Even virus outbreaks have many many conditions, you cannot
possibly say there are no conditions!!
The right conditions for outbreaks are perhaps bad hygiene, right
weather conditions, non-immunity, etc etc... and of course karma
does play a factor. There are countless causes and conditions that
results in a virus outbreak, you cannot ever say that it happens by
chance!
Everything is cause and conditions, there is nothing by chance at
all! Only those who doesn't understand cause and conditions would
say that things happen by chance.
http://www.geocities.com/Athens/Academy/9280/kamma1.htm
The laws of nature, although uniformly based on the principle of
causal dependence, can nevertheless be sorted into different modes
of relationship. The Buddhist commentaries describe five categories
of natural law, or niyama. They are:
1. Utuniyama: the natural law pertaining to physical objects and
changes in the natural environment, such as the weather; the way
flowers bloom in the day and fold up at night; the way soil, water
and nutrients help a tree to grow; and the way things disintegrate
and decompose. This perspective emphasizes the changes brought
about by heat or temperature.
2. Bijaniyama: the natural law pertaining to heredity, which is
best described in the adage, "as the seed, so the fruit."
3. Cittaniyama: the natural law pertaining to the workings of the
mind, the process of cognition of sense objects and the mental
reactions to them.
4. Kammaniyama: the natural law pertaining to human behavior, the
process of the generation of action and its results. In essence,
this is summarized in the words, "good deeds bring good results,
bad deeds bring bad results."
5. Dhammaniyama: the natural law governing the relationship and
interdependence of all things: the way all things arise, exist and
then cease. All conditions are subject to change, are in a state of
affliction and are not self: this is the Norm.
The first four niyama are contained within, or based on, the fifth
one, Dhammaniyama, the Law of Dhamma, or the Law of Nature. It may
be questioned why Dhammaniyama, being as it were the totality, is
also included within the subdivisions. This is because this
fourfold categorization does not cover the entire extent of
Dhammaniyama.