Phlebotomus and Residual DDT in Greece and Italy

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Summary and Conclusions

  1. 1.An evaluation in terms of Phlebotomus control has been made of the extensive DDT-malaria campaign which has been in progress in Greece since 1946. Observations were made in Attica and Crete throughout the sandfly season of 1948.
  2. 2.In unsprayed places the sandfly population was normal in abundance and distribution of species when compared with the reports of previous investigators. Nearly 3000 sandflies were caught and identified.
  3. 3.Sprayed buildings were uniformly negative for Phlebotomus of any species. Night observations out-of-doors showed sandflies to be at a very low level within sprayed areas. The testimony of the people was solidly to the effect that sandflies had been annoyingly abundant but ceased to bother them indoors after the first treatment, and that there has been little or no annoyance outdoors at night.
  4. 4.The reduced sandfly abundance in the cities of Athens and Canea, Crete, which have not been sprayed in toto, may be due in part to the peripheral effect of the many treated buildings scattered through the urban areas, and in part to the use of household sprays—factors which have not been measured.
  5. 5.A modification of the oiled paper trap is described.
  6. 6.The present status of leishmaniasis in Canea is compared with that of previous years.
  1. a.A very marked decline of kala azar had occurred prior to the use of DDT, and was associated with the destruction of infected dogs and the general reduction of the dog population. With the return of dogs to normal, it is difficult to assess the effect of the present low sandfly level because of lack of information about factors such as other reservoirs and normal kala azar cycles.
  2. b.A sharp drop in oriental sore with the development of relatively few cases in the last two years, coincided with the introduction of DDT in 1946.
  3. c.Definite conclusions on leishmaniasis control must await long-term observations in endemic foci.
  4. 7.A recently initiated project for the control of oriental sore in the Abruzzi, Italy, was visited. Observations on the dominant sandfly and supposed vector, P. perfiliewi, were made in treated and untreated areas. There was witnessed the actual destruction of great numbers of sandflies on encountering residual DDT, resulting apparently in the progressive reduction of the local sandfly population.
  5. 8.In Sardinia, where every man-made structure has been treated with DDT, houses were negative eight or nine months later, and sandfly incidence was at an extremely low level.
  6. 9.On the basis of the present and previously published work, the following general conclusions seem warranted:
  1. a.Treatment of interiors with residual DDT gives immediate and virtually complete protection from sandflies indoors.
  2. b.House spraying alone, in compact communities, with an annual, preferably pre-season, treatment, eventually reduces the Phlebotomus population within the sprayed areas to near the vanishing point.

Author Notes

Gorgas Memorial Laboratory, Panama, R. de P.