Improving waterborne disease outbreak investigations.

This article is a summary of discussions held and recommendations made at a workshop for the investigation of waterborne disease outbreaks in Chapel Hill, North Carolina, December 7-8, 1998. Suspected waterborne outbreaks in the United States are primarily investigated by state and local public health officials who may infrequently conduct enteric disease outbreak investigations. Thus, it is important that officials have a formal plan to ensure that epidemiological studies are methodologically sound and that effective collaboration occurs among the epidemiologists, scientists, and engineers who will conduct the investigations. Laboratory support to analyze water samples and clinical specimens should be arranged well in advance of when services may be needed. Enhanced surveillance activities can help officials recognize additional outbreaks and initiate investigations in a timely manner. Epidemiologists should pay more attention early in the investigation to study design, questionnaire development, and sources of bias, especially recall bias, that may affect the interpretation of observed associations. Improved investigations can increase our knowledge about important etiological agents, water systems deficiencies, and sources of water contamination so that waterborne outbreaks can be more effectively prevented.

Treatment of hemodialysis fistula pseudoaneurysms with detachable balloons: technique and preliminary results.

Pseudoaneurysm formation is commonly encountered during the life of a dialysis fistula. When these become excessively large or numerous, surgical revision of the graft has been the only treatment option. The authors have treated seven patients by using percutaneous placement of a detachable balloon to occlude a pseudoaneurysm of an upper extremity graft. In four cases the balloon was directed into the pseudoaneurysm from a femoral artery approach. In three cases a direct puncture was made into the pseudoaneurysm for placement of the balloon. The patients were followed up from 1 week to 7 months. Initial technical success was achieved in all seven cases with no complications. Thrombosis of two grafts occurred during the first week after the procedure: one because of herniation of the balloon out of the pseudoaneurysm and one for unknown reasons. One balloon was inadvertently punctured and deflated during subsequent dialysis. Treatment in the other four cases was successful, as evidenced by no further enlargement of the pseudoaneurysms. Direct puncture of the pseudoaneurysm simplifies the procedure and probably decreases the likelihood of balloon herniation because of the orientation of the balloon.

Cohort study of human immunodeficiency virus (HIV) antibody testing among patients receiving long-term dialysis at a university hospital.

In a longitudinal study to determine the seroprevalence of antibody to the human immunodeficiency virus (HIV) and the natural history of a positive enzyme immunoassay (EIA) result we followed a cohort of 98 patients receiving long-term dialysis. Eight patients (8.2%) in the cohort had a positive EIA and a negative Western blot test result. The EIA-positive results of all patients seroconverted to negative during follow-up. No illness suggestive of HIV infection developed in any of the patients. Significantly associated with a false positive EIA were prior renal transplantation, transfusions during the months just before the positive EIA result, and a greater number of lifetime transfusions before the positive test result. We confirm that routine HIV screening of patients receiving long-term dialysis is associated with a high rate of false positive EIA results and conclude that such testing is unnecessary in the absence of established risk factors for HIV infection.