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Fowl pox is a viral disease that occurs frequently in many birds, it is usually caused by several strains of the Variola avium virus, which belongs to the Poxiviridae family. This disease is identified by several levels, since according to its degrees it can be considered as moderate or in some extreme cases as severe. Fowl pox is a disease that develops slowly in the bird’s organism, in the following article we will know more about what is fowl pox, its causes and treatments.

Fowl pox

Fowl pox is a viral disease considered very common in different types of birds, this alteration is produced by several strains of the Variola avium virus, which belongs to the Poxiviridae family.

This disease is classified depending on the severity, in some may be identified as moderate and in others depending on the damage to the body can be severe, the development of the same is usually a slow process.

Birds that generally suffer from fowl pox show epidermal symptoms which in many cases are characterized by eruptive lesions and which are continuously distinguished in the form of warty growths or visible galls in the areas without feathers, which are usually very affected.

Fowl pox can also present various symptoms, which include alterations in the digestive tract and upper respiratory tract with membranous lesions that are more serious and can cause death by asphyxia or starvation, depending on how advanced it is in the organism of the species.

Fowl pox has been located in a wide variety of birds, which have been counted in order to generate a control, the number of birds that presented this pathology are more than 60 species of 20 families.

Including in these figures the domestic birds that are vulnerable to present this disease and which include the following species:

In general, fowl pox affects a large number of species, and is the cause of great losses of the same, depending on how advanced the disease is in the body of the bird, it is easy to recognize if there is in the animal the existence of this disease due to its physical characteristics and the notable alterations of the common habits.


In general, the term used as fowl pox includes other definitions, since it is also known by the following names:

  • Fowl diphtheria
  • Diphtherovirus
  • Contagious avian epithelioma
  • Kikuth’s disease
  • Avian poxivirus infection


Fowl pox is a disease caused by the Variola avium virus and is part of the subgroup of avipoxviruses, this is characterized by belonging to the group of poxviruses, which cause considerable alterations within the organisms of these species.

This disease usually affects a great percentage of bird species, its viral cause was described in 1902.Where everything related to this pathology was established as follows:

    • Variola avium is a strong virus that causes diverse alterations in the organism of the birds, this disease contains DNA of double strand
    • Although among the poxviruses present in these alterations is the human smallpox virus (Variola vera) there is no possibility that they are transmitted to humans
    • There is no evidence that avipoxviruses infect humans or cause any negative reaction in people’s bodies

There is a large number of strains of Variola avium virus, these have a complex classification which is focused on the effects that this generates in the infected species, due to its pathogenic effect on different species of birds such as chickens, turkeys, pigeons and canaries, considered animals of great importance to society.

The specificities of the strains usually attack the bird causing various alterations and damage to the organism, as these usually vary according to the degree they present, some have a certain specificity and others attack species of different families, depending on the complexity of the case, since each animal is different.

Although there are occasions where it has been proven that many bird species are sensitive to more than one strain, and are more vulnerable to the disease, it all depends on the species and the natural capacity it has.

In general, smallpox is a virus that has a significant resistance to the external environment, even in the lowest temperatures, since it is characterized by being resistant to desiccation.

It can be present on dry skin, since it has the level of resistance and can maintain its infective capacity for long periods of time, including years at normal temperatures, which makes it strong to attack when it is at an advanced level.

Routes of transmission

In general, the way of transmission of this virus is mechanical, this is established by the contact of the virus with small wounds of the skin or in some cases by the exposure of the mucous membranes of respiratory and ocular ways with infected particles brought by the air, because these are the most frequent ways of affecting the organism of the bird.

Because of this, the arthropods that come in contact with the virus are mechanical vectors of the disease, and for this reason when they bite or feed on wounds while going from a sick bird to a healthy one, this is a process that has been going on for long periods of time. Mosquitoes are considered to be the most common vectors for spreading this disease. Perches and water troughs used by sick birds can cause contagion quickly due to the way they are distributed.

For this reason, it is important to mention that any object, among which the following stand out:

  • Contaminated poultry cages
  • Food consumed by species at risk
  • The contaminated implement or clothing, are in many cases, the possible transporters of the virus in poultry farming this in a specific way due to its resistance measure

Many of the birds confined in large concentrations are considered as vulnerable and for this reason it is frequent that in poultry outbreaks the disease spreads quickly, since they present a high risk of the same. There is even a high percentage of contagion in species that do not usually get sick in the wild, this occurs when they are kept in captivity, because certain cases have been reported of species that get sick with strains that affect many birds, due to the rapid spread.

Many times the appearance of cases in areas close to an outbreak is probably related to the transfer of mosquito vectors located nearby.In many cases, wild birds are the ones that spread the transmission of the disease to great distances from the source of origin, due to the fast contagion that is established.

Affected species

For a long time, certain cases of fowl pox have been reported in a number of 60 species which belong to 20 families. But the different birds reported have varying susceptibility to the virus. There are certain passerine, galliformes and marine species that are frequently reported sightings due to the percentages of groups of birds sick with the viral smallpox and that spread the contagion to many species close to them. In the case of birds of prey, reports are occasional and come from isolated birds.

Some experts consider that the avian pox virus, in places like Hawaii, is the direct result of the extinction of bird species that previously inhabited different areas of this territory and that due to the decline of the avifauna of its forests became extinct.


Fowl pox is a disease that affects a large number of bird species, this virus has a worldwide distribution as it covers different and large territories, for this reason has over the years caused great damage to many birds and even an extensive spread of the same.

The increase in the frequency of the reports and in the number of affected species with the passage of time is high, being a contagious disease,? it has been proven that in temperate and warm humid climates it is more frequent, the appearance of the same, fact that is related to the presence of abundant mosquitoes transmitting the virus?


Fowl pox infection can originate at any time of the year, without presenting a specific pattern of stages. Although experts indicate that there is an association between outbreaks of the disease and climatic conditions which in many cases are favorable to the existence of abundant mosquitoes.

For this reason, the conditions where mosquitoes can be generated more frequently are the following:

  • During rainy periods
  • In warm temperatures (which favor sprouting)

Forms of the disease

The fowl pox virus affects many birds, it generates certain changes in the organism among which originates a rapid increase of the superficial layers in the skin and mucous membranes which form certain masses of proliferated tissue that are soon eliminated. Depending on the area of the skin where it is located, it generates diverse damages and certain alterations in the organism in a deep way, since this depends on the degrees in which the virus is found. (see article: Rainbow Parrot).

Cutaneous form

The cutaneous form of this disease is the most common, since it can be easily seen in the parts that are often devoid of feathers such as the bird’s legs, in some cases the base of the beak, and often around the eyes.

The mortality of this virus is usually low, because the disease begins with the appearance of certain factors that indicate its presence, begin to occur in the bird a series of pink or yellow white vesicles.

The vesicles are blisters containing fluid, which is abundant in infective viral particles. The nodules that occur in the species are formed from the growing vesicles, these usually coalesce and burst as part of a natural process, and in all cases create the formation of crusts.

The picture of this virus in birds is usually aggravated when the lesions are widespread, and reach different levels of depth in some species this process causes death.Other birds survive, because the lesions have the ability to heal completely, for a period of two to four weeks after the nodules fall off, with scar formation in the affected areas as a natural part of the process.

Each species of bird has the ability to react differently to the various effects of this disease, some can withstand the damage caused and present a considerable improvement after a while, it all depends on the level of each animal.


Fowl pox is a disease that can cause different signs and symptoms in most of the bird species it affects, these conditions are associated with the following signs:

  • Decay
  • Drowsiness
  • Lack of appetite
  • Presence of diarrhea
  • Significant weight loss
  • Respiratory conditions cause excessive nasal secretions
  • Shortness of breath
  • Difficult and noisy breathing

This disease can produce different inflammations in the head, and in certain areas of the animal’s body. In many cases it can reduce egg production and the growth of the chicks is reduced.


When some considerable signs are observed, a diagnosis can be made through a clinical examination, where the various skin lesions are analyzed in the uncovered areas and which make suspect the presence of fowl pox.

For the confirmation of the diagnosis it is important to send samples to specialized laboratories, these are usually samples of whole birds or affected parts, which must be frozen if not delivered the same day.

The most common laboratory tests for the confirmation of the disease can be the following:

  • Microscopic histopathology<br

These techniques are applied very frequently due to their good results and are the following:

  • Virus neutralization (NV)
  • The immunodiffusion test
  • Agar gel precipitation (IGDA)
  • Passive hemagglutination
  • Immunofluorescence assays
  • Immunoperoxidase staining
  • Enzyme-linked immunosorbent assay (ELISA)
  • Immunoblotting

Industrial Alternatives

The supply of certain amounts of vitamin A, serve to help the regeneration of the bird’s skin, for this reason many specialists indicate suitable medications for this process.

The veterinarians can indicate the use of anti-inflammatory creams, against the itching and healing, due to the wounds that the bird presents, in such case it is the specialist who gives the recommendations of what to do to treat the avian smallpox.

There are ample medicines created to maintain an adequate care to the needs of the bird, and that have the main function of generating positive results in a considerable way.


The best measure to maintain control in domestic birds and aviaries and prevent the spread of the disease is for endangered bird species to be isolated if there are any noticeable signs.

The main prevention is based on vaccination with live attenuated strains. No method has been developed for the vaccination of wild birds in the wild, for this reason they present a high risk of contagion.

Fowl pox is considered a contagious disease, for this reason it is required that the bird has a special care, also to avoid contact with other species that present symptoms very similar to the disease or that are known to be infected and that can put at risk other healthy birds.

There is an important factor which is based on the survival capacity of the dried viral particles, since they can live for long periods of time and for this reason, most of the birds are vulnerable and can be infected quickly.

Threatened birds have a high vulnerability index and are generally more susceptible when they are in a captive state, which is why they can influence the contagion of other species.

The use of vaccines generates positive effects in birds to avoid suffering from this disease since they are highly effective, even in endangered birds whose populations are captive and through special care can be protected to some extent.


Fowl pox (FMD) is a viral disease that occurs in different animals, which include chickens, turkeys and many other species, each of these birds have a certain risk of suffering from this disease. The main transmitters are mosquitoes and blood-sucking arthropods, which can spread the virus to healthy birds. Mosquitoes remain infective for several weeks as part of their natural process. Their incubation period averages 4 to 10 days.

How does Fowl Pox manifest itself?

This disease is usually contagious and manifests itself in various species among which are the hens these presents warts or certain (pellets) type mezquino at the level of the crest and other areas, also noted in the areas of the head, chins and legs.

They can also present avian pox in the mouth areas, as they can appear inside the throat, and affect significantly. They are yellow in color, with very noticeable white spots.

How is Fowl Pox transmitted?

There are several ways of transmission among which are mixing infested hens with healthy birds, since this is established by direct contact with another sick hen, for this reason it is important to completely isolate the affected species, also another common cause is the consumption of the same water and contaminated food.

How is avian smallpox cured?

There is actually no cure for this disease, which is why in some cases it causes fatal damage.

How can it be avoided?

You must vaccinate the bird from very early, in the case of chickens you must apply a vaccine the first day of birth, you must also give them certain vitamins A, B, C, D, E and K that are soluble in water, to ensure the proper development of the bird.

To vaccinate the bird, the chicken or hen is held tightly, the wing is stretched and injected at once to ensure that this species is protected, you can also apply a drop of vaccine which is designed to cause the same effect of protection in the bird.

Fowl pox disease is usually caused by a virus called (Borreliota avium), which spreads very slowly causing great damage to the bird’s organism.

Fowl pox occurs in two forms in birds, these forms are as follows:

1 – The wet or diphtheritic form, which affects the mucous membranes of the throat, certain areas such as the mouth and tongue, causing the formation of ulcers or false yellowish membranes, which are noticeable in the bird.

2 – The cutaneous or dry form, usually produces crusts or pimples on the crest, chins and face so that the areas are very vulnerable.

Although in many cases the cutaneous form is the more common; than the wet form, this is characterized by generating and producing more immediate mortality in bird species. This originates through severe outbreaks, the animals become sad, they have to change their typical habits, they stop eating so that they noticeably lose weight.

The characteristic symptoms of pustules or pimples located in the face and crest areas as well as the different yellow necrotic patches in the throat and mouth are difficult to confuse, since they clearly show the different alterations present in the bird’s organism.

These necrotic patches, frequently located in the mouth, are known in some places as nuggets. In the case of pimples, they should not be removed, because when they are removed, they leave bleeding ulcers in the bird and significantly increase the contagion to other animals that are close to the environment and that are healthy. (see article: Carduelis).


The virus is transmitted by direct contact with an infected animal, which can affect another animal through food or consumption of the same water.

Also a frequent cause is the mosquitoes or other insects that suck blood and for this reason could be transmitters of this disease among the different birds that are in contact with the disease.

Animals that have suffered from the disease and recover should remain in isolation, since in many cases they can remain as carriers of the virus to healthy birds.

Treatment and control

There is no effective treatment, although the use of antibiotics is recommended in order to avoid secondary infections. The use of the vaccine is a common practice among poultry farmers, who do it routinely because of its low cost and ease of application. It is recommended to revaccinate when any animal appears with the described symptoms.

To maintain control and avoid severe outbreaks of fowl pox, it is advisable to vaccinate immediately all animals that do not show any of the characteristic symptoms of this virus; although if there is any species that shows the alterations it is not advisable to vaccinate, because it causes a strong reaction to the vaccine and could cause severe damage to the bird and even death.

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