April, '12] KNAB: DISEASE TRANSMISSION 199 



and they speak of "domestic" and "wild" species.^ However the 

 significance of the phenomenon seems to have escaped them, as it 

 has subsequent investigators. There is no doubt in the writer's 

 mind that a critical review of the data will show that the Anopheles ■ 

 responsible for the transmission of malaria in India will be found among 

 the "domestic" species, as the term is apphed by the above mentioned 

 authors. 



There is a paper by Dr. Adolph Lutz of Brazil, on forest mosquitoes 

 and forest malaria, which apparently contradicts the ideas just ex- 

 pressed with reference to Anopheles and malaria.^ The probabilities 

 are, however, that Doctor Lutz has misinterpreted the facts. His 

 observations were made in the state of Sao Paulo, during the construc- 

 tion of a railroad from the coast to the capital. The first part of the 

 route was through the moist and heavily forested slope from the 

 table-land to the coast, and while at work here a large part of the 

 construction gang were afflicted with malaria. Lutz searched for 

 the transmitting Anopheles but could find no breeding-places upon 

 the steep slopes. Finally he determined that only one species of 

 Anopheles (cruzi) was present in the region, and that this bred abun- 

 dantly in the water held by epiphytic bromeliads. To this species 

 he attributed the outbreak of malaria. Most probably this Anopheles 

 had nothing to do with the outbreak of malaria among the laborers. 

 It is a well-known fact that in the tropics most persons, although 

 apparently in good health, have latent malaria. When such an indi- 

 vidual comes under some physical strain, such as overexertion, expo- 

 sure, or some form of overindulgence, the disease manifests itself. It 

 seems highly probable that this is the explanation of the outbreak 

 observed by Doctor Lutz. The men already harbored latent malaria 

 when they came into the region and the exertion and exposure incident 

 to the work caused the eruption of the disease. 



It must be noted in passing that the character of the disease itself, 

 the duration of the parasites in the human blood, has an important 

 bearing on the insect relation. Thus, in the case of yellow fever and 

 dengue, where the parasites are present in the blood only during a 

 very brief period, the association of the two hosts must be a very 

 intimate one. In the case of malaria, where the parasites are present 

 in the blood for a long time, the relation of the transmitting mosquito 

 may easily be a less intimate one. But even here it must be remem- 

 bered that the gametes, the sexual elements which are destined to 



3. James, vS. P., and Listen, W. Glen. A Monograph of the .\nopheles Mog'^uitoes 

 of India. Calcutta, 1904 (first edit.). 



< Lutz, Adolph, Waldmosquitos und Waldmalaria. Centralbl. f. Bakteriol., 

 Parasitenk., u. Infektionskr., Abt. 1, Bd. 33, p. 282- 292, 1903. 



