TDI-discuss August 2005

tdi-discuss@salilab.org

1 participants
2 discussions

TRYPANOSOMIASIS, FOODBORNE - SOUTH AMERICA
by Dr. Alfonso J. Rodriguez 29 Nov '05

29 Nov '05

Archive Number 20050327.0884 Published Date 27-MAR-2005 Subject PRO> Trypanosomiasis, foodborne - South America (03) TRYPANOSOMIASIS, FOODBORNE - SOUTH AMERICA (03) *********************************************** A ProMED-mail post <http://www.promedmail.org> ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org> 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 *##########################################################* ************************************************************ ProMED-mail makes every effort to verify the reports that are posted, but the accuracy and completeness of the information, and of any statements or opinions based thereon, are not guaranteed. The reader assumes all risks in using information posted or archived by ProMED-mail. ISID and its associated service providers shall not be held responsible for errors or omissions or held liable for any damages incurred as a result of use or reliance upon posted or archived material. ************************************************************ Visit ProMED-mail's web site at <http://www.promedmail.org>. Send all items for posting to: promed(a)promedmail.org (NOT to an individual moderator). If you do not give your full name and affiliation, it may not be posted. Send commands to subscribe/unsubscribe, get archives, help, etc. to: majordomo(a)promedmail.org. For assistance from a human being send mail to: owner-promed(a)promedmail.org. ############################################################ ############################################################ ______________________________________________ Renovamos el Correo Yahoo!: ¡250 MB GRATIS! Nuevos servicios, más seguridad http://correo.yahoo.es

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RE: [TDI-discuss] TDI Progress Report
by Marc A. Marti-Renom 05 Aug '05

05 Aug '05

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 ...

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TDI-discuss August 2005