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Published Date: 2010-11-15 21:00:09
Subject: PRO/EDR> Dengue/DHF update 2010 (57)
Archive Number: 20101115.4149

DENGUE/DHF UPDATE 2010 (57)
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International Society for Infectious Diseases
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In this update:

The Americas
[1] USA (Florida)
[2] Cayman Islands (control)
[3] Brazil (national)
[4] Cases in various countries: Viet Nam, Indonesia (Bali), India
(Uttar Pradesh), Pakistan (Sindh), Reunion, Brazil (Ceara)

******
[1] USA (Florida)
Date: Fri 12 Nov 2010
Source: Sun Sentinel.com [edited]
<http://www.sun-sentinel.com/health/fl-miami-dengue-fever-20101111,0,6881301.story>

The 1st locally acquired case of dengue fever in Miami-Dade County in
more than 50 years was confirmed Thursday [11 Nov 2010] by health
officials. They warned people countywide to take precautions against
the human-loving mosquitoes that carry it. "This is a big deal," said
Lillian Rivera, administrator of the Miami-Dade Health Department. "We
have not had a locally acquired case of dengue fever since the 1950s,"
said Dr. Fermin Leguen, the department's chief epidemiologist.

The victim, identified only as a man who had not traveled outside
Miami-Dade County for more than 2 weeks, was briefly hospitalized but
has fully recovered, Rivera said. His case was confirmed by laboratory
tests. Health officials said they don't know where the man acquired
the painful but seldom fatal disease. Dengue fever has been on the
rise in Florida for 2 years. Key West has reported 57 locally acquired
cases in 2009 and 2010. One locally acquired case was reported in
Broward in August [2010].

The new Miami-Dade case was a different strain from those in Key West
and Broward, so was not acquired there, Leguen said. The fact that the
new case was contracted locally means it apparently was the result of
a bite of a mosquito that had bitten another Dade resident who was
infected, health officials said. The disease does not pass from
mosquito to mosquito.

It raises questions about whether the disease might become endemic,
occurring widely in a local area and feeding upon itself.

The new dengue fever case occurred in a densely populated area of 77
properties somewhere in Miami-Dade County, said county Mosquito
Control Director Sandra Fisher.

County crews have gone house to house with hand held sprayers and have
emptied bird baths, rain-filled tires, stagnant pools and even bottle
caps filled with water, she said. Removing stagnant water is more
effective than spraying from trucks, she said, because the _Aedes
aegypti_ mosquito that carries the dengue virus from one human to
others seeks close contact with humans. She urged residents to remove
stagnant water sources in their own yards. "This mosquito lives and
breathes around people," she said. "It actually flies into houses
looking for a blood meal so it can lay eggs. So checking yards is our
1st line of prevention. This is everywhere in Dade County. Everyone
should consider themselves at risk no matter where they live."

--
Communicated by:
HealthMap Alerts via ProMED-mail
<promed@promedmail.org>

[It would be of interest to know which dengue virus serotype was
involved in this case. Dengue viruses 1 and 3 have been involved in
previous cases this year [2010] in Florida.

A HealthMap/ProMED-mail interactive map showing Florida in the
southeast USA can be accessed at <http://healthmap.org/r/07GD>. Dade
county in South Florida can be located on the map at
<http://www.digital-topo-maps.com/county-map/florida.shtml>. - Mod.TY]

******
[2] Cayman Islands (control)
Date: Thu 11 Nov 2010
Source: Miami Herald [edited]
<http://www.miamiherald.com/2010/11/11/1920669/mutant-mosquitoes-fight-dengue.html?story_link=email_msg#ixzz1514K0FR0>

Scientists have released genetically modified mosquitoes in an
experiment to fight dengue fever in the Cayman Islands, British
experts said Thursday [11 Nov 2010]. It is the 1st time genetically
altered mosquitoes have been set loose in the wild, after years of
laboratory experiments and hypothetical calculations. But while
scientists believe the trial could lead to a breakthrough in stopping
the disease, critics argue the mutant mosquitoes might wreak havoc on
the environment.

"This test in the Cayman Islands could be a big step forward," said
Andrew Read, a professor of biology and entomology at Pennsylvania
State University, who was not involved in the project. "Anything that
could selectively remove insects transmitting really nasty diseases
would be very helpful," he said. Unlike malaria, which is also spread
by mosquitoes, dengue outbreaks are unpredictable, and bed nets are of
limited use because dengue-spreading mosquitoes also bite during the
day. [Napping children and ill individuals are likely to take to their
beds, so the limited effectiveness would be restricted to those
instances. - Mod.TY]

Researchers at Oxitec Limited, an Oxford-based company, created
sterile male mosquitoes by manipulating the insects' DNA. Scientists
in the Cayman Islands released 3 million mutant male mosquitoes to
mate with wild female mosquitoes of the same species. That meant they
wouldn't be able to produce any offspring, which would lower the
population. Only female mosquitoes bite humans and spread diseases.

From May-October [2010], scientists released batches of genetically
mutated male mosquitoes in cages 3 times a week in a 40-acre
(16-hectare) area. By August 2010, mosquito numbers in that region
dropped by 80 percent compared with a neighboring area where no
sterile male mosquitoes were released. Luke Alphey, Oxitec's chief
scientific officer, said with such a small area, it would have been
very difficult to detect a drop in dengue cases. But their modeling
estimates suggested an 80 percent reduction in mosquitoes should
result in fewer dengue [virus] infections.

For years, scientists have been working to create mutant mosquitoes to
fight diseases like malaria and dengue, which they say could stop
outbreaks before they start. But others suspect it could be an
environmental nightmare. "If we remove an insect like the mosquito
from the ecosystem, we don't know what the impact will be," said Pete
Riley, campaign director of GM Freeze, a British non-profit group that
opposes genetic modification. He said mosquito larvae might be food
for other species, which could starve if the larvae disappear. Or
taking out adult mosquito predators might open up a slot for other
insect species to slide in, potentially introducing new diseases.
Humans have a patchy track record of interfering with natural
ecosystems, Riley said. In the past, such interventions have led to
the overpopulation of species including rabbits and deer. "Nature
often does just fine controlling its problems until we come along and
blunder into it."

Oxitec's Alphey said their genetically modified mosquitoes can't
permanently change the ecosystem because they only last for a
generation. But to stamp out dengue in endemic areas like Asia and
South America, billions of the special-order mosquitoes would likely
be needed to stifle their wild counterparts.

Yeya Toure, who leads the World Health Organization's team on
Innovative Vector Control Interventions, called the Cayman Islands
trial promising and said it's worth continuing the genetic
modification experiments.

He said genetically altered mosquitoes aren't meant to replace
existing tools like insecticides, but to compensate for their
limitations, like when mosquitoes develop resistance. Read said
creating mutated mosquitoes might actually be the least invasive way
to control dengue. By keeping a lid on the mosquito population via
genetic modification, Read said entire ecosystems would be spared the
toxic effects of indiscriminately spraying pesticides. He said the
bigger problem would be selling the idea of genetically altered
mosquitoes to the public. In the Cayman Islands, officials said they
worked closely with the local community and encountered surprisingly
little resistance. "We still have people who don't believe in
vaccines," Read said. "How are we going to convince them it's OK to
let scientists release genetically altered mosquitoes into the wild?"

[Byline: Maria Cheng]

--
Communicated by:
ProMED-mail <promed@promedmail.org>

[_Aedes aegypti_ themselves are an invasive species in the Americas
and, except for wild populations in Africa, are dependent on human
activities to provide breeding sites and maintain populations large
enough to transmit dengue and yellow fever viruses. As noted above,
reduction of _Ae. aegypti_ populations through the release of
genetically altered individuals appears to be far less disruptive to
local ecosystems than massive insecticide spraying. It will be
interesting to see what the outcome of the Cayman Island field trial
is. It would be of interest to know the cost and logistical
feasibility of maintaining _Ae. aegypti_ population reduction
continuously in the areas in the Americas and Southeast Asia where
dengue is a serious, ongoing public health problem.

A HealthMap/ProMED-mail interactive map showing the location of the
Cayman Islands in the Caribbean can be accessed at
<http://healthmap.org/promed/index.php?v=19.3,-81.2,6>. - Mod.TY]

******
[3] Brazil (national)
Date: Fri 12 Nov 2010
Source: China economic net [edited]
<http://en.ce.cn/World/Americas/201011/12/t20101112_21964788.shtml>

The number of deaths from dengue fever in Brazil increased 89.7
percent from January to mid-October year on year, the country's Health
Ministry announced on Thursday [11 Nov 2010]. According to the
ministry, 592 people died from dengue fever in Brazil this year
[2010], up from 312 in the same period in 2009. The number of dengue
fever cases in the period surpassed 936 000 from January to October
2010, a jump from the 489 819 cases a year earlier.

Health Minister Jose Gomes Temporao said that 70 percent of the dengue
fever cases occurred in 6 states: Sao Paulo and Minas Gerais in the
southeastern region, Mato Grosso do Sul and Goias in the mid-western
region, Acre and Rondonia in the northern region. Most of the deaths
were caused by type 1 dengue fever, which was common in Brazil in the
1990s and now has returned with full force.

According to Giovanini Coelho, coordinator of the ministry's
anti-dengue program, a high incidence of rain, hot weather and poor
sanitation in the country also contributed to the rise in the dengue
fever cases.

Temporao said Brazilian scientists are still working on a vaccine
against the dengue fever, and a prototype of the vaccine is being
tested in Santa Catarina state, southern Brazil.

--
Communicated by:
HealthMap Alerts via ProMED-mail
<promed@promedmail.org>

[A map of Brazil showing the states mentioned above can be accessed at
<http://www.lib.utexas.edu/maps/americas/brazil.jpg>. A
HealthMap/ProMED-mail interactive map of Brazil can be accessed at
<http://healthmap.org/promed/index.php?v=-10.8,-53.1,4>. - Mod.TY]

******
[4] Cases in various countries: Viet Nam, Indonesia (Bali), India
(Uttar Pradesh), Pakistan (Sindh), Reunion, Brazil (Ceara)

- Viet Nam: Ho Chi Minh City recorded 2054 dengue fever cases last
month [October 2010], an increase of 23 percent over September [2010].
HCM City is the city with the highest number of dengue fever patients
in the southern region, with 450 patients per week, reported on 5 Nov
2010
<http://vietnamnews.vnanet.vn//Social-Isssues/205449/Dengue-fever-cases-rising-in-HCM-City.html>.

- Indonesia (Bali): 10 Nov 2010; Dengue fever has killed 29 residents
of the Indonesian resort island of Bali over the past 10 months of
2010, the province's health authority said. They were among 10 230
residents who suffered from the dengue fever virus between
January-October 2010. Bali's population is 3.9 million
<http://www.antaranews.com/en/news/1289408104/dengue-fever-kills-29-bali-residents>.

- India (Uttar Pradesh): 10 Nov 2010; 5 more fatalities, suspected
dengue deaths, were reported from Khadra locality of the city, taking
the toll to 25, health department sources reported
<http://www.mynews.in/News/dengue_claims_five_more_lives_in_uttar_pradesh__N108179.html>.

- Pakistan (Sindh): 9 Nov 2010; 285 dengue fever patients are
currently admitted at different hospitals in Karachi besides 68 in the
interior parts of the province. Total cases of dengue reported during
past few months are 4303, including 270 from interior parts. In the
province, 19 dengue fever deaths were registered during past more than
a month, 15 from Karachi only.
<http://www.pakobserver.net/detailnews.asp?id=61208>.

- Reunion: 9 Nov 2010; To date for the year 2010, 53 cases of dengue
were reported, 2 confirmed and 27 probable which were indigenous; 15
probable and 9 confirmed cases, which were imported
<http://www.zinfos974.com/Retour-des-moustiques-Une-epidemie-de-dengue-plus-a-craindre-que-de-chik_a22890.html?com> in
French.

- Brazil (Ceara): 13 Nov 2010; In Ceara to date, 10 826 dengue cases
were confirmed with 16 deaths, 11 from dengue with complications and 5
from DHF <http://diariodonordeste.globo.com/materia.asp?codigo=884400>
in Portuguese.

See Also