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Rickettsial Infection (Ricketts)
The Rickettsiae
are minute infectious agents, smaller than most germs and larger
than most viruses. Most classifications put them midway between the
bacteria and the viruses. Rickettsia
are too large to pass through a bacterial filter and are visible
with an ordinary microscope.
Like the viruses, they multiply only in the
presence of living cells and many of them live inside living cells.
They usually are transferred from animals to men by ticks, mites,
fleas, or lice. Many of the rickettsial
diseases of men have been
identified as such only during the last fifty years. The word "Rickettsia"
comes from the name of Howard Taylor Ricketts, a physician in
Chicago who was one of the first to observe these organisms and
determine their nature.
A form of typhus
fever called "murine typhus" is
an acute infectious disease caused by
an organism of the rickettsia. The disease
usually begins with a sudden fever that lasts two or three weeks;
the rash is located mostly on the trunk. The disease was first
described in the United States by James Paullin of Georgia in 1913.
The chief mammalian carrier of murine typhus is the rat. The
infection is transmitted from rat to rat by fleas. The rat louse
will not feed on man but the flea will if given opportunity. The
flea bite is not infectious but when the flea bites a man, the flea
may deposit its excretions; then the human being scratches himself
and thus may force these excretions of the flea into his skin.
About six to fourteen days after such infection
has taken place, illness begins with a chill and muscular
aching, headache,
fever, loss of appetite, r and
cough; with this comes a feeling of severe illness. A skin
eruption helps make the diagnosis. This eruption is present in
90 per cent of white patients, but of course is difficult to see
on patients with a colored skin. The lesions of the skin are not
hemorrhagic. In many patients the spleen is enlarged. Usually
after eight to ten days the symptoms lessen and diminish-the
condition clearing up in about three weeks.
Fortunately, two of the new antibiotic drugs-aureomycin
and chloromycetin-have been established as valuable in
controlling the symptoms of
this virus infection. Most of those with murine typhus need lots
of fluids while they are ill; if they cannot drink water, it is
put into the body in other ways. About one out of every one
hundred people with the disease may be so severely sick as to
die of it. The ones who die are usually the very old or sick
people.
The extremely severe epidemic typhus that is
seen in Russia is exceedingly rare in the United States. A form
of typhus which occurred to our soldiers in the Far East is
called "scrub typhus" and known to the Japanese as tsutsugamushi
disease. In these conditions modem treatment involves the use of
aureomycin, chloromycetin and sometimes para-amino benzoic acid
which is effective in interfering with the nutrition of the
virus in the body.
Rocky Mountain
Spotted FeverRocky
Mountain spotted fever is a severe infectious disease with ,
chills, fever, prostration, and a hemorrhagic rash. It is
caused by a Rickettsial organism and is transmitted by wood
ticks. A disease called Brazilian typhus is identical, as
are Mediterranean fever, South African tick-bite fever and
Kenya fever.
Rocky Mountain spotted fever is largely a
rural disease; it has been I found in every state in the
United States except Maine and Vermont. It occurs chiefly
during the warm months of the year when the ticks are
active. Indeed the only insects known to spread the disease
are the ticks. These include the wood tick, the dog tick,
the lone star tick, and the rabbit tick. The tick attaches
itself to an infected animal and transfers the infection to
man.
Two to fourteen days after being bitten,
the illness comes on abruptly with chills, fever, severe
frontal, or occipital headache, pains in the I muscles and
joints and sensitivity of the eyes to pressure and to light.
Nausea, vomiting, constipation, nosebleed, a mild cough and
similar symptoms appear, along with a fever which will rise
rapidly from 103 to 105 degrees.
A rash is characteristic. It develops two
to six days after the onset of the illness, usually first
around the wrists and ankles and then spreading to involve
the entire body surface. Several crops of the rash may I
appear, one after the other. Sometimes the rashes become
hemorrhagic. The damage may be so great that gangrenous
changes occur in the skin on the tips of the fingers, the
toes, the earlobes and even on the soft palate. Secondary to
these infections may be pneumonias, hemorrhages of the
stomach and intestines and kidneys and serious inflammations
of the eyes.
Vaccines have been prepared which are used
to immunize people against Rocky Mountain spotted fever.
Fortunately, chloromycetin, aureomycin, terramycin and para-amino
benzoic acid have proved to be beneficial in Rocky Mountain
spotted fever. The condition was formerly much more severe
than since the new antibiotics have been developed. Once
from 12 to 25 per cent of those infected died of the
condition but it seems likely that with the new antibiotic
drugs something less than 5 per cent of deaths will occur.
Q Fever
Q fever is an acute illness often
accompanied by pneumonia which results from infection
with a form of Rickettsia. The first human cases of the
disease were observed in Australia in 1~33. Since they
originated in Queensland, the infection was named "Q
fever." Now a similar organism has been isolated from
ticks captured in Montana and cases have been found in
other areas of the United States.
Human beings are highly susceptible to
Q fever; from 25 to 40 per cent of those exposed may be
attacked by the disease. The condition was found much
more often in Australia among people exposed to cattle.
Before 1946 the disease was rare in the United States
but has now been found particularly in epidemics in
stockyards such as the one in Amarillo, Texas, in
Chicago, and among dairymen in Los Angeles county.
Workers in research institutes have frequently been
infected.
From twelve to twenty-six days after
exposure, the disease comes on with symptoms like those
seen in other Rickettsial diseases. The two striking
features that make Q fever different from other
infections with Rickettsia is the absence of any
characteristic rash and the almost invariable presence
of pneumonia. However, pulmonary symptoms are often mild
or absent. About one-half the patients have aches in the
X-ray of the chest shows that the lungs have been
infected in at least!11. 90 per cent of the cases.
Q fever may be confused with primary
virus pneumonia, with tuberculosis, with psittacosis or
infected bird fever, and must also be distinguished from
ordinary influenza, sinusitis, undulant fever, dengue,
and other Rickettsial infections. Here again aureomycin,
chloromycetin, and terramycin have been found useful in
treatment. Relapses are rare. Most of the patients
recover. Thus far only some eight or ten deaths have
occurred among perhaps 1,000 cases that have been
reported in medical writings.
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