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Applied and Environmental Microbiology, February 2007, p. 1033-1035, Vol. 73, No. 3
0099-2240/07/$08.00+0 doi:10.1128/AEM.00964-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Molecular Characterization of Cryptosporidium Isolates from Humans and Animals in Iran
Ahmad Reza Meamar,1
Karine Guyot,2
Gabriela Certad,2
Eduardo Dei-Cas,2
Mino Mohraz,3
Mehdi Mohebali,1
Kazem Mohammad,4
Amir Ali Mehbod,1
Sasan Rezaie,1 and
Mostafa Rezaian1*
Department of Medical Parasitology and Mycology, School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences, Tehran, Iran,1
Parasitology-Mycology Service, Microbiology Department, EA3609 Faculty of Medicine, Lille 2 University, University Hospital Centre and IFR-142, Lille Pasteur Institute, Lille, France,2
Department of Infectious Diseases, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran,3
Department of Biostatistics and Epidemiology, School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences, Tehran, Iran4
Received 24 April 2006/
Accepted 18 November 2006

ABSTRACT
Isolates of
Cryptosporidium spp. from human and animal hosts
in Iran were characterized on the basis of both the 18S rRNA
gene and the Laxer locus. Three
Cryptosporidium species,
C. hominis,
C. parvum, and
C. meleagridis, were recognized, and
zoonotically transmitted
C. parvum was the predominant species
found in humans.

INTRODUCTION
Cryptosporidium is an apicomplexan parasite that infects humans
and a wide range of domestic and wild animals. It is responsible
for significant diarrheal diseases in both developing and developed
nations. Molecular biology has provided powerful new tools for
characterizing
Cryptosporidium and has revealed considerable
variation within the genus. Currently, 16 species are recognized
(
22), of which 7 infect susceptible immunocompetent and immunocompromised
individuals.
C. parvum and
C. hominis are the species predominantly
found in humans, but others, such as
C. meleagridis,
C. felis,
C. muris,
C. canis, and
C. suis, have also been occasionally
identified (
3,
27).
Cryptosporidium has been previously reported in Iran (1, 10, 14, 17, 29), but apart from one documented case, in which a C. parvum infection was reported in the respiratory tract of an Iranian AIDS patient (14), no data are available on the molecular identification of the species infecting humans and animals in this country. Therefore, the present study was undertaken to identify Cryptosporidium species in human and animal hosts and to explore the transmission patterns of infection among them.

Specimens, DNA isolation, and Cryptosporidium genotyping.
Totals of 15 human and 9 animal stool specimens, collected from
2002 to 2005 in Iran and diagnosed positive for
Cryptosporidium by acid-fast staining, were analyzed (Table
1). DNA was extracted
using a QIAamp DNA stool kit (QIAGEN, Hilden, Germany) according
to the manufacturer's instructions. All specimens were genotyped
on the basis of the 18S rRNA gene by nested PCR-restriction
fragment length polymorphism (RFLP) (
25,
26,
28) and sequencing
(
8).
Cryptosporidium species were further confirmed by a Laxer
sequence-based tool as previously described (
9). Indeed, distinct
Laxer PCR-RFLP patterns allowed the differentiation of
C. hominis,
C. parvum, and
C. meleagridis, even distinguishing between two
subgenotypes of
C. parvum, as a result of DNA variation within
this species (
9).

Cryptosporidium species identified.
DNA of all specimens yielded products of the expected 830-bp
size by nested PCR of the 18S rRNA gene. Genotyping results
from RFLP analysis of the amplified product were in agreement
with those from DNA sequencing. The obtained 18S rRNA gene sequences
matched the sequences previously deposited in GenBank. In the
present study,
C. parvum was identified in isolates from seven
human immunodeficiency virus (HIV)-infected adults, four children,
and seven cattle, whereas
C. hominis was identified in isolates
from one HIV-infected adult and three children. The third species,
C. meleagridis, was identified in two turkey isolates (Table
1).
Results obtained by analysis of the Laxer DNA fragment were in agreement with those for the 18S rRNA gene locus (Table 1), except for three isolates in which, in spite of repeated attempts, DNA failed to amplify (the lower sensitivity of the PCR assay at the Laxer locus is the probable explanation). In human isolates, both the L1 and the L2 subgenotypes of C. parvum were recovered, while in cattle isolates, only the L1 subgenotype was found (Table 1).

Cryptosporidium species in HIV-infected adults and in children.
Recent studies on cryptosporidiosis in HIV-infected adults and
children in Iran have shown prevalences of 1.5% and 7%, respectively
(
10,
29). In the present study, the species responsible for
cryptosporidiosis in Iranian patients were identified. Accordingly,
in HIV-infected adults,
C. parvum was more frequently identified
than
C. hominis. In contrast, in children, no significant difference
in the distribution of
Cryptosporidium species (
C. parvum versus
C. hominis) was observed. This pattern of
Cryptosporidium species
distribution in adults and children in Iran seems different
from those in other countries, such as Peru, Thailand, Malawi,
Uganda, Kenya, South Africa, and South India, where
C. hominis is by far dominant either in HIV-infected adults or in children
(
7,
11,
15,
18,
19,
23-
25). However, in European countries,
C. parvum is slightly more commonly identified than
C. hominis in both immunocompetent and immunocompromised individuals (
2,
4,
8,
13). Recently,
C. parvum was also identified in children
in Kuwait (
21).
In the present study, among the C. parvum isolates, the L1 subgenotype was predominant, as it was identified in eight human cases out of nine and in all cattle cases. Interestingly, this subgenotype has also been the only one found in all cattle isolates from France and Tunisia, whereas both the L1 and the L2 subgenotypes were retrieved in humans from the same countries (K. Guyot, unpublished data). The failure to detect the L2 subgenotype in animals in the current study is in agreement with recent subtyping studies showing that not all C. parvum infections in humans are the result of zoonotic transmission (2, 12, 16). Indeed, this type of C. parvum would infect humans through anthroponotic transmission. Thus, it could be hypothesized that the adult infected by the H4-related isolate acquired the pathogen by an anthroponotic pathway.

Cryptosporidium species in animals.
Prior to this work,
Cryptosporidium parasites had been reported
in cattle in Iran (
17), but the present study reports the first
molecular characterization of these protists in animals from
this country.
C. parvum has been the sole species identified
in cattle. Other
Cryptosporidium species reported to infect
these animals, such as
C. bovis,
C. andersoni, and the
Cryptosporidium deer-like genotype (
5,
6,
20), were not found here. This work
is also the first report of
C. meleagridis infecting turkeys
in Iran.

Conclusion.
Few published reports on
Cryptosporidium are available in the
Middle East. In this study, despite the relatively small number
of isolates characterized, the clear predominance of
C. parvum in Iranian people might be considered the result of zoonotic
transmission. However, more comprehensive epidemiological studies
are needed to elucidate accurately the source of
Cryptosporidium infection. Especially, further subtyping of
C. parvum and
C. hominis isolates using highly polymorphic markers is needed
to improve our knowledge of parasite transmission pathways in
Iran.

ACKNOWLEDGMENTS
The Tehran University of Medical Sciences supported the Ph.D.-related
training of A.R.M. in the Ecology of Parasitism Department at
the Lille Pasteur Institute (Lille, France). The French Ministry
of Research (quadrennial EA3609-Lille 2 University contract)
supported this work.
We thank T. Ngouanesavanh for her generous and enthusiastic cooperation.

FOOTNOTES
* Corresponding author. Mailing address: Department of Medical Parasitology and Mycology, School of Public Health and Institute of Public Health Research, Tehran University of Medical Sciences, P.O. Box 14155-6446, Tehran, Iran. Phone: 98 21 88951392. Fax: 98 21 66462267. E-mail:
rezaiian{at}sina.tums.ac.ir.

Published ahead of print on 1 December 2006. 

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Applied and Environmental Microbiology, February 2007, p. 1033-1035, Vol. 73, No. 3
0099-2240/07/$08.00+0 doi:10.1128/AEM.00964-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.