The Type of Trypanosoma Cruzi Strain (Native or Non-Native) Used as Substrate for Immunoassays Influences the Ability of Screening Asymptomatic Blood Donors

BACKGROUND

The origin (native or non-native) of Trypanosoma cruzi strains used as substrate for immunoassays may influence their performance.

OBJECTIVE

To assess the performance of an immunoassay based on a native T. cruzi strain compared to another based on non-native T. cruzi strains, in asymptomatic blood donors from Mexico.

METHODS

Serum samples from a tertiary referral center were tested by both ELISA-INC9 (native) and Chagatest (non-native) assays. All reactive serum samples were further analyzed by indirect immunofluorescence.

RESULTS

Sera from 1,098 asymptomatic blood donors were tested. A 4.3 and 0.7% serum reactivity prevalence was observed using ELISA-INC9 and Chagatest, respectively (kappa = 0.13; -0.11 to 0.38). Subsequently, indirect immunofluorescence analyses showed higher positivity in serum samples reactive by ELISA-INC9 compared to those reactive by Chagatest (79 vs. 62.5%; p < 0.001). Furthermore, out of the 47 positive samples by both ELISA-INC9 and indirect immunofluorescence, only four (8.5%) were reactive in Chagatest assay. Meanwhile, four (80%) out of the five positive samples by both Chagatest and indirect immunofluorescence were reactive using ELISA-INC9.

CONCLUSION

Immunoassays based on a native T. cruzi strain perform better than those based on non-native strains, highlighting the need to develop and validate screening assays in accordance to endemic T. cruzi strains.

[National guidelines of diagnosis and treatment of the non-Hodgkin lymphoma]

Non-Hodgkin lymphoma comprises a heterogeneous group of haematological malignancies, classified according to their clinic, anatomic-pathological features and, lately, to their molecular biomarkers. Despite the therapeutic advances, nearly half of the patients will die because of this disease. The new diagnostic tools have been the cornerstone to design recent therapy targets, which must be included in the current treatment guidelines of this sort of neoplasms by means of clinical trials and evidence-based medicine. In the face of poor diagnoses devices in most of the Mexican hospitals, we recommend the present diagnose stratification, and treatment guidelines for non-Hodgkin lymphoma, based on evidence. They include the latest and most innovative therapeutic approaches, as well as specific recommendations for hospitals with limited framework and therapy resources.

Starch and albumin mixture as replacement fluid in therapeutic plasma exchange is safe and effective

Therapeutic plasma exchange (TPE) is an effective treatment in Myasthenia gravis (MG) and Guillain-Barré syndrome (GBS) and 5% human albumin is the replacement fluid of choice; however, it is expensive. More recently, it has been suggested that starch is a safe and cheaper choice to human albumin.

OBJECTIVE

To evaluate our 5-year experience using 3% hydroxyethyl starch (HES) and 5% human albumin mixture, as replacement fluid in TPE for these diseases.

MATERIALS AND METHODS

Retrospective study carried out from January 2001 through September 2006. We included those patients with MG and GBS undergoing TPE. We analyzed clinical outcome (CO) and adverse events (AE) and our results were compared with a previous study which included similar patients undergoing TPE using just 5% human albumin.

RESULTS

Thirty-one procedures were carried out in 26 patients, a total of 147 TPE sessions. In the group of MG we had 57% complete responses (CR) and 86% overall response (OR) while in the group of GBS we had 40% CR and 60% OR. When we analyzed our CO with the previous study no statistical differences were found. Mean processed plasma volume (PPV) was 4.2 in MG and 5.5 in GBS. Twenty patients had AE, being hypotension and catheter dysfunction the most frequent ones, while tachycardia, hypertension and paresthesias were statistically more frequent in the HES/albumin group.

CONCLUSIONS

TPE with a mixture of 3% HES and 5% human albumin is as effective and safe as 5% human albumin alone for patients with these diseases.

Detection of West Nile virus in the Mexican blood supply

BACKGROUND

West Nile virus (WNV) is the etiologic agent of an emerging disease in the Western Hemisphere that can be transmitted to humans by blood transfusion. WNV first appeared in the United States in 1999, in Canada in 2001, and in Mexico in 2002. The aim of this nationwide study was to determine the prevalence of WNV in blood donors in Mexico as a first step in preventing its transfusion-associated transmission.

STUDY DESIGN AND METHODS

In July and August 2004, a total of 3856 fresh plasma specimens collected from each state's center for blood transfusion in 29 of 31 Mexican states were screened with an investigational WNV assay (Procleix,(R) Gen-Probe Inc. and Chiron Corp.), a nucleic acid test based on transcription-mediated amplification (TMA). Reactive specimens were confirmed with a second TMA-based test, the alternative WNV assay (Gen-Probe), and with WNV capture enzyme-linked immunosorbent assays (ELISAs) for detection of immunoglobulin M (IgM) and IgG antibodies. In addition, 3714 frozen plasma samples collected in 2002 and 2003 were similarly tested.

RESULTS

One of 3856 fresh samples from an asymptomatic donor from Chihuahua was reactive by both TMA-based tests and IgM ELISA, suggesting a recently acquired infection. The observed percentage of viremic donors blood donors was 0.03 percent. Results from frozen samples were not included in the prevalence calculation and none were TMA-reactive for WNV.

CONCLUSIONS

WNV is present in the Mexican blood supply and measures should be taken to reduce the risk of transfusion transmission.

[Retrospective transfusional audit at the Centro Nacional de la Transfusión Sanguínea]

BACKGROUND

Prior to a blood transfusion, we should consider the risk benefit ratio. The literature shows that 18 to 57% of red blood cells, up to 96% of fresh frozen plasma and 26% of platelet concentrates are unnecessarily transfused. The goal of the present work is to know the appropriateness of transfusion at public and private health institutions supported by the Centro Nacional de la Transfusión Sanguínea.

MATERIAL AND METHODS

An observational, retrospective, transverse and descriptive study was carried out by analyzing the requirements of blood products considering the patient's diagnosis, requested blood components, complete blood count, prothrombin and activated partial thromboplastin time. The therapeutic indication was considered either adequate or inadequate according to the guidelines for the transfusion therapy of blood products. Descriptive statistics for the analysis of the data were used.

RESULTS

We analyzed 1,573 request forms received in year 2001. In 849 cases (55%) the indication was adequate, whereas in 724 (45%) the indication of the blood products was inadequate.

CONCLUSIONS

Our results show that overtransfusion is a common practice. We propose to follow the guidelines already established for the transfusion of blood components in order to avoid iatrogenia due to overtransfusion.

Serum hyperviscosity syndrome responding to therapeutic plasmapheresis in a patient with primary Sjögren's syndrome

Hyperviscosity syndrome is a disorder first described in patients with Waldenström's macroglobulinemia and is not commonly seen in rheumatic diseases. Its association with Sjögren's syndrome is very rare and it has been reported in very few patients. We report the case of a patient with primary Sjögren's syndrome presenting as hyperviscosity syndrome who was successfully treated with therapeutic plasma exchange.

Therapeutic plasma exchange in Mexico: experience from a single institution

Information about therapeutic plasma exchange (TPE) in developing countries is lacking. We report our experience with TPE performed for different indications during a 7-year period. We reviewed all TPE procedures performed in our institution during a 7-year period. Patients were divided in four groups according to the following indications: thrombotic microangiopathies (TM), myasthenia gravis (MG), polyneuropathies (PNP), and miscellaneous indications (MI). Clinical outcome (CO) and complications were evaluated. Eighty-seven procedures were carried out in 81 patients, for a total of 376 TPE sessions. Eighty-two procedures were analyzed for CO. In the group of TM we had 65% overall response rate (ORR): 35% complete response (CR) and 30% partial response (PR). Six (28.6%) patients died in this group. In the MG group we had 90% ORR: 69% CR and 21% PR. In the PNP group we had 78% ORR: 56% CR and 22% PR. In the MI group we had 92% ORR: 59% CR and 33% PR. We observed 47 adverse reactions in 40 (46%) procedures performed in 38 (47%) patients. This represented 12.5% of sessions. We had seven major complications leading to TPE discontinuation; this represented 8% of the procedures and 1.8% of sessions. One patient (0.2%) died during TPE. Our overall results are acceptable. In the TM group our results are somewhat lower than in other published reports, but in MG and PNP our results are similar to other published reports. Our complication rate is similar to that reported by others. Careful selection of patients and protocols is crucial to achieve maximum benefit from TPE programs in countries where plasmapheresis facilities are not widely available.