(Eh) y metanólico (Em) de Pera distichophylla sobre un aislado de ...

M. T. GALáN-PUCHADES and A. OSUNA
et al., 2002), i.e. both helminths are capable of
altering the progression of leishmaniosis. A preexisting
filarial infection enhanced the immune
response mounted against L. major. Co-infected
mice also exhibited a lower pathology during the
course of the experiment compared to mice singly
infected with L. major. Additionally, there was
a trend toward a larger L. major parasite load in
the co-infected mice. Therefore, the pre-existing
helminth infection may explain the elevated
number of parasites and delayed lesion size.
However, co-infection with tapeworm Taenia
crassiceps led to increased lesion sizes upon
subsequent L. major and L. mexicana infection
in mice (Roderiguez-Sosa et al., 2006). On the
other hand, comparison of the general course
of Leishmania infection in L. major singly and
L. major ⁄ Strongyloides ratti co-infected mice
revealed no difference in first and second L. major
infection (Kolbaum et al., 2011).
It seems clear that the results of co-infection are
not always consistent without taking into account
the helminth- and Leishmania species, the local or
systemic nature of the infections, and the timing
and the sequence of exposure to parasites.
Only one study carried out in human´s analysed
co-infection between helminths and L. braziliensis
(O’Neil et al., 2007). The authors concluded that
helminths influence both the clinical outcome and
the immune response of patients with leishmaniosis.
Patients with helminths tend to have smaller main
lesions whose healing takes longer than those in
their helminth-negative counterparts.
Toxoplasmosis and helminths
More than 30 years ago the concomitant
infection Schistosoma-Toxoplasma in albino mice
was studied (Kloetzel et al., 1977). The results
depended on the time-course evolution of the
initial infection. When toxoplasmic mice were
infected with S. mansoni few notable effects were
observed. However, S. mansoni infection was much
more severe in mice previously infected with the
helminth and subsequently by T. gondii. The same
results were obtained years later (Marshall et al.,
1999), since the mortality rate was higher when
mice with schistosomiasis were infected with the
protozoan.
In other helminth infections such as Nip-
8
postrongylus brasiliensis and Fasciola hepatica,
potent immune responses to T. gondii were capable
of suppressing the responses to helminth infections
(Liesenfeld et al., 2004; Miller et al., 2009). However,
infection of mice with N. brasiliensis did not
alter immune responses to subsequent infection
with T. gondii and did not alleviate gut pathology
or prevent death of mice, while prior infection with
Heligmosomoides polygyrus led to the development
of suboptimal adaptive immunity against T.
gondii, essential for long-term protection against
this parasite (Khan et al., 2008). Once more, the results
of co-infection are not always consistent, thus
highlighting the importance of the species involved
and the sequence of exposure to parasites.
Concerning susceptibility, it has been found
that persons infected with Toxocara spp. were
more likely to be infected with T. gondii, and
similarly, persons infected with T. gondii were
more likely to be infected with Toxocara spp.
(Jones et al., 2008).
CHAGAS DISEASE AND HELMINTHS
In humans
To our knowledge there is only one published
paper that deals with co-infection between CD and
helminths in humans. An epidemiological analysis
in patients co-infected with CD and cysticercosis
was conducted by means of data obtained from
autopsies performed in 1501 corpses (Faleiros
et al., 2009). The authors found that CD was 10
times more frequent in patients co-infected with
cysticercosis. Intriguingly, the authors also found
that co-infected patients had a longer survivorship
compared to those suffering from CD only or those
with cysticercosis only and even those persons
without any infection.
The impact of co-infection between CD
and concomitant helminth infections has been
analysed in some other hosts such as mice, dogs
and primates.
In mice
Almost 40 years ago, albino mice were exposed
concomitantly to S. mansoni and T. cruzi (Kloetzel
et al., 1973). The findings were very similar to those
obtained in the interaction between S. mansoni
Rev. Ibero-Latinoam. Parasitol. (2012); 71 (1): 5-13