Stochastic Analysis of a Closed SIS Malaria Model

A pseudo-equilibrium approximation model for the dynamics and transmission of malaria in human populations is studied. A stochastic version of this model is then formulated and analyzed based on the fact that the disease is endemic and therefore has a basic reproduction number greater than unity. Using a comprehensive theory on asymptotic approximation techniques in recurrent epidemics, approximations for the quasi-stationary distribution and the time to extinction are derived. We find that whenever the reproduction number is greater than unity, the time to extinction of the disease is exponentially distributed with positive exponent and therefore becomes very large within very large human population sizes. We then interpret the fact that it has been difficult to eradicate malaria with the exponentially large time to extinction of the number of infected individuals in the population of humans.Keywords: Pseudo-equilibrium Approximation, Stationary Distribution, Quasi-stationary Distributio

Effects of drug policy changes on the evolution of Pfmdr1 and Pfcrt resistance molecular markers of Plasmodium falciparum to chloroquine in Bangui, Central African Republic

<p>Malaria remains one of the main threats to public health. The emergence of drug resistance is a major obstacle to the fight against malaria. Due to the spread of parasites resistant to antimalarial drugs, treatment guidelines for malaria in the Central African Republic have evolved from monotherapy to artemisinin-based combination therapy. Prediction of decrease or increase in antimalarial susceptibility and fixation of multidrug resistance genotypes is essential in the fight against malaria. To assess the impact of drug policy, we examined molecular changes in the chloroquine-associated Pfcrt and Pfmdr1 resistance marker to monitor the evolution of mutant alleles since the withdrawal of chloroquine from the market following the adoption of Artemisinin based Combined Therapies (ACT) in the Central African Republic. To assess the evolution of these markers, dried blood spots were prepared from 138 children diagnosed positive for plasmodium falciparum malaria by rapid diagnostic test. DNA was then extracted from the blood and genotyped. The chi-square test was used to check for the association between the period of withdrawal and the time of sample analysis. The alleles conferring resistance to chloroquine in the Pfmdr1-86Y genotype showed a significant increase from 1.72% in 2010 to 99.1% in 2021, on the other hand, they was a reduction in the mutant alleles Pfcrt-76T and an increase in mixed infection from 0% in 2010 to 3.48% in 2021 (P<0.05). The results demonstrated a clear increase in the pfmdr1 resistant marker.  </p&gt

Assessing Asymptomatic Malaria Carriage of Plasmodium falciparum and Non-falciparum Species in Children Resident in Nkolbisson, Yaoundé, Cameroon

Malaria is still a threat to public health as it remains the first endemic disease in the world. It is a pervasive parasitic disease in tropical and subtropical regions where asymptomatic malaria infection among humans serves as a significant reservoir for transmission. A rapid and correct diagnosis is considered to be an important strategy in the control of the disease especially in children, who are the most vulnerable group. This study assessed the prevalence of asymptomatic malaria in children at the Nkolbisson health area in Yaoundé, Cameroon. A cross-sectional study design and a convenience sampling plan were used. A total of 127 participants were recruited after informed and signed consent from parents and/or guardians. Blood samples were collected by finger-pricking and venipuncture from children aged 6 months to 10 years and then screened for asymptomatic parasitemia by a rapid diagnostic test (RDT), light microscopy (LM) staining with Giemsa and 18S rRNA polymerase chain reaction (PCR) for speciation. The data were analyzed using SPSS version 20 software. The study identified 85 children who were positive from the PCR, 95 positive from the RDT and 71 from the LM, revealing a malaria prevalence of 66.9%, 74.8% and 55.9%, respectively. The prevalence was not observed to be dependent on the sex and age group of the participants. Plasmodium falciparum was the predominant species followed by Plasmodium malariae and then Plasmodium ovale. The RDT and LM had the same sensitivity (90.6%) with a slight difference in their specificity (RDT: 57.1%; LM: 54.8%). The RDT also demonstrated higher positive and negative predictive values compared with those of the LM

Effectiveness and safety of artesunate–amodiaquine versus artemether–lumefantrine for home-based treatment of uncomplicated Plasmodium falciparum malaria among children 6–120 months in Yaoundé, Cameroon:a randomized trial

BACKGROUND: Many studies have reported high efficacy and safety of artesunate-amodiaquine (AS-AQ) and artemether-lumefantrine (AL) when administered under direct observation in Cameroon. There is paucity of data to support their continuous use in home-based treatment of uncomplicated Plasmodium falciparum malaria in Cameroon. Hence, this study aimed to assess the effectiveness and safety of AS-AQ versus AL for home-based treatment of uncomplicated P. falciparum malaria among children 6–120 months in Yaoundé, Cameroon. METHODS: A two-arm, open-label, randomized, controlled trial comparing the equivalence of AS-AQ (experimental group) and AL (control group) was carried out from May 2019 to April 2020 at two secondary hospitals in Yaoundé. Participants were randomized to receive either AS-AQ or AL. After the first dose, antimalarial drugs were given at home, rather than under direct observation by a study staff. The conventional on-treatment and post-treatment laboratory and clinical evaluations were not done until day 3 of the full antimalarial treatment course. The evaluation of effectiveness was mainly based on per protocol polymerase chain reaction adjusted adequate clinical and parasitological response (PP PCR adjusted ACPR) on day 28 post-treatment. Safety was based on assessment of adverse events (AEs) and severe adverse events (SAEs) from day 1 to day 28. RESULTS: A total of 242 children were randomized to receive AS-AQ (n = 114) and AL (n = 128). The PP PCR adjusted day 28 cure rates were [AS-AQ = 96.9% (95% CI, 91.2–99.4) versus AL = 95.5% (95% CI, 89.9–98.5), P = 0.797]. Expected mild to moderate adverse events were reported in both arms [AS-AQ = 83 (84.7%) versus AL = 99 (86.1%), P = 0.774]. The most common adverse events included: transient changes of hematologic indices and fever. CONCLUSIONS: This study demonstrated that AS-AQ and AL are effective and safe for home management of malaria in Yaoundé. The evidence from this study supports the parallel use of the two drugs in routine practice. However, the findings from this study do not describe the likely duration of antimalarial effectiveness in holoendemic areas where multiple courses of treatment might be required. Trial registration: This study is a randomized controlled trial and it was retrospectively registered on 23/09/2020 at ClinicalTrials.gov with registration number NCT04565184. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12879-022-07101-2