source (see page 97): http://www.dadosefatos.turismo.gov.br/export/sites/default/d...
Its like arguing that some subset of people drive drunk right now, therefore it would be a great idea if more people would drive drunk this summer.
Automobiles, while often convenient, are one of the leading causes of death, and we should try to organize public policy around reducing their use and the deaths they cause to the extent possible without overly compromising their convenience.
Reducing the number of automobiles would also have a big positive environmental impact, and reducing the number and widths of roads and parking lots would free up a lot of space which could be used for other purposes. Other forms of transportation also scale a lot better with population density, and denser cities use a lot less other infrastructure per capita.
Once self-driving cars become effective, I have high hopes that they will replace a large proportion of current human drivers, something else which should save many lives.
So doubling the number of people congregated in Rio won't just double the danger, but quadruple it. If car accidents obeyed a similar dynamic -- where they increase (much) more than proportionally to the number of vehicle-miles driven, we should be similarly more cautious about additional drivers.
Nigeria: 265
India: 4,522
Indonesia: 0
Its not like in US, the sewage infrastructure in India is very bad. There are open air sewage drains, mosquito infestation is every day life and in cities people live in very densely crowded homes. All of this contributes to a rapid spread in case of a outbreak.
In fact dengue outbreaks are common in India every summer, or a few months.
http://data.london.gov.uk/dataset/number-international-visit...