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Parasite Genotypically Related to a Monoxenous Trypanosomatid of Dog's Flea Causing Opportunistic Infection in an HIV Positive Patient
Vol. 93(4): 531-537
Raquel S Pacheco /+, Mauro CA Marzochi*, Marize Q Pires, Célia MM Brito*, Maria de Fátima Madeira*, Elizabeth GO Barbosa-Santos*
Departamento de Bioquímica e Biologia Molecular, Instituto Oswaldo Cruz, Av. Brasil 4365, 21045-900
Rio de Janeiro, RJ, Brasil *Departamento de Ciências Biológicas, Escola Nacional de Saúde Pública, Fiocruz, Rio de Janeiro, RJ, BrasilAn HIV positive patient presenting a clinical picture of visceral leishmaniasis co-infection was submitted to a bone marrow aspiration after admission to hospital. Amastigotes forms were seen in the bone marrow aspirate and the parasite grew in culture as promastigotes. Molecular analyses showed that the flagellates isolated did not belong to the genera Leishmania, Trypanosoma or Sauroleishmania. It was not possible to establish infection in laboratory animals. In vitro culture of mouse peritoneal macrophages revealed the invasion of the host cells by the flagellates and their killing 48 hr after infection. Opportunistic infection with an insect trypanosomatid was suspected. Further hybridization analyses against a pannel of different monoxenous and heteroxenous trypanosomatids showed kDNA cross-homology with Leptomonas pulexsimulantis a trypanosomatid found in the dog's flea.
Key words: opportunistic infection - AIDS - monoxenous trypanosomatid - minicircle - hybridization
The family Trypanosomatidae of the order Kinetoplastida is characterized by the presence of a kinetoplast-mitocondrial complex rich in DNA. This family includes parasite flagellates that undergo cyclical development in both vertebrate and invertebrate hosts. These parasites are best known as agents of important diseases in humans, domestic animals and plants. In addition to these heteroxenous organisms, several genera such as Crithidia, Herpetomonas, Blastocrithia and Leptomonas are restricted to a single host (monoxenous). Usually they are found infecting different insect orders such as Diptera, Hemiptera and Siphonaptera (Wallace 1966, Vickerman 1976, 1994). Such monoxenous or "lower trypano-somatids" have never been confirmed as pathogenic for human beings. Five species of the genus Leptomonas hosted by fleas (Siphonaptera) have been listed (McGhee & Cosgrove 1980). These parasites exist as attached and free promastigotes and amastigotes in the gut of the dog fleas. Amastigote forms are resistent to external enviroment and are deposited via feces of infected fleas (McGhee & Cosgrove 1980). More recently, Beard et al. (1989) reported the isolation of a new species of Leptomonas (Leptomonas pulex-simulantis, ATCC 50186) from the dog's flea Pulex simulans. Giemsa-stained preparations of the flea feces colected from the scalp of a dog demonstrated the presence of round aflagellate forms.
In the past few years, new pathological aspects of protozoan infections caused mainly by Leishmania and Trypanosoma cruzi have emerged in immunosupressed patients. Particularly in cases of HIV co-infection the clinical symptoms are frequently peculiar. Cases of central nervous system tumor-like lesions (Ferreira et al. 1991, Pittella 1993, Rocha et al. 1994, Pacheco et al. 1998) and cutaneous lesions manifestations (Amato et al. 1997) related to the reactivation of Chagas' disease have been reported in association with immunosuppression. Distinct Leishmania isoenzymatic patterns and specific dermotropic zymodemes have also been found causing visceral leishmaniasis (Campino et al. 1994, Jimenez et al. 1995, Alvar et al. 1997).
A recent publication reported (Dedet et al. 1995) a case of diffuse cutaneous infection caused by a presumed monoxenous trypanosomatid in a patient infected with HIV. The patient developed a diffuse leishmaniasis-like syndrome with numerous amastigotes in the skin nodules. The parasite isolated differed isoenzymatically from Leishmania, Trypanosoma and Sauroleishmania. Another interesting paper (Jimenez et al. 1996) reported the finding of an "unusual Leishmania-like parasite" in a case of visceral leishmaniasis/HIV co-infection. No kDNA sequence homology was observed with Leishmania nor with other genera of lower trypanosomatids in cross-hybridization experiments. The authors stressed that immunocompro-mised patients could be vulnerable to other non-human trypanosomatids.
The present paper describes the isolation and the genotypic and phenotypic characterization of a monoxenous trypanosomatid found in the bone marrow of an HIV positive patient presenting a visceral leishmaniasis-like syndrome.
ACKNOWLEDGMENTS
To Prof. Maria Auxiliadora de Sousa (Núcleo de Tripanosomatídeos, Instituto Oswaldo Cruz) for the donation of monoxenous trypanosomatids, Dr Maurílio J Soares (Departamento de Ultraestrutura e Biologia Celular, Instituto Oswaldo Cruz) for the electromicros-copy studies and Drs Claudio Siqueira, Tania Amaral and Luiz Franco (Setor de Hematologia do Hospital da Lagoa, Rio de Janeiro) for the hematological and clinical follow up of the patient.
Figure 1 | Figure 2 | Figure 3 | Figure 4
This work received financial support from the International Atomic Energy Agency (IAEA, Vienna, Austria), PAPES (Fiocruz) and Fundação Nacional de Saúde.
+Corresponding author. Fax: +55-21-590.3495
Received 16 January 1998
Accepted 29 May 1998
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