Newcastle disease is a viral infection that mainly affects birds, and people usually catch Newcastle disease only after close contact with infected poultry or other birds. In humans, the early symptoms of Newcastle disease are most often red, painful eyes and sometimes mild flu-like illness. Not everyone will have the same experience. Newcastle disease in people is usually short-lived, often lasting a few days to a couple of weeks, and serious illness or death is very rare. Treatment for Newcastle disease is usually supportive, such as rest and care for eye irritation, while people with more severe symptoms may need medical attention.
How many people live with Newcastle disease?
Worldwide and U.S. prevalence estimates for human Newcastle disease are not consistently reported by a single authoritative source. In people, this infection is very rare and is usually recorded as isolated cases after close contact with infected birds, so there is no reliable current count of how many people are living with it worldwide or in the United States.
Overview
Newcastle diseaseSymptoms
Newcastle disease in people is uncommon and usually mild. Symptoms can include red, irritated eyes, fever, headache, and a sore throat, especially after close contact with infected birds.
Outlook and prognosis
For people with Newcastle disease, the outlook is usually very good. Human infection is uncommon and, when it happens, symptoms such as red, irritated eyes or a mild flu-like illness often improve fully within days to a few weeks.
Causes and risk factors
Newcastle disease is caused by infection with avian paramyxovirus, usually after contact with infected birds or their droppings. Risk is highest for poultry workers, bird handlers, and laboratory staff. Poor hand hygiene and lack of eye protection can raise exposure risk.
Genetic influences
Genetics matters mainly because different genetic variants of the Newcastle disease virus can change how severe illness is and how easily it spreads. Host genetics may also affect susceptibility, but this is less important than viral variation.
Diagnosis
Newcastle disease is diagnosed from symptoms, exposure history, and an eye exam. Doctors usually confirm the diagnosis of Newcastle disease with lab tests on eye or throat samples.
Treatment and drugs
Newcastle disease is managed mainly with supportive care for affected birds, such as fluids, warmth, and treatment for secondary bacterial infections. In flocks, rapid isolation, strict cleaning, and vaccination of healthy birds help limit spread.
Symptoms
Newcastle disease mainly affects birds, and it can range from a mild illness to a fast, severe one. Birds with Newcastle disease may seem tired, stop eating well, develop breathing problems, or pass loose green droppings, and some later have shaking, weakness, or a twisted neck. The early symptoms of Newcastle disease can be easy to miss in a single bird but may stand out quickly in a flock. Human infection is rare and usually mild, most often causing red, irritated eyes after close contact with infected birds.
Birds with Newcastle disease often become less active, less alert, and less interested in food or social interaction. A bird may sit puffed up, perch less, or stop coming eagerly for feed.
Sneezing, coughing, gasping, or noisy breathing are common, especially in more severe infections. Some birds breathe with an open beak, stretch the neck forward, or seem worn out after small movements.
Loose droppings, often watery and greenish, can happen along with poor appetite and weight loss. Owners may notice feed left untouched or feathers around the vent becoming soiled.
Some birds develop tremors, weakness, poor balance, circling, or a twisted neck. These signs can make walking, perching, or reaching food and water hard, and paralysis can occur in severe cases.
How people usually first notice Newcastle disease?
People usually first notice Newcastle disease after close contact with infected birds, often when red, irritated eyes develop suddenly, sometimes with tearing, swelling, or a gritty feeling. Some people also feel mildly unwell, with symptoms like fever, headache, sore throat, or body aches, but eye symptoms are often the first clue. In most people, Newcastle disease is uncommon and usually mild, but new eye irritation after poultry exposure is a reason to seek medical advice.
Types of Newcastle disease
Newcastle disease can range from a mild infection to a very severe illness in birds, and the different types mainly reflect how aggressive the virus is. In everyday terms, some birds may have only mild breathing problems, while others become very sick with major gut or nervous system symptoms. Researchers describe these categories to better understand patterns of the condition. The main types of Newcastle disease are based on how severe the infection is and which body systems are most affected.
Lentogenic
This is the mildest form, and birds often have few symptoms or only mild coughing, sneezing, or a drop in egg production. Some may seem a little tired or off their food, but severe illness is uncommon.
Mesogenic
This form causes more noticeable disease, often with breathing problems and some nervous system signs such as tremors or trouble moving normally. Birds may look clearly unwell, but it is usually less deadly than the most severe variants of Newcastle disease.
Velogenic
This is the most severe type and can spread quickly through a flock, causing sudden illness and high death rates. Symptoms can include major breathing trouble, green diarrhea, swelling, weakness, and nervous system problems such as twisting of the neck or paralysis.
Viscerotropic velogenic
This severe subtype mainly affects the digestive tract along with the lungs and airways. Birds may develop marked diarrhea, weakness, dehydration, and bleeding or damage in the intestines.
Neurotropic velogenic
This severe subtype is known for nervous system symptoms along with breathing illness. Birds may develop tremors, poor balance, circling, drooping wings, or paralysis, and many become critically ill.
Can I slow down the onset of symptoms?
No. For Newcastle disease, there is no good evidence that lifestyle changes or medicines can meaningfully slow the start of symptoms once you have been infected; the main proven step is prevention, such as avoiding contact with sick birds, using gloves and eye protection if you handle birds, and washing hands well, which lowers the chance of getting the infection rather than delaying it. There is no well-established preventive medicine for the general public, but if you may have been exposed and develop red, irritated eyes or flu-like symptoms, getting medical advice early can help with comfort and recovery, and careful exposure prevention is still worthwhile even though it cannot guarantee you will not get sick.
What genetics can tell you about symptoms
Genetics usually cannot tell you much about the symptoms of Newcastle disease in people, because this illness is caused by exposure to a virus from infected birds rather than by an inherited genetic change. In humans, symptoms are usually mild and may include eye irritation or redness, tearing, and sometimes flu-like symptoms, and these tend to depend more on the amount of exposure and your body’s response than on your genes. The virus strain can affect how severe the disease is in birds, but there is no well-established evidence that a person’s genetic differences reliably predict which symptoms they will have, how severe they will be, or when they will start.
Causes and risk factors
Newcastle disease is caused by a virus that spreads mainly from infected birds and their droppings, feathers, and respiratory fluids. The main risk is close contact with poultry or pet birds, especially during outbreaks or when birds are sick and unvaccinated. Risk also goes up in places with heavy bird exposure, such as farms, live bird markets, and labs, and when masks or eye protection are not used. Genetics are not thought to play a major role in Newcastle disease, and Knowing your family history is a good first step does not apply here. For most people, risk depends far more on exposure than on personal biology, and human spread is very rare.
What are the most common causes or risk factors?
Newcastle disease is caused by a virus carried by infected birds, especially chickens and other poultry. The main risk factors are close contact with sick or dead birds or with their droppings, spit, feathers, cages, feed, water, clothing, or tools that have the virus on them, so bird owners, farm workers, slaughterhouse workers, and lab workers are at higher risk. There are no well-known inherited risk factors in people, and human infection is rare and usually happens after direct bird exposure.
Environmental and biological risk factors
Newcastle disease is mainly a bird infection, and people usually get it only after close contact with infected birds or contaminated bird material. Most risk factors for Newcastle disease in humans relate to exposure around birds and in bird-handling environments. Doctors often group risks into internal (biological) and external (environmental). For Newcastle disease, the environmental side matters most.
Close contact with infected chickens, turkeys, pigeons, parrots, or other birds is the main risk factor for Newcastle disease. Human infection usually happens when virus from a bird reaches the eyes, nose, or mouth.
Working in poultry farms, hatcheries, slaughterhouses, or live bird markets raises the chance of repeated exposure. Risk is higher when many birds are housed close together or when a flock is having an outbreak.
Bird droppings, respiratory secretions, feathers, litter, and contaminated cages or tools can carry the virus. Touching these materials and then touching the face can spread Newcastle disease to people.
Cleaning coops, catching birds, or processing carcasses can stir virus-containing dust and droplets into the air. Breathing these particles in or getting them into the eyes increases exposure.
Genetic risk factors
Newcastle disease is not an inherited condition in people or birds; it is caused by infection with a virus. When genetics matter, they mainly involve the virus itself and, to a lesser extent, the natural susceptibility of different bird species or breeding lines. That is why the genetic risk factors for Newcastle disease are mostly about how aggressive the viral strain is rather than a family trait. Science continues to uncover how these elements interact.
Viral strain: Newcastle disease can be mild or very severe depending on the virus strain involved. Different genetic lineages of the virus behave differently, which helps explain why one outbreak may look very different from another.
Fusion site: A key genetic feature in the virus affects how easily it can spread through the bird's body. Strains with high-virulence changes in this region are linked to more severe disease.
Bird species: Natural susceptibility differs across bird species because their inherited biology is not the same. Chickens often become much sicker than ducks or geese, which may carry the virus with milder illness.
Breeding lines: Even within the same species, some breeding lines appear more resistant or more vulnerable than others. This likely reflects inherited differences in how the immune system recognizes and controls the virus.
Human genetics: No well-established inherited human gene change is known to cause Newcastle disease or clearly raise risk. In people, genetics are not considered a main driver of who becomes ill or how severe symptoms are.
Lifestyle risk factors
Newcastle disease is mainly driven by viral exposure, but day-to-day flock management can strongly affect how easily it spreads and how severe illness becomes. In practice, what people often mean by lifestyle risk factors for Newcastle disease are husbandry habits that increase stress, weaken resistance, or promote contact between infected and healthy birds. Diet, movement, and handling routines matter most because they can change immune resilience and transmission within a flock.
Inadequate energy, protein, vitamins, or minerals can weaken immune responses in birds. Malnourished birds may be less able to limit viral replication and may recover more poorly after infection.
Keeping too many birds in a limited space increases close contact and makes the virus easier to pass between flock members. Crowding also raises stress, which can worsen clinical signs and overall losses.
Frequently introducing new birds or mixing age groups and species increases opportunities for silent transmission. Birds without obvious signs can carry infection into a flock and trigger rapid spread.
Repeated stress from rough handling, transport, abrupt routine changes, or poor social conditions can suppress immune function. Higher stress can make birds more vulnerable to severe disease and secondary complications.
Risk prevention
Newcastle disease in people is uncommon and usually happens after close contact with infected birds, especially poultry. For most people, prevention is less about everyday public risk and more about reducing exposure at work, on small farms, or when caring for sick birds. Some prevention is universal, others are tailored to people with specific risks. If you handle birds regularly, simple protective steps can greatly lower the chance of infection.
Try not to handle birds that seem ill, are acting unusually, or have died suddenly unless you must do so safely. This is one of the most important ways to lower the risk of Newcastle disease.
Wear gloves and eye protection when cleaning cages, handling poultry, or touching bird droppings and secretions. A well-fitting mask can also help reduce splash or dust exposure, especially in enclosed spaces.
Wash your hands with soap and water after touching birds, eggs, cages, feed areas, or contaminated clothing. Avoid rubbing your eyes before you clean your hands, since Newcastle disease in humans often affects the eyes.
Disinfect cages, tools, surfaces, and transport crates regularly if birds may be infected. Good cleaning lowers the amount of virus in the environment and helps prevent it from spreading between birds and people.
Can you prevent Newcastle disease?
Newcastle disease cannot be prevented with complete certainty, but in people the risk can be lowered a lot by avoiding sick birds and bird droppings, washing your hands well after handling birds, and using gloves and eye protection if you work with poultry. Keeping pet and farm birds healthy, with routine veterinary care and vaccination of bird flocks where recommended, also helps reduce spread.
Transmission
Newcastle disease is a viral infection that spreads very easily among birds, but human infection is uncommon. People usually catch it after close contact with infected poultry or pet birds, or by touching droppings, secretions, feathers, cages, or dust carrying the virus and then getting it into the eyes, nose, or mouth.
If you are wondering how Newcastle disease spreads, it is mainly from birds to birds and, much less often, from birds to people. It is not known to spread easily from person to person, so for most people outside bird handling or lab work, the risk is very low.
When to test your genes
Newcastle disease is a viral infection, not a condition where your genes guide early detection or treatment. Genetic testing is not used to predict your risk or customize care; if Newcastle disease is suspected, doctors or veterinarians rely on exposure history, symptoms, and virus-specific lab testing instead.
Diagnosis
Newcastle disease is diagnosed in people mainly by looking at symptoms together with recent contact with sick birds or poultry settings, because human infection is rare and usually mild. Doctors usually begin by asking about eye redness, fever, cough, or flu-like symptoms and whether you work with chickens, turkeys, or other birds. For many, the diagnosis of Newcastle disease starts with that exposure history, then testing is used when the cause is unclear or public health confirmation is needed.
Doctors ask about recent work with poultry, contact with sick or dead birds, or time spent in places where outbreaks have occurred. This helps show whether Newcastle disease is a realistic cause of eye or flu-like symptoms.
Many people with Newcastle disease have red, irritated eyes, tearing, and sometimes mild fever, headache, or cough. Doctors use this pattern to judge whether the illness fits a bird-related viral infection.
If eye symptoms are present, your provider may examine the surface of the eye and surrounding tissues to check for conjunctivitis. This can help rule out more common causes such as allergies, irritation, or a routine viral eye infection.
A swab from the eye or nose may be sent for specialized virus testing, especially if the diagnosis is uncertain or there is a workplace exposure concern. Tests may feel repetitive, but each one helps rule out different causes and can confirm Newcastle disease when needed.
How is Newcastle disease diagnosed?
In people, Newcastle disease is usually diagnosed by asking about recent contact with sick birds or poultry work, reviewing symptoms such as red, irritated eyes and flu-like illness, and doing a physical exam. If needed, a doctor may confirm it with a lab test on a swab from the eye, nose, or throat, and sometimes a blood test to look for signs of the virus.
Stages of Newcastle disease
Newcastle disease does not have defined progression stages. It is usually described by how severe the infection is and which body systems are affected, rather than by a steady step-by-step worsening over time. Doctors and veterinarians look at the pattern of symptoms, such as breathing problems, diarrhea, or nervous system changes, and may ask about the early symptoms of Newcastle disease and recent exposure to sick birds. Different tests may be suggested to help confirm the virus, including swabs or samples checked in a laboratory.
Outlook and prognosis
In people, the outlook for Newcastle disease is excellent, because infection is usually mild and self-limited. Most affected individuals recover fully within a few days to about 1 to 2 weeks, with symptoms such as conjunctivitis, tearing, eye irritation, fever, or mild flu-like illness resolving without lasting effects. Severe disease is very uncommon and is mainly a concern after heavy occupational exposure in laboratory or poultry settings. Permanent complications are rare, although temporary eye discomfort or blurred vision can occur during recovery. Human mortality from Newcastle disease is exceedingly rare, and deaths have not been a typical feature of this infection.
Long-term effects
For most people, Newcastle disease does not lead to lasting health problems. In humans, this infection is usually short-lived, and the outlook is generally very good, even when the early symptoms of Newcastle disease feel uncomfortable for a few days. It’s important to remember that long-term doesn’t always mean progressive. Lasting effects are uncommon and, when they happen, they most often involve the eyes after a more intense exposure.
Most people with Newcastle disease recover fully without ongoing symptoms. Fever, eye irritation, and flu-like feelings usually clear within days to a few weeks.
Some may have lingering redness, watering, or light sensitivity after the infection has otherwise improved. This is uncommon, but it can last longer if the eyes were badly irritated at the start.
Long-term vision changes are rare in Newcastle disease. If blurred vision, eye pain, or worsening light sensitivity continues, doctors usually look for another eye condition or a complication rather than the infection alone.
People who handle poultry or work in labs may have repeat exposures over time. Even so, Newcastle disease does not usually cause a chronic infection or ongoing damage in otherwise healthy adults.
How is it to live with Newcastle disease?
For people, Newcastle disease is usually not a long-term illness to live with; it is mainly a disease of birds, and when humans do get infected, it most often causes short-lived eye irritation, redness, tearing, or mild flu-like symptoms, especially after close contact with infected poultry. Daily life is usually affected for only a few days by discomfort, time away from work, and the need to avoid further exposure while the eyes heal. The bigger impact often falls on people around you if you work with birds, because an outbreak can disrupt farming, household routines, and income, even though person-to-person spread is very uncommon.
Treatment and drugs
Treatment for Newcastle disease is usually supportive, because there is no standard antiviral drug that reliably clears the infection in people. Most people with Newcastle disease recover with rest, fluids, and treatment for symptoms such as fever, body aches, or eye irritation; if the eyes are involved, a doctor may suggest lubricating drops or other short-term care. Not every treatment works the same way for every person, and antibiotics do not treat the virus itself, though they may be used if a separate bacterial infection is suspected. If symptoms are severe, last more than a few days, or follow close contact with sick birds, it is important to seek medical care and let the clinician know about that exposure.
Can you cure Newcastle disease?
No, there is no cure for Newcastle disease. In people, it is rare and usually mild, so treatment is mainly rest and care to ease symptoms like red eyes or fever until the infection goes away on its own. In birds, there is also no cure, so care focuses on limiting spread and preventing infection with vaccination.
Non-drug treatment
Newcastle disease can spread quickly through a flock, so day-to-day care usually centers on limiting spread and helping sick birds stay as stable as possible. Managing this condition often means supportive care, strict separation of ill birds, and careful cleaning rather than a curative therapy. In birds, there is no non-drug treatment that clears the virus itself, but these steps can reduce suffering and protect other birds. The exact plan may differ for a pet bird, backyard flock, or large commercial setting.
Sick birds should be separated from healthy birds as soon as possible to reduce spread. This matters even more when early symptoms of Newcastle disease, such as low energy, breathing trouble, or diarrhea, first appear.
Birds may need warmth, easy access to clean water, and soft feed they can manage with less effort. For many, treatment begins not at the pharmacy, but with keeping the bird quiet, hydrated, and under close observation.
Gentle humidity and a calm environment can sometimes ease breathing strain in birds with nasal discharge or coughing. Reducing stress from noise, handling, and crowding can also help conserve energy.
Thorough cleaning of cages, feeders, drinkers, boots, and shared tools helps lower the amount of virus in the environment. Disinfection should be paired with removal of droppings and dirty bedding, because organic material can make cleaning less effective.
Your genes may have an impact on how drugs work for you
For Newcastle disease, genetic differences are not known to meaningfully change how treatment works in people. That is because there is no usual long-term medicine plan for this infection in humans, and care is mostly supportive, such as helping with eye irritation, fever, or other short-lived symptoms. In other words, unlike some conditions where your genes can affect which medicine works best, this is not considered an important part of care for Newcastle disease.
Pharmacological treatments
For Newcastle disease, there is no specific antiviral medicine that reliably treats the infection in people. Most cases are mild and short-lived, so treatment usually focuses on easing symptoms, especially red, irritated eyes and flu-like discomfort. Not everyone responds to the same medication in the same way, and many living with Newcastle disease only need short-term supportive care. In rare severe cases, treatment is given in a hospital based on the symptoms present.
Acetaminophen or ibuprofen may be used to lower fever, ease headache, and reduce body aches linked to Newcastle disease. These medicines do not treat the virus itself, but they can help people feel more comfortable while the illness passes.
Artificial tears or lubricating eye drops can help soothe burning, redness, and irritation when Newcastle disease affects the eyes. This can be especially helpful during the early symptoms of Newcastle disease, when conjunctivitis is often the main problem.
Antibiotic eye drops are not used routinely for the virus, but they may be prescribed if a doctor suspects a secondary bacterial eye infection. If one option isn’t effective, second-line or alternative drugs may be offered based on the eye findings and exam.
Rarely, if illness is more severe, doctors may use treatments such as intravenous fluids, oxygen, or other medicines aimed at specific symptoms. Drugs that target symptoms directly are called symptomatic treatments, and they are chosen based on what the person is experiencing rather than to cure the virus.
Genetic influences
If eye redness or flu-like symptoms show up after handling poultry, the bigger concern is usually recent bird exposure than anything inherited. In Newcastle disease, genetics are not thought to be a main cause; the illness is driven by infection with a virus, and family history usually does not predict who will get it. It’s natural to ask whether family history plays a role, but for Newcastle disease, contact with infected birds or contaminated materials matters much more. Researchers are still studying whether small differences in immune-response genes could slightly affect how someone reacts to infections, but this has not led to routine genetic testing or changed standard care. For most people, preventing Newcastle disease in humans focuses on avoiding exposure, washing hands well, and using eye and face protection when working closely with birds.
Is Newcastle disease genetic?
Genetics matters mainly because different genetic variants of the Newcastle disease virus can change how severe illness is and how easily it spreads. Host genetics may also affect susceptibility, but this is less important than viral variation.
Having a genetic risk is not necessarily a diagnosis
Genetic variants are a usual part of being human and are found widely across the population. Most do not directly affect health and simply contribute to normal human diversity. For many genes, having a variant associated with a condition suggests a possible link, not a certain diagnosis, particularly when several genes and environmental factors play a role. In some situations, though, one well-understood variant in a particular gene is enough to confirm a diagnosis.
Pharmacogenetics—how genetics influence drug effects
If Newcastle disease leads to red, painful eyes or a short flu-like illness after bird exposure, treatment is usually focused on easing symptoms rather than using a disease-specific drug. In people, there is no well-established pharmacogenetic test that guides treatment for Newcastle disease, partly because human cases are rare and usually mild. Not every difference in response is genetic, but medicines used for comfort, such as pain relievers or fever reducers, can still affect people differently based on age, liver and kidney health, other medications, and sometimes inherited differences in drug processing. For many living with Newcastle disease, this means the treatment for Newcastle disease is usually tailored to symptoms instead of a gene test result. If eye inflammation is more severe, a doctor may choose treatment based on the exam and your medical history, not on a known Newcastle disease gene pattern. In short, genetics currently play little direct role in how doctors treat Newcastle disease in people, and supportive care remains the standard approach.
Interactions with other conditions
For most people, Newcastle disease does not have well-known, specific interactions with other diseases in the way some long-term illnesses do. In humans, it is usually a short-lived infection linked to close contact with infected birds, and symptoms often stay limited to eye irritation, redness, or mild flu-like illness. The presence of another illness does not always mean Newcastle disease will be more severe, but people with weakened immune systems or significant eye disease may need closer medical attention if symptoms develop. If someone already has asthma, chronic lung disease, or another infection at the same time, it can be harder to sort out whether cough, fever, or feeling unwell is coming from Newcastle disease or something else. Talk with your doctor about how your conditions may influence each other, especially if early symptoms of Newcastle disease appear after bird exposure or if eye symptoms are getting worse instead of improving.
How genes can cause diseases
Humans have more than 20,000 genes, each carrying out one or a few specific functions in the body. One gene instructs the body to digest lactose from milk, another tells the body how to build strong bones and another prevents the body's cells from beginning to multiply uncontrollably and developing into cancer. As all of these genes combined are the building instructions for our body, a defect in one of these genes can have severe health consequences.
Through decades of genetic research, we know the genetic code of any healthy/functional human gene. We have also identified that in certain positions on a gene, some individuals may have a different genetic letter from the one you have. We call these hotspots "Genetic Variations" or "Variants" in short. In many cases, studies have been able to show that having the genetic letter "G" in the position makes you healthy, but having the letter "A" in the same position disrupts the gene function and causes a disease. Genopedia allows you to view these variants in genes and summarizes all that we know from scientific research, which genetic letters (Genotype) have good or bad consequences on your health or on your traits.
What other conditions can cause similar symptoms to Newcastle disease?
Newcastle disease in people can look a lot like common causes of pink eye, including viral or bacterial eye infections and eye irritation from allergies. If it also causes fever, headache, or body aches, it may be confused with the flu, COVID-19, or another common viral illness. In someone who works closely with birds, doctors may also think about other bird-related infections, especially bird flu, because the early symptoms can overlap.
History
Long before modern lab tests, farmers noticed sudden illness spreading through flocks, with birds developing breathing problems, weakness, and sharp drops in egg production. For families who relied on chickens or pigeons for food and income, that kind of outbreak could change daily life very quickly. Newcastle disease became especially important not only because of its impact on birds, but also because people working closely with infected poultry sometimes developed mild eye irritation or flu-like symptoms.
The disease was recognized in the early 20th century, after major outbreaks were reported in several parts of the world, including near Newcastle upon Tyne in England, which gave the illness its widely used name. At first, doctors and veterinarians understood it mainly through what they could see during outbreaks: fast spread, severe illness in some flocks, and very different patterns from one strain to another. Once considered rare, now recognized as a major animal health problem in many regions, Newcastle disease has been tracked for decades because of its effect on farming, food supply, and trade.
As medical science evolved, researchers learned that Newcastle disease is caused by a virus and that not all outbreaks are equally severe. Some forms cause mild illness, while others can be devastating in poultry. That helped explain why one community might see only a brief drop in production, while another could lose large numbers of birds in a short time.
Over time, public health and veterinary systems began to work more closely together on surveillance, vaccination programs for birds, and outbreak control. Human illness from Newcastle disease remained uncommon and usually mild, most often affecting laboratory workers or people handling infected birds, but awareness of these cases helped shape safety practices. Knowing the condition’s history helps explain why early symptoms of Newcastle disease in birds are taken seriously today, even when they seem mild at first, and why quick reporting remains such an important part of controlling its spread.