Search in checkbox field with pagination
The value is stored as a serialized array in your database,  you would need to filter for the string "["healthcare","food-fitness"]"

Since your query parameter is an array you just need to prepend an and parameter to it so it looks like 

articles_categories(['and',  '*healthcare*', '*food-fitness*'])


If you have only one parameter and want an exact match you need to search for the exact string

craft.entries.articles_categories('["healthcare"]')