Concurrent Infection With Dengue and Chikungunya Viruses in Humans and Mosquitoes: A Field Survey in Lower Moshi, Tanzania

Introduction: Dengue and Chikungunya have re-emerged as important diseases of global concern. Co-infections with Dengue virus (DENV) and Chikungunya virus (CHIKV) could have serious outcomes if not diagnosed and managed optimally. However, the key focal points for the maintenance of CHIKV and DENV infections and the extent of their co-infection remain poorly understood in many geo-ecologically distinct parts of Tanzania.Objective: We aimed to comparatively examine the prevalence and factors for seropositivity to DENV and CHIKV and their infection rates in humans and mosquitoesMethods: A cross-sectional study was performed in the Lower Moshi area of the Kilimanjaro region from April to July 2020. DENV and CHIKV exposure was determined by detecting IgM to the viruses using enzyme linked immunosorbent assay whereas infection was determined by real time quantitative polymerase chain reaction (RT-qPCR) assay.Results: Insecticide Treated Bed Net (ITN) use (χ2=3.504; p< 0.05), being ≥7 individuals living in the same household (χ2=4.655; p<0.05) and a recent travel to an urban destination (χ2=3.39; p< 0.05) were the only factors associated with CHIKV seropositivity. ITN use was the only factor associated with CHIKV infection (χ2=5.204; p<0.05). A recent travel to an urban destination (χ2=4.401; p< 0.05) was the only factor associated with DENV seropositivity. Five (1.5%) Ae. aegypti pools were positive for CHIKV whereas 1 (0.3%) was positive for DENV. Two Cx. pipiens, pools (1.9%) were positive for CHIKV. None of the Cx. pipiens mosquitoes was positive for DENV. No associations between DENV and CHIKV seropositivity was observed in humans but DENV infection was strongly associated with CHIKV infection (χ2 = 238.45; p<0.01). CHIKV infection was observed to be consistently higher in both, humans and mosquitoes.Conclusion: Detection of DENV and CHIKV in both humans and vector mosquitoes confirms that both viruses are actively circulating in the Lower Moshi area of Kilimanjaro region in Tanzania. Our findings point out the Lower Moshi area as a potential focal point for the maintenance of the two viruses and possibly other vector borne viruses. We call upon sustained active surveillance of arboviruses and other re-emerging infections to be better prepared for possible outbreaks by the viruses

Cellulose filtration of blood from malaria patients for improving <i>ex vivo</i> growth of <i>Plasmodium falciparum</i> parasites

BACKGROUND: Establishing in vitro Plasmodium falciparum culture lines from patient parasite isolates can offer deeper understanding of geographic variations of drug sensitivity and mechanisms of malaria pathogenesis and immunity. Cellulose column filtration of blood is an inexpensive, rapid and effective method for the removal of host factors, such as leucocytes and platelets, significantly improving the purification of parasite DNA in a blood sample. METHODS: In this study, the effect of cellulose column filtration of venous blood on the initial in vitro growth of P. falciparum parasite isolates from Tanzanian children admitted to hospital was tested. The parasites were allowed to expand in culture without subcultivation until 5 days after admission or the appearance of dead parasites and parasitaemia was determined daily. To investigate whether the filtration had an effect on clonality, P. falciparum merozoite surface protein 2 genotyping was performed using nested PCR on extracted genomic DNA, and the var gene transcript levels were investigated, using quantitative PCR on extracted RNA, at admission and 4 days of culture. RESULTS: The cellulose-filtered parasites grew to higher parasitaemia faster than non-filtered parasites seemingly due to a higher development ratio of ring stage parasites progressing into the late stages. Cellulose filtration had no apparent effect on clonality or var gene expression; however, evident differences were observed after only 4 days of culture in both the number of clones and transcript levels of var genes compared to the time of admission. CONCLUSIONS: Cellulose column filtration of parasitized blood is a cheap, applicable method for improving cultivation of P. falciparum field isolates for ex vivo based assays; however, when assessing phenotype and genotype of cultured parasites, in general, assumed to represent the in vivo infection, caution is advised. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12936-017-1714-2) contains supplementary material, which is available to authorized users

Plasma Ang2 and ADAM17 levels are elevated during clinical malaria; Ang2 level correlates with severity and expression of EPCR-binding PfEMP1

The pathogenesis of Plasmodium falciparum malaria involves a complex interplay between parasite adhesion and inflammatory response that includes release of cytokines and activation of the endothelium with accompanying release of Angiopoitin 2 (Ang2) to the plasma. A-disintegrin and metalloproteinase 17 (ADAM17) is a protein responsible for releasing cytokines, including Tumor Necrosis Factor α (TNFα), and shedding of adhesion proteins. In this study, we show that plasma levels of ADAM17 are increased in Tanzanian children hospitalized with a malaria infection compared with asymptomatic children but similar to children hospitalized with other infectious diseases. The plasma levels of ADAM17 decreased during recovery after an acute malaria episode. Plasma levels of Ang2 were associated with markers of malaria severity and levels of var transcripts encoding P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1) containing Cysteine Rich Inter Domain Region α1 (CIDRα1) domains predicted to bind Endothelial Protein C receptor (EPCR). ADAM17 levels were not associated with expression of var genes encoding different PfEMP1 types when controlling for age. These data are the first to report ADAM17 plasma levels in malaria-exposed individuals, and support the notion that parasite sequestration mediated by EPCR-binding PfEMP1 is associated with endothelial activation and pathology in severe paediatric malaria

<i>Plasmodium falciparum </i>var genes expressed in children with severe malaria encode CIDRα1 domains

Most severe Plasmodium falciparum infections are experienced by young children. Severe symptoms are precipitated by vascular sequestration of parasites expressing a particular subset of the polymorphic P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion molecules. Parasites binding human endothelial protein C receptor (EPCR) through the CIDRα1 domain of certain PfEMP1 were recently associated with severe malaria in children. However, it has remained unclear to which extend the EPCR‐binding CIDRα1 domains epitomize PfEMP1 expressed in severe malaria. Here, we characterized the near full‐length transcripts dominating the var transcriptome in children with severe malaria and found that the only common feature of the encoded PfEMP1 was CIDRα1 domains. Such genes were highly and dominantly expressed in both children with severe malarial anaemia and cerebral malaria. These observations support the hypothesis that the CIDRα1‐EPCR interaction is key to the pathogenesis of severe malaria and strengthen the rationale for pursuing a vaccine or adjunctive treatment aiming at inhibiting or reducing the damaging effects of this interaction

Serological evidence of exposure to Rift Valley, Dengue and Chikungunya Viruses among agropastoral communities in Manyara and Morogoro regions in Tanzania: A community survey.

Tanzania has recently experienced outbreaks of dengue in two coastal regions of Dar es Salaam and Tanga. Chikungunya and Rift Valley Fever outbreaks have also been recorded in the past decade. Little is known on the burden of the arboviral disease causing viruses (Dengue, Rift Valley and Chikungunya) endemically in the inter-epidemic periods. We aimed at determining the prevalence of the dengue, rift valley and chikungunya among humans in two geo ecologically distinct sites. The community-based cross-sectional study was conducted in Magugu in Manyara region and Wami-Dakawa in Morogoro region in Tanzania. Venous blood was collected from participants of all age groups, serum prepared from samples and subjected to ELISA tests for RVFV IgG/IgM, DENV IgG/IgM, and CHIKV IgM/IgG. Samples that were positive for IgM ELISA tests were subjected to a quantitative RT PCR for each virus. A structured questionnaire was used to collect socio-demographic information. Data analysis was performed by using SPSSv22. A total of 191 individuals from both sites participated in the study. Only one individual was CHIKV seropositive in Magugu, but none was seropositive or positive for either RVFV or DENV. Of the 122 individuals from Wami-Dakawa site, 16.39% (n = 20) had recent exposure to RVFV while 9.83% (n = 12) were seropositive for CHIKV. All samples were negative by RVFV and CHIKV qPCR. Neither infection nor exposure to DENV was observed in participants from both sites. Being more than 5 in a household, having no formal education and having recently travelled to an urban area were risk factors associated with RVFV and CHIKV seropositivity. We report a considerable exposure to RVFV and CHIKV among Wami-Dakawa residents during the dry season and an absence of exposure of the viruses among humans in Magugu site. In both sites, neither DENV exposure nor infection was detected

The Severity of <i>Plasmodium falciparum</i> infection is associated with transcript levels of <i>var</i> genes encoding endothelial protein C receptor-binding <i>P. falciparum</i> erythrocyte membrane protein 1

By attaching infected erythrocytes to the vascular lining, Plasmodium falciparum parasites leave blood circulation and avoid splenic clearance. This sequestration is central to pathogenesis. Severe malaria is associated with parasites expressing an antigenically distinct P. falciparum erythrocyte membrane protein 1 (PfEMP1) subset mediating binding to endothelial receptors. Previous studies indicate that PfEMP1 adhesins with so-called CIDRα1 domains capable of binding endothelial protein C receptor (EPCR) constitute the PfEMP1 subset associated with severe pediatric malaria. To analyze the relative importance of different subtypes of CIDRα1 domains, we compared Pfemp1 transcript levels in children with severe malaria (including 9 fatal and 114 surviving cases), children hospitalized with uncomplicated malaria (n = 42), children with mild malaria not requiring hospitalization (n = 10), and children with parasitemia and no ongoing fever (n = 12). High levels of transcripts encoding EPCR-binding PfEMP1 were found in patients with symptomatic infections, and the abundance of these transcripts increased with disease severity. The compositions of CIDRα1 subtype transcripts varied markedly between patients, and none of the subtypes were dominant. Transcript-level analyses targeting other domain types indicated that subtypes of DBLβ or DBLζ domains might mediate binding phenomena that, in conjunction with EPCR binding, could contribute to pathogenesis. These observations strengthen the rationale for targeting the PfEMP1-EPCR interaction by vaccines and adjunctive therapies. Interventions should target EPCR binding of all CIDRα1 subtypes

Diagnostic options for pulmonary fungal diseases in Africa

BACKGROUND: Fungal lung diseases are global in distribution and require specific tests for diagnosis. We report a survey of diagnostic service provision in Africa.METHODS: A written questionnaire was followed by a video conference call with each respondent(s) and external validation. To disseminate the questionnaire, a snowball sample was used.RESULTS: Data were successfully collected from 50 of 51 African countries with populations &gt;1 million. The questionnaire was completed by respondents affiliated with 72 health facilities. Of these 72 respondents, 33 (45.8%) reported data for the whole country while others reported data for a specific region/province within their country. In the public sector, chest X-ray and computed tomography are performed often in 49 countries (98%) and occasionally in 37 countries (74%), and less often in the private sector. Bronchoscopy and spirometry were done often in 28 countries (56%) and occasionally in 18 countries (36%) in the tertiary health facilities of public sector. The most conducted laboratory diagnostic assay was fungal culture (often or occasionally) in 29 countries (58%). In collaboration with the Africa Centre for Disease Control and Prevention, regional webinars and individual country profiles provided further data validation.CONCLUSION: This survey has found a huge disparity of diagnostic test capability across the African continent. Some good examples of good diagnostic provision and very high-quality care were seen, but this was unusual. The unavailability of essential testing such as spirometry was noted, which has a high impact in the diagnosis of lung diseases. It is important for countries to implement tests based on the World Health Organization Essential Diagnostics List.</p

Diagnostic options for pulmonary fungal diseases in Africa

Background Fungal lung diseases are global in distribution and require specific tests for diagnosis. We report a survey of diagnostic service provision in Africa. Methods A written questionnaire was followed by a video conference call with each respondent(s) and external validation. To disseminate the questionnaire, a snowball sample was used. Results Data were successfully collected from 50 of 51 African countries with populations >1 million. The questionnaire was completed by respondents affiliated with 72 health facilities. Of these 72 respondents, 33 (45.8%) reported data for the whole country while others reported data for a specific region/province within their country. In the public sector, chest X-ray and computed tomography are performed often in 49 countries (98%) and occasionally in 37 countries (74%), and less often in the private sector. Bronchoscopy and spirometry were done often in 28 countries (56%) and occasionally in 18 countries (36%) in the tertiary health facilities of public sector. The most conducted laboratory diagnostic assay was fungal culture (often or occasionally) in 29 countries (58%). In collaboration with the Africa Centre for Disease Control and Prevention, regional webinars and individual country profiles provided further data validation. Conclusion This survey has found a huge disparity of diagnostic test capability across the African continent. Some good examples of good diagnostic provision and very high-quality care were seen, but this was unusual. The unavailability of essential testing such as spirometry was noted, which has a high impact in the diagnosis of lung diseases. It is important for countries to implement tests based on the World Health Organization Essential Diagnostics List