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Biological hazards

Viimati uuendatud: 25.02.2017

Biological hazards are micro-organisms (bacteria, viruses, parasites, fungi, etc.), including genetically modified micro-organisms, cell cultures, human internal parasites and other biologically active substances, which can cause fungous diseases, allergies or poisoning.

Micro-organisms can penetrate the human body through damaged skin or mucous membrane, but also via animal bites or syringe entry wounds. Also all bodily fluids are biological hazards – including blood, lymphatic fluids, tissue cultures, hormones and enzymes.

  • Biological hazards are capable of causing three kinds of illnesses:
  • Infections caused by parasites, viruses or bacteria;
  • Allergies caused by contact with organic types of dusts (e.g. flour dust and bestial dandruff), enzymes and mites;
  • Poisonings.

Some biological hazards that can cause rubella or toxoplasmosis can also harm the human foetus. Based on their infectiousness, biological hazards are grouped into four hazard groups. 

Based on current knowledge, the hazards of the first hazard group do not cause illnesses to humans.

Hazards of the second group might make humans fall in, being thus hazardous for employees’ health, but do not threaten the entire population; effective preventive and cure methods exist for the hazards of the second group.

Legionellosis or Legionnaires’ Disease

Legionella spreads as a mist in a moist environment, causing a severe case of pneumonia. The spread is favoured by non-flowing water, water temperature from +25 to +45 °C, scale deposit and sediment.

Prevention: temperature in hot water systems must exceed +50°C, ventilation systems must be equipped with high-efficiency filters and antiprotozoals must be used in water systems.

Staphylococcus-Infections or Purulent Infections

Staphylococcus-bacteria spreads by unwashed hands, with infected bed linen, via air with mist and skin flakes.

Prevention: hand hygiene, disinfectants, and protective gloves.

Lyme Disease

The illness is caused by the bacteria Borrelia burgdorferi. The disease is transferred to humans via ticks. No vaccine exists. The disease can pass very difficultly and slow as the bacteria changes its’ form, thus antibiotics don’t always help.


Toxoplasmosis is an illness caused by the bacteria produced by the unicellular parasite Toxoplasma gondii, living and reproducing mostly in cats. The parasite can also be found in cat excrements, soil, game meat, unwashed vegetables and polluted drinking water.

In the infected human, the parasite can cause flu-like symptoms, encephalitis and neurological problems. In addition, it can also negatively influence also the heart, liver, inner ear and eyes. Primarily, people with a weak immune system (children, old persons, pregnant women) are in danger.

Prevention: avoid contact with stray cats; don’t eat raw meat, especially pork and lamb (do not taste raw minced meat); wash hands after preparing raw meat; wash fruit and vegetables; wash hands after contact with soil.

Hazards classified into the third hazard group can cause serious human illnesses, being thus very hazardous to the employee’s health; these hazards might pose a risk to the entire population, but effective preventive and cure measures exist.

Hepatitis or Yellow Jaundice or Liver Inflammation

Viral hepatitis is caused by several viruses that reproduce in and damage the liver, and are commonly referred to as “hepatitis viruses”.

The A-hepatitis virus is a so-called dirty hands’ disease as the virus exits an organism with faeces and spreads with direct contact, unwashed hands, contaminated water and food.

Prevention: thorough hand wash after visiting the risk area, vaccination.

The B-hepatitis virus is even more infectious than the A-hepatitis virus. B-hepatitis spreads with direct contact – both with infected blood and bodily fluids.

Prevention: protective gloves, masks, glasses, vaccination.

The C-hepatitis virus spreads mostly with infected blood. Virus can remain infectious also in dried blood.

Typical ways of getting the infection: piercing ears or other parts of the body; tattooing; using the same needle when injecting inter-venous drugs; transfer of blood and blood components (donor blood is checked in Estonia since 1994); the use of contaminated or insufficiently sterilised instruments and needles at medical and dental procedures.

Prevention: protective gloves, masks, glasses.

Hazards of the fourth hazard group can cause serious human illnesses, being thus very hazardous to the employee’s health; these hazards might pose an infection risk to the entire population; effective preventive and cure measures usually do not exist.

In general, Estonia does not have any of the 4th group hazards. An example of the 4th hazard group is, for instance, Ebola.

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