Whatman 903

The two papers selected for performance evaluation included the Whatman 903 and FTA classic cards (GE Healthcare Bio-Sciences, Pittsburgh, PA). S. pneumoniae isolates were suspended in phosphate buffered saline (PBS) to 0.5 McFarland, equivalent to 10⁸ CFU/mL [13 ]. These isolates were spiked into whole blood collected in sodium citrate tubes, and ten-fold serial dilutions of whole blood were prepared ranging from 0.5-5x10⁴ CFU/μL of blood. In addition, dilutions at 2 and 20 CFU/μL were prepared, based on previous studies identifying a detection limit in bacterial PCR within this range [14 (link)–16 (link)]. Hence, there were a total of 8 dilutions tested per serotype. Next, 100 μL from each dilution was spotted onto Whatman 903 and FTA filter paper until soaked through. Blood spots were allowed to dry overnight on the benchtop and then stored in sealed plastic bags at room temperature. We used as negative controls 9 strains of other bacterial species that are associated with invasive disease, as well as non-spiked samples of whole blood.

P. vivax isolates were collected between 2009 and 2020 from six different geographic sites in China. Finger-prick blood was spotted on filter paper (Whatman™ 903, GE Healthcare, USA) and dried. All patients were diagnosed as P. vivax using a microscopic examination and reconfirmed using polymerase chain reaction (PCR) by amplifying the small-subunit rRNA gene of Plasmodium spp [20 (link)]. Written informed consent was obtained from the patients prior to blood collection. This study was approved by the Ethical Review Committee of National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention.

Fifty microliters of venous whole-blood collected in ethylene diamine tetraacetic acid tube was spotted onto the filter paper card (Whatman 903; GE Healthcare Europe, Freiburg, Germany). The filter paper was dried at ambient temperature, stored in an individual sealed plastic bag with a desiccant package at − 20 °C. DBS samples collected from the Montpellier University Hospitals were stored at − 20 °C until used. Samples from the Viet Tiep hospital in Haiphong were defrosted and transported at ambient temperature during 72 h, and stored again at − 20 °C for a mean duration of 18 months until HCV RNA and HCVcAg testing.

Whole blood was drawn into EDTA or CPT tubes (Vacutainer, BD). 2 × 25 μL whole blood was spotted directly onto Whatman 903 filter paper (GE Healthcare) before the remaining whole blood was centrifuged within 30–40 minutes after collection to obtain plasma (EDTA tubes at 3000 × g for 10 min at room temperature (RT), and CPT tubes at 1800 × g for 20 min at RT). Afterwards, 2 × 25 µL plasma was spotted onto another Whatman 903 filter paper. The remaining plasma was stored at −80 °C. The filter papers were left to dry for 3–4 hours at RT before placed in zip-locked plastic bags with desiccants, and stored at −20 °C. The filter paper cards were transported at room temperature and the plasma samples on dry ice to Bergen, Norway, for analysis.

Two blood spots were collected from each participant, transferred on filter paper (Whatman #903, GE Healthcare) labelled with the participant’s study code and date. Each filter paper was dried individually to avoid any chance of contamination. The samples were then stored in small plastic bags with desiccant and transported to the Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna (MUV), Vienna, Austria for molecular analysis.

EMIS-2015 was a cross-sectional survey, which used a two-stage cluster sampling methodology [20 ]. Enumeration Areas (EA), the sampling unit, were selected proportional to population size and 25 households were selected by simple random sampling from each EA. Demographic, socioeconomic, malaria prevention, and malariometric data were also collected in the selected households. All children under 5 years of age in selected households and persons of all ages in every 4th household were eligible for biological sample collection and testing [20 ]. Whole blood from a single finger prick from consenting individuals (with or without fever) was collected for Plasmodium infection identification by RDT and microscopy, haemoglobin testing (Hemocue Hb 201+, Hemocue AB, Ängelholm, Sweden) and for collection of DBS samples. Whatman 903 (GE Healthcare, Pittsburgh, PA) filter paper cards were used for DBS collection. These were air dried, individually packed in a plastic bag together with a desiccant and stored at − 20 °C at EPHI before they were sent to the U.S. Centers for Disease Control and Prevention (CDC) in, Atlanta, Georgia, for processing.

During screening, a G6PD test was carried out on all patients, and a pregnancy test on all adult females. At enrolment, patients had a medical examination, a questionnaire was completed, and a capillary blood sample was collected for blood film examination and Hb measurement. Three 50-μl capillary blood spots were stored on filter papers (Whatman 903 and Whatman 3; GE Healthcare Biosciences, Westborough, MA, US). In consenting patients, venous blood samples were collected at enrolment and, if malaria recurred, on the day of recurrence.
Patients were asked to return for routine assessment daily for the first 3 d, then weekly until day 42, and thereafter monthly for an additional 10 mo. Patients were also asked to return to the clinic if they had signs or symptoms consistent with malaria, and those with recurrent clinical P. vivax malaria occurring more than 14 d following treatment received the same treatment as that allocated at enrolment, with subsequent follow-up according to the initial schedule.
A follow-up medical exam and blood film examination was undertaken on days 1, 2, 3, 7, 14, 21, 28, 35, and 42, and monthly thereafter for 10 mo. Adverse drug reactions and concomitant medications were recorded at every visit, with repeat Hb concentration measured on days 3, 7, 14, 21, 28, 35, and 42.