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Brief Statement Concerning Onchocercosis in Mexico
BRIEF STATEMENT CONCERNING ONCHOCERCOSIS IN MEXICO DR. RAFAEL SILVA, M.D., F.A.C.S. M E X I C O CITY
(Translated by W. H. Crisp) This very interesting communication as to methods recently adopted for fighting on chocercosis in two states of southern Mexico has a special importance for Central American and other tropical communities. Dr. Silva is chief of the Mexican department of public health.
In the year 1925 we received in Mexi co the first notices of the existence in the state of Chiapas of a disease which produced blindness; and since in the neighboring country of Guatemala the onchocercotic infection had been dem onstrated for some time in regions ly ing next to the international boundary, our thoughts were directed to an exten sion of onchocercosis into our own country. Physicians sent by the department of public health proved that such was the case and proceeded to install free dis pensaries, the purpose of which was to extirpate the filarial cysts which the patients show especially in the hairy skin, and also in the body. Later we learned that onchocercosis existed likewise in the mountainous re gion of the state of Oaxaca, and in car rying on an effective campaign against the endemic we encountered various difficulties, one of these being the fact that we had no exact knowledge as to which form of onchocercosis was ac tive ; another that we did not know the intermediary; and a third that the in fected areas were not well delimited. Facing this situation, we found it advisable to establish a commission whose duty it would be to clear up the points mentioned, and further—a very important matter—to elucidate the ac tual mechanism which gave rise to blindness, especially as some authors at tributed'it to toxic phenomena and al most no one suspected invasion of the eye by the parasites themselves. In a little less than a year of activity of the investigating commission, the onchocercotic areas were definitely de termined. A census of those afflicted
was taken, and we learned that there were about fifteen thousand in Chiapas and about five thousand in Oaxaca. It became manifest that we had to deal with Onchocerca volvulus csecutiens. We formed a definite picture of the symptomatology of the disease, which consists fundamentally in the appear ance of subcutaneous tumors in the hairy skin and more rarely in the re mainder of the body; in a mild elephan tiasis of the skin of the face, which assumes an olive-green tinge; and in ocular manifestations which take the form of punctate keratitis and plastic iritis. The keratitis may develop into complete infiltration of the cornea, with loss of visual acuity, and the iritis causes seclusion and occlusion of the pupil. The background of the eye is nor mal. By means of anatomopathological studies, in which we made use of eyes the vision of which had been lost, it became clear that the microfilarias penetrate the eye, and that it is they which are directly responsible for the ocular symptomatology, a fact which was unknown or at least had not been demonstrated previously. Since in Africa onchocercosis is transmitted by Simulium demnosum, the commission determined to make a study of the sand flies in the areas in vaded by onchocercosis, and it was completely demonstrated that among our people Simulium avidum, mooseri, and ochraeeum were responsible for the disease. While these various studies were be ing made, we had a dispensary in opera tion in Chiapas arid another in Oaxaca, to get rid of the cysts, which we were
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ONCHOCERCOSIS IN MEXICO
assured by the Guatemalan physicians was the best treatment for onchocercosis. Having learned the greater part of the obscure facts with regard to filariasis, we organized for this year, and there are in full activity, three sanitary brigades for the state of Chiapas and one for the state of Oaxaca; each of these being composed of a physician, a technical assistant, a male nurse, and a male servant, and being provided with all the necessary materials to undertake the work of extirpation of cysts, which as a matter of fact has so far yielded the best therapeutic results. The dominant idea of this campaign has been, not to expect, as we formerly used to, that the patients would seek treatment, but to reverse the procedure, and to have our personnel seek the pa tients. As our brigades can only travel in the infected areas in the dry months, and it is necessary to discontinue the work during the r,ainy season, we re quested the proprietors of the large coffee estates to take personal charge of plans for continuing the extirpation of the cysts after the withdrawal of our brigades, which it was understood would return to their task during the next dry season.
519
Furthermore, knowing the biology of the species of fly which transmits onchocercosis, we established among the proprietors of the farming estates the necessary regulations for prevent ing the procreation of carriers, and an entomologist travels the infected areas with the brigades, in order to insure the cleanliness of ditches, canals, streamlets, and so on; further we have required that copper screening should be placed in doors and windows and other necessary means adopted to pre vent the breeding of the sand flies and their access to workmen on the coffee estates. The work of publication of ideas with regard to onchocercosis, its dangers, and the means of preventing infection has not been neglected, although no great importance has been attached to it. So far we cannot speak of results of the campaign, since it has hardly begun, but inasmuch as it rests upon a scien tific knowledge of the disease and ap proaches the problem from the double point of view of patient and carrier, we shall doubtless see good results in the course of a few years of uninterrupted work. Avenida Insurgentes 195.
(Translated by W. H. Crisp) This very interesting communication as to methods recently adopted for fighting on chocercosis in two states of southern Mexico has a special importance for Central American and other tropical communities. Dr. Silva is chief of the Mexican department of public health.
In the year 1925 we received in Mexi co the first notices of the existence in the state of Chiapas of a disease which produced blindness; and since in the neighboring country of Guatemala the onchocercotic infection had been dem onstrated for some time in regions ly ing next to the international boundary, our thoughts were directed to an exten sion of onchocercosis into our own country. Physicians sent by the department of public health proved that such was the case and proceeded to install free dis pensaries, the purpose of which was to extirpate the filarial cysts which the patients show especially in the hairy skin, and also in the body. Later we learned that onchocercosis existed likewise in the mountainous re gion of the state of Oaxaca, and in car rying on an effective campaign against the endemic we encountered various difficulties, one of these being the fact that we had no exact knowledge as to which form of onchocercosis was ac tive ; another that we did not know the intermediary; and a third that the in fected areas were not well delimited. Facing this situation, we found it advisable to establish a commission whose duty it would be to clear up the points mentioned, and further—a very important matter—to elucidate the ac tual mechanism which gave rise to blindness, especially as some authors at tributed'it to toxic phenomena and al most no one suspected invasion of the eye by the parasites themselves. In a little less than a year of activity of the investigating commission, the onchocercotic areas were definitely de termined. A census of those afflicted
was taken, and we learned that there were about fifteen thousand in Chiapas and about five thousand in Oaxaca. It became manifest that we had to deal with Onchocerca volvulus csecutiens. We formed a definite picture of the symptomatology of the disease, which consists fundamentally in the appear ance of subcutaneous tumors in the hairy skin and more rarely in the re mainder of the body; in a mild elephan tiasis of the skin of the face, which assumes an olive-green tinge; and in ocular manifestations which take the form of punctate keratitis and plastic iritis. The keratitis may develop into complete infiltration of the cornea, with loss of visual acuity, and the iritis causes seclusion and occlusion of the pupil. The background of the eye is nor mal. By means of anatomopathological studies, in which we made use of eyes the vision of which had been lost, it became clear that the microfilarias penetrate the eye, and that it is they which are directly responsible for the ocular symptomatology, a fact which was unknown or at least had not been demonstrated previously. Since in Africa onchocercosis is transmitted by Simulium demnosum, the commission determined to make a study of the sand flies in the areas in vaded by onchocercosis, and it was completely demonstrated that among our people Simulium avidum, mooseri, and ochraeeum were responsible for the disease. While these various studies were be ing made, we had a dispensary in opera tion in Chiapas arid another in Oaxaca, to get rid of the cysts, which we were
518
ONCHOCERCOSIS IN MEXICO
assured by the Guatemalan physicians was the best treatment for onchocercosis. Having learned the greater part of the obscure facts with regard to filariasis, we organized for this year, and there are in full activity, three sanitary brigades for the state of Chiapas and one for the state of Oaxaca; each of these being composed of a physician, a technical assistant, a male nurse, and a male servant, and being provided with all the necessary materials to undertake the work of extirpation of cysts, which as a matter of fact has so far yielded the best therapeutic results. The dominant idea of this campaign has been, not to expect, as we formerly used to, that the patients would seek treatment, but to reverse the procedure, and to have our personnel seek the pa tients. As our brigades can only travel in the infected areas in the dry months, and it is necessary to discontinue the work during the r,ainy season, we re quested the proprietors of the large coffee estates to take personal charge of plans for continuing the extirpation of the cysts after the withdrawal of our brigades, which it was understood would return to their task during the next dry season.
519
Furthermore, knowing the biology of the species of fly which transmits onchocercosis, we established among the proprietors of the farming estates the necessary regulations for prevent ing the procreation of carriers, and an entomologist travels the infected areas with the brigades, in order to insure the cleanliness of ditches, canals, streamlets, and so on; further we have required that copper screening should be placed in doors and windows and other necessary means adopted to pre vent the breeding of the sand flies and their access to workmen on the coffee estates. The work of publication of ideas with regard to onchocercosis, its dangers, and the means of preventing infection has not been neglected, although no great importance has been attached to it. So far we cannot speak of results of the campaign, since it has hardly begun, but inasmuch as it rests upon a scien tific knowledge of the disease and ap proaches the problem from the double point of view of patient and carrier, we shall doubtless see good results in the course of a few years of uninterrupted work. Avenida Insurgentes 195.