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Some Japanese macaques in Texas have begun to show a pathological aversion to germs after surviving an epidemic outbreak of disease, similar to what occurred in early 2020 when much of the world was focused on preventing Covid-19.

After witnessing the devastation of their sanctuary by a contagious and deadly pathogen, these primates started adopting stricter precautions regarding food that appeared contaminated. Researchers suggest that due to the social learning capacity of primates, this aversion to parasites and germs may be transmitted among group members and persist over time.

Federico Rossano, the study's author, stated in a release that this finding demonstrates that germophobia also occurs in non-human primates. He explained that even without understanding the mechanism of disease transmission, exposure to individuals who fall ill and die alters the probability of the animals developing behaviors that could lead to illness.

This behavior was detailed in an article published in the journal Royal Society Open Science and may be crucial for scientists investigating the evolutionary origins of disgust, a fundamental emotion in the behavioral immune system used by animals to avoid harmful biological agents.

The studies were conducted at the Born Free USA Primate Sanctuary, located in southern Texas, an organization that had recently suffered a tragedy. Simian retrovirus (SRV) affected the Japanese macaques, resulting in dozens of deaths caused by immunodeficiency (similar to AIDS) and chronic wasting syndrome.

Given that SRV is highly transmissible—being spread through saliva, urine, blood, bites, scratches, and direct contact—infection from contaminated fluids can evolve rapidly, leading to death in about three to four weeks after contamination begins.

To manage the outbreak, the sanctuary implemented a protocol of separation, testing, and quarantine for the macaque groups. This generated four categories of groups: three that had been exposed to the outbreak (either by falling ill or by witnessing others fall ill) and one control group that had no interaction with SRV.

This situation established a unique natural experiment. Within the exposed groups, some individuals were infected, while others lived with sick macaques without contracting the infection. This allowed researchers to analyze whether merely experiencing an outbreak, even without getting sick, would alter animal behavior.

Fifty-five macaques underwent a choice test. In one container, grapes were placed on a clean wooden surface; in another, the same grapes were on a surface covered with monkey feces and coated with epoxy resin, which ensured protection against infection risks. Theoretically, the grapes attract the Japanese macaques because they are a rare treat at the sanctuary.

Previous research has indicated that feces are not always a repellent factor when there is an attractive reward, as monkeys consumed the food even on contaminated surfaces when presented with a preferred snack, such as peanuts. However, with less palatable meals, they avoided the dirty area.

However, in this specific experiment, the macaques that had experienced the SRV outbreak showed a lower inclination to ingest food from the contaminated surface. They consumed from the contaminated area in only 47% of attempts, compared to 79% observed in macaques from the group that never experienced the outbreak.

A notable aspect was that even macaques who did not contract SRV but merely witnessed others fall ill exhibited behavioral patterns similar to those of the infected. This suggests that the behavioral modification is linked to the experience of the outbreak, and not exclusively to having become ill.

The Ministry of Agriculture and Livestock confirmed the identification of an outbreak of Newcastle Disease (NDV) on a turkey farm located in the municipality of Nova Itaberaba, western Santa Catarina. Although the virus was detected in laboratory analyses, the affected animals showed no visible clinical signs.

This outbreak has led to partial or total suspensions in the purchase of Brazilian chicken by countries such as China and Mexico. However, authorities assure that the disease does not constitute a danger to human health.

Although human contamination is theoretically possible, it is described as extremely rare and mild. Consuming sick chickens that have been properly cooked does not transmit the illness. Cases in humans tend to occur in individuals who have direct contact with the birds, and they can be prevented through the correct use of Personal Protective Equipment (PPE).

When a human infection occurs, Newcastle Disease manifests symptoms similar to a common flu or mild conjunctivitis, conditions that usually resolve spontaneously.

NDV is caused by a strain of the Orthoavulavirus javaense and primarily affects birds. Its main characteristic is being highly contagious, spreading mainly through direct contact between healthy birds and secretions from contaminated birds.

All secretions from carrier animals carry a high amount of the NDV-causing virus, which has the ability to survive for days or weeks on surfaces. This combination facilitates the spread of the disease through mechanical routes, such as through clothing and footwear soiled with these secretions.

In commercial breeding environments, the confinement system significantly accelerates transmission. According to an informational material from the World Organisation for Animal Health, when the virus enters a vulnerable flock, almost all birds can be infected within a period of two to six days.

Contamination can be asymptomatic, as observed in the farms in SC. If symptoms appear, the virus affects the respiratory, nervous, and digestive systems of the birds. Clinical signs include difficulty breathing, nervous manifestations (such as depression, loss of appetite, muscle tremors, wing drops, head and neck twisting, circular movements, and total paralysis), swelling in the tissues around the eyes and neck, watery and greenish diarrhea, as well as eggs with thin or rough and deformed shells, resulting in lower egg production.

The mortality rate can reach 100%. Due to this, there is a specific protocol for managing outbreaks or epidemics of Newcastle Disease. Necessary actions include implementing quarantines, humane slaughter of all infected or exposed animals, followed by proper disposal of carcasses and general disinfection of the facilities.

Celes Regina de Matos, president of Cidasc, told Agência Brasil that the team is already on site, working on containing and eradicating the virus. She emphasized that the location will be treated as an outbreak focus, and eradication and disinfection will be carried out until the focus is eliminated. Cidasc will only leave the site after this elimination, aiming to do so as quickly as possible. Once the focus is controlled, everyone will be notified, fulfilling the commitment to the external market, which depends on the health of the flock to guarantee imports.