Plasmodium falciparum pfhrp2 and pfhrp3 gene deletions among patients enrolled at 100 health facilities throughout Tanzania: February to July 2021.

Plasmodium falciparum with the histidine rich protein 2 gene (pfhrp2) deleted from its genome can escape diagnosis by HRP2-based rapid diagnostic tests (HRP2-RDTs). The World Health Organization (WHO) recommends switching to a non-HRP2 RDT for P. falciparum clinical case diagnosis when pfhrp2 deletion prevalence causes ≥ 5% of RDTs to return false negative results.

Performance of antigen detection for HRP2-based malaria rapid diagnostic tests in community surveys: Tanzania, July-November 2017.

Background: Malaria rapid diagnostic tests (RDTs) based on the detection of the Plasmodium falciparum histidine-rich protein 2 (HRP2) antigen are widely used for detection of active infection with this parasite and are the only practical malaria diagnostic test in some endemic settings. External validation of RDT results from field surveys can confirm appropriate RDT performance.

Methods: A community-based cross-sectional survey was conducted between July and November 2017 enrolling participants of all ages in households from 15 villages in four border regions of Tanzania: Geita, Kigoma, Mtwara and Ruvuma.

Evaluation of a Multiplex Bead Assay against Single-Target Assays for Detection of IgG Antibodies to SARS-CoV-2.

Serological assays for SARS-CoV-2 antibodies must be validated for performance with a large panel of clinical specimens. Most existing assays utilize a single antigen target and may be subject to reduced diagnostic specificity. This study evaluated a multiplex assay that detects antibodies to three SARS-CoV-2 targets.

The use of a chimeric antigen for Plasmodium falciparum and P. vivax seroprevalence estimates from community surveys in Ethiopia and Costa Rica.

Background: In low-transmission settings, accurate estimates of malaria transmission are needed to inform elimination targets. Detection of antimalarial antibodies provides exposure history, but previous studies have mainly relied on species-specific antigens. The use of chimeric antigens that include epitopes from multiple species of malaria parasites in population-based serological surveys could provide data for exposure to multiple Plasmodium species circulating in an area.

Plasmodium falciparum pfhrp2 and pfhrp3 gene deletions among patients in the DRC enrolled from 2017 to 2018.

Rapid diagnostic tests (RDTs) detecting histidine-rich protein 2 (HRP2) and HRP3 are widely used throughout sub-Saharan Africa (SSA) to diagnose Plasmodium falciparum malaria. However, multiple SSA countries have reported pfhrp2 and pfhrp3 (pfhrp2/3) gene deletions. Blood samples (n = 1109) collected from patients with P.

Therapeutic efficacy of artemether-lumefantrine and artesunate-amodiaquine for the treatment of uncomplicated Plasmodium falciparum malaria in Mali, 2015-2016.

Background: The current first-line treatments for uncomplicated malaria recommended by the National Malaria Control Programme in Mali are artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ). From 2015 to 2016, an in vivo study was carried out to assess the clinical and parasitological responses to AL and ASAQ in Sélingué, Mali.

Methods: Children between 6 and 59 months of age with uncomplicated Plasmodium falciparum infection and 2000-200,000 asexual parasites/μL of blood were enrolled, randomly assigned to either AL or ASAQ, and followed up for 42 days.

HRP2 and HRP3 cross-reactivity and implications for HRP2-based RDT use in regions with Plasmodium falciparum hrp2 gene deletions.

Background: The Plasmodium falciparum antigen histidine rich protein 2 (HRP2) is a preferred target for malaria rapid diagnostic tests (RDTs) because of its abundant production by the parasite and thermal stability. As a result, a majority of RDTs procured globally target this antigen. However, previous reports from South America and recent reports from sub-Saharan Africa and Asia indicate that certain P.

Natural infections with different Plasmodium species induce antibodies reactive to a chimeric Plasmodium vivax recombinant protein.

Background: As malaria incidence and transmission in a region decreases, it becomes increasingly difficult to identify areas of active transmission. Improved methods for identifying and monitoring foci of active malaria transmission are needed in areas of low parasite prevalence in order to achieve malaria elimination. Serological assays can provide population-level infection history to inform elimination campaigns.

Community-based surveys for Plasmodium falciparum pfhrp2 and pfhrp3 gene deletions in selected regions of mainland Tanzania.

Background: Histidine-rich protein 2 (HRP2)-based malaria rapid diagnostic tests (RDTs) are effective and widely used for the detection of wild-type Plasmodium falciparum infections. Although recent studies have reported false negative HRP2 RDT results due to pfhrp2 and pfhrp3 gene deletions in different countries, there is a paucity of data on the deletions of these genes in Tanzania.

Methods: A community-based cross-sectional survey was conducted between July and November 2017 in four regions: Geita, Kigoma, Mtwara and Ruvuma.

Seroprevalence of Measles, Rubella, Tetanus, and Diphtheria Antibodies among Children in Haiti, 2017.

In Haiti, measles, rubella, and maternal and neonatal tetanus have been eliminated, but a diphtheria outbreak is ongoing as of 2019. We conducted a nationally representative, household-based, two-stage cluster survey among children aged 5-7 years in 2017 to assess progress toward maintenance of control and elimination of selected vaccine-preventable diseases (VPDs). We stratified Haiti into West region (West department, including the capital city) and non-West region (all other departments).

Prevalence of molecular markers of artemisinin and lumefantrine resistance among patients with uncomplicated Plasmodium falciparum malaria in three provinces in Angola, 2015.

Background: Artemisinin-based combination therapy is the first-line anti-malarial treatment for uncomplicated Plasmodium falciparum infection in Angola. To date, the prevalence of polymorphisms in the pfk13 gene, associated with artemisinin resistance, and pfmdr1, associated with lumefantrine resistance, have not been systematically studied in Angola.

Methods: DNA was isolated from pretreatment and late treatment failure dried blood spots collected during the 2015 round of therapeutic efficacy studies in Benguela, Lunda Sul, and Zaire Provinces in Angola.

Protective efficacy of a Plasmodium vivax circumsporozoite protein-based vaccine in Aotus nancymaae is associated with antibodies to the repeat region.

We have previously reported that Vivax Malaria Protein 001 (VMP001), a vaccine candidate based on the circumsporozoite protein of Plasmodium vivax, is immunogenic in mice and rhesus monkeys in the presence of various adjuvants. In the present study, we evaluated the immunogenicity and efficacy of VMP001 formulated with a TLR9 agonist in a water-in-oil emulsion. Following immunization, the vaccine efficacy was assessed by challenging Aotus nancymaae monkeys with P.

Mosquito infection studies with Aotus monkeys and humans infected with the Chesson strain of Plasmodiun vivax.

Oocyst counts were compared between mosquitoes that fed on humans versus mosquitoes that fed on Aotus monkeys, both of which were infected with the Chesson strain of Plasmodium vivax. Oocyst counts obtained from mosquitoes fed on humans were almost 10-fold higher in number. Mosquitoes were more likely to be infected and with a higher rate of infection when they fed on monkeys before the peak in the asexual parasite count.

Observations on the Uganda I strain of Plasmodium malariae and Plasmodium brasilianum in Aotus and Saimiri monkeys and Anopheles mosquitoes.

Splenectomized Aotus lemurinus griseimembra, A. azarae boliviensis, A. nancymaae, A.

Infection of mosquitoes with Plasmodium falciparum by feeding on humans and on Aotus monkeys.

Of 1,004 positive lots of mosquitoes fed on 229 humans infected with Plasmodium falciparum, 46.2% had 1-10 oocysts/(+)gut, 21.2% had 10-30 oocysts/(+)gut, 22.

The Santa Lucia strain of Plasmodium falciparum in Aotus monkeys.

The Santa Lucia strain of Plasmodium falciparum was studied in 150 Aotus lemurinus griseimembra, 30 A. azarae boliviensis, 103 A. nancymaae, and 121 A.

Studies on the Salvador I strain of Plasmodium vivax in non-human primates and anopheline mosquitoes.

A review is presented on studies conducted in New World monkeys and chimpanzees with the Salvador I strain of Plasmodium vivax. This isolate has been adapted to Aotus and Saimiri (squirrel) monkeys and developed as a model for the testing of antimalarial vaccines. After the injection of 10,000 sporozoites, the median prepatent period in S.

The Chesson strain of plasmodium vivax in humans and different species of Aotus monkeys.

Comparison was made between the parasitemia of Chesson strain Plasmodium vivax in humans and in splenectomized Aotus lemurinus griseimembra, A. nancymaae, A. vociferans, and A.

Transmission of different strains of Plasmodium cynomolgi to Aotus nancymaae monkeys and relapse.

Forty-four splenectomized Aotus nancymaae monkeys were infected with 6 different strains of Plasmodium cynomolgi, 11 via trophozoites and 33 via sporozoites. Sporozoites from Anopheles dirus, Anopheles freeborni, Anopheles gambiae, Anopheles maculatus, and Anopheles stephensi resulted in prepatent periods ranging from 9 to 39 days (median of 15 days). Importantly, relapse was demonstrated in 5 of 5 sporozoite-induced infections with the Rossan strain following treatment with chloroquine.

Observations on the sporozoite transmission of Plasmodium vivax to monkeys.

Saimiri boliviensis monkeys were infected via sporozoites with the Salvador I strain of Plasmodium vivax that had been stored frozen for periods ranging from 12 to 5,312 days. Prepatent periods ranged from 16 to 53 days.

Isolates of Plasmodium inui adapted to Macaca mulatta monkeys and laboratory-reared anopheline mosquitoes for experimental study.

Plasmodium inui is a parasite of macaques and other nonhuman primates in Asia that is studied as a model for the human malaria parasite P. malariae. Presented here are descriptions of the isolation, passage histories into Macaca mulatta monkeys, and infectivity to different Anopheles spp.

Adaptation of a multi-drug resistant strain of Plasmodium falciparum from Peru to Aotus lemurinus griseimembra, A. nancymaae, and A. vociferans monkeys.

A strain of Plasmodium falciparum from Peru was adapted to splenectomized Aotus nancymaae and Aotus vociferans monkeys. The Peru 134/CDC strain of P. falciparum was shown to be resistant to treatment with chloroquine in monkeys and partially resistant to mefloquine and malarone.

Studies on sporozoite-induced and chronic infections with Plasmodium fragile in Macaca mulatta and New World monkeys.

Plasmodium fragile continues to be investigated because of its biologic similarities to the human malaria parasite, Plasmodium falciparum. Two strains of P. fragile are available for study; one strain is able to infect mosquitoes, whereas the other strain is transmissible only by blood inoculation.

Observations on the exoerythrocytic stages of different isolates of Plasmodium cynomolgi in hepatocytes of New World aotus and Saimiri monkeys.

Sporozoites of 3 isolates of Plasmodium cynomolgi dissected from the salivary glands of Anopheles dirus and Anopheles quadrimaculatus were injected intravenously into 9 New World monkeys. Liver stage parasites were demonstrated in all 9 animals; 7 of these animals also produced blood stages after prepatent periods of 9 to 23 days.

Aotus nancymaae as a potential model for the testing of anti-sporozoite and liver stage vaccines against Plasmodium falciparum.

The Santa Lucia strain of Plasmodium falciparum was transmitted to Aotus lemurinus griseimembra, A. azarae boliviensis, A. vociferans, and A.