They now rule out the two Spanish avian flu infections in humans that occurred in October

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Last October, the Castilla-La Mancha Ministry of Health reported that a

in Guadalajara had tested positive for

, a case to which a second case was added days later, reported by the WHO.

Both workers became the

of a jump of this avian infection in humans, which reinforced surveillance and epidemiological controls on the transmission of zoonotic diseases, also taking into account the

that have occurred in

and in different species of animals.

A

of H5N1 avian influenza detected in Spain in the autumn of 2022 has confirmed the theory that there were no real infections, but that both were in contact with

that was in the

.

Spain will modify the protocols, according to the analysis published in Eurosurveillance.

The work, which has had the collaboration of animal health and public health authorities,

of detection of highly pathogenic H5N1 avian influenza viruses in humans in Spain.

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The authors report that both workers tested positive for the

of this virus in nasopharyngeal swabs during the initial review of all workers on the farm or who had been involved in slaughtering the birds and subsequent cleaning.

It is also indicated that

, that all the following tests were negative and that they did not develop

against the virus.

Absence of antibodies

According to the authors, "the absence of symptoms in both workers, together with the laboratory results, which showed a very low viral load and the

against the A/H5 virus, suggested that the positive PCR results were were most likely due to

, conclusions that coincide with previous Health reports in which it is stated that the positives were the result of "a context of

on the affected farm" and that, therefore, it was not he could rule out that more cases could arise.

Ursula Höfle

, a researcher at the Institute for Research in Hunting Resources IREC (CSIC-UCLM-JCCLM) of the University of Castilla-La Mancha, points out to SMC Spain that the data from the study conclude that it was not an infection as such, what which would imply "entry of the virus into the cells of the respiratory tract and

, and this in turn would have generated a response in people's antibodies"

They postulate, says this professional, "that rather what has been detected is a

-genetic material of the virus present in dust deposited in the respiratory tract of workers-, and that in order not to create

it is necessary to use

that detect only real infections as such.

This would mean that

exposed workers on affected farms is a measure that would improve early detection of zoonotic infections.

for carrying out the tests must be taken into account

to avoid contamination and the criteria for interpreting the results.

According to

, from the National Institute for Agricultural and Food Research and Technology (INIA-CSIC), "it had already been commented on many occasions that these two positive cases in the workers of the Guadalajara farm were possibly

", she tells SMC this researcher who had previously suggested the possibility that it was a

rather than an active infection.

Low capacity in humans

, also from INIA, spoke in a similar vein

, who told SMC that "the outcome of this viral outbreak shows that, for now, this H5N1 virus has

to efficiently transmit to

and that continuous and systematic in wild and domestic birds", an idea that Höfle refutes, who points out that the work of Eurosurveillance is in line with the data that affirm that "to date there is no

to infect humans or to be transmitted between people" , also stressing the

between the detection of genetic material of a pathogen and the confirmation of a real infection.

"It is very important not to confuse detection of

. We have become accustomed to the polymerase chain reaction (PCR) as a means of diagnosis, mainly due to covid-19."

However, and in her opinion, a positive PCR by itself does not really confirm that the

of the genetic material of what we are looking for is present", indicates this expert who also insists that once the exposure is confirmed, it should "reinforce acceptance of the need to follow

for all farm workers," concludes Höfle.

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