EMERGENCY REPORT ON SURRA.

SUMMARY.

Surra has been diagnosed among the horses in the Philippines, and has led to the prohibition of landing any animals from those islands at any ports of the United States or of the dependencies thereof.

This disease is caused by a microscopic parasite (Trypanosoma Evansi) which lives in the blood, and the evidence now accessible indicates that this organism is transmitted by means of biting flies, especially by members of the genus Tabanus (horseflies); other methods of dissemination are not excluded. It is chiefly a wet-weather disease, and is reported as invariably fatal to horses and mules. It occurs in other animals such as camels, elephants, dogs, cats, etc.-more rarely in ruminants, and may be transmitted to goats, sheep, and other mammals, but is not yet reported for birds. It is more or less common in India. Its introduction into the Philippines is unexplained, but it has probably existed there for some years past.

Parasites closely allied to this species occur in Europe, Africa, and South America, in some cases causing diseases known as tsetse-fly disease, dourine, mal de caderas, and rat trypanosomiasis. Certain authors believe that some of these maladies are identical with surra.

The chief symptoms of surra are fever, of an intermittent, remittent, and sometimes relapsing type; urticarial eruption; petechiae on the mucous membranes; progressive anemia and emaciation; ravenous appetite and extreme thirst; more or less paralysis.

Treatment has not been satisfactory, but arsenic has been followed by good results in some cases. Prevention is difficult, but should consist in protecting horses from flies. Immediate isolation of the sick animals and protecting them from flies will result in restricting the disease. In some cases it will perhaps be better to kill and immediately destroy the diseased animals.

From both the military and the economic points of view surra must be looked upon as a very serious matter, and its introduction into the United States would result in very heavy losses.

INTRODUCTION.

ORIGIN OF THE PRESENT REPORT.

A cablegram from Major-General Chaffee, Manila, P. I., asking for information regarding surra, has been referred to this Bureau. This dispatch reached us simultaneously with a preliminary report on a parasitic disease prepared by Dr. John G. Slee, formerly an inspector of this Bureau, so that we conclude that since the report was mailed

the diagnosis of surra has been made. Dr. Slee's letter reads as follows:

OFFICE OF THE INSULAR BOARD OF HEALTH FOR THE PHILIPPINES, Manila, P. I., October 24, 1901. DEAR SIR: I inclose a few notes upon a new disease that has appeared in the islands this season among the native and foreign horses (I use the word foreign, as we have American, Australian, and Chinese ponies, in all of which I have noted the trouble). The parasite was first discovered in the blood of a horse taken by myself to the laboratory of the board of health, but for further information and many experiments made I am indebted to Dr. J. J. Kinyoun, United States MarineHospital Service.

By a later mail I shall probably be able to give further information, but at present I should like very much to obtain an idea of what we have found, and if you know of a similar parasite-if there is any literature on the subject. Dr. Kinyoun seems to think that it is entirely new.

I am, very respectfully,

Dr. D. E. SALMON,

Chief of Bureau, Washington, D. C.

JOHN G. SLEE, D. V. S.,

Assistant Veterinarian, Board of Health.

[Inclosure.]

NOTES ON A NEW DISEASE OF HORSES. a

During the past rainy season a disease of a febrile type affecting the foreign and native horses has been noted by the veterinarians.

The history was at first very obscure, the disease usually being far advanced when first seen, the death rate high, and treatment unsatisfactory.

The resident veterinarians and horse owners had noted the same conditions in former years, which they described as calentura, or fever, but did not think it had been so widely spread or the mortality so large as during the present season. Dr. H. H. Muecke, veterinarian of the Land Transportation Corral, says that he had not noted it during the past two seasons, but he was able to give considerable information concerning the disease as it appeared this season in the Government horses.

That the disease was widespread was evident from the reports to the board of health, and investigation showed it to be generally present in the island of Luzon. In one place all the native horses had died, while of the Government stock about one-half were affected.

The first cases in native horses came under notice about the first part of June, and presented swellings of the sheath, legs, and pads under the belly, in many respects similar to those of purpura; the membranes were colorless, hemorraghic spots were present on the membrana nictitans, but no petechial spots were observed on the Schneiderian membrane, as in purpura. These were not seen in the foreign horses. There was always a temperature, very irregular, from normal at times to 105° F. In the native horses the disease would not run a very long course, anorexia appearing in the final stages, followed by death.

When the horses in the corrals became affected the symptoms could be more easily noted. This was simply due to the fact that the native never notices that an animal is sick until it is past recovery. I have seen horses with a well-advanced case being used.

In the corral the sick animal at first showed a temperature of from 103° to 107° F.; pulse full; breathing increased and abdominal; appetite variable, from poor to good, but never entirely lost; the membranes slightly injected, but no hemorrhagic spots,

"Same as Slee, 1902a, pp. 819-821.

as noted in the native animal. The swellings of the belly, sheath, and legs soon appear. In some cases they may not be present, emaciation taking the place, but in the native horses swellings seem to be always a marked symptom. At this point the temperature is variable, of an intermittent character, and is not controlled by any of the febrifuges; it may be higher immediately after giving medication than before. Some of the cases last for a long time, being in the hospital for two or three months, and ending in recovery or death. If the swellings suddenly disappear, death soon follows in the native horse; but this is also a symptom of recovery in the foreign horse.

As the disease progresses toward a fatal termination the animal grows very weak, particularly in his hind legs, weaves from side to side when walking, and may go down and be unable to rise.

The feces are of a normal character, no marked constipation or diarrhea being present; the urine seems to be increased in quantity, but as to color or changes I have been unable to note particulars.

Postmortem.-No special lesions are found, the organs and tissues showing an anemic condition, but in some cases abscesses were noted in the stomach and abdominal cavity. The pericardial sac and pleural cavity are always full of a serous fluid, but no appearances of inflammatory changes are present; antemortem clots are found in the heart.

As there were so many cases the disease was supposed to be of a contagious type, but this did not seem probable, as in a stable of several horses one would be affected and the others remain healthy, although the horses were standing side by side and eating out of the same manger.

The character of the disease being so much like malarial fever, the infection was looked for from some other source and a parasite in the blood was suspected. Upon the examination of the blood of a well-marked case, an animal parasite was discovered which was also found in all the cases examined. In the new cases the parasites were seen, and as the cases progressed they increased in number, but toward recovery they grew less and finally disappeared.

The parasite is an animal organism, rather blunt at one end, with a flagellum at the other; in advancing the tail seems to advance, becomes entangled with the corpuscles, and it drags itself forward. It can go backward, but the most of its movements are with the tail advancing. They are of different sizes, the smaller seemingly a male, the larger a female. They often come together, the blunt ends being attached and the flagellum moving very rapidly.

That they have some action on the red blood corpuscles is very evident, as the blood count is diminished and the leucocytes increased.

Where the parasite comes from is not known. To learn its life history will probably necessitate examination of the fly and mosquito, for the disease is widespread, and the affected animals are fed and watered in so many ways (the Filipino depending upon grass and rice, while the Government stock have hay and oats), that this would in a measure exclude feeding as a source of infection.

After the present report was nearly completed, we received, through the courtesy of Dr. George M. Sternberg, Surgeon-General, United States Army, the following report by Drs. Allen M. Smith and J. J. Kinyoun, dated Manila, October 17, 1901:

A PRELIMINARY NOTE ON A PARASITIC DISEASE OF HORSES."

By ALLEN M. SMITH, Captain, Assistant Surgeon, U. S. A., and J. J. KINYOUN, Surgeon, U. S. MarineHospital Service.

On October 15, 1901, information was given us by J. W. Jobling, assistant bacteriologist of the board of health at Manila, that an epidemic sickness of an unde

termined nature was now prevailing in this city, and also that he had just taken a specimen of the blood from a sick animal which on examination revealed the presence of a parasite. Whether this was accidental or was the causative agent of the disease in question, he was unable to say. . On investigation and inquiry, it was learned from the veterinarian in charge of the corral of the quartermaster's department and from the city veterinarian that there was now and had been a fatal epidemic among the horses in Manila, the quartermaster's department having lost over 200 within the last four months.

One of the corrals was visited by us on the 15th instant, where we were shown by the veterinarian in charge 20 horses and mules ill with an undetermined disease. These animals presented the several stages of the malady. Some were quite recently attacked, while others had been ill for over two months.

The symptoms first noticed are impairment of appetite, constipation, fever, and thirst. These are followed within a few days by a rapid and progressive emaciation. The temperature for the first few days ranges from 104° to 107° F.; the pulse is full and strong. This may be termed the acute state. Then begins an asthenic stage, which may terminate fatally within a variable period, or by a slow convalescence. During this stage, usually within ten days after the onset, there appears a commencing edema above the belly, involving the soft parts; coincident with this, or soon after, the edema extends to the feet and legs. The pulse becomes rapid, weak, and dichrotic; the respiration increased, shallow, and jerky; the gait staggering. Emaciation is rapid and extreme.

The disease has a tendency to relapse; this may occur at any time, even after convalescence appears to have been fully established. The relapses are invariably fatal.

The mortality in this epidemic has been about 75 per cent for American horses and mules and 100 per cent for native ponies.

The gross pathology shows serous effusions into the pleurae, pericardium, and sometimes the peritoneum. There is also a serous exudate into the cellular tissue of the legs and abdomen. The organs are pale, but otherwise normal in appearance.

At the time of our inspection, 5 acute cases were examined, the duration of the attack being from 6 days to 2 weeks. All these animals presented the several clinical appearances as above described.

Blood specimens were taken from the jugular vein of each and examined microscopically shortly afterwards. In 4 of these a parasite was demonstrable. The other was negative, but a specimen taken the following day showed the presence of this same parasite.

On the day following, specimens were obtained from 12 others, all chronic cases, with the result of finding this same parasite in the blood of 4. In 3 they were few, while in the fourth they were present in great numbers; as many as 20 could be seen in one microscope field. The animal from which the specimen was taken had suffered a relapse.

It would appear that the parasite may disappear from the peripheral circulation, or exist there in such few numbers that it is not easily demonstrable after the acute stage has passed. It would require repeated blood examinations to decide this point.

Description of the parasites.

The parasite resembles a whip-like worm, having much the appearance of the Trichocephalus dispar. Its length is from 10 to 14 microns, and it is from 1 to 1.2 microns in diameter through its body; the neck is nearly one-half its length, tapering gradually to a point representing the mouth (?). It has a limiting membrane which is well defined; the contour is in most cases symmetrical, but in some the body line is quite irregular. The larger part of the parasite (body) contains granular material and clear spaces, which latter vary in size and number; they are irregularly dis

tributed, and may encroach on the wall so as to cause irregular outline. The granular material does not extend to the neck.

The parasite is actively motile, having both a vermicular (contractile) and spiral movement. It moves forward in a very peculiar manner; the long whip-like process is thrust forward by a spirillar motion, followed by a contraction of the body.

We have not so far been able to determine its intimate structure, further than the limiting membrane, and the protoplasmic substance of the body.

Two sizes of the parasite have been seen in all the specimens examined; the larger appears to be more numerous and contains considerably more granular material than the smaller, and usually two or more vacuoles. Whether these two sizes represent male and female has not been determined. We are inclined to believe from our observations that these do represent the male and female, because we have observed, in more than half the fresh specimens, the joining of a large and small parasite in such a way as to appear to be something more than accidental.

The pathological change caused by this parasite is a rapid destruction of the red blood cells causing an acute anemia. The changes occur in the blood coincident to the invasion of the parasite. In one horse which had been ill 7 days the red blood cells numbered 3,500,900; the white cells, 14,500. In another, ill 6 weeks, the red blood cells were 3,200,000, and the white were 13,900. The blood of a healthy horse, taken as a comparison, gave red blood cells 6,900,000; white, 9,800. There is also a slight diminution in the amount of hemoglobin-about 85 per cent.

After convalescence has been fully established no parasites can be found; the blood gradually assumes its normal constitution.

The parasite is not confined to the blood, as it can be demonstrated in the serous effusions.

It is quite easy to detect. All that is necessary is to make a microscopical examination of fresh-blood films; a one-sixth-inch objective will suffice. Dried films, fixed, and stained with any of the nuclear dyes.

The organism appears to be a strict parasite. It lives but a short time after removal from the body. The longest time which it has been kept alive in blood serum was not more than 10 hours.

The parasite has many of the properties in common with the filaria and resembles more nearly that of the Filaria perstans, only it is smaller and its movements dissimilar. Yet, on the other hand, the clinical history of animals infested by it-the changes occurring in the blood, the lesions observed in postmortem-point very strongly toward its classification with the spirochate.

The mode of transmission has not yet been studied. It does not appear to be highly contagious, as it does not appear to spread from one to another, even under the most favorable circumstances.

It more nearly resembles malaria in this respect. It is more than probable that its extra corporeal state is different, or another supposition equally tenable is that its intermediate host is some insect, such as the fly or mosquito.

ARMY PATHOLOGICAL LABORATORY, Manila, October 17, 1901.

Dr. Kinyoun has now returned to the United States, and, according to information we have received from him, the disease found is beyond question identical with surra. It further appears from his letter that Mr. Jobling made the first observation on the disease in Manila. Dr. Kinyoun adds:

From what I could learn, the disease surra appears to be distributed all over Luzon and has been there for many years. No one seems to know where it came from. I do not think it came from China, as no cases have been reported in Hongkong, where a considerable number of artillery horses are kept.