[leish-l] Leishmaniasis in Brazil and dogs

[Harry Noyes]

I suppose somebody has to spring to Dick's defence even if he doesn't 
deserve it when he stirs it like that.

As far as I am aware every case of L. infantum from South America that has 
been typed by the Montpellier isoenzyme system has been identified as MON1. 
This is the principal zymodeme of L. infantum but there are at least a 
dozen others. There is certainly variation within MON1 as mentioned by Jeff 
for South American strains and well demonstrated by Michel Tibayrenc, so it 
will be no surprise if some stocks of L. chagasi can be uniquely identified 
(Hide, M., Banuls, A.L., and Tibayrenc, M. (2001) Genetic heterogeneity and 
phylogenetic status of Leishmania (Leishmania) infantum zymodeme MON-1: 
epidemiological implications. Parasitology) 123:425-432.)

However if  the genetic distance for creation of a species is less than the 
distance within a zymodeme we are going to completely lose our grip on all 
Leishmania classification. Perhaps Dedet could tell us how many zymodemes 
there are in Leishmania? It is certainly several hundred. I cannot believe 
that anybody would want to see that many species of Leishmania.

Furthermore,  there may have been multiple introductions of L. infantum 
into South America. Assuming that these came from subtly different subtypes 
of MON1 then it is likely that each new introduction is are more closely 
related to a Mediteranean L. infantum strain than to other South American 
L. infantum. We would then have to call each new introduction by a new name!

Dick's justification for abolishing L. chagasi (because we have to obey the 
rules) was enough to make anybody rebel and demand to keep it. However 
classification can only be useful it is reasonably consistent and L. 
chagasi is the most glaring inconsistency in the genus. Its got to go!


Harry

BTW we have had cases of "autochonous" VL in a dog in Britain. A case was 
brought to the Liverpool School of Tropical Medicine in 1996. According to 
the owners it had not been out of the country. It had spent sometime at a 
dog rescue centre where it is presumed to have contracted the disease by 
direct contact. This may be a more significant route of transmission than 
usually thought. Eg the US east coast outbreak (has it been settled how 
that one was transmitted).

*****************************NOTE NEW ADDRESS AND PHONE 
NUMBERS*****************

Harry Noyes
Room 231
Biosciences Building
School of Biological Sciences,
University of Liverpool,
Crown St.
Liverpool
L69 7ZB
Internal 7334
Tel  0151-794-7334
Fax 0151-795-4408
email harry at liv.ac.uk
http://www.genomics.liv.ac.uk/

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