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 Fever
Rocky 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 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.