16989
The major protozoan infections of humans , namely malaria , Chagas disease , human African trypanosomiasis , and leishmaniasis , are primarily centered in the tropics , with a reach into some subtropical regions of the world .
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Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None