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SUMMER 2012
Once a person is infected, the parasite travels through the
blood to the liver, where it goes through an incubation period
that lasts from one week to several months. After that, the
parasites enter red blood cells, where they replicate to the
point of rupturing the red blood cells. This rupturing causes
flu-like symptoms and may cause darkening of the urine.
Resistance to commonly used medicines is a growing
worldwide problem. The WHO Department of
Communicable Disease Surveillance and Response defines
drug resistance as “the ability of a parasite strain to survive
and/or multiply despite the administration and absorption
of a drug given in doses equal to or higher than those
usually recommended but within tolerance of the subject.”
This generally applies to the persistence of parasites after
treatment. There are individual parasites that are resistant to
particular medicines.
The risk of contracting malaria differs by location. For
most people traveling to regions where the disease is present,
prevention is much easier, safer and less expensive than the cure.
Dengue Fever
Dengue fever is also a mosquito-borne disease. Transmitted
by several species from the genus Aedes, the incidence and
geographic spread of this viral infection is increasing. The
mosquito species that spread dengue include Aedes aegypti
and Aedes albopictus. Unique features of these mosquitoes
are that they live and breed in proximity to human dwellings
and are low-level flyers. According to the WHO, dengue is
the most prevalent, worldwide, mosquito-borne viral disease,
with more than 50 million infections estimated each year.
The initial infection may go unnoticed, or it may appear as
flu-like symptoms. Individuals who experience no symptoms
or mild, unremarkable symptoms may become carriers
who enable international spread. Clinical manifestations of
the disease typically occur within four to six days of being
bitten. Symptoms include a sudden onset of chills, fever,
severe headaches and intense muscle and joint aches, often
referred to as “breakbone fever.” Other symptoms may
include abdominal pain, vomiting and, in children, a cough.
Each year mosquitoes transmit disease to hundreds of millions of people, and between 1 million and 3 million people die
from mosquito-borne diseases including malaria, dengue fever, yellow fever, west Nile virus and others.
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