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Zoonotic
diseases are diseases which can be passed from animal to man.
In the case of this article, we are concentrating on bacterial
infections
which can be transferred from cat to man. This isn't to say
that the diseases mentioned in this article are exclusive to
cats, many of them can also be found in other species of
animal. People most at risk from zoonoses are the young
& elderly & people with a compromised immune system
such as those with HIV, chemotherapy patients & organ
recipients. Pregnant women should also be careful as some
infections can harm the unborn child.
Many diseases
are passed from cat to cat via fleas, which enforces the
important of proper flea control!!!
Cat bites are
to be taken seriously! Cat mouths (as are human mouths) are
teeming with bacteria, due to the nature of cat's teeth, when
it bites you, bacteria are injected under the skin. If you are
bitten by a cat, it is important that you go to your doctor.
S/he will probably give you a course of antibiotics. It is
important you make sure you're up to date with your Tetanus
shot.
Before you
panic, many of these infections are extremely rare. If you
take proper precautions you will greatly reduce the chances of
picking up an infection from your cat.
This will be
broken up the type of infective "agent", ie:
bacterial, viral, fungal, protozoal, external parasite &
internal parasite.
Bacterial
Infections
Bacteria fall
into two "classes" Gram-positive &
Gram-negative.
What does
gram positive & gram negative mean?
Danish
scientist Hans Christian Gram invented the gram staining test
in 1884. The organism is killed, dyed with crystal
violet (or ethylene blue) for around 60 seconds, it's then
washed in water for 5 seconds, following this, it's rinsed
with iodine & left to stand for 60 seconds, then
washed with alcohol or acetone. If the bacteria retains the
dye, it is gram positive, if it is washed off, it is gram
negative.
Why is it
necessary to know if a bacteria is gram positive or negative?
This
enables doctors etc. to have some idea of the nature of
the microbe. Generally,
gram negative bacteria are more dangerous than gram positive
bacteria.
Streptococcosis
Streptococci
are gram positive bacteria. It is often a cause of death in
kittens & puppies. It is rarely passed on from cats to
humans. The most common strain of streptococcosis
in felines is S canis. There are three forms of
streptococcal infections in cats.
1) Epizootic
2) Neonatal
3) Localised
Epizootic is
most often seen in large cat cat colonies.
Neonatal is
most often seen in catteries. S canis can be found in the
vagina of approximately 50% of queens. The rate of infections
is higher in queens under 2 years of age. S canis is a cause
of neonatal mortality.
Localised is
most often seen can be isolated either by itself or as a part
of a "mixed" bacterial infection from infections
such as abscesses, pyometra, mastitis etc.
Penicillin is
the antibiotic of choice in treating streptococci infections.
Due to the over use of antibiotics, there are some strains of
streptococcus which have become resistant to antibiotics.
Pasteurellosis
Pasteurella
is a gram negative bacteria. Pasteurella multocida found in
the mouths of approximately 75-80% of all cats. Cats with
tartar build up & gingival disease have a higher rate of
infection than cats with clean teeth.
It is
believed that Pasteurella is the most common disease passed
from cat to human. Humans are usually infected via bites or
scratches. Symptoms are usually a swelling & local
infection around the wound, which may lead to an abscess. More
serious systemic symptoms can include sinusitis, pneumonia
& brain abscess.
Treatment is
generally a course of penicillin, tetracycline, or
cephalosporin.
Salmonellosis
Most commonly
known as a cause of food poisoning, there are almost 2,000
serotypes of the genus Salmonella. They live in the intestinal
tracts of many species of mammal, birds, amphibians &
reptiles. Salmonella appears to be uncommon in cats, the rate
of infection is higher in stressed cats, such as ones living
in overcrowded conditions. Salmonella is shed orally,
conjunctively & in the faeces. It can grow on food &
can survive on objects for long periods of time. Cats often
become infected from catching prey.
In humans,
salmonella can cause severe intestinal problems, although
salmonella infection from cats is not very common. One study
in north-central Colorado showed less than 1% of cats carried
the Salmonella bacteria. Treatment is generally
dependent on the severity of symptoms. Symptoms of infection
are gastroenteritis, with vomiting, diarrhoea & fever. Due
to the over use of antibiotics there are some strains of
Salmonella that are now resistant, so some doctors may
avoid the use of antibiotics in minor cases in both humans
& felines. Chloramphenicol & trimethoprim-sulfonamides
are used to treat salmonellosis.
Cat
Scratch Disease (Cat Scratch Fever, Bartonellosis)
As the name
suggests, Cat Scratch Disease is most often associated with
cat scratches (although cat bites & licks can often lead
to CSD too). It is caused by a recently discovered gram
negative bacterium called Bartonella henselae & is found
worldwide. Cats are the main reservoir of CSD although
puncture wounds & scratches from dogs, thorns, splinters
& even fish bones have been implicated in a few cases too.
It is found in approximately 30%-41% of all clinically healthy
cats. Although the bacterium is relatively common in cats, it
is quite uncommon to catch CSD, which indicates that it's
quite difficult to catch. It can be transmitted from cat
to cat by fleas.
Typical
CSD
Usually, the
first sign is a "lesion" which appears 1-2 weeks
after the initial scratch. Lymphadenopathy...swollen lymph
nodes (especially those in the armpits) & sometimes
abscess 1-3 weeks after the scratch , headache, joint pain,
lethargy, loss of appetite & flu like symptoms lasting
several weeks. 75-80% of cases are people under 20 years of
age. In healthy people, CSD usually resolves itself, treatment
is not necessary.
Atypical
CSD
Bacillary
angiomatosis is a "syndrome" that is most often seen
in immunocompromised people. Serious skin lesions
develop, patients may develop high fever, sweats, chills, poor
appetite, vomiting and weight loss. If not treated, it can
lead to death. Antibiotic treatment has been shown to cure the
infection.
12-29% of
veterinarians have shown positive skin tests & 5% of
healthy people in other jobs, which indicates that while they
have had the infection, symptoms have been mild it not
apparent at all.
Campylobacter
jejuni (campylobacteriosis)
Campylocacter
jejuni is a gram negative bacterium which is responsible for
gastrointestinal illness. It is one of the most common causes
of gastrointestinal illness in the United States. Most cases
of campylobacteriosis in humans is caused by handling or
consuming contaminated food. Birds are a common reservoir of
this bacterium & therefore care & safety when handling
& cooking raw meat should be carried out. This includes
thoroughly washing chopping boards & utensils which have
been used to prepare raw meat.
Cats can
become infected with campylobacter, which can then be passed
onto their human owners via cat faeces.
Symptoms
include fever, abdominal cramps, watery or bloody stools and
usually begin 2 - 5 days after exposure. People infected
should drink plenty of fluids. Usually this illness will
resolve itself, if not antibiotics may be prescribed. It's
important to note that any case of vomiting or diarrhea be
seen by a doctor urgently. Young children can dehydrate
quickly.
Rochalimaea
henselae
(see Cat
Scratch Disease)
Leptospira
Infection (leptospirosis)
Leptospira
(also known as also known as canicola fever, hemorrhagic
jaundice, infectious jaundice, mud fever, spirochetal
jaundice, swamp fever, swineherd's disease, caver's flu
or sewerman's flu) is a gram negative bacteria. Leptospirosis
can infect many species of wild & domestic animal although
leptospirosis infection in cats is very rare. It has been
shown that cats have tested positive to exposure to leptospira
but typically don't go on to display symptoms of illness. This
is possibly because cats have a long history of exposure to
this bacteria via their long association with rats.
Infection
occurs via contact with infected urine either via the skin
(especially broken skin) or the mucous membranes (eyes, nose
& mouth).
The
incubation period varies from 2 days to 12 days.
Symptoms includes flu like symptoms, headache, nausea. The
patient usually recovers after 2 - 3 weeks. However, in some
cases may develop into the more severe form known as Weils
disease. Symptoms of Weils disease include jaundice,
severe headache & vomiting, bloodshot eyes. This may
progress on to liver & kidney failure. Treatment is a
course of one of the following antibiotics: penicillin,
streptomycin, tetracycline and erythromycin.
Plague (Yersinia pestis) Infection
The plague is
caused by a gram negative bacteria known as Yersinia pestis.
There are three types of plague (bubonic, septicemic &
pneumonic). The most common mode of infection is via a bite
from the rat flea (Xenopsylla cheopis), however
infection can also occur in cats from eating rodents
(including rats & squirrels) infected with Y. pestis. Cats
can pass it onto humans via two ways. Either bringing in
infected fleas which then go on to bite the human or if the
cat is infected with plague it can pass it on via a bite or
scratch.
Bubonic
plague (infection of the
lymph glands): The bubonic plague is the most common form of
plague & is almost always caused by a bite from an
infected flea. The bubonic form affects the lymph system.
Symptoms usually appear within 3 - 7 days of being bitten
& include flu like symptoms, extreme exhaustion, and
swollen/painful lymph nodes (called buboes) closest to
the bite. Bubonic plague is not contagious.
Pneumonic
plague (infection of the
lungs): Pneumonic plague is the second most common form
of the plague & occurs when the Y. pestis bacterium
infects the lungs. It may also occur in a patient who has
untreated bubonic or septicemic plague & the bacteria
spreads to the lungs. This form of plague is passed from
person to person. Symptoms appear within 2 - 3 days &
include coughing, frothy/bloody sputum, fever, difficulty
breathing & shock.
Septicemic
plague (infection of the
blood): Septicemic plague is the rarest form of the plague
& occurs when the Y. pestis bacterium infects the blood.
It is usually contracted the same way bubonic plague is.
Bubonic & pneumonic plague can also lead to septicemic
plague. It is rarely contagious. Symptoms include fever,
chills, abdominal pain, vomiting, exhaustion, bleeding under
the skin.
Streptomycin
is the antibiotic of choice. Gentamicin is used when
streptomycin is not available. Tetracyclines and
chloramphenicol are also effective.
Plague is an
extremely dangerous disease & medical attention should be
sought immediately if you suspect you or your pet have been
exposed.
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