MOBILE X-RAY UNIT

The new Mobile X-Ray Unit of the Connecticut State Tuberculosis Commission came to New Haven early in May for a survey of tuberculosis in industry, conducted under the auspices of the New Haven Department of Health. Plans had been made in cooperation with the Employees' Tuberculosis Relief Association and the industries and labor groups for X-raying approximately 1,500 employees of industrial plants, most of them war workers.

The unit was under the general direction of Dr. Paul S. Phelps and staffed by Miss Helen Green, R.N., Mr. Joseph Gaffney, X-ray technical and clerical assistance.

Although X-raying of the school population has been carried on annually in New Haven since 1938 by the Bureau of Tuberculosis of the local Health Department, this was the first time that a survey of this kind had been conducted in the i ndustrial population. It is in this group that the incidence of tuberculosis is high and surveys made elsewhere have uncovered from two to three cases in every hundred persons X-rayed.

With the facilities of the mobile unit about two-hundred persons can be X-rayed each day. All X-ray reports are confidential and will be sent directly to the individual in sealed envelopes. If abnormal findings are noted in the X-ray th e individual will be advised to receive the interpretation of his X-ray film from his family physician.

During the past four years an annual tuberculin X-raying Program has been carried on in the six high schools. This Program includes tuberculin testing (Mantoux two-test method) both freshman and senior classes each year, and X-rayin g all positive reactors in the school regardless of class.

We have had no difficulty in obtaining the cooperation of the students in carrying out the tuberculin testing part this program. Ninety-two per cent of the freshman class has been tested each year on a voluntary basis with an average of 23.1 per cent positive to the tuberculin test.

However, in the Fall of 1942, it was decided to use the Tuberculin Patch Test (Vollmer) instead of the Mantoux in order to test its reliability and accuracy in school programs. The advantages of the Patch Test are that it can be applied quickly and painlessly by any nurse without the use of a needle and syringe. It is stated by some authors that the Patch Test compares very favorably with the standard Mantoux test, (1,2,3). If this is so, then the Patch Test should be used more extensiv ely in school tuberculin testing programs.

In order to make sure that the correct technique was carried out, the procedure of Patch testing was described in detail to the high school nurses. Details such as thorough cleansing of the skin with acetone and proper placing of the Pa tch Test so as to make contact with the skin were emphasized. Moreover, as the interpretation of a positive reaction was not clear at the time we undertook this program, one small school with some 200 students was tested first. As a result of experience i n this school it was decided to call a positive reaction one in which there was an area of erythema upon which were several vesicular-like eruptions.

Two thousand, two hundred and five freshmen in six different schools were tuberculin tested (Patch Test) by some 10 or 12 school nurses with 181 or 82 percent showing positive reactions, (Table A). The percentage of positive reactors va ried from 3.8 per cent for the Commercial High School to 12.5 per cent for the New Haven High school. Nevertheless, there is good agreement with regard to the percentage of positive reactors in four out of six schools tested.

Table B. shows the results of the Mantoux testing of freshman classes from 1938 through 1941, and Patch (Vollmer) testing in 1942. The average percentage of negative reactors for the freshman group in 1942 was 181 or 8.2 per cent. As th is was less than half of what previous experience with the Mantoux test had led us to expect, it was decided to retest one school with the intradermal method. In this particular school (Troup),409 students had been Patch tested and 38 or 9.2 per cent had been found positive, (Table C). Two hundred and forty seven reactors to the Patch test were retested by the Mantoux method, using old tuberculin; none reacted to the first test (1/50 mgm.), and 31 were found positive to the second test, (1 mgm.).

Before drawing any definite conclusions from the above, one must note that regardless of the fact that proper precautions were taken before beginning this program with regard to correct procedure, many aspects of Patch testing are not d efinitely known. For example, what is meant by thorough cleansing with acetone? Does it mean simply swabbing the area of the skin once or a dozen times with a pledget of cotton soaked with acetone? In our testing the skin was swabbed six to eight tunes. < /P>

The area on which to place the Patch has caused us some concern. In one large school the patches were placed on the inner side of the forearm. This did not prove satisfactory as many of the patches became wrinkled and loose, preventing good contact of the tuberculin patch with the skin. Further, there was a good deal of confusion regarding the interpretation of a positive reaction. Many children showed only an area of erythema with no vesicules; while others had the erythema bilaterally , but only 1 or 2 vesicules in one patch of erythema.

It should be pointed out that most authorities who have reported on the Patch test have compared its accuracy to 0.1 mgm. O. T. However, the standard in use today by most clinics is still 1.0 mgm. O. T After taking into consideration po ssible faulty technique and the difficulty in reading the Patch test, one must conclude that this test does not find as many positive reactors as the routine two-test method of Mantoux testing with both 1/50 mgm. and 1.0 mgm. old tuberculosis.

The tuberculin testing of high school students is done primarily to cut down the cost of X-rays. Nevertheless, it is highly important to pick out of the school population every infected individual. If by Patch testing, a large percentag e of positive reactors will be missed, then it becomes evident that this method of tuberculin testing does not adapt itself to mass school testing.

Results of Tuberculin Testing in Six High Schools by Years

Table B

Table C

This pamphlet was digitized on October 16, 1998 by Anthony Pacheco as part of the New Haven Health project.