Are you one of those many people who are delighted with the pigeons? Do you usually take food for the pigeons and like to feed them in public squares? Do you encourage your child to give bread crumbs to the pigeons?

I think you could “waste” a few minutes reading my comments.

I believe I can understand why many people like pigeons. After all, they are the symbol of peace. And this strong relationship between the pigeon and peace has been going on for a long time. To begin with the passage of the Bible, involving Noah and his ark with the animals, among them, the pigeon that guided Noah, after the flood of the Earth for 150 days. The story says that the pigeon returned to the ark with an olive branch, meaning that the waters had already subsided. The aspirations for peace were well represented in a souvenir that showed a pigeon “holding” an olive branch; this souvenir was developed in German cities in the 17th Century, during the war that lasted about 30 years and caused a lot of destruction in Europe. Later, the painting of a “white dove flying” by Picasso was sent to the World Peace Congress as a symbol of world peace.

But did you know that pigeons can pose serious health risks to the population?

Many people like to feed them pieces of bread, leftover food, and popcorn, which are unsuitable foods, addicting animals and harming their health.

You need to know that, according to experts, in their natural environment, the pigeons can live up to 15 years. However, in the cities, they usually live for only 3 to years; this is probably due to the effects of inadequate food offered to them.

Pigeons are hardly hunted by other animals, so their population grows very fast. They usually live in the buildings, making their nests on roofs, ceilings, air conditioning boxes, marquees, etc. But in addition to causing losses by damaging the structures of buildings, they have become a serious health problem, causing serious illnesses, which can lead to death or leave sequelae.

In addition to transmitting diseases to humans, pigeon feces have the potential to infect domestic animals. It is estimated that this bird can transmit more than fifty types of diseases. Some of these diseases often lead to hospitalization and, sometimes, patients need to be followed up in Intensive Care Units.

Here is brief information about some of the important diseases caused by pigeons:

Cryptococcosis — It is one of the main diseases transmitted by urban pigeons and is caused by a fungus that lives e develops in the feces of these birds, Cryptococcus neoformans. When the fungus spores are inhaled, the lung is affected as well as other parts of the body through the bloodstream, reaching the central nervous system, in the stage of deep mycosis and resulting in the appearance of meningitis, which is a serious complication of cryptococcosis.

Most of the time, it is called an opportunistic disease, as it occurs in immunocompromised individuals, such as patients undergoing chemotherapy or transplant patients treated with immunosuppressive drugs. The disease in these patients is often severe. On the other hand, this fungus can cause disease even in immunocompetent patients, although the cryptococcosis disease in these patients can also be caused by another species, Cryptococcus gattii (many experts believe that the disease caused by this species of Cryptococcus would not be related to pigeons).

Salmonellosis — this bacterial infection occurs most often after eating poorly washed or poorly prepared foods, but the transmission of Salmonella bacteria can also occur due to pigeon droppings. This is because the dry feces of these animals turn to dust and can be carried by the wind and settle on fruits and vegetables that, if not properly washed, can contaminate people. The most common symptoms are gastroenteritis (usually, attacking the gastric and intestinal mucosa) and acute enterocolitis (in this case, also affecting the terminal part of the intestines, the large intestine). The incubation period (the period for the onset of clinical manifestations since ingestion of contaminated food or liquids) varies from eight to 48 hours. The disease can progress to more severe conditions, such as dehydration and septicemia.

Histoplasmosis — is a disease caused by a fungus (Histoplasma capsulatum) that is best known, when the infection occurs after visiting an environment where bats are present, such as a grotto, for example. However, this fungus is also recognized in the droppings of pigeons. After inhaling the spores present in the pigeon feces, a disease manifests itself in about 10 days and, often, the disease is not correlated with the pigeons. Then, the transmission occurs through the inhalation of dust generated by the excrement and feces of pigeons or secretions of sick birds. The clinical manifestations and changes in radiological examinations of the lungs can be confused with those that occur in other diseases, delaying the appropriate treatment and causing sometimes the involvement of the Central Nervous System.

Viral encephalitis — pigeons are reservoirs for viruses that cause viral encephalitis. When viruses reach the Nervous System, they cause different symptoms, including loss of consciousness and risk of death. The infection has a vector: mosquitoes that become contaminated after biting pigeons, and then can bite humans, transmitting the disease agent (the virus).

Ornithosis — ornithosis is also known as psittacosis (chlamydiosis), it is an infectious disease caused by the bacterium Chlamydia psittaci. One of the main reservoirs of this agent is birds, mainly pigeons. Contamination occurs when the powder from infected birds’ feathers or feces is inhaled and the incubation period is about four weeks. The disease can be serious depending on the age of the infected person and the extension of the affected lung area.

Pigeons can be responsible for many other diseases or clinical manifestations, such as dermatitis (rash on the skin — redness of the skin — and itching, caused by pigeon louse — a mite), respiratory allergies (rhinitis, asthma, allergic bronchitis, all conditions caused by an air laden with fluff or dust with pigeon droppings).

In summary, pigeons can transmit diseases to humans in 4 different ways:

• Inhalation of contaminated dust from excrement that may even be near ventilation ducts, such as air conditioning, can be transported inside buildings.
• Transfer through parasites (ticks, mites, and fleas).
• Direct contact with pigeon feces.
• Water and food contaminated with pigeon droppings.

How to avoid contamination when cleaning the pigeon poop?

Pigeon feces, as we have seen, are components of high propagation of pathogenic microorganisms, thus requiring constant cleaning and hygiene of infested places. Before cleaning pigeon droppings, first wet the affected area with chlorinated water to prevent dust from developing. Use a mask and gloves to avoid contamination.

So, to avoid the risk of dispersion of pathogens, avoid sweeping dry feces, as the wastes are dispersed in the air and there is a risk of inhaling the particles.

In conclusion, pigeons are birds that nest and reproduce quickly when there are four factors: water, food, shelter, and access. The infestation of these birds in urban centers is a serious problem for public health and also causes material damage to homes.

Controlling the population of these animals in cities is important for our health, and creating physical barriers makes these birds look for more suitable places to nest, with the correct food and away from the dangers of cities. As we have seen, there is a three to four-fold increase in the survival of these birds, if they are outside urban centers.

But, as long as we have pigeons in urban centers, some protection and/or control measures can be adopted:

• use gloves and a mask or damp cloth to cover the nose and mouth when cleaning the place where the feces are;
• moisten pigeon feces with disinfectant before sweeping;
• remove nests and eggs;
• plug holes or gaps between walls, roofs, and ceilings;
• placing screens on balconies, windows, and air conditioning boxes;
• do not leave food scraps that serve pigeons, such as dog and cat food;
• use staples on eaves to prevent the pigeons from landing;
• properly dispose of garbage in closed containers;
• never feed pigeons.

References

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• Shinohara NS et al — Cienc saúde pública Vol 13 no.5, Sep/Oct 2008
• Haag-Wackernagel D — Advances in Vertebrate Pest Management Vol 4: 31–58, 2006
• Weber W — Bird Control Seminars Proceedings 21, 1979
• Haag-Wackernagel D et al — J Infect 2004 May: 48 (4):307–313
• __________ Do pigeons spread virus pneumonia? JAMA 1945: 129(12): 805
• Gramer C et al — European Respiratory Journal 2016, 48: 818–825