Surveillance of low-density infections and of exposure to vectors is crucial to understand where malaria elimination might be feasible, and where the risk of outbreaks is high. Archived rapid diagnostic tests (RDTs), used by national malaria control and elimination programs for clinical diagnosis, present a valuable, yet rarely used resource for in-depth studies on malaria epidemiology.
rapid diagnostic tests
Low-density (LD) Plasmodium infections are missed by standard malaria rapid diagnostic tests (standard mRDT) when the blood antigen concentration is below the detection threshold. The clinical impact of these LD infections is unknown. This study investigates the clinical presentation and outcome of untreated febrile children with LD infections attending primary care facilities in a moderately endemic area of Tanzania.
In Togo, the National Malaria Control Programme, in collaboration with the Global Fund to Fight AIDS, Tuberculosis and Malaria, has implemented a pilot study for malaria sentinel surveillance since 2017, which consists of collecting information in real time and analysing this information for decision-making. The first 20 months of malaria morbidity and mortality trends, and malaria case management in health facilities included in the surveillance were assessed.
The recent expansion of tools designed to accurately quantify malaria parasite-produced antigens has enabled us to evaluate the performance of rapid diagnostic tests (RDTs) as a function of the antigens they detect—typically histidine rich protein 2 (HRP2) or lactate dehydrogenase (LDH).
Rapid diagnostic tests are first line assays for diagnosing infectious diseases, such as malaria. To minimize false positive and false negative test results in population screening assays, high quality reagents and well characterized antigens and antibodies are needed. An important property of antigen - antibody binding is recognition specificity which best can be estimated by mapping an antibody's epitope on the respective antigen.
Back in March when COVID-19 hit, some scientists worried malaria cases and deaths might soar. African countries went on lockdown; worried about mass gatherings, they suspended campaigns to distribute mosquito-fighting bed nets. Fears abounded that with clinics overwhelmed by COVID-19, patients would be unable to get treatment for malaria.
Malaria rapid diagnostic tests (RDTs) are largely responsible for the gains made in the proportion of malaria cases confirmed with a parasitological test. However, quality assurance programs to support their use remain a challenge. A dried tube specimen (DTS) method was developed that showed potential for use as a stable source of quality control (QC) sample for RDTs and for use in external quality assessments or proficiency testing (PT). DTS was further assessed with focus on sample stability under field settings in Benin and Liberia.
Rapid diagnostic tests (RDTs) play a critical role in malaria diagnosis and control. The emergence of Plasmodium falciparum parasites that can evade detection by RDTs threatens control and elimination efforts. These parasites lack or have altered genes encoding histidine-rich proteins (HRPs) 2 and 3, the antigens recognized by HRP2-based RDTs.
In low-malaria-transmission areas of Madagascar, annual parasite incidence (API) from routine data has been used to target indoor residual spraying at sub-district commune levels. To assess validity of this approach, we conducted school-based serological surveys and health facility (HF) data quality assessments in seven districts to compare API to “gold-standard” commune-level serological measures.
Histidine-rich protein 2 (HRP2) detecting rapid diagnostic tests (RDTs) have played an important role in enabling prompt malaria diagnosis in remote locations. However, emergence of pfhrp2 deleted parasites is threatening the efficacy of RDTs, and the World Health Organization (WHO) has highlighted surveillance of these deletions as a priority. Nested PCR is used to confirm pfhrp2 deletion but is costly and laborious.