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Human leishmaniasis

Lys Guilbride lys at welchlink.welch.jhu.edu
Sun Oct 29 15:58:58 EST 1995

In article <M_Doherty-2909560823010001 at db449.niaid.nih.gov>,
M_Doherty at NIH.gov (M. Doherty) wrote:

> In article <46di69$9vv$1 at mhafm.production.compuserve.com>, Eberhard Kniehl
> <100674.1442 at CompuServe.COM> wrote:
> > Hi, to all !
> > 
> > I don´t know very much about leishmaniasis and I´ve only seen a 
> > few cases in humans (leishmaniasis is not very often seen here in 
> > Germany). So please excuse my "stupid" question:
> > 
> > My question is, whether there is the possibility of  relapsing 
> > cutaneous leishmaniasis in humans. And if so, where do the 
> > amastigotes reside ?
> > 
> > Suppose the following hypothetic case:
> > HIV-positive person from Sudan, staying in Germany since more 
> > than 3 years (i.e. no recent contact to sandflies). No history of 
> > leishmaniasis, but perhaps inapparent infection. Now multiple 
> > cutaneous granuloma and ulcerations (head, neck, upper 
> > extremities).
> > 
> > Is "relapsing" leishmaniasis, due to immundeficiency,  
> > "reasonable" in differential diagnosis ?
> > 
> Reappearance of the parasite is certainly possible even in the absence of
> immunodeficiency, although relatively rare.  As you have described, when
> you get recurrence, itoften occourrs at different sites and often presents
> with multiple lesions.  Although the parasite is often difficult to find,
> it is probably never completely eliminated even in immunocompetent hosts.
> If the the lesions do not respond to pentostam (or whatever equivalent you
> have available) you might like to check on the availability of
> experimental combined cytokine/drug treatment, which is being used on some
> similar cases here in teh states.
> Hope this helps.
> Cheers, Mark Doherty

The leishmania parasites reside in the macrophage cells of the host, and
in an immunocompetent host they can 'hide' there for years, without the
host presenting symptoms.  In an HIV positive person, it would be expected
that as the immune system deteriorated, the parasite would be able to
expand.  Also, the host may carry multiple species or strains of
parasites, since isolates from lesions have been found to contain mixed
populations of parasites.  Different strains of leishmanial parasites
respond differently to arsenic-based drugs, and it appears that even when
a patient responds to such treatment, it is not possible to be sure that
the parasites have been eliminated.  Hope this info is useful, good luck.
Lys Guilbride

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