second). Both in the rest of the workers and in the
In close contacts, passive surveillance for possible symptoms of infection was carried out during
seven days after the last exposure date, as well as screening by RT-PCR in
nasopharyngeal exudate.
Regarding the mink farm, the same measures were taken as established in the
Action against outbreaks in poultry farms. All workers were monitored
exposed and a screening by RT-PCR was performed on all of them. During the follow-up period,
one of the workers developed compatible symptoms but the laboratory tests
they ruled out the diagnosis of influenza and confirmed that of COVID-19.
...
Risk assessment for Spain
Risk of appearance of new human cases and secondary cases
The probability of transmission of the avian influenza virus to humans is very rare, even
being in contact with sick animals. In Spain there are specific protocols for the
management of these sources that include collective and individual protection measures and monitoring of
exposed persons to detect possible cases of infection in humans. These measures of
early detection have been reinforced after the recent increase in the number of animal outbreaks.
For people with occupational exposure to birds, the risk is still considered low. The risk
of autochthonous human cases in the general Spanish population is considered very low.
The possibility of transmission to humans through contaminated food is considered
practically nonexistent.
In the event of human cases, with the epidemiological and microbiological information
currently available data on human-to-human transmissibility of different virus subtypes
of avian influenza detected to date, the possibility of causing secondary cases would be
very low. The possibility of co-infection with human influenza viruses and the
A(H5N1) virus, which could facilitate the reassortment of the virus and give rise to a new virus more
adapted to inter-human transmission, is also very low, but must be taken into account in the
poultry farm workers.
Impact on human health
Although it is possible that the clinical evolution of the cases may be associated with a serious clinical picture,
based on the low probability of the appearance of new cases and non-sustained transmission
evidenced in the rest of the world, the potential impact on the general population would be considered very
under.
Conclusions
Given the pandemic potential of zoonotic influenza viruses, surveillance and control measures
prevention and control from a “One Health” perspective are of great importance to avoid
or mitigate the effects of possible transmission to humans.
Although for now the transmission from birds to people continues to be very rare and the
transmission between people is highly inefficient, the persistence of virus circulation
of avian influenza in our environment on a continuous basis implies a greater probability of
exposure to sick birds and, especially, it is important in risk groups (farmers,
veterinarians, farm workers, hunters, ornithologists, environmental workers, staff
zoos, etc.). In Spain, surveillance of possible human cases around the
animal spotlights. Unlike what happens in other European countries, screening is included
by RT-PCR of all people exposed during an outbreak of avian influenza, even if they did not
present symptoms, which increases the sensitivity of the system. However, the characteristics of
these first two detections in exposed workers: absence of symptoms, viral loads
low, negative result of the following PCR and negative serology in one of the cases, indicate that it is
It is likely that these are environmental contaminations of the nasopharyngeal mucosa rather than
effective infections, and show the need to establish criteria on how to address these
inconclusive results and to implement the necessary measures to minimize the possibility of
contaminations in the performance of the screenings.
It is very important to maintain and strengthen surveillance both in the animal sector and in the
workers related to farms and prevention and control measures, including
collective and individual protection measures for people most at risk of exposure
in your work environment.
Recommendations
Prevent, detect and control the appearance of cases of avian influenza, both in humans and in
animals, as well as continue with the development and maintenance of surveillance systems and
guarantee coordination between the different sectors of public health, environmental health, health
animal and occupational health under a single health approach, in order to make a correct approach to
these events, potentially serious for public health.
Minimize exposure to potentially infected animals in settings where it occurs
closer contact between people and animals.
Reinforce biosecurity measures, especially those measures aimed at avoiding the
contact with wild birds in poultry farms or with the remains of detritus that could be
contaminated with viruses.
Reinforce passive surveillance both in poultry farms and in wild birds, notifying
the official veterinary services any suspicion of disease.
Follow the measures established for the control of HPAI outbreaks in poultry farms.
Workers and people exposed to animals infected with influenza viruses should follow the
measures described in the corresponding action protocols.
Reinforce the recommendation of seasonal flu vaccination to occupational groups at risk
exposure to infected animals.
Recommend to people in contact with birds and other susceptible species (ranchers,
veterinarians, farm workers, hunters, ornithologists, environmental workers, staff
zoos, etc.) appropriate protection measures when in contact with animals,
especially if they show clinical symptoms compatible with the disease.
...
https://www.sanidad.gob.es/en/profes...ripe_aviar.pdf
HEALTH AND CONSUMPTION
GENERAL DIRECTORATE OF
PUBLIC HEALTH, QUALITY AND
INNOVATION
Alert Coordination Center and
Health Emergencies
RAPID RISK ASSESSMENT
Avian influenza A(H5N1) in Spain
2nd update: February 2, 2023
Summary of the situation and conclusions
Throughout 2022 there has been a high number of outbreaks of high-risk avian influenza
pathogenicity (HPAI) A(H5N1) of clade 2.3.4.4b in birds in Spain. In connection with the work of
control around an outbreak on a poultry farm in Guadalajara, there were two detections
in nasopharyngeal swabs from farm workers on September 23 and 13 October 2022.
However, the absence of symptoms and the low viral load in both cases together
with the negative results of the serological tests in the first of them suggest that he was treated
of environmental contamination in the context of a high presence of the virus on the farm
affected. However, given the pandemic potential of avian influenza viruses, precautions were taken
appropriate public health measures to prevent possible transmission to others.
On the other hand, on October 13, 2022, an outbreak of HPAI A(H5N1) was confirmed on a farm in
minks in La Coruña that produced a high mortality among the animals. carried out the
control measures and early detection around said focus, there was no detection
among exposed workers.
Avian influenza A(H5N1) is an infection with a high lethality in birds and with important
economic repercussions. Human cases can be serious, but are rare
because bird-to-human transmission is rare and transmission between
people is extremely rare. Despite the magnitude of the current epizootic, the largest
of those registered so far worldwide, only four other detections have been reported
confirmed and one pending confirmation in humans since 2021.
In Spain there are protocols for the surveillance and control of avian influenza that include the
Surveillance of possible human cases related to outbreaks in animals.
Despite the fact that cases can become serious, the low capacity to transmit between
individuals causes the risk to be considered very low for the general population. Also, the risk
continues to be considered low for workers with occupational exposure in the
Affected farms with sick animals. The risk associated with the consumption of poultry meat or
eggs is virtually non-existent.
Rationale for updating the risk assessment
Since the last risk assessment, there has been a second detection of the influenza virus
avian A(H5N1) in humans. Both this and the first have been produced in samples of
workers exposed to the same outbreak on a poultry farm and are the result of RTPCR screening
of exposed asymptomatic workers. The low viral load, the absence of symptoms and the
Negative serology results suggest that these events correspond to contaminations
environmental rather than true infections.
On the other hand, an outbreak of HPAI A(H5N1) has been confirmed in a mink farm.
This event does evaluation of a possible adaptation of the virus to mammals is necessary.
Both the new data on detections in samples of exposed workers and the
confirmation of the outbreak on the mink farm justify this new risk assessment.
Contributions from previous updates of this
Risk evaluation
01.31.2022 Detection of the first foci of avian flu or High Avian Influenza
Pathogenicity (HPAI) A(H5N1) in wild birds and in a poultry farm in
Spain.
04.10.2022 First detection of the HPAI A(H5N1) virus in an asymptomatic worker
exposed to a focus of birds on a farm in Spain.
...
Description of events
On September 27 and October 21, two HPAI A(H5N1) detections were confirmed in
Samples from asymptomatic workers from a poultry farm in Guadalajara, Castilla-La Mancha.
The two detections occurred in the context of control and early detection of
possible cases in exposed humans carried out around the animal outbreak confirmed in said
exploitation on September 20. The farm was less than 10 kilometers away
from another previously affected farm, within the surveillance zone established around it, and the
September 17, the suspected focus had been reported due to an increase in mortality
of the birds.
In accordance with the prevention, early detection and control protocol, on September 23
performed tests for the detection of the virus by means of RT-PCR in nasopharyngeal exudate at 12
workers, all of them asymptomatic. On September 27, the National Center for Microbiology
(CNM) confirmed that one of the samples, corresponding to a 19-year-old male, was positive for
influenza A(H5N1). The RT-PCR result indicated a high Ct value, which corresponded to
a low viral load. Subsequently, the H5N1 subtype could be confirmed by sequencing. The
Comparative sequence analysis with those of two of the affected birds on the farm confirmed that
they were closely related. In addition, a serum sample was obtained from worker 13
days after the positive result of the RT-PCR and serology tests were carried out in the laboratory of
reference of the World Health Organization (WHO) that demonstrated the absence of antibodies
specific against the virus.
On October 13, the day the birds were slaughtered on the farm, they underwent
workers to a new screening by RT-PCR in which the second detection occurred.
In this case, the sample belonged to a 27-year-old man, equally asymptomatic. On the 21st of
In October, the characterization of the virus as influenza A(H5N1) was confirmed at the CNM, again with
high Ct values indicating a low viral load. The serological tests in this case are still
pending results.
Both the absence of symptoms and the low viral load in both cases and the negative results of
serological tests in the first of them suggest that these isolated findings possibly
they correspond to environmental contamination of the nasal or pharyngeal mucosa and not to an infection. Not
However, as established in the case definition reflected in Decision 2018/945 of June 22,
2018 from the European Commission, anyone with a positive test for influenza A(H5) or A(H5N1)
carried out by a National Reference Laboratory that participates in the Community Network of
Reference Laboratories for human influenza is considered a confirmed case, without it being
the presence of symptoms is necessary to establish this confirmation (1). Likewise, following the
precautionary principle, control measures should be taken around these detections in people
asymptomatic Both workers were isolated in their homes until obtaining a
sample with negative result by RT-PCR. Contact studies were carried out
they located a single close contact in the first case and two in the second. Both these contacts
Like the rest of the workers, they remained asymptomatic during the established period of seven
follow-up days. In addition, RT-PCR tests were performed on close contacts who also
they turned out negative.
On the other hand, on October 13, an outbreak of HPAI A(H5N1) was confirmed in a mink farm in La
Coruña that produced a high mortality among the animals. The confirmation was made in the
Central Veterinary Laboratory using RT-PCR on samples from two of the deceased animals.
The viruses have been characterized in the European reference laboratory for avian influenza. Even though
do not present known mutations of adaptation to mammals, it has been possible to identify a
mutation in the PB2 protein that is associated with increased polymerase activity in cells of
mammals (2,3). All the farm animals were slaughtered and their carcasses destroyed, after
which proceeded to the cleaning and disinfection of the facilities. There have been no detections in the
exposed workers related to this outbreak.
Public health actions
The pertinent focus control measures established in the Practical Manual of
operations of the Ministry of Agriculture, Fisheries and Food (4). Among them, around the farm
poultry farm in Guadalajara, protection and surveillance zones were delimited with a radius of 3 and 10 km
respectively, in which inspection visits were carried out by the Veterinary Services
Officials, to verify the absence of infection in birds and compliance with safety measures.
adequate biosecurity. The birds were sacrificed in situ, the destruction of materials
stubborn people who could carry the virus and the cleaning and disinfection of the facilities.
The measures aimed at detecting cases in humans were established in accordance with the
Protocol for the prevention, early detection and control of avian influenza approved on March 4,
2022 (5). This protocol updates the "Protocol of action for workers and people
asymptomatic exposed to animals infected with influenza viruses with pandemic potential” of 2017
(6) and adds to the passive surveillance of the appearance of infection symptoms, which already contemplated the
original protocol, screening by RT-PCR in asymptomatic people exposed to foci of influenza
avian. Since the publication of the new protocol, workers have been screened in all
of the farms affected, which have been a total of twelve. All tests performed on people
exposed were negative, with the exception of the two detections in workers exposed to the focus
from the Guadalajara farm.
After the first positive result, additional screenings were established. In total they were carried out
three rounds of screening on September 23, September 29 and October 13. In the first
the twelve farm workers were included and in the second and third 9 were added
workers involved in control tasks and 5 veterinarians.
After the positive RT-PCR results in the two asymptomatic workers, one in the screening of the
on September 23 and another on October 13, a contact study was carried out and
home isolation of both until a negative sample is obtained (September 28
in the first of them and October 22 in the second). Both in the rest of the workers and in the
In close contacts, passive surveillance for possible symptoms of infection was carried out during
seven days after the last exposure date, as well as screening by RT-PCR in
nasopharyngeal exudate.
Regarding the mink farm, the same measures were taken as established in the
Action against outbreaks in poultry farms. All workers were monitored
exposed and a screening by RT-PCR was performed on all of them. During the follow-up period,
one of the workers developed compatible symptoms but the laboratory tests
they ruled out the diagnosis of influenza and confirmed that of COVID-19.
...
Risk assessment for Spain
Risk of appearance of new human cases and secondary cases
The probability of transmission of the avian influenza virus to humans is very rare, even
being in contact with sick animals. In Spain there are specific protocols for the
management of these sources that include collective and individual protection measures and monitoring of
exposed persons to detect possible cases of infection in humans. These measures of
early detection have been reinforced after the recent increase in the number of animal outbreaks.
For people with occupational exposure to birds, the risk is still considered low. The risk
of autochthonous human cases in the general Spanish population is considered very low.
The possibility of transmission to humans through contaminated food is considered
practically nonexistent.
In the event of human cases, with the epidemiological and microbiological information
currently available data on human-to-human transmissibility of different virus subtypes
of avian influenza detected to date, the possibility of causing secondary cases would be
very low. The possibility of co-infection with human influenza viruses and the
A(H5N1) virus, which could facilitate the reassortment of the virus and give rise to a new virus more
adapted to inter-human transmission, is also very low, but must be taken into account in the
poultry farm workers.
Impact on human health
Although it is possible that the clinical evolution of the cases may be associated with a serious clinical picture,
based on the low probability of the appearance of new cases and non-sustained transmission
evidenced in the rest of the world, the potential impact on the general population would be considered very
under.
Conclusions
Given the pandemic potential of zoonotic influenza viruses, surveillance and control measures
prevention and control from a “One Health” perspective are of great importance to avoid
or mitigate the effects of possible transmission to humans.
Although for now the transmission from birds to people continues to be very rare and the
transmission between people is highly inefficient, the persistence of virus circulation
of avian influenza in our environment on a continuous basis implies a greater probability of
exposure to sick birds and, especially, it is important in risk groups (farmers,
veterinarians, farm workers, hunters, ornithologists, environmental workers, staff
zoos, etc.). In Spain, surveillance of possible human cases around the
animal spotlights. Unlike what happens in other European countries, screening is included
by RT-PCR of all people exposed during an outbreak of avian influenza, even if they did not
present symptoms, which increases the sensitivity of the system. However, the characteristics of
these first two detections in exposed workers: absence of symptoms, viral loads
low, negative result of the following PCR and negative serology in one of the cases, indicate that it is
It is likely that these are environmental contaminations of the nasopharyngeal mucosa rather than
effective infections, and show the need to establish criteria on how to address these
inconclusive results and to implement the necessary measures to minimize the possibility of
contaminations in the performance of the screenings.
It is very important to maintain and strengthen surveillance both in the animal sector and in the
workers related to farms and prevention and control measures, including
collective and individual protection measures for people most at risk of exposure
in your work environment.
Recommendations
Prevent, detect and control the appearance of cases of avian influenza, both in humans and in
animals, as well as continue with the development and maintenance of surveillance systems and
guarantee coordination between the different sectors of public health, environmental health, health
animal and occupational health under a single health approach, in order to make a correct approach to
these events, potentially serious for public health.
Minimize exposure to potentially infected animals in settings where it occurs
closer contact between people and animals.
Reinforce biosecurity measures, especially those measures aimed at avoiding the
contact with wild birds in poultry farms or with the remains of detritus that could be
contaminated with viruses.
Reinforce passive surveillance both in poultry farms and in wild birds, notifying
the official veterinary services any suspicion of disease.
Follow the measures established for the control of HPAI outbreaks in poultry farms.
Workers and people exposed to animals infected with influenza viruses should follow the
measures described in the corresponding action protocols.
Reinforce the recommendation of seasonal flu vaccination to occupational groups at risk
exposure to infected animals.
Recommend to people in contact with birds and other susceptible species (ranchers,
veterinarians, farm workers, hunters, ornithologists, environmental workers, staff
zoos, etc.) appropriate protection measures when in contact with animals,
especially if they show clinical symptoms compatible with the disease.
...
https://www.sanidad.gob.es/en/profes...ripe_aviar.pdf