NO. I 



BLACK FLIES OF GUATEMALA DALMAT 



13 



sidered to be located between the two main zones, have workers in- 

 fected with Onchocerca volvulus, but no investigation has been made 

 to determine whether or not the disease is autocthonous to those areas. 

 The above data appear sufficient to warrant the union of the two 

 former zones into one larger zone. The population of this principal 



Map 4. 



zone has been conservatively estimated as 60,000 persons, of whom 

 30 percent are infected with onchocerciasis. 



In addition, there are two smaller disease zones (further study will 

 probably prove them to be really only one zone) in the western De- 

 partment of Huehuetenango (total of 85 square miles), near the 

 Mexican border. This endemic region, like the Mexican disease zone, 

 is situated in the eastern part of the "Valley of Chiapas," between two 

 branches of the Andean chain, rather than on the Pacific slope of the 

 more southern branch. There is also a suspected focus at La Carretera 

 near San Jose Acatempa, located between Cuilapa and Jutiapa in the 



