Persistent transmission of Plasmodium malariae and Plasmodium ovale species in an area of declining Plasmodium falciparum transmission in eastern Tanzania.

A reduction in the global burden of malaria over the past two decades has encouraged efforts for regional malaria elimination. Despite the need to target all Plasmodium species, current focus is mainly directed towards Plasmodium falciparum, and to a lesser extent P. vivax. There is a substantial lack of data on both global and local transmission patterns of the neglected malaria parasites P. malariae and P. ovale spp. We used a species-specific real-time PCR assay targeting the Plasmodium 18s rRNA gene to evaluate temporal trends in the prevalence of all human malaria parasites over a 22-year period in a rural village in Tanzania.We tested 2897 blood samples collected in five cross-sectional surveys conducted between 1994 and 2016. Infections with P. falciparum, P. malariae, and P. ovale spp. were detected throughout the study period, while P. vivax was not detected. Between 1994 and 2010, we found a more than 90% reduction in the odds of infection with all detected species. The odds of P. falciparum infection was further reduced in 2016, while the odds of P. malariae and P. ovale spp. infection increased 2- and 6-fold, respectively, compared to 2010. In 2016, non-falciparum species occurred more often as mono-infections. The results demonstrate the persistent transmission of P. ovale spp., and to a lesser extent P. malariae despite a continued decline in P. falciparum transmission. This illustrates that the transmission patterns of the non-falciparum species do not necessarily follow those of P. falciparum, stressing the need for attention towards non-falciparum malaria in Africa. Malaria elimination will require a better understanding of the epidemiology of P. malariae and P. ovale spp. and improved tools for monitoring the transmission of all Plasmodium species, with a particular focus towards identifying asymptomatic carriers of infection and designing appropriate interventions to enhance malaria control.

Performance of the Simplexa™ Flu A/B & RSV Direct Kit on respiratory samples collected in saline solution.

BACKGROUND: Molecular assays for diagnosis of influenza A, influenza B, and respiratory syncytial virus (RSV) with short turnaround time are of considerable clinical importance. We have evaluated the diagnostic performance of the Simplexa(™) Flu A/B & RSV Direct Kit, which has a run time of 60 min, using different types of respiratory samples collected from patients with a suspected respiratory tract infection, including materials not previously evaluated on this kit. METHODS: In total, 210 clinical respiratory samples were analyzed using both the Simplexa direct assay and a laboratory-developed assay (LDA). The 210 clinical samples included 99 nasopharyngeal aspirates collected in 0.9% saline, 91 nasopharyngeal swabs in Σ-Virocult transport medium, 9 tracheal secretions, 8 bronchoalveolar lavages (BAL), and 3 other respiratory sample materials. RESULTS: The specificity of the Simplexa assay, using the LDA as gold standard and excluding secondary viral findings, was 100% for all three viruses, whereas the sensitivity was 94.0% for influenza A (47/50), 90.7% for influenza B (49/54), and 90.1% for RSV (46/51), respectively. Discordant results were only observed for samples with cycle threshold values (Ct) > 31 in the LDA. The Simplexa assay generated higher Ct values than the LDA for all three viruses and performed equally well on nasopharyngeal swabs and aspirates. CONCLUSIONS: The short run time of the Simplexa direct assay, in combination with high specificity and good sensitivity regarding the sample materials used in this study, make it an interesting option for rapid detection of these three important viral respiratory pathogens in a variety of clinical sample materials.