Sentence:  Besides this, yellow fever and scarlatina are two of the gravest maladies on the catalogues of the nosologists, and produce, everywhere, a serious mortality when they prevail.  But nobody dies of dengue or <WSD>breakbone</WSD>; no, not one in one thousand, taken promiscuously, and under all circumstances of discomfort or mal-treatment.  As to its relations with malaria and malarious diseases, it suffices to remark that it is not produced, nor has I been known to spread, in the worst malarious localities. 
Meaning of the word marked with <WSD> tags:  dengue fever