Biology Reference
In-Depth Information
4.1 Introduction
Between November 2002 and March 2003, hundreds of people in Guangdong
Province of China were hospitalized with a mysterious respiratory illness.
On February 15, 2003, one of these individuals traveled to Hong Kong to visit
his family. Six days later, he checked into a hotel where he infected 12 other
people. Public health investigators later said these 12 individuals spread the
illness to many others in Hong Kong, Vietnam, Singapore, Ireland, Germany,
and Canada (CDC 2003; National Public Radio 2008). This pattern of infection
continued and, by October of that year, severe acute respiratory syndrome
(SARS) was reported in nearly 30 different countries, affecting more than
8000 individuals, and causing 774 deaths worldwide (Marley et al. 2004). Six
years later, in April 2009, the World Health Organization (WHO) announced
the emergence of a novel influenza A (H1N1) virus (also referred to as
swine
lu
), which had not previously circulated in humans. This new virus was first
reported in early April in Mexico and in the United States and quickly spread
via human-to-human contact (CDC 2009). By June 2009, nearly 30,000 con-
firmed cases had been reported in 74 countries, including 141 deaths (WHO
2009). The rapid global spread of the virus prompted WHO to raise the level
of influenza pandemic alert from Phase 5 to Phase 6 (the highest level on
WHO's six-point scale) on June 11, 2009, making this outbreak the first influ-
enza pandemic in more than 40 years (WHO 2009).
As these two examples illustrate, the growth of international travel and trade
has dramatically accelerated the spread of infectious diseases. As a result,
diseases such as SARS and swine flu are able to quickly spread across many
countries around the world. Beyond the understandable concerns regarding
public health, disease outbreaks can also lead to significant economic conse-
quences by affecting world trade and tourism. For example, in an effort to stop
the spread of the swine flu, several countries strongly discouraged or alto-
gether imposed bans on travel to Mexico, and some to the United States and
Canada as well. The economic impact of such restrictions can be considerable,
and particularly costly for countries already experiencing financial hardship.
In Mexico City alone, losses of approximately $88 million a day occurred due
to various restrictions on commerce and tourism (Gibbs 2009). Potential losses
in tourism revenues presented a challenge to the United States as well as the
nation continues to deal with the financial strains of a recession.
In light of these consequences, controlling a disease outbreak in its early
stages is absolutely essential to ensure both global public health as well as eco-
nomic stability. However, early and accurate detection of outbreaks is not easy,
as illustrated by the outbreak of cryptosporidosis in Milwaukee, Wisconsin,
in early 1993. This outbreak was caused by a breakdown of a water filtration
process at a water supplier. Approximately 403,000 individuals in the greater
Milwaukee area were infected. On April 7, laboratory tests confirmed that the
outbreak was caused by the parasite
Cryptosporidum
oocyst (Mac Kenzie et al.
