The disease that is killing birds can reach the human brain

Red eyes, irritation, swelling of the eyelids and itching – these are some of the symptoms associated with conjunctivitis common, however, when newcastle disease is the origin of this condition, science clarifies that symptoms can scale to more serious problems – namely neurological problems.

The virus of newcastle disease, who is killing birds in Portugal, registered first cases in several islands of the Autonomous Region of the Azores.

Check here what the regional Secretary for Agriculture, António Ventura, said about the development of the disease in these regions and measures that can be taken to prevent the continued spread of the disease.

Other recent cases in Portugal

Previously caused by avian orthoavulavirus 1 (AOAV-1), this strain, according to a Portuguese study of 2025, focused on turtledoves in northern Portugal, demonstrated “to represent a global threat to domestic and wild birds”.

“In early 2025, an outbreak of pigeon paramyxovirus type 1 (PPMV-1, genotype VI AOV-1) was detected in a rehabilitation center for wild animals in northern Portugal, affecting Streptopelia decaocto , Streptopelia risaria and Columba livia”, they described.

According to investigators, “the birds that showed acute neurological signs died quickly”.

Afraid to contract this virus?

Here's what you need to know about Newcastle disease

Distributed as Newcastle disease, this “common and highly contagious zoonotic infection” is behind avian paramyxovirus type 1 (AMV-1), which according to Centers for Disease Control and Prevention (CDC), it is a bird virus.

The Directorate-General for Food and Veterinary (DGAV) ensures that the main targets are birds, however, the CDC adds that monkeys, rabbits and pigs will also have been identified with the virus. 

And attention, these experts also warn of possible risks to human health.

What are the symptoms associated with this condition?

Although eye problems, as conjunctivitis, be the symptoms most associated with Newcastle disease, these experts point out that “humans are rarely affected”.

Nevertheless, they identify a “variety of clinical manifestations since asymptomatic infections up to outbreaks of respiratory systemic disorders and neurological, depending on the viral strain and the affected avian species”.

Despite being an isolated case, the same source describes “a fatal episode of neurological infection caused by PPMV-1 in a child in Australia.”

In these cases, they describe that “inflammation of the brain tissue”, also recognized by encephalitis, as well as symptoms associated with “loss of neurons”, “injuries to the brain stem, cerebellum and other regions of the nervous system”. In severe cases, “brain oedema and extensive neurological disorders”.

In behavioral terms, this clinical analysis can be translated into:

• Confusion or alteration of consciousness;
• Difficulty in speaking or swallowing;
• Changes in movements;
• Lack of coordination, weakness/paralysis and, in extreme cases, coma.

How can you protect yourself from the disease?

Regardless of strain, DGAV makes some recommendations:

• Avoid touching sick or dead birds, especially wild birds;
• If you have any species or rearing of birds and have to touch them, choose to wear suitable protective equipment such as gloves, glasses and something that protects the airways, such as a macara;
• Wash hands thoroughly after any contact with birds, feces, secretions or equipment used in the rearing of these animals;
• Avoid touching eyes, nose and mouth after being in contact with these potentially contaminated species or materials.

In case of mistrust of the presence of the virus, these experts suggest that you seek medical help and isolate infected species.