Occupational diseases

Question 1

Clostridium difficile (C. diff)

Answer 1

Clostridium  difficile  (C.  diff)  is  a  bacterium  that  is  present  naturally  in  the  gut  of 
around two-thirds of children and 3% of adults. 

C. diff does not cause any problems in healthy people. However, some antibiotics
that are used to treat other health conditions can interfere with the balance of ‘good’
bacteria in the gut. When this happens, C. diff bacteria can multiply and produce
toxins (poisons), which cause illness such as diarrhoea and fever.

Clostridium difficile is an anaerobic bacterium. This means it does not need oxygen
to survive and multiply. Therefore, it usually survives well in the large intestine
(bowel), where there is very little oxygen.

C. diff is not a ‘superbug’ as it lives harmlessly in many peoples’ intestines, and can
be treated relatively easily. However, it forms very hardy spores, which can survive
for long periods in the environment, for example: on floors and around toilets, and
spreads in the air.

Question 2

Escherichia coli (E. coli)

Answer 2

The pathogenic strains include a group of bacteria which are known as Vero
cytotoxin-producing E. coli or VTEC.

The most important VTEC strain to cause illness in the UK is E. coli O157, which can
be found in the intestine of healthy cattle, sheep, goats and other species. Humans
may be infected via food or water that has become contaminated by faeces from
infected animals.

The infectious dose of VTEC O157 is very low at less than 100 bacterial cells.
Infection is readily spread between family contacts, particularly those who may be
caring for infected children, and in settings such as children’s day nurseries.

Question 3

Farmer’s lung

Answer 3

Farmer’s lung is a noninfectious allergic disease that is caused by inhaling mould
spores in the dust from mouldy hay, straw, or grain. This debilitating disease disrupts
the normal function of the lungs, where oxygen enters and carbon dioxide exits the
bloodstream. Many farmers are forced to leave the occupation due to the physical
limitations caused by farmer’s lung.

Unfortunately, farmer’s lung cannot be cured.

Question 4

The main BBVs of concern are:

Answer 4

 Hepatitis B, C and D virus, which all cause hepatitis, a disease of the liver
(Hepatitis A is not a BBV).
 Human immunodeficiency virus (HIV) which causes acquired immune deficiency
syndrome (AIDS), affecting the immune system of the body.

Question 5

The word hepatitis means

Answer 5

an inflammation of the liver

Question 6

Leptospirosis

Answer 6

Leptospirosis is a type of bacterial infection that is spread by animals. It is caused by
a spirochaetal bacteria called leptospira.

Question 7

MRSA

Answer 7

Methicillin-Resistant Staphylococcus Aureus (MRSA) is a bacterium responsible for
several difficult-to-treat infections in humans. It is also called ‘Multidrug-Resistant
Staphylococcus Aureus’.

The key point about MRSA is that it’s no more aggressive than other infections, but
it is more resistant to treatment. MRSA is dangerous because it takes us back to
the days when little could be done to stop an infection.

The reason hospitals seem to be hotbeds for resistant MRSA is because with many
vulnerable patients, infections are common and easily spread. So many different
strains are thrown together with so many doses of antibiotics, vastly accelerating this
natural selection process.

Question 8

Psittacosis

Answer 8

Psittacines are birds of the parrot family. The terms
psittacosis was first used after an outbreak of ‘parrot fever’
in the 1930’s. The bacteria responsible for the infection
Chlamydia psittaci, is rife in the general birds population.
In other types of birds, such as pigeons, the disease is
called ornithosis.

In many cities, a large proportion of wild pigeons carry the bacteria.

Chlamydia psittaci can remain infective for many months in dried excrement. Birds
that have had the disease or are under treatment are fully susceptible to reinfection
since the disease does not convey immunity. It’s very infectious and spreads easily,
not just to humans, but also to other animals.

In wild birds, psittacosis is controlled naturally by the inability of sick birds to keep up
with the flock. Additionally, infective droppings fall to the ground below the trees in
which the birds perch. The clinical disease that we see in pets is promoted by
confining, crowding, transporting, dietary changes, exposure to other infections and
forced exposure to infective excrement.