About $816 million is needed for rescue and relief in Pakistan, more than 2,000 people have died from floods and subsequent infections since mid-June.
The report said 2,049,532 houses were destroyed, and 1,120,261 livestock perished in different parts of Pakistan.
In severe cases, dengue can cause joint pain, nausea, vomiting, rashes, breathing problems, haemorrhaging and organ failure.
The Pakistani government had inaugurated an anti-dengue campaign, raising public awareness in response to the alarmingly high cases.
The UN launched a flash appeal of $160 million to help Pakistan tackle devastating floods that have killed more than 1,500 people.
428,098 children under five suffer from diarrhoea, while another 51,191 are being treated for dysentery in the worst-hit province of Sindh.
Iran was previously an observer member.
The D-8 countries are Bangladesh, Egypt, Indonesia, Iran, Malaysia, Nigeria, Pakistan and Turkey.
“Lower the temperature — now,” said Mr Guterres. “Don’t flood the world today; don’t drown it tomorrow.”
The total death toll in Pakistan from this season’s monsoon rains and floods since mid-June has risen to around 1,481, along with 12,748 injured.