The World Health Organisation's office in Fiji says the majority of deaths suspected to have resulted from flooding in the Western division, are likely to be from leptospirosis.
A medical officer with the WHOs Suva office, Dr Jacob Kool, says leptospirosis is usually the first disease that arises after flooding because of the way it spreads.
The Ministry of Health has confirmed several cases of the disease along with dengue, and typhoid, and seven people are suspected to have died from communicable diseases during the post-flood period.
Dr Kool says leptospirosis starts off as a flu like illness but, left untreated, can be deadly.
"And it can get suddenly much worse and it's actually a very dangerous disease there could be a mortality rate of about up to 20 percent if they're not treated."
Dr Jacob Kool says if anyone who has been forced to walk bare foot through mud in flood affected areas, develops a fever, they should report to a doctor straight away.