Pedro Paulo Chieffi, Yvoty A.S. Sens, Maria Aparecida Paschoalotti, Luiz Antonio Miorin, Hélio Gomes C. Silva and Pedro Jabur
Tropical Medicine Institute of São Paulo, Brazil (LIM 06) and Medicine School of Santa Casa de São Paulo, Brazil.
Abstract The frequency of infection by Cryptosporidium parvum was determined in two groups of renal patients submitted to immunosuppression. One group consisted of 23 renal transplanted individuals, and the other consisted of 32 patients with chronic renal insufficiency, periodically submitted to hemodialysis. A third group of 27 patients with systemic arterial hypertension, not immunosuppressed, was used as control. During a period of 18 months all the patients were submitted to faecal examination to detect C. parvum oocysts, for a total of 1 to 6 tests per patient. The results showed frequencies of C. parvum infection of 34.8%, 25% and 17.4%, respectively, for the renal transplanted group, the patients submitted to hemodialysis and the control group. Statistical analysis showed no significant differences among the three groups even though the frequency of C. parvum infection was higher in the transplanted group. However, when the number of fecal samples containing C. parvum oocysts was taken in account, a significantly higher frequency was found in the renal transplanted group.
Key-words: Cryptosporidiosis. Cryptosporidium parvum. Renal transplantation.
Resumo Determinou-se a freqüência de infecção por Cryptosporidium parvum em dois grupos de pacientes com doença renal, submetidos a imunossupressão. O primeiro grupo era constituído por 23 pacientes submetidos a transplante renal e o segundo por 32 indivíduos portadores de insuficiência renal crônica, periodicamente submetidos a hemodiálise. Um terceiro grupo de 27 pacientes com hipertensão arterial sistêmica, não imunossuprimidos, foi utilizado como controle. Os pacientes, acompanhados durante 18 meses, foram submetidos a exames parasitológicos para detecção de oocistos de C. parvum nas fezes, em quantidade que variou de 1 a 6 exames por paciente. Os resultados revelaram freqüências de infecção por C. parvum iguais a 34,8%, 25,0% e 17,4%, respectivamente, para os pacientes submetidos a transplante renal, hemodiálise e os pertencentes ao grupo controle. Não se observaram diferenças significantes entre os três grupos embora note-se tendência a maior freqüência de infecção entre os pacientes submetidos a transplante renal. Todavia, quando se considerou o número de amostras fecais com presença de oocistos de C. parvum encontrou-se freqüência significativamente maior entre os pacientes transplantados.
Palavras-chaves: Cryptosporidiose. Cryptosporidium parvum. Transplante renal.
From the beginning of the eighties on, infection by Cryptosporidium parvum has been recognized as a frequent cause of enteric alterations, and less commonly extraintestinal disease in immunosuppressed patients, mainly those who have AIDS, with several grades of severity, depending on the level of involvement of their immune system23. Cryptosporidiosis has been observed even in non-immunosuppressed individuals, but without the same severity because of a self-limited clinical course18.
The consumption of food as well as the utilization of, and contact with, water contaminated by the oocysts of C. parvum, as well as contact with either animals or human beings infected by this coccidian are considered to be sources of Cryptosporidium infection11. The occurrence of intrahospital transmission of Cryptosporidium 12, as well as the vulnerability of patients submitted to either bone-marrow7 16 or renal transplantation2 23 has been reported.
Cryptosporidiosis shows a worldwide distribution and has been diagnosed at higher prevalence rates in developing countries2 23. In Brazil it has frequently been found in AIDS patients4 and in non-immunosuppressed diarrhoeal children15, but C. parvum oocysts have been found even in patients with non-diarrhoeal faeces13 25.
In the present study we investigated the occurrence of C. parvum infection in renal immunosuppressed patients submitted either to renal transplantation or hemodialysis. Elsewhere we had analyzed the presence of other intestinal parasites in the same patients9.
MATERIAL AND METHODS
Three groups of adult patients of both sexes seen at the Nefrology Clinic of the Department of Medicine, Medical School of Santa Casa de São Paulo (Brazil) from September 93 to April 95, were examined for the presence of C. parvum oocysts in the stool by staining with carbol-fuchsin1 after concentration by the formol-ether technique14. The first group consisted of 23 renal transplanted patients kept in immunosuppression in order to avoid rejection; the second of 32 patients with chronic renal insufficiency immunosuppressed as a consequence of their disease and kept on hemodialysis, and the third one, considered as a control group, consisted of 27 patients with systemic arterial hypertension without any immunosuppression.
Each patient was submitted to different numbers of faecal examinations for the detection of C. parvum oocysts during a period of 18 months according to the schedule shown in Table 1.
RESULTS
No significative difference in the frequency of infection by C. parvum was found among groups, as shown in Table 2 (Chi square = 2.70; DF = 2; p = 0.259), although the difference between the transplanted group and the control group almost achieved significance (p = 0.09).
However, when the number of faecal samples that were positive for C. parvum oocysts was considered (Table 3) a significant difference was found between the transplanted group and the control group (Chi square = 5.77; DF = 1; p = 0.016).
DISCUSSION
Infection by C. parvum has been considered as one of the most important causes of diarrhoea in immunocompetent children and as an important morbid agent, hardly controlled and, sometimes, uncontrollable, in immunosuppressed patients2 23.
Many times, especially when CD4+ cells counts are below 180 per mm3, cryptosporidiosis had been found to impair the clinical outlook of patients presenting congenital hypogammaglobulinemia, neoplasms, and mainly AIDS, or submitted to bone-marrow and solid organ transplantations3 6 7 10 16 19 22 26.
On the other hand, frequently C. parvum oocysts have been found in both asymptomatic and oligosymptomatic patients, especially children17 24 25, who, in addition to some synantropic animal species, are the major natural sources of cryptosporidiosis infection11.
Experiments carried out on animals have shown either activation of latent Cryptosporidium infections or aggravation of mild infections by the prolonged use of immunosuppressive drugs20 21. Thus, organ transplantation patients submitted to immunosuppression to avoid rejection could be considered as a group of risk for cryptosporidiosis5, as they are for other opportunistic infections. Indeed, there are some reports of the occurrence of severe diarrhoea caused by C. parvuminfection in transplanted patients7 16 22 26. At the same time, asymptomatic or oligosymptomatic infections caused by this coccidian in transplanted patients or even in individuals immunosuppressed due to other causes, may often become exacerbated because of the impaired immune system of the host8.
Roncoroni et al22 detected 11 patients infected by Cryptosporidium among 14 who had presented diarrhoea after renal transplant. In another group of patients examined for Cryptosporidium oocysts before and after the renal transplant, they frequently found Cryptosporidium asymptomatic infections. In the present study, among 23 patients submitted to renal transplant 8 (34.8%) were shedding C. parvum oocysts at least one of the stool samples examined during a period of 18 months (Tables 1 and 2). Most of these patients had no diarrhoea when they were eliminating C. parvum oocysts and they did not differ significantly from the control groups in terms of frequency of Cryptosporidium infection (p = 0.09). However, the number of stool samples that were positive for C. parvum oocysts was significantly higher in the transplanted patients when compared to the control group (p = 0.01), probably as a consequence of a larger number of infectious episodes or to the prolonged course of C. parvum infection in these patients.
Among the patients with chronic renal insufficiency submitted to hemodialysis, 25% showed at least one faecal sample containing C. parvum oocysts and 10.3% of all the samples examined were positives (Tables 2 and 3). No significant differences were found between this group and the control group, suggesting that the level of immunosuppression in these patients was not sufficient to increase their risk of being infected by Cryptosporidium.
In summary, the results of the present paper suggest that patients submitted to renal transplant should be considered as a group at risk for Cryptosporidium infection and that it would be worthwhile to periodically submit these patients and the medical staff to coprological tests for C. parvum oocysts in order to avoid intrahospital transmission22. Special care should be taken as well to prevent person-to-person transmission when there is someone infected in the transplantation section, since the available treatment of Cryptosporidium infection for immunosuppressed patients is not so efficient18 27.
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Tropical Medicine Institute of São Paulo, Brazil (LIM 06) and Medicine School of Santa Casa de São Paulo, Brazil.
Address to: Dr. Pedro P. Chieffi. Instituto de Medicina Tropical de São Paulo. Av. Dr. Enéas de Carvalho Aguiar 470, 05403-000 São Paulo, SP, Brasil. Fax: (5511) 3064-5132.
Recebido para publicação em 15/07/97.
