Sidebilder
PDF
ePub

communicable diseases have approached an epidemic stage, health officers have issued statements, detailing the situation and advising the public of individual responsibilities and duties in checking the disease spread.

Such a situation means that health workers of the state are becoming more generally cognizant every day of the fact that they must take the public into their confidence if they are to achieve the best results. Gum-shoe methods are out of date.

By displaying a willingness to let the public know what he is doing, the health officer gains a powerful ally in the press and enables the people of his district to take an intelligent interest in his wark.

If John Smith knows diphtheria is prevalent in town, he is more likely to take his daughter Mary's sore throat seriously than if the facts have been concealed.

The average newspaper is glad to print both news and educational propaganda pertaining to public health if the health officer is willing to come half-way. The general interest of the press of the state in such material has been demonstrated to the State Department of Health by the cordial reception which its own publicity matter regularly gets in the editorial sanctums.

The State Department of Health is planning considerable extensions of its own work in this field, to be carried out soon, and has no doubt of the co-operation of the newspapers.

Local health workers can do much to aid in this work by helping their home-town papers to get an appreciation of the local phases of health work, and, in case there are a few papers which do not see the opportunity for community service presented by the health news field, by pointing out that the readers both need and desire such material.

CHILDREN ARE OUR

LAST DEFENSE LINE

Children mean more to America and to the world today than ever before. They are our last line of defense, therefore no sounder patriotic service can be offered than that which will protect the children and safeguard baby life. Here in America, before war is actually upon us, it is nothing more than common sense for each community to study its needs and put into ac

tion the means of preserving child life and safeguarding the health of the children. England has learned so well the need for protecting her mothers and babies that infant-welfare work has redoubled there since the war began.

For the first year of war her infant mortality rate was higher than in previous years,

but for 1916 it was the lowest rate on record for that country. — North Carolina State Board of Health.

Rabies (Hydrophobia)

By Fred Berry, Bacteriologist, Division of Laboratories, Ohio State

Department of Health

T

HE object in presenting this paper is to give health officials, physi

cians, and the public some of the more important facts concern

ing rabies, with the idea of facilitating the care of persons exposed to rabies infection. No attempt has been made to go into detail on any phase of the subject and for those who care to obtain additional information a list of references which were consulted in preparing this paper is appended. The subject will be discussed under the following heads:

'Nature of rabies.
Cause.
Animals affected.
Incubation period.
Diagnosis —

Clinical.

Laboratory.
Shipment of specimens.
Care of persons bitten.
Care of animals bitten.
Prevalence.
Control and prevention.

NATURE OF RABIES Rabies is a specific infectious disease common to man and animals. It is characterized by (1) a variable incubation period, (2) a short course with almost certain death after symptoms develop, (3) a peculiar localization of the virus in the central nervous system and (4) definite symptoms which develop as a result of changes in the central nervous system. The disease is essentially the same in all of the many species of animals that are susceptible. Although rabies is usually more prevalent in thickly settled areas, there are very few parts of the globe in which it has not been reported at one time or another. Climate has little effect on rabies and in localities where there are marked seasonal variations it occurs practically as often during the winter as during the summer months.

Rabies is by no means a disease of recent origin. It was described by Aristotle as early as 200 B. C. The first description of rabies in human beings was written by Celsus in the first century A. D. However, no important facts regarding the cause or manner by which rabies is transmitted were brought out until 1804 when it was shown that the saliva of dogs carries the virus. The most important advance in the study of rabies was made by Pasteur. In 1884 he announced that he was able to immunize animals against rabies. The method of preventive treatment outlined by Pasteur is followed with slight modifications even today and the procedure carried out to protect those who have been exposed by rabid animals is commonly known as the Pasteur treatment.

CAUSE

Rabies Virus. The cause of rabies is known as rabies virus. It is a living organism, too small to be seen with the microscope and it will pass through a very fine filter. Numerous attempts to grow this virus have been almost uniformly negative, so that it is impossible to study it as one can study the cause of most infectious diseases. However, a number of important facts are known concerning rabies virus, and fortunately, the failure to grow the organism has not interfered seriously with the progress toward prevention of the disease in human beings. The virus is more resistant to certain chemical agents than are many disease producing organisms. However, some disinfectants, formalin for example, kill rabies virus quite quickly.

Distribution of the Virus in the Body. (Nervous System): Rabies virus with a few exceptions is iocalized in the central nervous system of animals suffering with the disease. The brain contains a very large amount of the virus, the spinal cord a less amount, and other parts of the nervous system still smaller quantities. (Glands): The salivary glands in most species of animals contain a considerable amount of the virus. It is from these glands that the virus enters the saliva. Thus it may be transferred to wounds already present or those inflicted by the rabid animal. (Milk): A few instances are recorded where milk from rabid cows has produced rabies in animals fed with it. Numerous other attempts to produce the disease in this manner have failed. The conclusion to be drawn is, that while the danger from milk infection is very slight, it is, however, possible if there are abrasions in the mucosa of the mouth or æsophagus. The gastric juice will kill rabies virus. Pasteurization of milk will certainly destroy the virus. (Blood): About the same results have been obtained with blood that were obtained with milk. That is, a few investigators have succeeded in transmitting the disease with blood from rabid animals, but by far the larger number of experiments in this line have been negative. It is possible that some of the positive results may have been due to improper technic. The actual danger from blood is certainly very slight. Nevertheless, precautions should be taken to prevent contamination of wounds with blood from suspected animals. (Organs of the body): Although it has been shown experimentally that rabies virus may be found in some of the internal organs this fact is of slight practical significance with regard to the transmission of the disease.

ANIMALS AFFECTED It is possible under favorable conditions to successfully inoculate practically all warm-blooded animals with rabies virus, but in nature rabies occurs to a large extent in a relatively few species, and these consist of animals which are most likely to become inoculated by the bites of dogs and cats. The figures in accompanying Table I are representative of the average frequency with which different animals in Ohio become infected with rabies. Of all cases submitted in 1917, 47.1 per cent were shown to be rabies. These figures correspond fairly closely to those given by writers who collected statistics on several thousand cases in France and Austria.

In the western states, rabies has been found in skunks. In California and Montana coyotes have been infected and have spread the disease to a considerable extent. Rats have been infected by feeding them fixed virus, but it is doubtful if these animals ever become infected under natural conditions. One specimen of suspected rabies in a rat was submitted to this laboratory the past year, but no examination could be made on account of the condition of the brain. The physician stated that the animal showed symptoms of rabies. One ferret was submitted for examination with negative results.

TABLE I. RABIES EXAMINATIONS BY OHIO STATE DEPARTMENT
OF HEALTH IN 1917, CLASSIFIED AS TO THE KIND OF ANIMAL:

Total Percent Number
Kind of animal

cases

of positive Percent examined total

cases positives Dogs

204
82.3

103

50.4 Cats

18
7.2

5

27.7 Cattle

16
6.4

5

31.2 Horses

4
1.6

2

50.0 Sheep

3
1.2

66.6 Swine

1

0.0 Rat

1

0.0 Ferret

1
.5

0.0

Total

248

117

INCUBATION PERIOD The incubation period is the time necessary for symptoms to develop after infection with rabies virus. As already stated, the variability of this period is considered one of the characteristics of rabies. Since the virus must travel along the nerves to the brain and spinal cord, it can be readily seen that the incubation period in any given case will depend altogether on the location of the wound and the amount of virus introduced. This latter factor is largely determined by the number and severity of the wounds. Knowing all the facts in a case, one cannot say definitely what the incubation period will be, but an approximate idea can be had from the following figures which are averages for a considerable number of cases : In Man (Figures by Bauer, 537 cases, quoted by Stimson):

Per cent. 1 to 19 days.

8.24 20 to 39 days.

28.43 40 to 59 days.

21.18 60 to 79 days.

15.30 80 to 99 days.

9.22

Per cent. 100 to 149 days.

7.65 150 to 199 days.

5.69 200 to 249 days.

.98 250 to 330 days.

2.35 1 to 1/4 years.

1.18 In Animals

(Nocard and Leclainche give the folowing figures):
Dog and cat, 15 to 60 days average. Shortest, 8 days; longest, 1 year.

Horses, 15 to 60 days average. Cases as high as 10, 14, and 20 months. Fourfifths of cases under 60 days.

Cows, 1 to 3 months average. Cases as high as 20 and 23 months.
Sheep and goats, 15 to 30 days average.
Swine, 15 to 30 days average. Extremes, 6 days (?); 6 months.

The age of a person or animal appears to have a distinct influence on the incubation period. It is shown by statistics that this period is

TABLE II. RABIES EXAMINATIONS BY OHIO STATE DEPARTMENT

OF HEALTH, CLASSIFIED BY YEARS, 1907-17:

Year

1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917

[blocks in formation]

shorter in young persons and young animals. This point is also apparent in artificially inoculated laboratory animals.

The incubation period is shortest in persons bitten in the face. The shortest periods that have come to the writer's notice in this state are two cases, one in Akron and one in Middletown, with incubation periods of 10 and 16 days respectively, following bites around the eye.

DIAGNOSIS Clinical. The clinical diagnosis of rabies, while at times sonewhat difficult, is, nevertheless, fairly easy in the majority of cases, provided, of course, the disease has progressed sufficiently for definite symptoms to appear. For this reason it is advisable, whenever possible, to capture and confine a suspected animal, so that he may be observed. Animals afflicted with rabies live but a few days. If a suspected animal is alive and well two weeks after biting a person it is safe to release the animal and have no fear that it had rabies. A competent veterinarian should be called to make a diagnosis on suspected animals. However, some of the most characteristic clinical signs of rabies may be pointed out here so that an untrained person may recognize suspicious cases. The disease takes two forms in dogs and the symptoms have been well summarized by one observer as follows:

« ForrigeFortsett »