919
during the first documented outbreak of human infections with h5n1 , which occurred in hong kong in 1997 , the 18 human cases coincided with an outbreak of highly pathogenic avian influenza , caused by a virtually identical virus , in poultry farms and live markets .
 cause effect: influenza, virus
Given a phrase that describes the relationship between two words, extract the words and the lexical relationship between them. The output format should be "relation1: word1, word2; relation2: word3, word4". 
Option: component whole, NA, instrument agency, member collection, cause effect, entity destination, content container, message topic, product producer, entity origin 
Text: {0} 
Answer:
 cause effect: influenza, virus