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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 125 



usually incriminated as being the principal transmitters of the disease. 

 The ecological and meteorological conditions seemed identical for this 

 region and the adjoining onchocerciasis zones. To further justify join- 

 ing the two zones, a questionnaire was presented to those workers on 

 the finca and annexes who were found to have onchocerciasis, in an 



Map 3. 



attempt to determine in which regions they most probably contracted 

 the disease. More than half of the infected group were born in regions 

 considered to be outside the disease zones, and of this number several 

 were born on the finca El Zapote, never having left it ; of the other 

 40 percent questioned, one-third had been born in an onchocerciasis 

 zone but left it when still infants and had since that time resided on 

 the finca El Zapote. Nodules did not begin to appear on these indi- 

 viduals until they had reached maturity. The remaining persons had 

 actually lived in a known infected zone where they had contracted the 

 disease. Other fincas in the same region as Zapote, also formerly con- 



