Everything you need to know about the largest outbreak of bird flu in Europe that also affects Spain with the first case in humans

• Avian flu "There are no reasons for alarm. The risk to the population remains low"

The European Center for Disease Prevention and Control (ECDC) and the European Food Safety Authority (EFSA) have just warned

2021-2022

.

In their report they point out that there have been 2,467 outbreaks in poultry, 48 million birds slaughtered in affected establishments, 187 detections in captive birds and 3,573 events of highly pathogenic avian influenza in wild birds.

The Ministry of Health points out in its latest alert report from yesterday, October 4, that in Spain, "

the Ministry of Agriculture, Fisheries and Food (MAPA) has notified a total of

of Highly Pathogenic Avian Influenza (HPAI) corresponding to subtype A(H5N1)

.

Of these, 31 outbreaks (26 in wild birds and 5 in poultry) have been detected during the summer months.

In this epidemic flu season (2021/2022), an unusual increase has been detected, since historically, in our country, the number of HPAI outbreaks in wild birds compared to northern and central Europe is very low."

The last Agriculture document dated September 29, states that only since July 1 and until that date,

located in Huelva (2) Badajoz (1) and Guadalajara ( two);

distributed in Huelva, Cádiz, Seville, Badajoz, Cáceres, Toledo Guadalajara, Ciudad Real, Guipúzcoa, Vizcaya, Madrid Pontevedra, La Coruña Cantabria, Barcelona and La Rioja;

and

in a zoological nucleus in Toledo.

Both the ECDC and the EFSA state that

.

This includes personnel who provide their services on farms, slaughterhouses, as well as veterinary services related to poultry production.

Despite the slight risk indicated by both European authorities, in Spain,

on a farm in the province of Guadalajara where one of the outbreaks has been located.

This is the worker of a poultry farm who

reports

.

The ECDC document does not yet record the identified Spanish case.

The focus on this farm in the province of Guadalajara was detected, according to different information, when the managers of the ship verified and reported an

in one of the caged ships.

HOW DOES BIRD FLU DEVELOP IN BIRDS?

Avian

is a bird disease

belonging to the

, the group known as "type A influenza".

These viruses are classified according to two types of proteins that they present on their surface for which "H" and "N" are used (for the surface antigens "hemagglutinin" and "neuroaminidase").

16 types of hemagglutinin (H1-H16) and 9 types of neuraminidase (N1-N9) are known.

The virus that is predominantly affecting Europe and that has been detected in wild birds and some cases in domestic birds in Spain is of the H5N1 subtype.

Most of these viruses cause no or mild disease and

.

Viruses that are capable of producing disease and high mortality are known as "high pathogenicity viruses".

Both types of virus can be differentiated in the laboratory using molecular biology techniques (sequencing).

IN WHAT TYPES OF BIRDS IS IT MOST FREQUENT?

All avian species are susceptible to the disease

, including both poultry and wild birds;

within birds, hens and turkeys are more sensitive to show clinical symptoms;

geese and ducks seem to be more resistant to illness.

HOW DOES INFECTION BETWEEN BIRDS OCCUR?

Infected animals

The disease is transmitted primarily by direct contact between healthy and diseased birds, although it can also be spread by contact with contaminated materials, equipment, vehicles, or food or water.

The incubation period is 3 to 5 days

.

The clinical symptoms vary in intensity depending on the strain in question (high or low pathogenicity), and the sensitivity of the affected species (for example, galliformes are generally more sensitive than anseriforms).

In general

, petechial hemorrhages in internal membranes, pancreatitis and sudden death.

HOW IS THE TRANSMISSION FROM THESE ANIMALS TO HUMANS?

In general,

(some specific cases with the H9 subtype have also been described).

To date, all cases of avian influenza transmission to humans have always occurred under conditions of close direct contact with infected birds and no cases of human-to-human transmission have been reported.

What are the symptoms of infection in humans?

Human infections, almost always produced after close and prolonged contact with infected birds, generally cause, according to the Ministry of Health,

etc.

Some of the subtypes have been associated with the development of severe disease, particularly A(H5N1) and A(H7N9), which have been associated with

, multiple organ dysfunction, and plasma detection of elevated levels of proinflammatory cytokines and chemokines.

How many cases have been detected in humans to date?

Until now, according to the Ministry of Health, in 2022, not counting the case of Guadalajara,

.

in the

.

The case was asymptomatic and the laboratory tests were performed in the context of a study of contacts with infected birds in a poultry farm.

was reported on April 29

in a worker who presented asthenia after participating in a slaughter of birds in a poultry farm affected by influenza A (H5N1).

The patient did not develop any further symptoms and made a full recovery.

"

.

Although the transmission of the influenza A (H5N1) virus from birds to humans is considered a rare phenomenon, the lethality of the detected cases amounts to 35% and, occasionally, important outbreaks occur," Health details.

Since 2003, a cumulative number of 1,321 confirmed human cases, including 455 deaths, have been reported to the World Health Organization (WHO) in 20 countries

.

The two states that have detected major outbreaks are Indonesia and Egypt.

The first, between 2005 and 2017, reported 368 cases, with a peak of 55 in 2006 and a fatality rate of 46%.

Egypt reported a total of 479 with a peak of 136 cases in 2015 and a case fatality rate of 25% between 2006 and 2017. Since then, the detection of cases of influenza A(H5N1) in people has occurred sporadically worldwide.

Between 2018 and 2022, the total number has been 6 cases and 2 deaths (2.3).

Conforms to The Trust Project criteria

Know more

• Europe

• Infectious diseases