Some coronavirus causes diarrhoea - and SARS was spread by super carriers with diarrhoea which caused faecal "plumes"
in apartment toilets and spread through other apartments by the wind
.
It is possible that COVID-19 also causes diarrhoea and may then spread via the same method.
The current new cases on cruise ships occurring under quarantine were likely contracted before quarantine was imposed.
China sealed the Hubei provincial borders IIRC on January 23. However millions would have got out before the quarantine was imposed. Add 14 days and its Feb 6.
Within that quarantined area and in other areas in China, movements are limited - factories not opening, streets are relatively empty, people taking escalated hygiene measures. And If sick either go to hospital, or self isolate.
Feb 6 add in another week, and if the chinese quarantine measures are effective we should see a taper off of new cases assuming all cases are reported quickly and not picked up in retrospect. This is separate to the speculation that not all cases are reported within China. Though I suspect that it is not possible with a stretched health system, it is impossible to surveil everyone (50-60 million) with daily temperature readings as is occuring on Christmas Island
It is not clear from all the data when new cases are reported when those people first experienced symptoms.