Archive Number 20050327.0884
Published Date 27-MAR-2005
Subject PRO> Trypanosomiasis, foodborne - South
America (03)
TRYPANOSOMIASIS, FOODBORNE - SOUTH AMERICA (03)
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A ProMED-mail post
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International Society for Infectious Diseases
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Date: Sun 27 Mar 2005
From: Luiz Jacintho da Silva
<luiz_jacintho(a)uol.com.br>
Source: Fiocruz.br [translated from Portuguese by
Mod.LJS, edited]
<http://www.fiocruz.br/ccs/novidades/dez04/chagas_fer.htm>
Study confirms a different form of Chagas?
disease transmission
-----------------------------------------------
When one hears of the transmission of the
protozoan _Trypanosoma cruzi_, the 1st thing that
comes to the mind is the Reduviid bug vector.
This insect, when biting an individual,
eliminates parasite-contaminated feces that, as
the individual scratches himself, penetrates
through abraded skin or mucosa [intact]. This is
the most common route, but the occurrence of
certain outbreaks has led scientists to consider
the possibility of oral transmission of _T.cruzi_.
A study by the Goncalo Muniz Research Center, a
FIOCRUZ unit in Bahia, presents evidence that
this protozoan can indeed be transmitted by the
ingestion of contaminated food [or beverages]. On
Sun 20 Mar 2005, an episode in Santa Catarina
confirmed the results of the research.
The deaths of 3 [now 5] persons, and the report
of another 15 cases of the disease in the state,
have led health authorities in the state to
prohibit the sale of sugarcane juice. The
infection seems to have been transmitted by this
beverage.
In 1968, a member of a farming community in
Teotonia (Rio Grande do Sul) fell ill with a
severe febrile illness. No one suspected Chagas
disease, as there were no Reduviid bug vectors in
the local dwellings. After much investigation,
food borne transmission through vegetables served
in the common dining-room was accepted as the
cause. Possibly, marsupials had contaminated the
vegetables by droppings from their anal glands,
usually rich in _T.cruzi_.
Years later [1986], another outbreak occurred,
this time in Catole do Rocha (Paraiba). A large
wedding anniversary party had been held on a
farm. Days later, some of the guests fell ill
with a febrile illness, similar to the one in
Teotonia. Sugarcane juice and other foodstuffs or
beverages had been contaminated by animal
droppings. The couple that had celebrated their
50th anniversary eventually died as a consequence
of Chagas disease acquired at the party.
Recently, oral transmission of _T. cruzi_ has
been responsible for small outbreaks in the state
of Para. Entire families acquired Chagas disease
in the absence of insect vectors in their homes.
These insects live in palm trees and, attracted
by the lights, fall into the machinery used to
grind acai to obtain juice (much the way
sugarcane juice is obtained). The insects are
ground and contaminate the juice with _T. cruzi_,
transmitting the infection to those drinking it.
All of these cases in Rio Grande do Sul, Paraiba
and Para attracted the attention of scientists.
The question which was brought forward was why
didn't gastric juice destroy _T. cruzi_? The
physician Sonia Gomes Andrade from CPqGM, who
specializes in experimental pathology, formulated
an experiment:
- We introduced _T. cruzi_ through a tube
directly into the stomach of mice, she says. She
studied the strains isolated from cases in
Paraiba and Para.
- We observed that the parasite not only survived
gastric juice but was able to infect the mice.
They developed disease identical to the one
produced when mice are infected directly via the
bloodstream. The findings of the researcher
confirm that _T. cruzi_, when swallowed, can
cause infection through the digestive system.
- In the most common manner of infection,
scratching, _T. cruzi_ is able to penetrate the
skin. [It is easy to] imagine [that], when
someone ingests a large quantity of parasites,
the [infection] will be more severe, says Sonia.
The researcher stated that there is no reason to
stop eating vegetables or drinking sugarcane or
acai juice.
- The problem lies not with the kind of food but
with _T. cruzi_. These are mainly parasites of
biodem type III -- from wildlife -- that are able
to cause infection through the digestive system.
A biodem is a group of [genetically close]
_T.cruzi_ strains with similar characteristics.
Biodem type III strains are, as a rule, highly
pathogenic. In the experiment, a strain of this
type showed a higher capacity to cross the
gastric barrier and cause infection in mice than
strains from biodems I and II.
- It is significant to point out that biodem III
strains are associated with wildlife disease
cycles, causing outbreaks in places where
Reduviid bugs are not domiciled.
--
ProMED-mail
<promed(a)promedmail.org>
[It seems beyond doubt that _T. cruzi_ can infect
hosts, including humans, by the oral route, but
it still remains unclear how important this route
of transmission is for maintaining infections in
humans and causing outbreaks like the present
one. The mouse experiment cited above confirms
previous reports [cited in ProMED-mail,
Trypanosomiasis, foodborne - South America
20050324.0847; Hoft et al. Infect Immun
1996,64:3800-10] that _T. cruzi_ can indeed
infect the host through the gastric mucosa. The
key question is how long a time _T. cruzi_ can
survive in feces outside the triatomid bug, and
how long a time in different forms of fluids
after the triatomid bugs have been crushed. Oral
transmission, either from bug feces or from
crushed bugs, presumes that _T. cruzi_ can
survive for at least several hours, possibly
days, in juice. Information on this survival time
is key to determining whether the present
outbreak is a rare coincidence or just part of a
more widespread problem. - Mod.EP]
[see also:
Trypanosomiasis, foodborne - South America (02)
20050325.0870
Trypanosomiasis, foodborne - South America
20050324.0847
1998
----
Trypanosomiasis - Brazil: RFI 19980306.0426
1997
----
Chagas disease - Latin America 19970114.0066
Chagas disease vector (05) 19970118.0105
1996
----
Trypanosomes, New World, Symposium - Guyana 1996
19960830.1493]
...............ep/msp/lm
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Dear all,
I would like to add my 2 cents on the last submission in the mailing-
list by Dr. Stephen Maurer on the meeting we held at Duke. I really
recommend the lecture of his text since it nicely summarizes what we
talked on the meeting celebrated last May.
As you can read in the manuscript, the TDI initiative will start
getting some concrete form when Dr. Kepler and his colleagues at Duke
university finish the first alpha version of the target analysis
system. We really hope that will give to all of us a tool to start
contributing to this initiative. In my opinion, the main idea behind
the new server is to allow people to annotate genes from pathogens
(starting with Malaria) with the goal of generating a list of
possible drug target candidates. Hopefully the server will be running
before the TropMed meeting so we can get some exposure by then.
I would also like to comment on the IP (Intellectual Property)
discussion at the meeting. As a researcher in biology, I know that
our IP are our "ideas" about what could make a difference in our
research fields. To ask people to actually contribute to TDI in some
form (including some "ideas") could be difficult. Therefore, there
may be the need to find solutions to that particular problem. One of
the solutions would be to team up with a publisher to create or use
an existing journal where to publish research done with the help of
the TDI effort. That would help to give credit to the people that
deserves it. Additionally, the TDI server should keep record of all
entries so that it is clear who and when input information into the
system. This is, in my opinion, one of the topics that needs to be
clarified if we want to have a successful TDI initiative.
Finally, I would like to encourage all of us in the mailing list to
continue discussing the points outlined in Stephen's document. We
could certainly used the mailing list to add to what few of us could
discuss in the last meeting at Duke.
All the best,
Marc
-------
Marc A. Marti-Renom, Adj. Assistant Professor
Departments of Biopharmaceutical Sciences and Pharmaceutical
Chemistry and
California Institute for Quantitative Biomedical Research
Mission Bay QB3. University of California, San Francisco
San Francisco, CA 94143-2552 (94158 for courier delivery)
Tel 1 (415) 514-4232; Fax 1 (415) 514-4231
Email marcius(a)salilab.org; Web http://salilab.org/~marcius
...
