We have already mentioned on our Rodent Control page that rats have been recorded carrying up to 45 different pathogens dangerous to man.  We're very sure that you didnt really need to be reminded of why you don't want rodents in your home or business but here is a more indepth look at five of the worst diseases and their symptoms.

PLEASE NOTE that the following information is not intended for use as diagnosis or health care advice.  Anyone showing signs of any of the following symptoms should seek advice from their GP without delay.

Salmonella

We generally know Salmonella as a type of food poisoning although it is in fact the name of the group of bacteria that cause it.  Salmonellosis is the disease caused by eating food that is raw, under-cooked or in many cases too frequently re-heated.  The three main strains of Salmonella bacteria found to be carried by rats and transferred to food are S. enteriditis, S. typhimurion and S. dublin.

Salmonellosis sufferers develop symptoms between 12 and 72 hours after infection and these are generally fever, vomitting, diarrhoea and abdominal cramps.  Although most cases recover without treatment, after a period ranging between four and seven days from the onset of symptoms, it can be very serious for certain groups.  The elderly, very young and those with impaired imune systems are more likely to dvelop severe illness, requiring hospitalisation.  Rehydration and replenishment of the electrolyte balance is the most usual way of getting through the unpleasent period of illness.

A series of scientific investigations carried out in the 1990's showed that up to 25% of the UK rat population can carry Salmonella at any one time.

Listeria

The genus of Listeria most commonly related to infection in humans and found to be carried by rodents is L. monocytogenes.  Correct food treatment such as pastuerisation and stringent hygiene controls will reduce the risk of infection but it has been found in uncooked meats and vegetables, some fruits and soft cheeses.

The illness caused through Listeria infection is listeriosis and in its non-invasive form has very similar symptoms to salmonellosis, taking up to 30 days from infection for symptoms to appear.  However the invasive form can be extremely dangerous due to the bacteria spreading to the bloodstream and central nervous system; almost always neccessitating intenstive antibiotic care in hospital.

Listeria has been found in a large number of rodent population with rates of infection ranging from 10-75%.

Leptospira

Rodent urine and contaminated soil are the most common sources of the bacteria Leptospira.  The early symptoms of Leptospirosis are often flu-like with high fever, chills, severe headache, muscle ache and vomitting.  For this reason, infection is often misdiagnosed and therefore registered infections are lower than actually exist.  Symptoms appear after an incubation period of 4-14 days and in the most severe form of the disease, Weil's disease, those infected can develop meningitis, hearing loss, extreme fatigue and respiratory problems.

Activities such as fishing, swimming in open water and gardening can all lead to infection and so relevent care should be taken wherever possible; wearing gloves when weeding for example.

E.Coli or Esherischia Coli

The most important strain in humans is E.Coli 0157. It is a major source of foodborne illness with symptons ranging from nausea, vomitting, stomach cramps and diarrhoea.   Occasionally infection can lead to more serious complications such as kidney failure and aneamia with children being in the highest risk group.

Around 40% of the rat population is infected with E.Coli and many reported cases of infection can be related to rodent transfer of the disease.

Hantavirus

Less commonly known than many of the disease mentioned above, hantavirus is no-less dangerous.  Early symptoms are flu-like and can lead to acute respiratory distress syndrome, kidney failure, low blood pressure and low blood oxygen levels, giving the sufferer a blue tinge to their skin tone.

The most common accepted source of hantavirus is from the dust of dry rodent droppings.  Exposure coming from activities such as cleaning an enclosed area (shed, house etc) that has been empty for a long period of time.