What are the biological agents?

What are the biological agents? Biological agents are found in many sectors of work. They are rarely visible. So, workers cannot always recognize the risks they pose. The risk of exposure to biological agents are allergies, toxic effects or poisonings, and infections. What is a biological agent examples?: Fungi, Bacteria, Viruses, Protozoa etc.

The infection is the result of contact and multiplication of the biological agent in the body of the worker; for example, brucellosis in agricultural activities or tetanus in construction. Some infectious diseases, mainly those caused by viruses, can become chronic and over time trigger a cancerous process, such as hepatitis B, which can lead to liver cancer. 

The allergy is the result of a strong reaction of the immune system induced by certain substances known as allergens or sensitizers. The clinical manifestations can affect the respiratory tract such as rhinitis, asthma or hypersensitivity reactions; or the skin such as itching, inflammation, excoriations, etc.

Toxic effects or intoxications are produced by the substances released by certain biological agents, known mainly as toxins (exotoxins, endotoxins, and mycotoxins). The above risk solution you can find in this blog namely What are the biological agents?

Biological agents are commonly classified according to their taxonomy, with the most important taxa being bacteria, viruses, fungi (yeasts and moulds) and protozoa (parasites). This classification is important for its implications for detection, identification, prophylaxis, and treatment. Based on What are the biological agents? can be:
  1. Group 1 biological agent: one that is unlikely to cause an infectious disease in man. 
  2. Group 2 biological agent: one that can cause mild or moderate infectious disease in humans and can pose a danger to workers, being unlikely to spread to the community and generally having effective prophylaxis or treatment.
  3. Biological agent of group 3: one that can cause serious disease in man and presents a danger to workers, with the risk of spreading to the community and there is generally effective prophylaxis or treatment.
  4. Biological agent of group 4: one that can cause serious or very serious disease in man and poses a danger to workers, with a high probability of spreading to the community and without there generally being effective prophylaxis or treatment.
Jobs where there may be exposed to biological hazards:
  • Person-to-person transmission: Personnel in health centres, security personnel, civil protection, teachers, nursing homes, reception centres, penitentiaries, personal services, etc. 
  • Animal-to-person transmission (zoonosis): Veterinarians, ranchers, dairy industries, slaughterhouses, etc.
  • Transmission through contaminated objects or material: Cleaning or health personnel, public sanitation, farmers, cooks, miners, wool, fur and leather industries, laboratory personnel etc.

Biological agents are present in many sectors. As they are rarely visible, the risks involved are not always recognized. These include bacteria, viruses, fungi (yeasts and moulds) and parasites, detailed by the specialists of the European Agency for Safety and Health at Work.


Fungi can exist as single-celled yeasts or as larger multicellular moulds and are classified according to the type of sex spore they form. Most fungi are decomposers and commonly cause disease in immunosuppressed individuals. Fungi can be spread by direct contact or they can be transmitted through the air.

What-are the biological agents
What are the biological agents?

Mushrooms are sometimes overlooked in biology, especially compared to bacteria, plants, and animals. This is in part because many fungi are microscopic and the field of mycology did not develop until after the invention of the microscope. Fungi are also often associated with food. Mushrooms are examples of edible mushrooms.


They are prokaryotic organisms. They are made up of a cell that contains both types of nucleic acid. Its DNA is organized in a circular chromosome dispersed in the cytoplasm that contains very few structures or organelles useful for its development. Among them are the ribosomes responsible for the synthesis of proteins. Bacteria can have up to three envelopes: the cytoplasmic membrane, the bacterial wall, and the capsule

They are single-celled organisms that are essential for all life and live independently or as parasites. Bacteria have three basic shapes which include bacillus, coconut, and spiral. Bacteria multiply through cell division and, in most cases, antibiotics can destroy them.

What-are the biological agents
What are the biological agents?

It is spread by aerosols (coughing and sneezing). For example, Streptococcus. It is spread by contact with the skin and the surface. For example, Staphylococcus aureus. It is also spread through body fluids, such as blood and saliva. For example, meningococcal disease (meningitis). 


They are the simplest microbiological entities. Viruses are extremely small and require the use of an electron microscope to see them. They are acellular and need a host cell to reproduce by taking control of the reproductive material in cells. Because viruses live in a host cell, they are immune to the use of antibiotics and can spread in many ways, including direct contact or by air. 

What-are the biological agents
What are the biological agents?

COVID-19. A new coronavirus that emerged from China in 2019 can cause pneumonia-like illnesses, with signs and symptoms including fever, cough, and shortness of breath.


What are the biological agents?

They live in soil or water and many can be part of the normal flora of larger animals. Protozoa reproduce asexually and have many forms. The pathogenic spread of protozoa includes vectors, transmitted by food or by direct contact. Transmission of protozoa that live in the intestine from one human being to another human.

What-are the biological agents
What are the biological agents?

Usually occurs through a faecal-oral route (for example, contaminated food or water or person-to-person). Protozoa live in the blood or tissues of humans. And transmission to other humans by an arthropod vector (e.g., through the bite of a mosquito or sandfly). Examples: Giardia (ingested), Plasmodium falciparum.

How are biological agents transmitted and come into contact with the worker?

Biological agents are dispersed and transmitted through the air, by bioaerosols; through water or food; by contamination of surfaces, tools or objects (fomites) and through other living beings (reservoirs, hosts and/or vectors). Once dispersed in the work environment, how the biological agent enters the worker’s body and becomes pathogenic is known as the route of entry. 

The routes of entry of biological agents are:

Respiratory or inhalation: it is the main route of entry of biological agents. Exposure is due to the presence of biological agents in the work environment in the form of bioaerosols, that is, suspended in the air that the worker inhales. Bioaerosols are usually produced by coughing, speaking and in powder or pressurized water processes.

What-are the biological agents
What are the biological agents?

Dermal or injection: the entry of the biological agent is through intact skin, slightly damaged skin or mucous membranes (eyes, nose). Exposure occurs by coming into contact with contaminated items such as tools, surfaces, samples, and raw materials, and with sick patients or animals; also by projections and splashes to the mucous membranes.

Ingestion: the entry of the biological agent through the intake of food, water or contaminated elements. Exposure in the workplace is mainly caused by poor hygiene practices (lack of personal hygiene before meals, smoking with dirty hands, etc.).

Absorption or percutaneous: the entry of the biological agent is through the inoculation of the biological agent in the deep layers of the skin. Exposure, in this case, occurs as a result of an occupational accident, puncture, cut, bite or animal sting. This form of exposure is frequent in the health and veterinary sector, in laboratory work and animal experimentation centres; also in outdoor work due to animal bites and stings.

Biological agents: Health effects and control measures

What are the biological agents?

The infectious characteristic of a biological agent reflects its ability to enter, survive, and multiply in a host. The most important property of biological agents is their ability to multiply in a host. The disease affects depends (including the immune, nutritional and general health status) and the environment (for example, sanitation, temperature, water quality, and population density).

Influenza viruses

Influenza viruses spread when someone suffering from the infection coughs, sneezes, or talks. The germs also can pick up from an object, such as a telephone or a computer keyboard, and then transfer to the eyes, nose, or mouth.

If future flu viruses are similar to those you’ve encountered before, either from having the disease or from vaccination, those antibodies can prevent infection or lessen its severity.

But antibodies to influenza viruses that you have encountered in the past cannot protect you from new subtypes of influenza that may be very different immunologically from what you had before. But colds generally develop slowly, while the flu tends to come on suddenly.

  • Pain in the muscles, especially in the back, arms and legs.
  • Chills and sweats
  • Headache
  • Dry and persistent cough
  • Fatigue and weakness
  • Nasal congestion
  • Throat pain

For a young, healthy person, seasonal flu is generally not serious. Although one can feel miserable while suffering from it, the flu usually clears up within a week or two with no lasting effects. But high-risk children and adults can develop complications such as:

  • Pneumonia
  • Bronchitis
  • Asthma flare-ups
  • Heart problems
  • Ear infections

Pneumonia is the most serious complication. For people with chronic illnesses, pneumonia can be deadly. The following measures can help relieve symptoms:

Drink lots of fluids. Choose hot water, juice, and soups to prevent dehydration. Consider pain relievers. Use an over-the-counter pain reliever, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others), to combat pain associated with the flu. Do not give aspirin to children or adolescents because of the risk of Reye’s disease. The flu vaccine is not 100 per cent effective, so it is important to take steps like these to reduce the spread of infection as well:

Wash your hands: Washing your hands thoroughly and frequently is an effective way to prevent many common infections. 

Contain your coughs and sneezes: And, if you are sick, stay home for at least 24 hours after the fever subsides to reduce the chances of infecting others.


Malaria is spread to humans through mosquitoes. In humans, parasites grow and multiply first in the liver and then in red blood cells. Eventually, destroy the red blood cell, parasites that continue to invade other red blood cells.

People who live or travel to tropical areas where malaria is common are at higher risk of becoming infected. Occasionally, malaria is transmission by blood transfusion. People can also be suffering malaria from exposure to infected blood, including:

  • From mother to fetus
  • Through blood transfusions
  • Sharing needles used to inject drugs

Symptoms: A malaria infection is generally with the following signs and symptoms:

  • Moderate to severe chills
  • High fever
  • Sweating
  • Fatigue
  • Headache
  • Vomiting
  • Diarrhoea

By itself, it can cause low blood sugar levels, as can quinine, one of the most common drugs used to fight malaria. Very low blood sugar can lead to coma or death.

Control measures:

If you are travelling to a place where malaria is common, talk to a doctor a few months in advance about the medications, before, during and after the trip, which can help protect against the parasites of malaria.

Sleeping under a net. Mosquito nets, particularly insecticide-treated ones, are for pregnant women and young children. Covering your skin. During times of mosquito activity, usually from dusk to dawn, wear pants and long-sleeved shirts.

Assessment of exposure to biological agents

What are the biological agents?

The health effects are highly variable and depend on the biological agent in question, the conditions of the exposure and the conditions of the worker (immune or health status and pregnancy). The employer must identify the risks related to exposure to biological agents during work, to evaluate them by determining the nature, degree and duration of the workers’ exposure.

The additional risk for those workers who are especially sensitive is based on their characteristics or known biological status, due to circumstances such as previous pathologies, medication, immune disorders, pregnancy or lactation.

Risk assessment, prevention and control

When a work activity involves the intentional use of biological agents, such as the cultivation of a microorganism in a microbiological laboratory or its use in food processing, the biological agent will be known and it will be easier to control. It is then appropriate to include information on the nature and effects of the biological agent in the inventory of hazardous substances.

When the existence of biological agents is an unintended consequence of work – for example, in waste sorting or agricultural activities – the assessment of the risks to workers will be more difficult. European legislation obliges the employer to the following:

  • Assess the risks posed by biological agents.
  • Reduce the risk to workers through elimination or substitution, prevention and control of exposure, information and training of workers.
  • Ensure health surveillance as appropriate.

Who and how can be harmed

What are the biological agents?

If you have identified any activities that expose workers to biological agents, collect information on these exposures. Think about the people directly involved and also others who may be affected, such as the cleaning staff. Examine how the work is done, rather than how it should be done or how you think it is done. Biological agents can cause three types of diseases:

  1. Infections are caused by parasites, viruses or bacteria.
  2. Allergies are triggered by exposure to organic mould dust such as flour dust and animal scale, enzymes, and mites.
  3. Poisoning or toxic effects.

Microorganisms can enter the human body through damaged skin or mucous membranes. They can be inhaled or swallowed, leading to infections of the upper respiratory tract or digestive system. Exposure is also possible from accidental causes due to animal bites or syringe needle injuries.

Assess and reduce risks

Think about whether the existing measures offer enough protection or what more could be done to reduce the risks. Is it possible to eliminate all risks at once by using a different agent or process?

If exposure is unavoidable, it should be minimized by limiting the number of workers exposed and the time of exposure. Control measures need to be tailored to the work process and workers need to be trained in safe work practices.

The measures necessary to eliminate or reduce the risks to workers will depend on the specific biological risk, but there are common actions that can be applied:

  • Many biological agents are airborne, such as exhaled bacteria or toxins from mouldy grain. Avoid the formation of aerosols and dust, even during maintenance work. Good management, hygienic work procedures and the use of proper warning signs are basic elements of safe working conditions.
  • Many microorganisms have evolved mechanisms to survive or resist heat, dehydration, or radiation, for example through the production of spores. Adopt measures for the decontamination of waste, equipment and clothing, and appropriate hygienic measures for workers. Include instructions for the safe disposal of waste, emergency procedures, and first aid.
  • In some cases, preventive measures include vaccination, which will be provided to workers who so wish.

Decide on control measures

Organize work in such a way as to reduce the number of exposed workers. It is especially interesting to introduce modifications in work methods that give protection to the entire group of workers. Take other precautions such as:

  • Adopt safe handling and transport measures.
  • Safe means of collection, storage and disposal of waste and/or samples.
  • Mark the risk areas.
  • Design emergency plans, when necessary, based on the expected risks, developing specific protocols for different contingencies, and depending on the dangerousness of the agent.
  • Order and apply general hygiene measures as necessary such as prohibitions on eating food and drinks in areas with risk of biological contamination, appropriate protective clothing or other types of special clothing, have appropriate and adequate toilets. And washrooms for the use of workers, which include products for eye cleaning and antiseptics for the skin, Have a specific place for the adequate storage of protective equipment and verify that they are cleaned and checked for good performance, etc.)
  • Provide information about the preventive measures adopted, with precise instructions in writing.
  • Organize and provide training and awareness activities for workers, repeating them as often as necessary.
  • Flow the OSHA standard

Health surveillance

The health surveillance of workers must be organized, according to the guidelines and protocols established by the Health Authorities. An individual medical history should be kept for each worker. The doctor responsible for health surveillance may propose collective prevention or protection measures and also measures aimed at protecting specific people (for example, through vaccinations or a temporary change of job).


When there is a risk for which there are vaccines, these will be offered by the employer to the workers by the following guidelines:

  • The offer and acceptance shall be in writing.
  • Workers should be informed about the advantages and disadvantages of vaccination.
  • Its dispensation will not entail any expense to the worker.
  • A vaccination certificate may be drawn up.

Record your findings

Review and revise your assessments when necessary, when significant changes have been made to the material, equipment, work methods, places or people involved, and if there have been accidents or work-related complaints.

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