The Collaborative International Dictionary
Ochlesis
Ochlesis \Och*le"sis\, n. [NL., fr. Gr. ? disturbance, fr.
'o`chlos crowd, mob.] (Med.)
A general morbid condition induced by the crowding together
of many persons, esp. sick persons, under one roof.
--G.
Gregory.
Wiktionary
ochlesis
n. (context medicine English) crowd-poisoning; a disease occasioned or aggravated by overcrowding, especially due to lack of ventilation.