Chagas parasite found in insects in Arizona

[alert]

This is a bit puzzling, but likely a bad sign.

http://www.promedmail.org/pls/otn/f?p=2400:1001:1899367737916692::NO::F2400_P1001_BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1060,81343

Trypanosoma cruzi INFECTED TRIATOMIDEOS HIGH RATE - USA (ARIZONA)
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A ProMED-mail
<http://www.promedmail.org>
ProMED-mail is a program
International Society for Infectious Diseases
<http://www.isid.org>

Date: February 11, 2010
Source: Univision
<http://www.univision.com/contentroot/wirefeeds/usa/8141504.shtml>
[Edited by J. Torres]

Over 40% of the triatomines collected by researchers in
Tucson _Trypanosoma carry the cruzi_. Although the numbers
insects that carry the parasite that causes Chagas disease
is much higher in the southern Arizona city to what was supposed
there has been no human infection associated with
exposure to them in the state.

It is likely that insects here do not act the same way as those of
South of the continent, or that the disease is caused by a different strain,
Reisenman said Carolina, a biologist at the University of Arizona. Is
coauthor of the study to be published in the March issue of
Emerging Infectious Diseases, a publication of the Center for
Control and Prevention.

Reinsenman team recruited local residents to collect
insects, and researchers from the Center collaborated with the analysis,
said the biologist.

Of the 164 bugs submitted to investigators, DNA testing
indicated that over 40% were carriers of the causative agent of
Chagas disease. The only previous investigation in early
the 60s, revealed that 4% of the insects in the Tucson area
carrying the infection.

The results indicate that the risk of infection in southern Arizona
could be greater than what was expected, the researchers concluded.
The study does not measure the risk of infection in other parts of southern
United States, where insects are known carriers of
parasite.

Chagas disease is endemic in poor areas in Latin America,
where there are 8 to 11 million infected, according to the Center. In the
recent years have reached U.S. immigrants infected with
_T. cruzi_ and in 2009, the Center estimated that at least 300,000
immigrants were carriers of the disease.


Reported by: Jaime R. Torres <torresjaime@cantv.net>

[Comment:

Importantly, while the socio-economic or
Epidemiological City Ttucson not seem to favor the
establishment of intra-household cycles of vector-borne
of the disease as it occurs in different regions
Latin America, the conditions for the occurrence of outbreaks
Oral transmission of infection by contamination of cold drinks
or F oods are present, as observed in populations
of some non-endemic areas of South America during the last
decades. Moderator Jaime R. Torres]

[alert]

Re: Chagas parasite found in insects in Arizona

http://www.promedmail.org/pls/otn/f?p=2400:1001:182645190805241::NO::F2400_P1001_BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,81384

Archive Number 20100215.0533
Published Date 15-FEB-2010
Subject PRO/AH/EDR> Trypanosomiasis, triatomine vector - USA: (AZ)


TRYPANOSOMIASIS, TRIATOMINE VECTOR - USA: (ARIZONA)
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ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>

Date: 10 Feb 2010
Source: AZ Central [edited]
<http://www.azcentral.com/news/articles/2010/02/10/20100210kissing-bug-disease-arizona.html>


A new study shows that more than 40 percent of "kissing bugs"
collected by researchers in Tucson carry a parasite that can cause a
disease that kills tens of thousands of people a year in Central and
South America.

But while the number of bugs hosting the single-cell parasite that
causes Chagas disease is much higher in the southern Arizona city than
earlier thought, no human infections have been traced to bites that
occurred in the state.

That may mean doctors are not looking for a disease that is rare in
the U.S. But it is more likely that the triatomine insects don't act
the same way as their cousins to the south, or that the disease is a
different strain, said Carolina Reisenman, a University of Arizona
research biologist. She co-authored the study, which is to be
published in the March 2010 edition of the Centers for Disease Control
and Prevention journal Emerging Infectious Diseases.

"People have been bitten here for a long time, for decades, so my
suspicion is we should see cases already if the transmission is
efficient," Reisenman said. More research will be needed before an
explanation is found.

Reisenman's team enlisted local residents to collect the bugs in and
around their homes, and CDC researchers collaborated in the analysis,
Reisenman said.

Of the 164 insects turned over to researchers, DNA tests showed more
than 40 percent carried Chagas disease. The only previous research, in
the early 1960s, showed 4 percent of the kissing bugs around Tucson
carried the disease.

The results indicate that the risk of infection in southern Arizona
may be higher than previously thought, the researchers concluded. The
study doesn't measure infection risks in other parts of the southern
U.S., where the bugs are known to live and also carry the parasite.

Chagas disease is endemic in poor areas in Latin American countries,
where an estimated 8 million to 11 million people are infected,
according to the CDC. In recent years, immigrants infected with Chagas
have come to the U.S., and in 2009, the CDC estimated at least 300 000
migrants carried the disease.

It also is known to be carried by kissing bugs in the southern U.S.,
although the disease is rare here, with only 7 cases of locally
acquired infection identified.

Estimates on the number of worldwide deaths from Chagas per year range
from 15 000 to 50 000. But the numbers are declining because of
prevention and treatment efforts, said CDC researcher Ellen Dotson.

Kissing bugs transmit the disease as they drink blood from humans,
typically at night, and spread the parasite through feces. After a
brief period of relatively minor symptoms, including a sore at the
bite and a fever, the disease usually goes dormant. It re-emerges
years or decades later, with severe heart or gastrointestinal problems
in about 20 percent to 40 percent of patients. There are treatments
for acute infections, but once the disease causes major organ damage,
it cannot be reversed.

The disease is also transmitted by blood transfusions, organ
transplants and in childbirth.

Screening of the blood supply began in most areas of the nation in
early 2007, and the CDC says 1000 infected donors have been
identified. Nearly all donors acquired it in their home country, but a
handful had never been in south or central America, and officials are
investigating where they contracted the parasite.

The risk of infection is much greater for domestic animals like dogs,
which are more often exposed to kissing bugs while outdoors, said
Susan Montgomery, a CDC veterinary medical officer.

Reisenman said knowing that Tucson area residents have a higher chance
of exposure than previously thought will raise awareness of its
potential in the health community.

"It's nothing to raise an alert, but as with a lot of these diseases,
it's important to be ahead of the problem," she said.

[Byline: Bob Christie]

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

[The newspaper story cites a paper which will appear in the March 2010
issue of the journal Emerging Infectious Diseases, published by the
CDC. Triatomine bugs are common in the southern states of the United
States.

The presence of _Trypanosoma cruzi_ in triatomines in the US has been
reported before. In a study published in 2009 (Klotz et al. Feeding
behavior of triatomines from the southwestern United States: an update
on potential risk for transmission of Chagas disease. Acta Trop.
2009;111:114-8), 21 percent of _T. protracta_ were positive for _T_.
cruzi by PCR.

There are several possible explanations for not finding human cases in
the same area. Firstly, triatomines usually live in cracks and
crevices in mud walls, and this habitat may be rare in Arizona.
Secondly, regarding feeding habits in the area, specific species of
triatomine bugs may prefer hosts other than humans, and there is a
huge genetic variation in the triatomine bug population in northern
Mexico and Arizona (See:
<http://www.ncbi.nlm.nih.gov/pubmed?term=%22Pfeiler%20E%22%5BAuthor%5D&itool=En trezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pub med_RVAbstract>. Pfeiler E et al. Genetic variation, population structure, and phylogenetic relationships of Triatoma rubida and T. recurva (Hemiptera: Reduviidae: Triatominae) from the Sonoran Desert, insect vectors of the Chagas' disease parasite Trypanosoma cruzi. Mol Phylogenet Evol. 2006;41:209-21). Finally, caution must be observed when translating a positive PCR result in live, infectious trypanosomes. -
Mod.EP]

{Triatomine "kissing bug" (_Triatoma infestans_)
<http://www.scielo.br/img/revistas/ne/v32n1/15563f2.jpg>
Trypanosomes (_T. cruzi_) in blood slide
<http://www.astmh.org/source/ZaimanSlides/index.cfm?photo=BEA37DB1-E0C7-F0E4-A4AA3E8CDA5414E0>
- Mod.JW]