Forest Malaria. Adolpho Lutz

Forest Malaria *

By Adolpho Lutz

I have received from doctors Knab and Dyar answer to my statements concerning the transmission of malaria by wood mosquitoes, in which they not only refuse to be convinced but repeat their accusations of overlooking and misunderstanding elementary facts. I give up convincing them. If facts are stubborn things, hobbies may prove more stubborn yet and if those gentlemen like to ride theirs I cant help it. I only want to make plain why I have protested and leave it to members to decide if their way of arguing ought to be approved.

In order to suit their pet theory Galli-Valerio must have mistaken another anophelid for Myzomyia lutzi, though this is an extremely characteristic species which can be distinguished from all others by a glance at the scutum. Lutz and Chagas must have overlooked the presence of other anophelids at the places of their observations, though Messrs. Knab and Dyar can see them from Washington. Now, Lutz and Chagas might be expected to know anophelids, as they worked with them for years and together indicated most of the Brazilian species. Both made formal declarations and I have a written statement from Dr. Chagas to the point that he looked carefully for other anophelids while he treated the epidemic on the spot. At that time he did not know me nor my paper and made his observation quite independently. Those facts are considered of no account, because Dr. Knab found in Central America other anophelids, in localities which he takes to be similar. He even mentions Anopheles eiseni, a species which has never been found in the states of Rio and São Paulo, where the observations were made. I am also accused of overlooking that men are men, and it is stated that the men must have got away at night and infected themselves elsewhere. I have already declared that they lived many miles away in the woods and there was no other way to travel than on foot. Even if they had escaped control, the nights would not have been long enough to let them reach a place where they might have found what is suggested, nor would that help in any way, as there was and is no malaria in those places. Arguing like that you might also say that the Italian sailors who got yellow fever on board of a man-of-war anchored in Rio harbor, far away from the land, were attacked because they swam on shore at night time, following a classical example.

Messrs. Dyar and Knab think that mosquitoes, which have never been in contact with men before, cannot transmit disease. In order to test their thesis, you must put men in absolutely uninhabited places. This is, generally speaking, rather difficult, but it so happens that in Brazil roads and railways have been made in such conditions and nearly always there have been epidemics of malaria. I know also of epidemics of Leishmania sores, with good reasons attributed to the transmission by Phlebotomus, observed in absolutely deserted zones. I have also seen a small yellow fever epidemics amongst people living in a place where only wood mosquitoes could be expected. All this shows that the theoretical considerations have not been respected by the facts and all that is wanted is that the transmitter, whatever may be its past, belong to a category in which the parasite can thrive; then it must have repeated access to human beings, some of them being infected and some not immune. As the process of development takes time, its life must not be too short. For that reason repeated oviposition is a favorable condition.

The transmission of malaria by bromeliabreeders is not without practical interest. That is why I object to have my observations dismissed with the observation: It is probable that the doctor was mistaken which seems to imply that it is a habit of mine to make mistakes in scientifical observations. As I am in less a hurry to communicate my observations than a good many people nowadays, I don't think that my share of mistakes is an unusually large one. Thus the discussion from my side is closed but I fully maintain the correctness of my observations.

* Adolpho Lutz's communication published in Proceedings of the Entomological Society of Washington, v.15, n.4, p.169-70. Reply to Frederick Knab's “Dr. Lutz's contentions regarding ‘Forest Malaria’,” published also in Proceedings of the Entomological Society of Washington (v.XV, Part 2, p.110-8, 1913). The copy printed by the North American periodical omitted some parts of Lutz's original communication, which we have included in the present edition in italics. Typewritten copies of the original, dated 7.9.1913, can be found in BR. MN. Fundo Adolpho Lutz, caixa 23, pasta 85, maço 3. [E.N.]