Do early-season hurricanes result in greater transmission of mosquito-borne infectious diseases??
The timing of a hurricane is one of the common primary factors
influencing its impact on the spread of mosquito-borne infectious diseases such
as West Nile Virus, dengue, chikungunya and Zika etc.
Researchers from Georgia State and Arizona State University
developed a mathematical model to study the impact of heavy rainfall events
(HREs) such as hurricanes on the transmission of vector-borne infectious
diseases in temperate areas of the world, including the southern coastal U.S. In
the impact of this type of extreme weather event, the mosquito population often
booms in the presence of stagnant water. At the same time, the breakdown of
public and private health infrastructure can set people at increased risk of
infection. The study, which was published in Philosophical Transactions of the
Royal Society B, found that the risk of a disease outbreak is highest if the
HRE occurs early in the transmission season, or the period of time when
mosquitoes are able to pass on the virus to humans.
According
to the study, an HRE that occurs on July 1 results in 70% fewer disease cases
compared to an HRE that occurs on June 1.
Mosquitos
are very sensitive to temperature not only in terms of their ability to survive
and reproduce, but also in their ability to infect individuals. The warmer it
is, the faster an infected mosquito will be able to transmit the virus.
Considering that mosquitos have an average lifespan of less than two weeks that
temperature difference can have a dramatic effect on disease outbreaks.
Population displacement can also affect
the spread of vector-borne disease in a few ways, the researchers found. When
people opt to leave the area, it reduces the number of local infections, while
potentially increasing the number of infections elsewhere. However, those
individuals who are not displaced during an HRE may be at higher risk because
standard measures to combat mosquito breeding are neglected when fewer people
remain in the area. And as people move into a disaster area to offer emergency
relief or when they return after the event the number of local infections
rises.
Since mosquito-borne diseases tend to be
spread by the movement of people rather than the movement of mosquitoes,
disaster-induced movements of people can shift where and when outbreaks occur…..
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