Severe Anemia Observed in a Chinese Patient with COVID-19 and Plasmodium Falciparum Malaria Co-Infection.

BACKGROUND: COVID-19 and malaria share some similar symptoms such as fever, difficulty in breathing, fatigue, and headaches of acute onset. With overlapping symptoms and travel history significant for COVID-19 and malaria, healthcare systems and professionals will face a great challenge in the case of COVID-19 and malaria co-infection. METHODS: Here we presented a patient with COVID-19 infection and refractory anemia of unknown reason. A diagnostic test for malaria was later performed. RESULTS: The patient was ultimately diagnosed with COVID-19 and plasmodium falciparum malaria co-infection. He recovered gradually after receiving anti-malaria treatment. CONCLUSIONS: The present case highlights the danger of focusing only on a diagnosis of COVID-19, reminding clinicians to be vigilant about the possibility of co-infections.

Automated Recognition of Plasmodium falciparum Parasites from Portable Blood Levitation Imaging.

In many malaria-endemic regions, current detection tools are inadequate in diagnostic accuracy and accessibility. To meet the need for direct, phenotypic, and automated malaria parasite detection in field settings, a portable platform to process, image, and analyze whole blood to detect Plasmodium falciparum parasites, is developed. The liberated parasites from lysed red blood cells suspended in a magnetic field are accurately detected using this cellphone-interfaced, battery-operated imaging platform. A validation study is conducted at Ugandan clinics, processing 45 malaria-negative and 36 malaria-positive clinical samples without external infrastructure. Texture and morphology features are extracted from the sample images, and a random forest classifier is trained to assess infection status, achieving 100% sensitivity and 91% specificity against gold-standard measurements (microscopy and polymerase chain reaction), and limit of detection of 31 parasites per µL. This rapid and user-friendly platform enables portable parasite detection and can support malaria diagnostics, surveillance, and research in resource-constrained environments.

Rapid magneto-enzyme-linked immunosorbent assay for ultrasensitive protein detection.

Protein-based diagnostics are the standard of care for screening and diagnosing a broad range of diseases and medical conditions. The current gold standard method for quantifying proteins in clinical specimens is the enzyme-linked immunosorbent assay (ELISA), which offers high analytical sensitivity, can process many samples at once, and is widely available in many diagnostic laboratories worldwide. However, running an ELISA is cumbersome, requiring multiple liquid handling and washing steps, and time-intensive (∼2 - 4 h per test). Here, we demonstrate a unique magneto-ELISA that utilizes dually labeled magnetic nanoparticles (DMPs) coated with horseradish peroxidase (HRP) and an HRP-conjugated detection antibody, enabling rapid immunomagnetic enrichment and signal amplification. For proof of concept, this assay was used to detect Plasmodium falciparum histidine-rich protein 2 (PfHRP2), a malaria parasite biomarker, which exhibited a lower limit of detection of 2 pg mL-1 (33 fM) in human serum. Measurements of PfHRP2 in clinical blood samples from individuals with and without P. falciparum infection revealed that this magneto-ELISA offers a superior diagnostic accuracy compared to a commercial PfHRP2 ELISA kit. We also demonstrate the versatility of this platform by adapting it for the detection of SARS-CoV-2 nucleocapsid protein, which could be detected at concentrations as low as 8 pg mL-1 (174 fM) in human serum. In addition to its high analytical performance, this assay can be completed in 30 min, requires no specialized equipment, and is compatible with standard microplate readers and ELISA protocols, allowing it to integrate readily into current clinical practice.

Pandemic-related delay of falciparum malaria diagnosis in a traveller leading to cerebral malaria.

We report the case of a 29-year-old male in whom COVID-19 concerns led to a delayed diagnosis of falciparum malaria. The patient developed symptoms of cerebral malaria with cytotoxic lesions of the corpus callosum in magnetic resonance imaging.

Failure of rapid diagnostic tests in Plasmodium falciparum malaria cases among travelers to the UK and Ireland: Identification and characterisation of the parasites.

OBJECTIVES: Our objective was to systematically investigate false-negative histidine-rich protein 2 rapid diagnostic tests (HRP2-RDT) in imported Plasmodium falciparum malaria cases from travelers to the UK and the Republic of Ireland (RoI). METHODS: Five imported malaria cases in travellers returning to the UK and RoI from East Africa were reported to the PHE Malaria Reference Laboratory as negative according to histidine-rich protein (HRP2)-RDT. The cases were systematically investigated using microscopic, RDT, molecular, genomic, and in in vitro approaches. RESULTS: In each case, HRP2-RDT was negative, whereas microscopy confirmed the presence of P. falciparum. Further analysis revealed that the genes encoding HRP2 and HRP3 were deleted in three of the five cases. Whole-genome sequencing in one of these isolates confirmed deletions in P. falciparum chromosomes 8 and 13. Our study produced evidence that the fourth case, which had high parasitemia at clinical presentation, was a rare example of antigen saturation ('prozone-like effect'), leading to a false negative in the HRP2-RDT, while the fifth case was due to low parasitemia. CONCLUSIONS: False-negative HRP2-RDT results with P. falciparum are concerning. Our findings emphasise the necessity of supporting the interpretation of RDT results with microscopy, in conjunction with clinical observations, and sets out a systematic approach to identifying parasites carrying pfhrp2 and pfhrp3 deletions.

Emergence of Undetectable Malaria Parasites: A Threat under the Radar amid the COVID-19 Pandemic?

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. Surveillance of such parasites is dependent on identifying false-negative RDT results among suspected malaria cases, a task made more challenging during the current pandemic because of the overlap of symptoms between malaria and COVID-19, particularly in areas of low malaria transmission. Here, we share our perspective on the emergence of P. falciparum parasites lacking HRP2 and HRP3, and the surveillance needed to identify them amid the COVID-19 pandemic.