Surveillance of measles in the Sudan using filter paper blood samples

Abstract

Dried blood spots collected on filter paper are considered potential clinical specimens for measles surveillance because of their ease of collection, storage, and transport. The usefulness of these samples for surveillance of measles was evaluated in a field setting. Blood spots were collected by finger-prick from 316 clinically diagnosed measles patients in suburban Khartoum, mostly within a week after onset of the rash. Samples were collected between October, 2000 and April, 2003, and stored at 4 degrees C. Measles virus-specific IgM antibodies were detected in 200 (63%) of the samples using an "in-house" IgM capture ELISA. For 201 samples reconstitution and IgM measurement was repeated 1 year after initial testing with essentially the same results, showing the stability of IgM in the filter paper under these conditions. In a limited number of samples (n = 38) measles virus-specific IgM was also tested with a commercial indirect IgM ELISA. Although the results of the two assays correlated well, the "in-house" IgM capture ELISA proved slightly more sensitive. Measles virus-specific reverse transcriptase polymerase chain reaction (RT-PCR) amplicons were obtained from 16 of 57 (28%) samples tested. Sequencing of the 3' 456 nucleotides of the nucleoprotein gene showed the continued endemic circulation of genotype B3 viruses identified previously in this region. Although problems related to limited sample quantities were encountered, the present study confirms the usefulness of dried blood spots for measles surveillance. The results also demonstrate that measles continues to be endemic in the Sudan.

Evaluation of Biological Sample Preparation for Immunosignature-Based Diagnostics

“…The remainder of the immunosignature did lose some correlation to that for fresh samples over time but did not decrease below the variance in technical replicates. These observations are in line with previous reports of the use of dried blood to collect blood antibodies for ELISA in tropical and subtropical regions (2,6,9,22). Addition of a protease inhibitor to the spotted sample reduced the degree of degradation, keeping the correlation at 2 weeks within the range of acceptability for technical replicates.…”

Investigating the Use of Protein Saver Cards for Storage and Subsequent Detection of Bovine Anti-Brucella abortus Smooth Lipopolysaccharide Antibodies and Gamma Interferon

“…Therefore, appropriately stored serum samples on Protein Saver cards may be stored at ambient temperature and transported through the post with a reduction in the risk of exposure to live agents in serum, thus enabling greater access to samples from countries where cold transport is unavailable. This is in keeping with the findings of other studies that determined the longevity of titers from samples stored on cards (14,30,31).…”

“…Since the development of these cards, they have been used in hospital laboratories for testing card eluates by ELISA and PCR for the clinical diagnosis of multiple diseases (12)(13)(14)(15)(16)(17)(18). These cards have also been used in veterinary diagnostics, most recently for the detection of anti-Brucella antibodies in caribou (19)(20)(21).…”

Dried Blood Spots versus Sera for Detection of Rubella Virus-Specific Immunoglobulin M (IgM) and IgG in Samples Collected during a Rubella Outbreak in Peru

“…Recent studies have suggested that filter paper dried blood spots (DBS) are suitable for laboratory detection of measles-specific immunoglobulin M (IgM) (2,3,(6)(7)(8). In this study, we compared the detection of rubella virus-specific IgM and IgG in DBS to their detection in serum samples collected from health care provider-diagnosed rubella patients.…”