Global travel and spread of certain species
Explanation:
Many pathogenic species of bacteria, virus, and
other microbes are more prevalent in
developing or tropical countries rather than in
developed countries.
When an individual's immune system is weak
they become more susceptible to get infected
and become carriers of that particular species.
The species grows, develops, and multiplies in
the host's body and when the traveler travels to
his/her home country or any other place he/she
can transmit the disease to others and again the
species grows in numbers. Higher the rate of
spread of infection higher is the increase in
species.
