PROSPECTIVE STUDY OF STRONGYLOIDOSIS IN PATIENTS WITH HEMATOLOGIC MALIGNANCIES

in many parts of the world and a serious hazard for individual patients even outside endemic areas due to the possibility of hyperinfection or disseminated disease7 10 13. Patients with hematological malignancies may be at special risk for disseminated strongyloidosis by immunosupression, either induced by treatment or secondary to leukemia or lymphoma. Treatment and especially prophylaxis guidelines in these populations are not a established issue, needing more extensive, population-based longitudinal studies. We report here our first observations in such a long term study.

Strongyloidosis is still a public health problem in many parts of the world and a serious hazard for individual patients even outside endemic areas due to the possibility of hyperinfection or disseminated disease 7 10 13 .Patients with hematological malignancies may be at special risk for disseminated strongyloidosis by immunosupression, either induced by treatment or secondary to leukemia or lymphoma.Treatment and especially prophylaxis guidelines in these populations are not a established issue, needing more extensive, population-based longitudinal studies.We report here our first observations in such a long term study.

MATERIAL AND METHODS
From 108 patients admitted for treatment of hematologic neoplasic diseases, at the Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul, between 15 July 1994 and 14 July 1995, 72 were asked to collect fecal samples in three sucessive days.Exclusion criteria were: HIV positivity and antiparasitic treatment in previous 30 days.Approximately 1g of fresh feces were immersed in warm tap water, contained in surgical gauze and placed in 10ml plastic centrifuge tubes (Willcox-Coura modification of the Baermann method) 16 .The tubes were incubated for 90 minutes at 35 O C and centrifuged at 15xg for 5 minutes and larvae were identified in the sediment.Underlying disease, demographic characteristics, risk condition for infection (barefoot), clinical manifestations and presence of peripheral eosinophilia (≥ 4%) was tested for independence of events by the Fisher's or χ2 test.

DISCUSSION
The severe forms of strongyloidosis, hiperinfection and disseminated disease, are so worriesome that routine "treatment" with thiabendazole is implemented empirically in situations where immunodepression can be antecipated, like kidney cadaveric transplantation 5 .The lack of a consensus on such issue of blind treatment for eradication of a possible S. stercoralis infection, partially results from gaps in the knowledge on prevalence and natural history of infection, both in general and selected populations.Prevalences reported in literature vary from 2% to more than 60%, with variable methology and sample composition 1 9 .Samples defined by a disease, like AIDS, may not have an elevated prevalence of strongyloidosis, contrary to what would be expected 2 6 .Even when prevalence is high, hyperinfection and/or disseminated disease is apparently not proportionally more frequent 11 .These data should not shadow the importance of a single episode of hyperinfection and disseminated strongyloidosis, with its severe morbidity and p o t e n t i a l l o w r e s p o n s e t o p r o l o n g e d treatment 12 13 .
Patients with hematological malignancies may develop imunosupression both as part of the disease and due to chemotherapy schemes, especially those including corticosteroids, one of the well known predisposing factor for complicated strongyloidosis 13 .The prevalence in the presente series, 8.3% is much lower than 21% found in a retrospective study in a similar population in Rio de Janeiro (RJ) 11 and there was agreement in low incidence of complicated infection: zero and 1.9% in RJ.One important difference between these data is the retrospective design of RJ study and the smaller sample and prospective present study.Probably the disseminated disease was underdiagnosed in the retrospective RJ study and was underevaluated in the small sample of the present prospective study.
Only eosinophilia was found significantly associated with positive identification of S. stercoralis larvae in stools in our series.The eosinophilic response is important for its association to a better prognosis 4 and for its proposed role to monitor amplification of existing infections or recent acquisition 15 .Other clinical manifestations lack especificity, since they are common to the neoplasic processes.
There are few doubts that intensive efforts to rule out S. stercoralis infection by serial stool examinations should always be carried out in immunosupressed patients, especially when immunosupression can be antecipated.Sensitive techniques must be employed, like the classical Baermann method or the new agar-plate method 8 14 , in order to isolate larvae, from stools or from duodenal aspirates 15 .
The guidelines for empirical treatment or secondary prophylaxis in selected populations are to be established and they depend on longitudinal studies with adequate evaluation of risk for disseminated disease versus unsuccessful monitoring of uncomplicated S. stercoralis infection, including control of household and community sources of infection for those patients 3

Petry, Tamara Mucenic, Cláudio Pandolfi, Susana Barcellos and Fani Job Immunocompromised
individuals infected with Strongyloides stercoralis may develop severe hyperinfection or disseminated disease with high mortality.Patients with hematological malignancies are at risk because of immunodepression produced either by the disease or its treatment.A prospective study was undertaken at the Hospital de Clínicas de Porto Alegre, from July 1994 to July 1995.Seventy-two (HIV negative), had 3 stool samples collected at different days and had not received recent anti-helmintic therapy.Larvae, isolated in a modified Baermann method, were found in 6 patients, with a resultant prevalence of 8.3%.No complicated strongyloidosis was documented.The positive result for S. stercoralis larvae was significantly associated (p < 0.001) with eosinophilia.Knowledge of prevalence figures and incidence of severe disease is important to adequate guidelines for empirical treatment besides the rigorous search for strongyloidosis in patients with hematological malignancies.withpositivity in stool examination for S. stercoralis (Table1).No episode of hyperinfection or disseminated disease was documented.

Table 1 -
Comparison of epidemiological, clinical and laboratorial findings in 72 patients with hematological malignancies, according to positive or negative search for S. stercoralis (S.s.) larvae in 3 stool samples, from 15 July 1994 to 14 July 1995, Hospital de Clínicas de Porto Alegre, Brazil.