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• DATES OF GEEATEST INTENSITY.

The period of greatest intensity of fall hay fever in the Eastern, Middle, and Southern States is in September, as the common and giant ragweeds, the principal cause of the disease, reach their full stage of pollination during this month, and during a large portion of Sept-ember the wind is sufficiently high to cause a general distribution of the pollen. At our New Orleans station, for instance, in September, 1917, the wind renchea" a velocity of 10 or more miles per hour during 28 days; in September, 1918, during 25 days; in September, 191°, during26 days; in September, 1020, during 25 da}Ts; in September, 1921, during 24 days; and in September, 1922, during 26 days. The active pollination of the weeds supplying the pollen and the general wind disturbances for distribution of the pollen are therefore the reasons that September is the lete rtoir of hay-fever sufferers.

The rain is nature's most effective means of pcrcipitating the pollen for the relief of the patient; but. unfortunately, the rainfall during September is usually below the average in most hay-fever sections. At our New Orleans station, for instance, the rainfall during August and September, respectively, was as follows: 1917—August 6.92 inches, September 2.69 inches; 1918—August 6.19 inches, September 4.82 inches; 1919—August 7.38 inches, September 2.93 inches; 1920—August 4.18 inches, September 6.47 inches; 1921—August 3.09 inches, September 3.51 inches; 1922 (omitting a heavy rainfall on August 1)—August 3.56 inches, September 0.93 inch.

It will be noted that with exception of September, 1920, in which month it totaled 6.47 inches, the rainfall for this month for the other rears was between 2.69 and 4.18 inches. The records of our clinic also show that the general average of hay-fever attacks during September, 1920, was considerably below the general average, and that during September, 1922, when the rainfall was only 0.93 inch, they were unusually severe.

These records also show that the seasons of marked intensity of fall hay fever were as follows: 1917, August 30 to October 12; 1918, August 17 to September 29; 1919, August 24 to September 26; 1920, September 3 to October 7; 1921, August 18 to October 13; 1922, September 18 to October 3.

TERMINATION OF THE ATTACKS.

The cessation of the fall hay fever, uncomplicated with mixed infection, was as follows: 1917, October 24; 1918, October 28; 1919, October 23; 1920, October 11; 1921, October 24; 1922, October 26. The long hay-fever season in the Southern States is due to the mildness of the climate, which prolongs the pollinating season of the ragweeds. At our station at Hendersonville, N. C. (altitude, 2,250 feet), the cool nights check the pollination much earlier, and the hay-fever season is rarely prolonged after September 30.

LOCAL TEMPORARY RELIEF.

Marked natural relief from the attacks during the hay-fever season, except in localities where the wind may blow from a noninfected area, as on the seashore, results from a general rain that settles the pollen. On October 17, 1916, a rain of 2.58 inches caused the ragweed pollen to disappear from the plates during that day, showing the air to be free of pollens, and this was also the case the following day (1 per square centimeter), in spite of the fact that the wind had reached a velocity of 24 miles per hour and was from a northerly direction. The complete local precipitation of pollen, and the consequent relief to hay-fever sufferers, also occurred in 1917 on August 17, 28, and September 15;. 1918—August 19 to 21, September 20, October 11; 1919—August 18 to 24, and September 13; 19.20—only on September 21; 1921— August 24 and September 25; 1922—October 3 only., The rains on these occasions were so continued and extensive that the absence of atmospheric pollen gave entire relief from hay fever for several successive days.

Unless the physician is familiar with the natural course of hay fever and the influence of weather and other extraneous conditions, the apparent beneficial results of the treatment may be misleading. The numerous so-called "cures" of hay fever depend mainly on these natural causes for their apparent benefits. In no other disease is it so important to take cognizance of the numerous circumstances that may affect the course of hay fever, and the successful immuniologist should be fully equipped for making careful records in order to attain success in the master}7 of this disease.

SPLEEN AND BLOOD EXAMINATIONS FOR MALARIA.

A STUDY OF THE RELATIVE MERITS OF THE SPLEEN AND BLOOD PARASITE INDICES FOR DETERMINING MALARIA PREVALENCE AS FOUND IN DUNKLIN COUNTY, MO.

By M. V. Veluee, Assistant Surgeon, United States Public Health Service.

The positive diagnosis of malaria by the blood smear method is very reliable in the hands of a trained laboratory diagnostician. However, the method is time consuming and is usually not available on short notice. This is especially true with reference to the public health official who, in doing field work, must often examine a large number of individuals and know the results promptly. The development of a method of diagnosis equally reliable and less time consuming would greatly facilitate the work in the field. It is the purpose of this paper to present certain evidence of the value of spleen palpation, obtained during the course of investigations in child hygiene made b}r the United States Public Health Service.

During December, 1921, Maxcy and Google, of the malaria field forces. United States Public Health Service, made a malaria survey of a large group of boys of school age in Dunklin County, Mo. (1). It was tly^privilege of the writer to go over essentially the same ground during the months from August, 1922, to March, 1923. The data collected by Maxcy and Coogle and some of the data collected by the writer are combined in this report as evidence of the value of the enlarged spleen method in demonstrating the malaria prevalence of a community. It is a yardstick, applicable at once in the field rather than at some later date in the laboratory.

METHODS EMPLOYED.

Blhoif smears.—As a routine procedure, blood smears were taken of all the' children examined in a given school. The semithick method was used. Each slide received at least 10 minutes of examination in th* hands of a trained technician, unless found positive sooner.

Spleen.—Similarly, palpation of the spleen was routine for all the grammar-school children, irrespective of sex. The examination was made with the child in the standing position and loaning forward until the body made approximately a right angle. In this position most children relax their abdominal walls sufficiently to allow deep palpation during a deep inspiration and expiration. Simultaneously with the inward pressure of the examining fingers, forward pressure is made with the palm of the other hand placed dorsally over the region of the spleen. Boys and girls were examined separately and away from the remainder of the class. Maxcy and Coogle used essentially the same technique.

The method is believed to give consistent results. One school of 114 children with a high percentage of positives was reexamined with the greatest care, and there was no important difference in the total number of palpable spleens found. Examination with the relaxation of the abdomen is fully as good as that made with the patient lying down with the knees flexed.

DATA ON BLOOD SMEAR AND SPLEEN METHODS.

A comparison between the blood smear findings and the palpable spleens is shown in Table I.

Table I.—Relative value of blond smear and spUen methods as a malaria index, at shown by the examination of 880 school children (both sexes) in Dunklin County, Mo.

[table]

The same group of 880 children was examined for palpable spleens and blood parasites. Forty-six, or 5.2 per cent, were found to have parasites in their blood, whereas 45, or 5.1 per cent, had palpable spleens—a difference of only 0.1 per hundred in the two methods.

Table II.—Number of children with both positive blood and spleen; also the number with

only one index positive.

[table]

That the groups of children having positive bloods and palpable spleens, respectively, were not the same children, is shown in Table II. In this group of 880 children, only 21 had both positive blood and spleen, 25 had positive blood and negative spleen, and 24 had positive spleen and negative blood. Accepting both indices as evidence of malaria infection, we find 70 infected children in this group. On the basis of blood parasites alone only 40 were found, and by the spleen method alone, 45. Thus, each method falls short of the two methods combined, but in each case the difference is essentially the same.

In the Beech Corner school the parasite rate ran 5.3 per hundred higher than the spleen rate. Believing that perhaps the first examination was inaccurate, these children were again examined in a most careful manner and the same number of positives were found.

There was also considerable variation between tbe two indices in the Cardwcll school as found on two different examinations. The children who were examined in October, 1922, were those who lived in town and did not go out to pick cotton. The group examined in January. 1923, consisted of more rural children, the cotton pickers. The much greater opportunity for infection during the vacations and cotton picking is believed to explain this higher rate. Both indices increased, especially the spleen index.

Table III.—A comparison of certain methods for the determination of malaria prevalence as shown by two surveys in Dunklin County, Mo.

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A. HISTORY INDEX.

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1 Practically aU of theic occurred within two years.

In Table III there is given a summary of all the data collected by Maxcy and Coogle in December, 1921, and of that collected by the writer a year later. Maxcy and Coogle. examined only boys in schools selected because of their proximity to the swamps, using only volunteers for blood smears. The writer included both boys and girls; and in getting blood smears in a school every child was included. Some of the schools included in the last survey were not located in the swamp sections. Again, the mosquitoes were less prevalent in the summer and fall of 1922 because of a longer dry season. It was to be expected, therefore, that the indices for the two surveys would not be the same. However, if independent workers are equally proficient, the parasite-spleen ratio should be the same in the same community at the same time of the year, provided both methods are consistently reliable. Maxcy and Coogle report a parasite index

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