Disease vectors include all those agents (person, object or animal) capable of transporting and transmitting a pathogen to another living organism. This article focusses on those disease vectors of special interest in poultry.

The most important disease vectors in poultry are rodents, wild birds, insects and nematodes. The control of these disease vectors is essential to ensure the biosecurity of our farm and avoid the economic losses associated with the diseases they transmit.

1. Rodents

In any farm, one of the main biosecurity measures is to establish a rodent control protocol. These small animals cause direct economic losses, such as consumption of stored products (an adult rat is able to ingest 10% of its body weight per day) or damage the facilities. At the same time, they act as disease vectors of a large number of diseases.

Both rats and mice can transmit bacterial diseases as important as salmonellosis or colibacillosis and even viral diseases such as Newcastle disease and the avian influenza virus. These diseases are mechanically transmitted (pathogens are carried in the hair, in the body and on the legs) as well as through their excreta, faeces and urine, which contaminate food and water.

The control of these animals is a complicated task due to their reproductive capacity. They reach sexual maturity at a very young age (35 days old). Rodents have many offspring a year, so that the number of individuals present on the farm increases fast. An example of such reproductive capacity is that a single pair of rodents is capable of producing 10,000 individuals a year.

2. Wild birds

The importance of the control of wild birds lies in their great capacity for movement, as they are able to transmit diseases from very distant geographical points. Nowadays, factors such as climate change cause changes in their migratory routes, a fact that is relevant in animal production as it widens the spread of diseases.

Wild birds act as disease vectors of bacterial pathogens, such as Salmonella, Pasteurella multocida or Campylobacter; viral diseases such as infectious bronchitis, Gumboro disease or Newcastle disease, and even parasitical agents such as Heterakis gallinarum, Cochlosoma or Histomonas.

3. Insects

Due to their ubiquity and reproductive capacity, insect control is a main point of the biosecurity of any farm. Within poultry production the most important insects are the bed beetle, Alphitobius diaperinus, and flies.

3.1 Alphitobius diaperinus

Alphitobius diaperinus, also known as bed beetle, is a widely distributed coleopteran and is one of the main pests affecting the poultry industry.

The biological cycle of this insect is favored by the environmental conditions present in poultry farms, such as a warm and controlled temperature, along with relatively high humidity, conditions that favor its reproduction.

This coleopter causes serious economic losses, on one hand, arising from its effects on the facilities. These beetles are introduced into the walls through cracks and damage the insulating materials, that leads to energy loss, which will eventually translate into economical losses. On the other hand, they act as disease vectors of many pathogens that affect poultry, such as the Marek’s disease virus or coronavirus, bacteria like Escherichia coli or Staphyloccocus spp. and even fungi like Aspergillus spp.

3.2 Flies

Flies are the most economically important ectoparasites that affect productive species, including poultry. The most common species are the domestic fly (Musca domestica) and the small domestic fly (Fannia spp.).

As in the case of the bed beetle, the environmental conditions of the farms constitute the ideal environment for the development of these diptera, which, together with their short biological cycle, which lasts between 8 and 30 days, makes it difficult to control.

The presence of flies in farms causes an increase in stress, both for animals and the staff, which can affecte productivity. They act as disease vectors of numerous diseases, such as salmonellosis or avian influenza, as they quickly spread these diseases among the different sheds.

In the case of laying hens, the presence of these insects may affect egg production, and increase the percentage of dirty egg due to excretions and regurgitations of flies cause stains on them.

4. Nematodes

Although their role as disease vectors is not well known, they are able to transmit diseases of great importance for the poultry industry.

An example of this is the nematode Heterakis gallinarum, a parasite that is located in the caecum of certain birds such as turkeys and chickens and whose pathogenic effect is limited. However, it acts as a biological vector of the parasite Histomonas melleagridis, which causes histomoniasis or blackhead disease. Turkeys eat the nematode infected with the parasite (Histomonas melleagridis) and get the disease.

Histomoniasis is a disease that mainly affects turkeys, characterized by necrotic liver and caecum lesions that cause high mortality. Therefore, in certain species such as turkeys, the control of nematodes is also relevant to prevent disease transmission.

5. Biosecurity

Biosecurity refers to all measures, both infrastructure and management practices, aimed to prevent or reduce the risk of the entrance of disease in farms.

Among the many measures aimed to prevent the presence of disease vectors in farms is the application of rodent and insect control protocols, the proper maintenance of facilities that prevent the entry of wild animals and birds, and the application of appropriate cleaning and disinfection protocols.

Despite the application of numerous biosecurity measures, the ubiquity of these vectors, their high reproductive capacity and their capacity to contaminate and spread diseases make their control a complicated task.

Therefore, the control of the different disease vectors mentioned in this article cannot be carried out through isolated measures but by a combination of measures that, together, reduce the risk of the presence of these vectors.

From a productive point of view, we can improve the health status of animals, so that they are able to deal with vector-borne diseases more effectively, avoiding their dissemination.

For this purpose, there are natural solutions on the market that contribute to improve the health status of birds.

There are natural products based on immunostimulant pronutrients, organic molecules from a botanical origin, able to increase vaccine immunity against viral diseases transmitted by insects and rodents, such as Marek’s disease or Gumboro disease, improving the immune response.

Also, there are products based on intestinal conditioner pronutrients that improve gut health, increasing the renovation of enterocytes and improving intestinal integrity, so that animals are able to deal with the bacteria and parasites they are exposed to.

 The use of this natural solutions constitutes an additional control method of the diseases transmitted by rodents, wild birds, insects and nematodes that generate great economical losses for the poultry industry.