Diseases carried in the blood

Lesson Progress:

Leptospirosis (Weil’s disease)

  • This disease is caused by bacteria that are present mainly in the urine of infected rats. It can enter the bloodstream through cuts and grazes, or from hand to mouth contact (for example, if the bacteria is present on your hands when eating or smoking).
  • It is a particular problem when working on or near water, sewage, waterlogged sites or rat infested areas.

You can minimise the risks by taking the following precautions.

  • Wear suitable gloves.
  • Keep all cuts and grazes covered with a waterproof plaster.
  • Wash your hands before eating or smoking.

Wherever possible discourage rats from coming onto site by using the welfare or canteen facilities provided and putting all food waste in covered bins.

The early symptoms of leptospirosis (Weil’s disease) are like influenza (flu). If left untreated the disease may lead to kidney problems and can be fatal, sometimes causing death within three to six weeks.
  • This is a disease of the nervous system.
  • It enters the body through cuts, grazes or puncture wounds.
  • The bacteria that cause tetanus are found in contaminated soils or manure.
  • An early symptom is an increasing difficulty in opening the mouth or jaw.


Treat discarded needles with care

Hepatitis is usually caught from contact with infected needles and syringes. A needlestick injury is an accidental puncture of the skin by a hypodermic needle.

If not handled in a safe manner, discarded needles can pose serious health risks to anyone whose skin is accidentally pricked. Blood on a needle could be infected with a blood borne virus (for example, hepatitis B or C or HIV).

If you find any suspected drug taking equipment leave it alone and contact your supervisor or employer.


This is a form of pneumonia, which can be caught by breathing in contaminated water vapour or mist (for example, from air conditioning and cooling towers or hot and cold water systems).

A safe system of work is needed if a water system is suspected of being contaminated by legionella bacteria.

If you think you may be suffering from tetanus, hepatitis or legionella, get medical advice urgently and tell your supervisor.