Search

Most rapid diagnostic tests for Plasmodium falciparum malaria target the Histidine-Rich Proteins 2 and 3 (HRP2 and HRP3). Deletions of the hrp2 and hrp3 genes result in false-negative tests and are a threat for malaria control. A novel assay for molecular surveillance of hrp2/hrp3 deletions was developed based on droplet digital PCR (ddPCR). The assay quantifies hrp2, hrp3, and a control gene with very high accuracy. The theoretical limit of detection was 0.33 parasites/µl. The deletion was reliably detected in mixed infections with wild-type and hrp2-deleted parasites at a density of >100 parasites/reaction. For a side-by-side comparison with the conventional nested PCR (nPCR) assay, 248 samples were screened in triplicate by ddPCR and nPCR. No deletions were observed by ddPCR, while by nPCR hrp2 deletion was observed in 8% of samples. The ddPCR assay was applied to screen 830 samples from Kenya, Zanzibar/Tanzania, Ghana, Ethiopia, Brazil, and Ecuador. Pronounced differences in the prevalence of deletions were observed among sites, with more hrp3 than hrp2 deletions. In conclusion, the novel ddPCR assay minimizes the risk of false-negative results (i.e., hrp2 deletion observed when the sample is wild type), increases sensitivity, and greatly reduces the number of reactions that need to be run.

Author(s): Aita Signorell, Phyllis Awor, Jean Okitawutshu, Antoinette Tshefu, Elizabeth Omoluabi, Manuel W. Hetzel, Proscovia Athieno, Joseph Kimera, Gloria Tumukunde, Irene Angiro, Jean-Claude Kalenga, Babatunde K. Akano, Kazeem Ayodeji, Charles [...]

Background For a full treatment course of severe malaria, community-administered pre-referral rectal artesunate (RAS) should be completed by post-referral treatment consisting of an injectable antimalarial and oral artemisinin-based combination therapy (ACT). This study aimed to assess compliance with this treatment recommendation in children under 5 years. Methods and findings This observational study accompanied the implementation of RAS in the Democratic Republic of the Congo (DRC), Nigeria, and Uganda between 2018 and 2020. Antimalarial treatment was assessed during admission in included referral health facilities (RHFs) in children under 5 with a diagnosis of severe malaria. Children were either referred from a community-based provider or directly attending the RHF. RHF data of 7,983 children was analysed for appropriateness of antimalarials; a subsample of 3,449 children was assessed additionally for dosage and method of ACT provision (treatment compliance). A parenteral antimalarial and an ACT were administered to 2.7% (28/1,051) of admitted children in Nigeria, 44.5% (1,211/2,724) in Uganda, and 50.3% (2,117/4,208) in DRC. Children receiving RAS from a community-based provider were more likely to be administered post-referral medication according to the guidelines in DRC (adjusted odds ratio (aOR) = 2.13, 95% CI 1.55 to 2.92, P < 0.001), but less likely in Uganda (aOR = 0.37, 95% CI 0.14 to 0.96, P = 0.04) adjusting for patient, provider, caregiver, and other contextual factors. While in DRC, inpatient ACT administration was common, ACTs were often prescribed at discharge in Nigeria (54.4%, 229/421) and Uganda (53.0%, 715/1,349). Study limitations include the unfeasibility to independently confirm the diagnosis of severe malaria due to the observational nature of the study. Conclusions Directly observed treatment was often incomplete, bearing a high risk for partial parasite clearance and disease recrudescence. Parenteral artesunate not followed up with oral ACT constitutes an artemisinin monotherapy and may favour the selection of resistant parasites. In connection with the finding that pre-referral RAS had no beneficial effect on child survival in the 3 study countries, concerns about an effective continuum of care for children with severe malaria seem justified. Stricter compliance with the WHO severe malaria treatment guidelines is critical to effectively manage this disease and further reduce child mortality. Trial registration ClinicalTrials.gov (NCT03568344)., Author(s): Aita Signorell 1,2,*, Phyllis Awor 3, Jean Okitawutshu 1,2,4, Antoinette Tshefu 4, Elizabeth Omoluabi 5, Manuel W. Hetzel 1,2, Proscovia Athieno 3, Joseph Kimera 3, Gloria Tumukunde 3, Irene [...]

Objective To investigate changes in malaria prevalence in Papua New Guinea after the distribution of long-lasting Insecticide-treated nets, starting in 2004, and the introduction of artemisinin-based combination therapy in 2011. Methods Two malaria surveys were conducted in 2010-2011 and 2013-2014. They included 77 and 92 randomly selected villages, respectively. In each village, all members of 30 randomly selected households gave blood samples and were assessed for malaria infection by light microscopy. In addition, data were obtained from a malaria survey performed in 2008-2009. Results The prevalence of malaria below 1600 m in altitude decreased from 11.1% (95% confidence interval, CI: 8.5-14.3) in 2008-2009 to 5.1% (95% CI 3.6-7.4) in 2010-2011 and 0.9% (95% CI 0.6-1.5) in 2013-2014. Prevalence decreased with altitude. Plasmodium falciparum was more common than P. vivax overall, but not everywhere, and initially the prevalence of P. vivax infection decreased more slowly than P. falciparum infection. Malaria infections were clustered in households. In contrast to findings in 2008-2009, no significant association between net use and prevalence was found in the later two surveys. The prevalence of both fever and splenomegaly also decreased but their association with malaria infection became stronger. Conclusion Large-scale insecticide-treated net distribution was associated with an unprecedented decline in malaria prevalence throughout Papua New Guinea, including epidemic-prone highland areas.The decline was accompanied by broader health benefits, such as decreased morbidity. Better clinical management of nonmalarial fever and research into residual malaria transmission are required. Objectif Etudier les changements observes a legard de la prevalence du paludisme en Papouasie-Nouvelle-Gulnee suite a la distribution, depuis 2004, de moustiquaires impregnees d'Insecticides de longue duree et a l'introduction, depuis 2011, d'une combinaison therapeutique a base d'artemisinine. Methodes Deux enquetes portant sur le paludisme ont ete menees en 2010-2011 et 2013-2014. Elles incluaient respectivement 77 et 92 villages, selectionnes d'une maniere aleatoire. Dans chacun de ces villages, tous les membres de 30 foyers selectionnes aleatoirement ont donne des echantillons sanguins et ete soumis a un test de depistage de l'infection palustre par microscopie optique. Des donnees ont par ailleurs ete tirees d'une enquete sur le paludisme realisee en 2008-2009. Resultats La prevalencedu paludisme a moins de 1600 m d'altitude est passee de 11,1 % (intervalle de confiance, IC, a 95%: 8,5-14,3) en 2008-2009 a 5,1 % (IC a 95%: 3,6-7,4) en 2010-2011 et 0,9% (IC a 95%: 0,6-1,5) en 2013-2014. La prevalence diminuait avec l'altitude. Plasmodium falciparum n'etait pas systematiquement plus courant que R vivax, mais l'etait dans l'ensemble et, dans un premier temps, la prevalence de l'infection a R vivax a diminue plus lentement que la prevalence de l'Infection a P. falciparum. Les infections palustres ont ete regroupees par foyers. Contrairement a ce qu'indiquaient les resultats obtenus en 2008-2009, aucune correlation significative entre l'utilisation d'une moustiquaire et la prevalence n'a ete constatee dans le cadre des deux dernieres enquetes. Les prevalences de la fievre et de la splenomegalle ont egalement diminue, mais leur correlation avec l'infection palustre est devenue plus forte. Conclusion La distribution a grande echelle de moustiquaires impregnees d'insecticides a ete associee a un declin sans precedent de la prevalence du paludisme dans l'ensemble de la Papouasie-Nouvelle-Guinee, et notamment dans les reglons montagneuses sujettes aux epidemies. Ce declin s'est accompagne d'autres bienfaits sur la sante, et notamment d'une diminution de la morbidite. Il est necessaire d'ameliorer la prise en charge clinique de la fievre non palustre ainsi que les recherches sur la transmission residuelle du paludisme. Objetivo Investigar los cambios en la prevalencia de la malaria en Papua Nueva Guinea tras la distribucion de mosquiteros tratados con insecticida de larga duracion, a partir de 2004, y la introduccion de terapias combinadas basadas en la artemisinina en 2011. Metodos Se llevaron a cabo dos encuestas sobre la malaria en 2010-2011 y 2013-2014. Incluian 77y 92 aldeas seleccionadas al azar, respectivamente. En cada aldea, todos los miembros de 30 hogares seleccionados al azar dieron muestras de sangre y se evaluaron de infeccion de malaria con microscopio optico. Ademas, se obtuvieron datos de la encuesta sobre la malaria realizada en 2008-2009. Resultados La prevalencia de la malaria por debajo de 1600 m de altitud descendio del 11.1% (intervalo de confidencia (IC) del 95%: 8.5-14.3) en 2008-2009 al 5.1% (95% IC 3.6-7.4) en 2010-2011 y 0.9% (95% IC 0.6-1.5) en 2013-2014. La prevalencia descendia con la altitud. Plasmodium falciparum fue mas comun que P. vivax en general, pero no en todas partes e inicialmente la prevalencia de la infeccion P. vivax descendio mas lentamente que la infeccion P. falciparum. Las infecciones de malaria se agruparon en los hogares. Al contrario que los hallazgos en 2008-2009, no se encontro ninguna asociacion significativa entre el uso del mosquitero y la prevalencia en las dos ultimas encuestas. La prevalencia tanto de la fiebre como de la esplenomegalia tambien descendio, pero su asociacion con la infeccion de malaria se hizo mas fuerte. Conclusion La distribucion de mosquiteros tratados con insecticida a gran escala se asocio con un descenso sin precedentes en la prevalencia de la malaria en toda Papua Nueva Guinea, incluidas las areas altas con propension a causar epidemias. El descenso estuvo acompanado de beneficios saludables mas amplios, como el descenso de la morbilidad. Se requieren una mejor gestion clinica de la fiebre no relacionada con la malaria y la Investigacion de la transmision residual de la malaria., Introduction Historically, malaria has been endemic throughout Papua New Guinea, except in highland areas over 1600 m, where temperatures are low and there is no stable local transmission, though imported [...]