Sources of Malaria in California

DR. MEYER: Last spring Dr. Walker and myself, under the auspices of the George Williams Hooper Foundation for Medical Research, attempted to make an investigation of the malaria problem in California. The object of this investigation was two-fold, namely:

(a) To collect exact data concerning the endemicity of malaria in the State;

(b) To study the various mosquitos present in the endemic region, their bionomics and their ability to act as transmitters of malaria.

It was thought that the information which we might collect would be very useful for the consideration of a plan of eradicating malaria in the State of California. So far, no figures are available relating to the average number of infected persons; certain data published by the California State Board of Health, which indicate the mortality from malaria in the two valleys, are for various reasons incomplete and unsatisfactory. On the other hand, only very vague information concerning the type of fevers (tertian or aestivo-autumnai) could be found in the existing literature, and nothing is known regarding the average number of carriers in the well-known malarial districts.

Dr. Walker intended to handle part "b" of the problem, but he was unfortunate in this undertaking because the mosquitos were very scarce on account of the heavy rainfall. The investigation was conducted in the northern part of the Sacramento Valley from May 17th to 31st. On account of other urgent work, we were unable to resume our task late in the summer.

Results of Survey

The result of our brief and very incomplete survey revealed certain, probably already known, conditions which-in the light of tropical medicine and sanitation and the discussions of this evening-are important and profitable for consideration.

In our survey we attempted to establish a so-called "endemic index" or "parasite rate" which would denote the percentage of persons carrying malarial parasites in their blood. By collecting and staining with special dyes a drop of blood from every human being in a given territory, and by statistical enumeration of malarial parasites therein, a very good idea of the percentage of infection of the population can be obtained; but inasmuch as such an action is, for various reasons, impossible, the examination of school children under fifteen years of age is considered just as reliable. The number of infected, apparently healthy children will give a fair idea of the average infection among the inhabitants of a certain locality. According to expert opinion,

however, the endemic index should be made up of a "parasite rate" and a "spleen rate," of which the latter is the more convenient in tropical countries. In our experience, it is difficult to obtain a spleen rate in a white population, and inasmuch as the endemic index is sure to be higher than the mere spleen rate, the endemic index based on the parasite rate is more accurate. Numerous cases of infantile malaria do not show any enlargement of the spleen and yet they harbor the parasites in such numbers and in such stages of development that they represent a constant source of infection for their surroundings.

Education Needed

We examined the blood of 272 children in Gridley and of 364 children in Chico, and found a tertian infection in each place (one seventeen-year-old Japanese boy in Gridley and one nine-year-old girl in Chico). The school authorities in both places extended to us the best of receptions and were very glad to co-operate. On the other hand, the parents did not realize the value of such an examination and therefore the percentage of permissions to submit to the blood test was, in some classes, less than ten per cent. Only about one-sixth of the total number of pupils in Chico consented to an examination. This failure to volunteer to assist us in our endeavors to determine the truth demonstrates a lack of appreciation which would exert a well-marked influence on the accuracy of the "endemic index." In a large community, where it was impossible to reach the population by means of a few explanatory talks, the results were less satisfactory than in smaller rural communities.

In my experience an educational campaign is primarily necessary to bring the public into contact with malaria problems and to create such an interest that they will volunteer freely in any measure adopted, be it in connection with an investigation or be it in applying measures of control. In a city like Chico the people can easily be aroused by newspapers, but, in the rural districts, Saturday evening or Sunday afternoon meetings with demonstrations, lantern slides, illustrated pamphlets, etc., will convince the educated public of the monetary losses caused by malaria and will properly enlighten them so that they will understand the reasons of their frequent illness and the preventable mortality among their relations. Such meetings are well fitted to be followed up by extensive blood tests and the determination of an endemic index.

An investigation of an endemic malarial region is incomplete without a determination of the species of anopheles, and the average number of these anopheles in the affected areas. On account of the cli

matic condition last spring, we were unable to obtain even the minimum of information which would permit conclusions and suggestions.

Methods of Eradicating Malaria

After having once established-through a thorough investigation— the points of importance, we can now consider those methods which, when applied, seem most adapted for success. I want to say in advance that a combination of methods is better than any one individual method, and that the scheme decided upon for a city and its suburbs will, in all probability, not be applicable to rural districts.

I was exceedingly surprised to note the results which have been obtained in Oroville, but just ten miles from that city the same measure, adopted for a country village, would be ineffective. When walking through the streets of such a village, I noticed that the people did not even know the fundamental principles of bite-prevention. They know nothing about the mosquito-curtain, gnat-proof rooms, houses and verandas. They sleep in the gardens and orchards without the least concern as to self-protection. An educational demonstration of the intelligent use of the various means of reducing the chances of being bitten by mosquitos will be of assistance in reducing malaria infections.

Another point of importance was brought out by the observation that most of the inhabitants of a city contract malaria in the surrounding rural districts. They know that they will become infected with malaria in certain localities, but they consider the malady a kind of children's disease, and neglect its treatment accordingly. Our main efforts, therefore, should be directed to control the mosquito menace in these districts, a point which has already been discussed by Professor Herms. From what I have seen, I feel justified in saying that it is not a very easy task.

Treatment of Malaria Carriers

I feel that we should pay as much attention to man as we do to the anopheles in any malaria campaign. We must cure him of the already contracted disease, or prevent his again being exposed to reinfection. The conditions in California are similar to those in the Cam pagna Romana in Italy, and the rural conditions are of the same character in both countries. For Italy, the expert opinion of Celli and others has shown that a mosquito control is not crowned with success; and the health authorities, supported by laws, had to resort to a systematic quinine treatment of the population. Malaria has not been eradicated, but by combined quinine prophylaxis plus anti-mosquito protection, they

have reduced the percentage of infections from 33 to 2.5 per cent. and even lower. Measures of such character can only be enforced with the assistance of the medical profession.

From our survey we received the impression that, in the rural communities, there is a lack of appreciation of the malaria problem on the part of the medical profession. As a rule they have difficulties in diagnosing malaria by means of the microscope, or, for unknown reasons, they classify all kinds of fevers with malaria. Why do we not gather these men at a big meeting, show them malaria on clinical cases, teach them the fundamental points of differential diagnosis of the disease as it concerns man? In many cases their patients will profit by such an undertaking, and, through their experience, they will advise others to take a more active part in suppressing malaria. Furthermore, the infected people will receive more adequate attention and proper treatment with quinine.

We do not know how resistant the California plasmodia are towards quinine, but the observations made in Brazil that the parasites of the fever contracted along the Amazon are very drug-resistant, justifies an investigation by itself. This word "quinine" leads to the discussion of another very important subject of discussion, namely, the specific treatment of malaria. As already pointed out by President Wilbur, patent medicines containing quinine are sold and are extensively used in all of the malaria regions of California. The advertisements on the house walls in Chico sufficiently warrant this suspicion. The people consume these drugs irregularly and in insufficient quantities, and, by doing so, obtain temporary relief only and thus favor the development of parasite carriers. Inasmuch as malaria is conferred from one season to another by the agency of these carriers only, the importance of this existing condition is quite apparent. We must, by all means, eradicate these carriers by proper scientific quinine treatment, and we have to ask here the earnest co-operation of the physicians attending such cases. Would it not be better to thoroughly treat suspicious case of malaria, instead of giving him a prophylactic dose of quinine to prevent a relapse during the recovery from an operation, which, as Dr. Ebright has mentioned, is frequently done. All such cases should be segregated and kept under mosquito curtains until completely cured. They are a menace to a household and to a community. By systematically treating the carriers, malaria will also be reduced. In certain localities this will be the only method by which we can finally eradicate malaria.

Conclusions

All other points necessary to render a malaria campaign successful have been illustrated by Prof. Herms, and I can therefore summarize the methods of prophylaxis, which I venture to put forth for consideration, in addition to the mosquito control, namely:

(1) An educational campaign in the rural communities and among the medical profession.

(2) Instruction regarding the reduction of mosquito bites by advocating personal prophylaxis (mosquito-curtains, screening of house, etc.).

(3) Proper treatment and care of carriers.

(4) Systematic quinine treatment in badly infected ranches and rural districts.

(5) A campaign has to be based on a careful, systematic and scientific survey of all the conditions in the endemic region, before a campaign of eradication promises the best success.

A mosquito control will do a great deal of good, and malaria will be remarkably reduced in the cities, but I beg you to pay the closest attention to the rural communities, where help is most urgently needed to relieve the people from this menace which we are discussing this evening, namely: malaria. (Applause.)

THE PRESIDENT: What has been done in other countries, of course, is useful in the solution of our problems here. Most of the laymen among us probably are more familiar with the conditions in Panama than they are with the malaria problem in our own State. We have read a great deal of what has been accomplished down there. Dr. George H. Whipple, who is director of the George Williams Hooper Foundation of Medical Research here, was with General Gorgas in the mosquito campaign in Panama, and he will speak to us now upon that subject.