08 Gezondheids- en werkplekaspecten
 >  Biological agents

While performing various work activities, you may consciously or unconsciously be exposed to biological agents (microorganisms). Biological agents are small living organisms, such as viruses, bacteria, moulds and parasites. These agents can cause infection, allergies or poisoning. Infectious diseases can be spread from a source to a potential victim (host). A person/animal spreads biological agents through, for example, coughing, hands, blood or defecation. Spreading may also occur through the air, water and soil. Most biological agents are not harmful, but some are.

Risks > Sources, effects and how can I become exposed

Sources of biological agents can include:

  • A sick person
  • A sick animal, for example infected with the rabies virus
  • Amphibians (may be carriers of a mould/virus and by touching them you potentially could infect other amphibians)
  • Waste or (spoiled) food
  • Contaminated materials
  • Water; misting systems/devices or polluted water

The health effects:

  • Infectious diseases
  • Allergies
  • Cancer
  • Effects on the birth of a baby (congenital defects, premature births/stillbirths)


As a result of an infection you can, for example, contract Hepatitis A (via faeces), Weil’s disease (via water), Q fever (via air), and hepatitis B or HIV (via blood). However, the best-known infection is Lyme disease. You can contract this disease from infected ticks that primarily shelter in grass and bushes.

HOW can you become exposed?

  • A poor immune system
  • Respiratory infection
  • Inadequate hygiene
  • Polluted water
  • Direct contact with skin and mucous membranes, or open wounds
Measures > What you must do

Below is a summary of the measures that are applicable to Heijmans and that can be taken to promote healthy and safe working and avoid exposure to biological agents.

Control at source:

  • Prior to the work ensure that waste has been removed
  • Prior to the work ensure that the workplace is ‘clean’ (flush the sewer)
  • Keep sanitary facilities clean
  • Mow grass and prune bushes

Technical measures:

  • Ensure the area is shielded (no direct contact with...)
  • Ensure there are filters
  • Provide over/under-pressure

Organisational measures:

  • Minimize the number of people that need to be near a source
  • Set up clean/dirt zones
  • Limit the number of employees at a specific spot
  • Especially keep high-risk groups (for example pregnant women) away from the source
  • Provide optimal and continuous instruction
  • Keep everything clean

Hygienic measures:

  • Behaviour: avoid shaking hands (if possible), nose-picking, rubbing eyes
  • Wash you hands, if necessary take a shower
  • Avoid contacts

Personal protective equipment:

  • Protect skin: safety gloves, clothing, apron, hair cap, safety shoes.
  • Protect eyes: safety glasses, screens
  • Protect respiratory tract: face masks, masks (mouth/nose)
  • Use the right equipment


  • Insofar as this is possible, every employee who is not immune to the biological agents to which he/she has been or can be exposed will be offered vaccination.
  • Vaccination is meant to supplement other measures and never must be used as a substitute.
  • The company doctor provides the employer with advice on the basis of a risk assessment of the work.
  • We offer vaccinations with the accompanying individual counselling. Employees must be informed of the advantages and disadvantages and are assisted in making an individual assessment.
Examples of symptoms

Some infections do not cause any or few symptoms and can lapse virtually unnoticed.

The appearance of certain symptoms may also depend on the location of the infection:

  • Respiratory system: coughing
  • Intestines: cramp and diarrhoea
  • Skin: inflammatory symptoms such as heat, pain, redness and swelling
  • General malaise and fatigue, although this can also include high fever with chills and shock
  • Sometimes the infection develops slowly (tuberculosis, toxoplasmosis) or only expresses itself after many years (madcow disease, Lyme disease)
Lyme disease - what it is

Lyme disease is caused by ticks infected with Borrelia. This bacterium is transmitted through the tick's bites. A tick's bite is painless and may only start itching after several hours or it may go unnoticed altogether. A few hours can be sufficient to transmit the disease.

Ticks thrive best in plant-rich environments with high grass, bushes and dense undergrowth. They are also more often spotted in gardens in particularly green regions or because they hitchhike with animals (such as dogs and cats). They vary in size from half a millimetre to a few millimetres and seldom grow larger than one centimetre. They live from the blood they suck. In the above-mentioned environments, they wait for a living being to attach themselves to it. Ticks can cling anywhere, but prefer the groin, the inside of the knee, armpits, buttock crack, edges of underwear, behind the ears and around the hairline in the neck. Ticks are generally active from March through to October. However, in case of a mild winter, they may be active sooner and longer.

Because 25% of the ticks in the Netherlands are infected with Borrelia, not everyone bitten by a tick will contract Lyme disease. The initial symptoms of Lyme disease may include:

  • Discoloration of the skin at the site of the bite, approximately 5 cm in size (see photo)
  • Fever
  • Muscle and joint pain
  • Headache
  • Stiff neck

The ultimate symptoms may only appear years later, such as arthritis, inflammation of the lymph vessels and fever. So be sure to regularly check your body for ticks, particularly in the spring and summer, to avoid Lyme disease. See the Ticks toolbox for more information.

Tips > For more information

Tick bite app | External sources | Occupational Health & Safety Portal

Biological agents: what are they? | Occupational Health & Safety Portal

Biological agents (arbokennisnet.nl)

Scan de volgende code met de app om deze toolbox te bekijken.