Concurrent malaria and arbovirus infections in Kedougou, southeastern Senegal

Worldwide distribution, symptoms and diagnosis of the coinfections between malaria and arboviral diseases: a systematic review

The coinfection between malaria (ML) and arboviral diseases represents a major global public health problem, particularly in tropical and subtropical countries. Despite its relevance, this topic is still insufficiently discussed in the current literature. Here, we aimed to investigate the worldwide distribution, symptoms, and diagnosis during coinfection between ML and arboviral diseases. We conducted a systematic review following the Preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement and assessed the selection and eligibility criteria, created and diagrammed maps, and analysed major symptoms with 95% confidence intervals (CI) using prevalence ratio and effect size, also performing latent class analysis. A total of 85,485 studies were retrieved, of which 56 were included: 57.14% in Asia, 25% in Africa, 14.30% in South America, and 3.56% in Europe. A total of 746 individuals were reported to be coinfected with Plasmodium and arbovirus. Concurrent ML, Dengue (DEN), Chikungunya (CHIK), and Zika (ZIK) patients are more likely to present headache and skin rash. Regarding diagnosis, 58,253 were made, of which 38,176 were positive (ML and at least one arboviral disease). The magnitude of these pathogens' coexistence points out the pressing need for improvements in public health policies towards diagnosis and prevention of both diseases, especially in endemic areas.

Clinical description of dengue and chikungunya virus infections amongst acute febrile patients in a malaria endemic area of Mfou, the Centre region of Cameroon

This study aims to determine the frequency and clinical manifestations of dengue and chikungunya viral infections in the district hospital of Mfou, Centre region of Cameroon where malaria is endemic. Blood samples were collected from suspected cases and tested for Plasmodium parasites and for the molecular detection of viral RNAs (dengue, zika and chikungunya viruses) using TRIOPLEX qPCR. A total of 108 patients were clinically suspected among which 25 % were male and 50 % were less than 15.5 years old. Of these 14.8 % (16/108) and 2.8 % (3/108) had acute dengue and chikungunya fevers respectively. Co-infection with malaria was reported in 56.3 % (9/16) of Dengue cases and 33.3 % (1/3) of chikungunya cases. Clinical profiling further revealed that nausea and vomiting show a significant difference in dengue infected individuals to those of non-infected individuals (P = 0.027). The presence of dengue fever and chikungunya fever and the absence of specific clinical manifestations highlight the need to strengthen surveillance of acute febrile infections for a better estimation of the burden of arboviruses.

Reemergence of Sylvatic Dengue Virus Serotype 2 in Kedougou, Senegal, 2020

In 2020, a sylvatic dengue virus serotype 2 infection outbreak resulted in 59 confirmed dengue cases in Kedougou, Senegal, suggesting those strains might not require adaptation to reemerge into urban transmission cycles. Large-scale genomic surveillance and updated molecular diagnostic tools are needed to effectively prevent dengue virus infections in Senegal.

Increasing prevalence of malaria and acute dengue virus coinfection in Africa: a meta-analysis and meta-regression of cross-sectional studies

BACKGROUND

Malaria and dengue fever are the leading causes of acute, undifferentiated febrile illness. In Africa, misdiagnosis of dengue fever as malaria is a common scenario. Through a systematic review of the published literature, this study seeks to estimate the prevalence of dengue and malaria coinfection among acute undifferentiated febrile diseases in Africa.

METHODS

Relevant publications were systematically searched in the PubMed, Cochrane Library, and Google Scholar until May 19, 2023. A random-effects meta-analysis and meta-regression were used to summarize and examine the prevalence estimates.

RESULTS

Twenty-two studies with 22,803 acute undifferentiated febrile patients from 10 countries in Africa were included. The meta-analysis findings revealed a pooled prevalence of malaria and dengue coinfection of 4.2%, with Central Africa having the highest rate (4.7%), followed by East Africa (2.7%) and West Africa (1.6%). Continent-wide, Plasmodium falciparum and acute dengue virus coinfection prevalence increased significantly from 0.9% during 2008-2013 to 3.8% during 2014-2017 and to 5.5% during 2018-2021 (p = 0.0414).

CONCLUSION

There was a high and increasing prevalence of malaria and acute dengue virus coinfection in Africa. Healthcare workers should bear in mind the possibility of dengue infection as a differential diagnosis for acute febrile illness, as well as the possibility of coexisting malaria and dengue in endemic areas. In addition, high-quality multicentre studies are required to verify the above conclusions. Protocol registration number: CRD42022311301.

Understanding yellow fever-associated myocardial injury: an autopsy study

BACKGROUND

Yellow fever (YF) is a viral hemorrhagic fever, endemic in parts of South America and Africa. There is scarce evidence about the pathogenesis of the myocardial injury. The objective of this study is to evaluate the cardiac pathology in fatal cases of YF.

METHODS

This retrospective autopsy study included cases from the São Paulo (Brazil) epidemic of 2017-2019. We reviewed medical records and performed cardiac tissue histopathological evaluation, electron microscopy, immunohistochemical assays, RT-qPCR for YF virus (YFV)-RNA, and proteomics analysis on inflammatory and endothelial biomarkers.

FINDINGS

Seventy-three confirmed YF cases with a median age of 48 (34-60) years were included. We observed myocardial fibrosis in 68 (93.2%) patients; cardiomyocyte hypertrophy in 68 (93.2%); endothelial alterations in 67 (91.8%); fiber necrosis in 50 (68.5%); viral myocarditis in 9 (12.3%); and secondary myocarditis in 5 (6.8%). Four out of five patients with 17DD vaccine-associated viscerotropic disease presented with myocarditis. The cardiac conduction system showed edema, hemorrhages and endothelial fibrinoid necrosis. Immunohistochemistry detected CD68-positive inflammatory interstitial cells and YFV antigens in endothelial and inflammatory cells. YFV-RNA was detected positive in 95.7% of the cardiac samples. The proteomics analysis demonstrated that YF patients had higher levels of multiple inflammatory and endothelial biomarkers in comparison to cardiovascular controls, and higher levels of interferon gamma-induced protein 10 (IP-10) in comparison to sepsis (p = 0.01) and cardiovascular controls (p < 0.001) in Dunn test.

INTERPRETATION

Myocardial injury is frequent in severe YF, due to multifactorial mechanisms, including direct YFV-mediated damage, endothelial cell injury, and inflammatory response, with a possible prominent role for IP-10.

FUNDING

This study was funded by Fundação de Amparo à Pesquisa do Estado de São Paulo, Bill and Melinda Gates Foundation, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.

Analysis of dengue fever disease in West Africa

Dengue fever disease (DFD) which is caused by four antigenically distinct dengue viruses (DENV) presents a global health threat, with tropical and subtropical regions at a greater risk. The paucity of epidemiological data on dengue in West African subregion endangers efforts geared toward disease control and prevention. A systematic search of DFD prevalence, incidence, and DENV-infected Aedes in West Africa was conducted in PubMed, Scopus, African Index Medicus, and Google Scholar in line with the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) guidelines. A total of 58 human prevalence studies involving 35,748 people from 8 countries were identified. Two incidence and six DENV-infected studies were also reviewed. Nigeria and Burkina Faso contributed the majority of the prevalence studies which spanned between 1968 and 2018, with a considerable variation in coverage among the countries reviewed in this study. An average prevalence of 20.97% was observed across both general prevalence and acute DENV infection study categories, ranging between 0.02% and 93%. The majority of these studies were conducted in acute febrile patients with a prevalence range of 0.02-93% while 19% (n = 11) of all studies were general population-based studies and reported a prevalence range of 17.2-75.8%. DENV-infected Aedes aegypti were reported in four out of the five countries with published reports; with DENV-2 found circulating in Cape Verde, Senegal, and Burkina Faso while DENV-3 and DENV-4 were also reported in Senegal and Cape Verde, respectively. High prevalence of DFD in human populations and the occurrence of DENV-infected A. aegypti have been reported in West Africa, even though weaknesses in study design were identified. Epidemiological data from most countries and population in the subregion were scarce or non-existent. This study highlights the epidemic risk of DFD in West Africa, and the need for research and surveillance to be prioritized to fill the data gap required to enact effective control measures.

Contemporary epidemiological data of Rift Valley fever virus in humans, mosquitoes and other animal species in Africa: A systematic review and meta-analysis

Rift Valley fever (RVF) is a severe zoonotic mosquito-borne disease that represents an important threat to human and animal health, with major public health and socioeconomic impacts. This disease is endemic throughout many African countries and the Arabian Peninsula. This systematic review with meta-analysis was conducted to determine the RVF prevalence in humans, mosquitoes and other animal species in Africa. The review also provides contemporary data on RVF case fatality rate (CFR) in humans. In this systematic review with meta-analysis, a comprehensive literature search was conducted on the PubMed, Embase, Web of Science and Global Index Medicus databases from January 2000 to June 2022 to identify relevant studies. Pooled CFR and prevalence estimates were calculated using the random-effects model. Subgroup analysis and sensitivity analysis were performed, and the I2 -statistic was used to investigate a potential source of heterogeneity. A total of 205 articles were included in the final analysis. The overall RVF CFR in humans was found to be 27.5% [95% CI = 8.0-52.5]. The overall pooled prevalence was 7.8% [95% CI = 6.2-9.6] in humans and 9.3% [95% CI = 8.1-10.6] in animals, respectively. The RVF prevalence in individual mosquitoes ranged from 0.0% to 25%. Subgroup analysis showed substantial heterogeneity with respect to geographical regions and human categories. The study shows that there is a correspondingly similar prevalence of RVF in human and animals; however, human CFR is much higher than the observed prevalence. The lack of a surveillance programme and the fact that this virus has subclinical circulation in animals and humans could explain these observations. The implementation of a One Health approach for RVF surveillance and control would be of great interest for human and animal health.

The Importance of Including Non-Household Environments in Dengue Vector Control Activities

Most vector control activities in urban areas are focused on household environments; however, information relating to infection risks in spaces other than households is poor, and the relative risk that these spaces represent has not yet been fully understood. We used data-driven simulations to investigate the importance of household and non-household environments for dengue entomological risk in two Kenyan cities where dengue circulation has been reported. Fieldwork was performed using four strategies that targeted different stages of mosquitoes: ovitraps, larval collections, Prokopack aspiration, and BG-sentinel traps. Data were analyzed separately between household and non-household environments to assess mosquito presence, the number of vectors collected, and the risk factors for vector presence. With these data, we simulated vector and human populations to estimate the parameter m and mosquito-to-human density in both household and non-household environments. Among the analyzed variables, the main difference was found in mosquito abundance, which was consistently higher in non-household environments in Kisumu but was similar in Ukunda. Risk factor analysis suggests that small, clean water-related containers serve as mosquito breeding places in households as opposed to the trash- and rainfall-related containers found in non-household structures. We found that the density of vectors (m) was higher in non-household than household environments in Kisumu and was also similar or slightly lower between both environments in Ukunda. These results suggest that because vectors are abundant, there is a potential risk of transmission in non-household environments; hence, vector control activities should take these spaces into account.

Investigating the etiology of acute febrile illness: a prospective clinic-based study in Uganda

BACKGROUND

Historically, malaria has been the predominant cause of acute febrile illness (AFI) in sub-Saharan Africa. However, during the last two decades, malaria incidence has declined due to concerted public health control efforts, including the widespread use of rapid diagnostic tests leading to increased recognition of non-malarial AFI etiologies. Our understanding of non-malarial AFI is limited due to lack of laboratory diagnostic capacity. We aimed to determine the etiology of AFI in three distinct regions of Uganda.

METHODS

A prospective clinic-based study that enrolled participants from April 2011 to January 2013 using standard diagnostic tests. Participant recruitment was from St. Paul's Health Centre (HC) IV, Ndejje HC IV, and Adumi HC IV in the western, central and northern regions, which differ by climate, environment, and population density. A Pearson's chi-square test was used to evaluate categorical variables, while a two-sample t-test and Krukalis-Wallis test were used for continuous variables.

RESULTS

Of the 1281 participants, 450 (35.1%), 382 (29.8%), and 449 (35.1%) were recruited from the western, central, and northern regions, respectively. The median age (range) was 18 (2-93) years; 717 (56%) of the participants were female. At least one AFI pathogen was identified in 1054 (82.3%) participants; one or more non-malarial AFI pathogens were identified in 894 (69.8%) participants. The non-malarial AFI pathogens identified were chikungunya virus, 716 (55.9%); Spotted Fever Group rickettsia (SFGR), 336 (26.2%) and Typhus Group rickettsia (TGR), 97 (7.6%); typhoid fever (TF), 74 (5.8%); West Nile virus, 7 (0.5%); dengue virus, 10 (0.8%) and leptospirosis, 2 (0.2%) cases. No cases of brucellosis were identified. Malaria was diagnosed either concurrently or alone in 404 (31.5%) and 160 (12.5%) participants, respectively. In 227 (17.7%) participants, no cause of infection was identified. There were statistically significant differences in the occurrence and distribution of TF, TGR and SFGR, with TF and TGR observed more frequently in the western region (p = 0.001; p < 0.001) while SFGR in the northern region (p < 0.001).

CONCLUSION

Malaria, arboviral infections, and rickettsioses are major causes of AFI in Uganda. Development of a Multiplexed Point-of-Care test would help identify the etiology of non-malarial AFI in regions with high AFI rates.

Seroprevalence of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in human population in Senegal from October to November 2020

Objectives

Rift Valley Fever and Crimean-Congo Hemorrhagic Fever are two infections classified among the emerging diseases to be monitored with highest priority. Studies undertaken in human and animals have shown endemicity of these two arboviruses in several African countries. However, most of the investigations were carried out on domestic cattle and the studies conducted on human populations are either outdated or limited to a small number of well-known endemic areas. It is then critical to better evaluate the burden of these viruses in Senegal at a national scale.

Methods

This work relies on a previous seroprevalence survey undertaken in all regions of Senegal at the end of 2020. The existing biobank was used to determine the immunoglobulin G [IgG] Rift Valley Fever and Crimean-Congo Hemorrhagic Fever seroprevalences by indirect enzyme-linked immunosorbent assay.

Results

The crude seroprevalences of Rift Valley Fever and Crimean-Congo Hemorrhagic Fever were 3.94% and 0.7% respectively, with the northern and central part of the countries as the main exposed areas. However, acute infections reported in both high and low exposed regions suggest sporadic introductions.

Conclusions

This study gives updated information and could be of interest to support the stakeholders in the management of these zoonoses.

Seroprevalence of viral and bacterial pathogens among malaria patients in an endemic area of southern Venezuela

BACKGROUND

Malaria remains a leading public health problem worldwide. Co-infections with other pathogens complicate its diagnosis and may modify the disease's clinical course and management. Similarities in malaria clinical presentation with other infections and overlapping endemicity result in underdiagnosis of co-infections and increased mortality. Thus, the aim of this study was to determine the seroprevalence of viral and bacterial pathogens among diagnosed malaria patients in malaria-endemic areas in Venezuela.

METHODS

A cross-sectional study was conducted on malaria patients attending three reference medical centres in Ciudad Bolivar, Venezuela. Clinical evaluation and laboratory tests for dengue virus (DENV), chikungunya virus (CHIKV), viral hepatitis [hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis C virus (HCV)], and leptospirosis (LEP) were performed by enzyme-linked immunosorbent assays. Previous exposure to these pathogens was defined by the presence of specific immunoglobulin (Ig) G, and co-infection or recent exposure (CoRE) was determined by the presence of specific IgM alone or IgM + IgG. Data analysis considered descriptive statistics. Parameter distribution was statistically evaluated using Kolmogorov-Smirnov test and the necessary comparison tests. Odds ratio (OR) for complications was determined according to CoRE presence with a 95% confidence interval (CI).

RESULTS

A total of 161 malaria patients were studied, 66% infected with Plasmodium vivax, 27% with P. falciparum, and 7.5% harboured P. vivax/P. falciparum mixed infection. Previous exposure to DENV (60%) and CHIKV (25%) was frequent. CoRE was confirmed in 55 of the 161 malaria patients (34%) and were more frequent in P. falciparum (49%) than in P. vivax (29%) and mixed malaria patients (25%) (OR = 2.43, 95% CI: 1.39-4.25, P = 0.018). The most frequent CoRE was DENV (15%), followed by HAV (12%), HBV (6.2%), CHIKV (5.5%), and LEP (3.7%); HCV CoRE was absent. Complicated malaria was significantly more frequent in patients with CoRE (56%) than those without CoRE (36%; OR = 2.31, 95% CI: 1.18-4.92, P = 0.013).

CONCLUSIONS

We found high CoRE prevalence in malaria patients as determined by serology in the study region; cases were associated with a worse clinical outcome. Further prospective studies with samples from different infection sites and the use of molecular tools are needed to determine the clinical significance of these findings.

Co-circulation of dengue virus serotypes 1 and 3 in the Fatick region of senegal 2018

On 10th September 2018, the Syndromic Sentinel Surveillance network that monitors febrile illnesses in all 14 regions of Senegal detected a peak of fever in the Fatick region. On 13 September 2018, 10 samples were sent to the WHO Collaborating Centre for Arboviruses and Viral Haemorrhagic Fevers at the Institut Pasteur de Dakar (IPD). Laboratory investigations revealed an epidemic of dengue 1 genotype V and dengue 3 genotype III. Fatick neighbors the Holy City of Touba where 3.5 million people from all over the word gather every year for the Grand Magal pilgrimage. This article discusses the impact of mass gatherings and their role in the recent introduction of dengue serotypes in Senegal. Dengue is now endemic in Senegal and across many countries in Africa, highlighting the need for early detection, control measures and prevention of severe dengue cases in highly connected urban settings.

Arbovirus Epidemiology: The Mystery of Unnoticed Epidemics in Ghana, West Africa

It is evident that all the countries surrounding Ghana have experienced epidemics of key arboviruses of medical importance, such as the recent dengue fever epidemic in Burkina Faso. Therefore, Ghana is considered a ripe zone for epidemics of arboviruses, mainly dengue. Surprisingly, Ghana never experienced the propounded deadly dengue epidemic. Indeed, it is mysterious because the mosquito vectors capable of transmitting the dengue virus, such as Aedes aegypti, were identified in Ghana through entomological investigations. Additionally, cases may be missed, as the diagnostic and surveillance capacities of the country are weak. Therefore, we review the arbovirus situation and outline probable reasons for the epidemic mystery in the country. Most of the recorded cases of arbovirus infections were usually investigated via serology by detecting IgM and IgG immunoglobulins in clinical samples, which is indicative of prior exposure but not an active case. This led to the identification of yellow fever virus and dengue virus as the main circulating arboviruses among the Ghanaian population. However, major yellow fever epidemics were reported for over a decade. It is important to note that the reviewed arboviruses were not frequently detected in the vectors. The data highlight the necessity of strengthening the diagnostics and the need for continuous arbovirus and vector surveillance to provide an early warning system for future arbovirus epidemics.

Molecular screening reveals non-uniform malaria transmission in western Kenya and absence of Rickettsia africae and selected arboviruses in hospital patients

Background

In sub-Saharan Africa, malaria is the common diagnosis for febrile illness and related clinical features, resulting in the under-diagnosis of other aetiologies, such as arboviruses and Rickettsia. While these may not be significant causes of mortality in malaria-endemic areas, they affect the daily life and performance of affected individuals. It is, therefore, important to have a clear picture of these other aetiologies to institute correct diagnoses at hospitals and improve patient outcomes.

Methods

Blood samples were collected from patients with fever and other clinical features associated with febrile illness at selected hospitals in the malaria-endemic counties of Busia, Bungoma, and Kakamega, and screened for Crimean-Congo haemorrhagic fever, Sindbis, dengue and chikungunya viruses, Rickettsia africae, and Plasmodium spp. using high-throughput real-time PCR techniques. A logistic regression was performed on the results to explore the effect of demographic and socio-economic independent variables on malaria infection.

Results

A total of 336 blood samples collected from hospital patients between January 2018 and February 2019 were screened, of which 17.6% (59/336) were positive for Plasmodium falciparum and 1.5% (5/336) for Plasmodium malariae. Two patients had dual P. falciparum/P. malariae infections. The most common clinical features reported by the patients who tested positive for malaria were fever and headache. None of the patients were positive for the arboviruses of interest or R. africae. Patients living in Busia (OR 5.2; 95% CI 2.46–11.79; p < 0.001) and Bungoma counties (OR 2.7; 95% CI 1.27–6.16; p = 0.013) had higher odds of being infected with malaria, compared to those living in Kakamega County.

Conclusions

The reported malaria prevalence is in line with previous studies. The absence of arboviral and R. africae cases in this study may have been due to the limited number of samples screened, low-level circulation of arboviruses during inter-epidemic periods, and/or the use of PCR alone as a detection method. Other sero-surveys confirming their circulation in the area indicate that further investigations are warranted.

Chikungunya (Togaviridae) and dengue 2 (Flaviviridae) viruses detected from Aedes aegypti mosquitoes in Burkina Faso by qRT-PCR technique: Preliminary results and perspective for molecular characterization of arbovirus circulation in vector populations

In 2016, an entomological study was carried out in a railway transect between Banfora and Ouagadougou, Burkina Faso. The objective was to assess the risk factors of arbovirus outbreaks, including vector-borne infection status within representative regions of the country. Aedes aegypti mosquitoes were collected at the larval stage from their natural rearing habitats in four study sites when estimating the main larval index, then reared until adult stage and kept in RNAlater for the detection of arbovirus RNA. In the laboratory, mosquito samples were tested for dengue virus (DENV) and Chikungunya virus (CHIKV) using a real-time qRT-PCR stage. A DENV-2 positive pool was detected in Ouagadougou with a minimum infection rate (MIR) of 16.67 and other six CHIKV-positive pools with a MIR of 66.67 in Ouagadougou, Banfora, and Boromo. This qRT-PCR approach, if validated with various samples also comprising wild blood-fed adults, is a useful tool for arbovirus circulation and disease monitoring in Burkina Faso.

Epidemiology of yellow fever virus in humans, arthropods, and non-human primates in sub-Saharan Africa: A systematic review and meta-analysis

Yellow fever (YF) has re-emerged in the last two decades causing several outbreaks in endemic countries and spreading to new receptive regions. This changing epidemiology of YF creates new challenges for global public health efforts. Yellow fever is caused by the yellow fever virus (YFV) that circulates between humans, the mosquito vector, and non-human primates (NHP). In this systematic review and meta-analysis, we review and analyse data on the case fatality rate (CFR) and prevalence of YFV in humans, and on the prevalence of YFV in arthropods, and NHP in sub-Saharan Africa (SSA). We performed a comprehensive literature search in PubMed, Web of Science, African Journal Online, and African Index Medicus databases. We included studies reporting data on the CFR and/or prevalence of YFV. Extracted data was verified and analysed using the random effect meta-analysis. We conducted subgroup, sensitivity analysis, and publication bias analyses using the random effect meta-analysis while I2 statistic was employed to determine heterogeneity. This review was registered with PROSPERO under the identification CRD42021242444. The final meta-analysis included 55 studies. The overall case fatality rate due to YFV was 31.1% (18.3–45.4) in humans and pooled prevalence of YFV infection was 9.4% (6.9–12.2) in humans. Only five studies in West and East Africa detected the YFV in mosquito species of the genus Aedes and in Anopheles funestus. In NHP, YFV antibodies were found only in members of the Cercopithecidae family. Our analysis provides evidence on the ongoing circulation of the YFV in humans, Aedes mosquitoes and NHP in SSA. These observations highlight the ongoing transmission of the YFV and its potential to cause large outbreaks in SSA. As such, strategies such as those proposed by the WHO’s Eliminate Yellow Fever Epidemics (EYE) initiative are urgently needed to control and prevent yellow fever outbreaks in SSA.

Evaluation of Zika rapid tests as aids for clinical diagnosis and epidemic preparedness

BACKGROUND

Development and evaluation of diagnostics for diseases of epidemic potential are often funded during epidemics, but not afterwards, leaving countries unprepared for the next epidemic. United Nations Children's Emergency Fund (UNICEF) partnered with the United States Agency for International Development (USAID) to address this important gap by investing in an advance purchase commitment (APC) mechanism to accelerate the development and evaluation of Zika rapid diagnostic tests (RDTs) for case detection and surveillance. This paper describes the performance evaluation of five Zika RDTs eligible for procurement.

METHODS

A network of European Union-funded ZikaPLAN sites in Africa, Asia, Latin America with access to relevant serum specimens were selected to evaluate RDTs developed for the UNICEF APC mechanism. A standardised protocol and evaluation panels were developed and a call for specimens for the evaluation panels issued to different sites. Each site contributed specimens to the evaluation from their biobank. Data were collated, analysed and presented to the UNICEF Procurement Review Group for review.

FINDINGS

Three RDTs met the criteria for UNICEF procurement of sensitivity and specificity of 85% against a refence standard. The sensitivity/specificity of the ChemBio anti-Zika Virus (ZIKV) immunoglobulin M (IgM) test was 86.4 %/86.7% and the ChemBio ZCD system for anti-ZIKV IgM was 79.0%/97.1%, anti-dengue virus (DENV) IgM 90.0%/89.2%, anti-Chikungunya virus (CHIKV) IgM 90.6%/97.2%. The sensitivity/specificity of the SD Biosensor anti-ZIKV IgM was 96.8 %/90.8%, anti-DENV IgM 71.8%/83.5%, the DENV nonstructural protein 1 (NS1) glycoprotein 90.0%/90.2%, anti- yellow fever virus (YFV) IgM 84.6%/92.4%, anti-CHIKV IgM 86.3%/97.5%.

INTERPRETATION

Three RDTs fulfilled the performance thresholds set by WHO and were eligible for UNICEF procurement. These tests will improve the diagnosis of ZIKV and other arboviral infections as well as providing countries with better tools for surveillance and response to future epidemics.

FUNDING

This work was supported by the USAID grant GHA-G-00-07-00007 and ZikaPLAN (European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 734584).

Serological Evidence of Zika Virus Circulation in Burkina Faso

Zika virus (ZIKV) and dengue virus (DENV) are two closely related members of the Flaviviridae family, both transmitted by mosquitoes of the genus Aedes, and are among the arboviruses most at risk to human health. Burkina Faso has been facing an upsurge in DENV outbreaks since 2013. Unlike DENV, there is no serological evidence of ZIKV circulation in humans in Burkina Faso. The main objective of our study was to determine the seroprevalence of ZIKV and DENV in blood donors in Burkina Faso. A total of 501 donor samples collected in the two major cities of the country in 2020 were first tested by a competitive enzyme-linked immunosorbent assay to detect flavivirus antibodies. Positive sera were then tested using Luminex to detect ZIKV and DENV antibodies and virus-specific microneutralization tests against ZIKV were performed. The ZIKV seroprevalence was 22.75% in the donor samples and we found seropositivity for all DENV-serotypes ranging from 19.56% for DENV-1 to 48.86% for DENV-2. Molecular analyses performed on samples from febrile patients and Aedes aegypti mosquitoes between 2019 and 2021 were negative. Our study showed the important circulation of ZIKV and DENV detected by serology although molecular evidence of the circulation of ZIKV could not be demonstrated. It is essential to strengthen existing arbovirus surveillance in Burkina Faso and more broadly in West Africa by focusing on fevers of unknown origin and integrating vector surveillance to assess the extent of ZIKV circulation and identify the circulating strain. Further studies are needed to better understand the epidemiology of this virus in order to define appropriate prevention and response methods.

Malaria transmission in Africa: Its relationship with yellow fever and measles

Background

Malaria has been strongly linked to the transmission and pathophysiology of some viral diseases. Malaria and vaccine-preventable diseases often co-exist in endemic countries but the implication of their co-existence on their transmission dynamics and control is poorly understood. The study aims to evaluate the relationships between the incidence of malaria and cases of measles and yellow fever in Africa.

Methods

The malaria incidence, death due to malaria, measles and yellow fever data were sourced from the WHO database. Poisson and zero-inflated time-trend regression were used to model the relationships between malaria and the two vaccine-preventable diseases. P-values <0.05 were considered statistically significant.

Results

A significant negative relationship existed between malaria incidence and measles cases (P<0.05), however, malaria showed a positive relationship with yellow fever (P<0.05). The relationships between death due to malaria and measles/yellow fever cases followed similar trends but with a higher level of statistical significance (P<0.001).

Conclusions

Malaria varied negatively with measles cases but positively with yellow fever. The relationships observed in this study could be important for the management of malaria and the studied vaccine-preventable diseases. Increase vaccination coverage and/or malaria treatment could modulate the direction of these relationships.

Viral haemorrhagic fevers and malaria co-infections among febrile patients seeking health care in Tanzania

Background

In recent years there have been reports of viral haemorrhagic fever (VHF) epidemics in sub-Saharan Africa where malaria is endemic. VHF and malaria have overlapping clinical presentations making differential diagnosis a challenge. The objective of this study was to determine the prevalence of selected zoonotic VHFs and malaria co-infections among febrile patients seeking health care in Tanzania.

Methods

This facility-based cross-sectional study was carried out between June and November 2018 in Buhigwe, Kalambo, Kyela, Kilindi, Kinondoni, Kondoa, Mvomero, and Ukerewe districts in Tanzania. The study involved febrile patients seeking health care from primary healthcare facilities. Blood samples were collected and tested for infections due to malaria, Crimean-Congo haemorrhagic fever (CCHF), Ebola virus disease (EVD), Marburg virus disease (MVD), Rift Valley fever (RVF) and yellow fever (YF). Malaria infections were tested using rapid diagnostics tests while exposure to VHFs was determined by screening for immunoglobulin M antibodies using commercial enzyme-linked immunosorbent assays. The Chi-square test was used to compare the proportions.

Results

A total of 308 participants (mean age = 35 ± 19 years) were involved in the study. Of these, 54 (17.5%) had malaria infection and 15 (4.8%) were positive for IgM antibodies against VHFs (RVF = 8; CCHF = 2; EBV = 3; MBV = 1; YF = 1). Six (1.9%) individuals had both VHF (RVF = 2; CCHF = 1; EVD = 2; MVD = 1) and malaria infections. The highest co-infection prevalence (0.6%) was observed among individuals aged 46‒60 years (P < 0.05). District was significantly associated with co-infection (P < 0.05) with the highest prevalence recorded in Buhigwe (1.2%) followed by Kinondoni (0.9%) districts. Headache (100%) and muscle, bone, back and joint pains (83.3%) were the most significant complaints among those infected with both VHFs and malaria (P = 0.001).

Conclusions

Co-infections of VHF and malaria are prevalent in Tanzania and affect more the older than the younger population. Since the overlapping symptoms in co-infected individuals may challenge accurate diagnosis, adequate laboratory diagnosis should be emphasized in the management of febrile illnesses.

Uncovering the Burden of Dengue in Africa: Considerations on Magnitude, Misdiagnosis, and Ancestry

Dengue is a re-emerging neglected disease of major public health importance. This review highlights important considerations for dengue disease in Africa, including epidemiology and underestimation of disease burden in African countries, issues with malaria misdiagnosis and co-infections, and potential evidence of genetic protection from severe dengue disease in populations of African descent. The findings indicate that dengue virus prevalence in African countries and populations may be more widespread than reported data suggests, and that the Aedes mosquito vectors appear to be increasing in dissemination and number. Changes in climate, population, and plastic pollution are expected to worsen the dengue situation in Africa. Dengue misdiagnosis is also a problem in Africa, especially due to the typical non-specific clinical presentation of dengue leading to misdiagnosis as malaria. Finally, research suggests that a protective genetic component against severe dengue exists in African descent populations, but further studies should be conducted to strengthen this association in various populations, taking into consideration socioeconomic factors that may contribute to these findings. The main takeaway is that Africa should not be overlooked when it comes to dengue, and more attention and resources should be devoted to this disease in Africa.

Emergence of dengue virus serotype 2 in Mauritania and molecular characterization of its circulation in West Africa

The number of sporadic and epidemic dengue fever cases have reportedly been increasing in recent years in some West African countries, such as Senegal and Mali. The first epidemic of laboratory-confirmed dengue occurred in Nouakchott, the capital city of Mauritania situated in the Saharan desert, in 2014. On-site diagnosis of dengue fever was established using a rapid diagnostic test for dengue. In parallel, the presence of Aedes aegypti mosquitoes in the city was confirmed. The initial diagnosis was confirmed by RT-PCR, which showed that all samples from the 2014 dengue epidemic in Nouakchott were dengue virus serotype 2 (DENV-2). The whole genome or envelope protein gene of these strains, together with other DENV-2 strains obtained from travelers returning from West African countries to France between 2016 and 2019 (including two Mauritanian strains in 2017 and 2018), were sequenced. Phylogenetic analysis suggested a recent emergence of an epidemic strain from the cosmopolitan genotype belonging to West African cosmopolitan lineage II, which is genetically distinct from African sylvatic genotype. The origin of this DENV-2 lineage is still unknown, but our data seem to suggest a recent and rapid dispersion of the epidemic strain throughout the region. More complete genome sequences of West African DENV-2 are required for a better understanding of the dynamics of its circulation. Arboviral surveillance and outbreak forecasting are urgently needed in West Africa.

In Africa, dengue viruses 1 to 4 are transmitted to primates by Aedes mosquitoes in a sylvatic cycle or an urban/epidemic cycle involving humans. Infection in humans may be asymptomatic or may range from mild flu-like illness to severe hemorrhagic fever. The dengue viruses have a pantropical distribution, mostly in urbanized areas where vectors have become well adapted. This report shows dengue can also emerge in desert areas, as seen for the first time in an outbreak in 2014 in Nouakchott, Mauritania, where climatic, environmental, and human behavioral changes favor the emergence of Aedes mosquitoes. Dengue virus 2 was found in multiple human samples collected during the outbreak. Genomic analysis of dengue virus 2 isolates from the Mauritanian outbreak and from infected travelers revealed the rapid emergence of a specific “West African epidemic strain” of the virus throughout West Africa during the last decade, which is distinct from other strains found elsewhere and from historical or sylvatic strains. More genomic data would help us understand the circulation of dengue virus in West Africa, to help forecast and mitigate outbreaks in this region.

Evidence of chikungunya virus infections among febrile patients at three secondary health facilities in the Ashanti and the Bono Regions of Ghana

BACKGROUND

Chikungunya is now of public health concern globally due to its re-emergence in endemic areas and introduction into new areas of the world. Worldwide, the vectors for transmission of the chikungunya virus are Aedes mosquitoes and these are prevalent in Ghana. Despite its global significance, the true burden of chikungunya virus infection in Ghana is largely unknown and the threat of outbreak remains high owing to international travel. This study sought to determine chikungunya virus infection among febrile patients suspected of having malaria infections at some selected health facilities in the Ashanti, Bono East, and Bono Regions of Ghana.

METHODOLOGY

This cross-sectional study recruited six hundred (600) febrile patients suspected of having malaria who submitted their clinical samples to the laboratories of the selected health facilities for the diagnosis of their infections. Five to ten millilitres (5-10ml) of venous blood were collected from each study participant. Sera were separated and tested for anti-chikungunya (IgM and IgG) antibodies using InBios ELISA kit following the manufacturer's instruction. Samples positive for chikungunya IgM and IgG were selected and tested for chikungunya virus RNA using Reverse Transcription-quantitative Polymerase Chain Reaction. Malaria Rapid Diagnostic Test kits were used to screen the participants for malaria. Structured questionnaires were administered to obtain demographic and clinical information of the study participants.

RESULT

Of the 600 samples tested, the overall seroprevalence of chikungunya was 6%. The seroprevalence of chikungunya IgM and IgG antibodies were 1.8% and 4.2% respectively. None of the chikungunya IgM and IgG positive samples tested positive for chikungunya RNA by RT-qPCR. Of the 600 samples, tested 32.3% (194/600) were positive for malaria parasites. Malaria and chikungunya co-infection was detected in 1.8% (11/600) of the participants.

CONCLUSION

Findings from the current study indicate low-level exposure to the chikungunya virus suggesting the virus is circulating and potentially causing morbidity in Ghana.

Yellow Fever Outbreak in Eastern Senegal, 2020-2021

Yellow fever virus remains a major threat in low resource countries in South America and Africa despite the existence of an effective vaccine. In Senegal and particularly in the eastern part of the country, periodic sylvatic circulation has been demonstrated with varying degrees of impact on populations in perpetual renewal. We report an outbreak that occurred from October 2020 to February 2021 in eastern Senegal, notified and managed through the synergistic effort yellow fever national surveillance implemented by the Senegalese Ministry of Health in collaboration with the World Health Organization, the countrywide 4S network set up by the Ministry of Health, the Institut Pasteur de Dakar, and the surveillance of arboviruses and hemorrhagic fever viruses in human and vector populations implemented since mid 2020 in eastern Senegal. Virological analyses highlighted the implication of sylvatic mosquito species in virus transmission. Genomic analysis showed a close relationship between the circulating strain in eastern Senegal, 2020, and another one from the West African lineage previously detected and sequenced two years ago from an unvaccinated Dutch traveler who visited the Gambia and Senegal before developing signs after returning to Europe. Moreover, genome analysis identified a 6-nucleotide deletion in the variable domain of the 3′UTR with potential impact on the biology of the viral strain that merits further investigations. Integrated surveillance of yellow fever virus but also of other arboviruses of public health interest is crucial in an ecosystem such as eastern Senegal.

Seroprevalence and associated risk factors of selected zoonotic viral hemorrhagic fevers in Tanzania

OBJECTIVE

To determine the seroprevalence of selected zoonotic viral hemorrhagic fevers (VHFs) and their associated risk factors in Tanzania.

METHODS

Blood samples were collected from consenting outpatients and community members in eight districts selected from five ecological zones of Tanzania. Serum was harvested and tested for the presence of immunoglobulin G (IgG) and M (IgM) antibodies against Crimean-Congo hemorrhagic fever (CCHF), Ebola virus disease (EVD), Marburg virus disease (MVD), Rift Valley fever (RVF), and yellow fever (YF).

RESULTS

The presence of IgM and IgG antibodies against CCHF, EVD, MVD, RVF, and YF was detected in 64 of 500 samples (12.8%). The prevalences of IgM and IgG antibodies to CCHF, EVD, MVD, RFV, and YF were 2.0%, 3.4%, 1.2%, 4.8%, and 1.4%, respectively. Contact with wild animals (OR = 1.2, CI = 1.3-1.6) and keeping goats (OR = 1.3, CI = 1.5-1.9) were significantly associated with RVF, while contact with bats (OR = 1.2, CI = 1.1-1.5) was associated with MVD.

CONCLUSION

The findings of this study provide evidence of exposure to CCHF, EVD, MVD, RVF, and YF in Tanzania. Since most of these VHFs occurred without apparent clinical forms of the disease, these findings call for the need to strengthen the surveillance system and management of febrile illnesses in Tanzania.

Prevalence of Malaria and Chikungunya Co-Infection in Febrile Patients: A Systematic Review and Meta-Analysis

Background: Co-infection with malaria and chikungunya could exert a significant public health impact with infection misdiagnosis. Therefore, this study aimed to collect qualitative and quantitative evidence of malaria and chikungunya co-infection among febrile patients. Methods: Potentially relevant studies were identified using PubMed, Web of Science, and Scopus. The bias risk of the included studies was assessed using the checklist for analytical cross-sectional studies developed by the Joanna Briggs Institute. The pooled prevalence of malaria and chikungunya co-infection among febrile patients and the pooled prevalence of chikungunya virus (CHIKV) infection among malaria patients were estimated with the random effect model. The odds of malaria and chikungunya co-infection among febrile patients were also estimated using a random effect model that presumed the heterogeneity of the outcomes of the included studies. The heterogeneity among the included studies was assessed using the Cochran Q test and I² statistics. Publication bias was assessed using the funnel plot and Egger’s test. Results: Of the 1924 studies that were identified from the three databases, 10 fulfilled the eligibility criteria and were included in our study. The pooled prevalence of malaria and chikungunya co-infection (182 cases) among febrile patients (16,787 cases), stratified by diagnostic tests for CHIKV infection, was 10% (95% confidence interval (CI): 8–11%, I²: 99.5%) using RDT (IgM), 7% (95% CI: 4–10%) using the plaque reduction neutralization test (PRNT), 1% (95% CI: 0–2%, I²: 41.5%) using IgM and IgG ELISA, and 4% (95% CI: 2–6%) using real-time RT-PCR. When the prevalence was stratified by country, the prevalence of co-infection was 7% (95% CI: 5–10%, I²: 99.5%) in Nigeria, 1% (95% CI: 0–2%, I²: 99.5%) in Tanzania, 10% (95% CI: 8–11%) in Sierra Leone, 1% (95% CI: 0–4%) in Mozambique, and 4% (95% CI: 2–6%) in Kenya. The pooled prevalence of CHIKV infection (182 cases) among malaria patients (8317 cases), stratified by diagnostic tests for CHIKV infection, was 39% (95% CI: 34–44%, I²: 99.7%) using RDT (IgM), 43% (95% CI: 30–57%) using PRNT, 5% (95% CI: 3–7%, I²: 5.18%) using IgM and IgG ELISA, and 9% (95% CI: 6–15%) using real-time RT-PCR. The meta-analysis showed that malaria and chikungunya co-infection occurred by chance (p: 0.59, OR: 0.32, 95% CI: 0.6–1.07, I²: 78.5%). Conclusions: The prevalence of malaria and chikungunya co-infection varied from 0% to 10% as per the diagnostic test for CHIKV infection or the country where the co-infection was reported. Hence, the clinicians who diagnose patients with malaria infections in areas where two diseases are endemic should further investigate for chikungunya co-infection to prevent misdiagnosis or delayed treatment of concurrent infection.

Diagnosis of Chikungunya Virus in Febrile Patients From a Malaria Holoendemic Area

INTRODUCTION

Accurate diagnosis of chikungunya (CHIK) is essential for effective disease management and surveillance. In a cohort of febrile Congolese patients, available diagnostic methods widely used in CHIK diagnosis were evaluated. In addition, plasma cytokines were quantified in CHIK patients and those coinfected with malaria compared with healthy controls.

METHODS

Between June and November 2019, a total of 107 febrile patients with suspected CHIK were subjected to differential diagnosis both for CHIK and malaria. Patients were screened for CHIK virus using molecular diagnosis by real-time PCR, serologic testing by IgM-specific and IgG-specific ELISAs, and lateral flow-based method with rapid diagnostic test (RDT), while malaria diagnosis was confirmed by PCR methods. Pro-inflammatory (IL-12, IL-16, IFN-γ, TNF-α) and anti-inflammatory (IL-4, IL-10, IL-13) cytokines were quantified in patients and healthy controls by ELISA assays.

RESULTS

Molecular diagnoses revealed that 57% (61/107) were positive for CHIK by RT-PCR, while serologic testing revealed 31% (33/107) and 9% (10/107) seropositivity for anti- IgM and IgG, respectively. None of the patients were CHIK RDT-positive. Also, 27% (29/107) were PCR-positive for malaria. Among the malaria-positive patients, 14% (15/107) were co-infected with CHIK and 13% (14/107) were monoinfection. Plasma IL-12 and TNF-α levels were increased in patients with malaria and IL-13 levels were increased in patients with co-infection (p<0.05).

CONCLUSION

Co-infection of malaria and CHIK were common in febrile Congolese patients. Real-time PCR was a better tool for detecting actual occurrences of CHIK in a malaria holoendemic area.

Genomic Epidemiology of 2015-2016 Zika Virus Outbreak in Cape Verde

During 2015–2016, Cape Verde, an island nation off the coast of West Africa, experienced a Zika virus (ZIKV) outbreak involving 7,580 suspected Zika cases and 18 microcephaly cases. Analysis of the complete genomes of 3 ZIKV isolates from the outbreak indicated the strain was of the Asian (not African) lineage. The Cape Verde ZIKV sequences formed a distinct monophylogenetic group and possessed 1–2 (T659A, I756V) unique amino acid changes in the envelope protein. Phylogeographic and serologic evidence support earlier introduction of this lineage into Cape Verde, possibly from northeast Brazil, between June 2014 and August 2015, suggesting cryptic circulation of the virus before the initial wave of cases were detected in October 2015. These findings underscore the utility of genomic-scale epidemiology for outbreak investigations.

High Dengue Burden and Circulation of 4 Virus Serotypes among Children with Undifferentiated Fever, Kenya, 2014-2017

Little is known about the extent and serotypes of dengue viruses circulating in Africa. We evaluated the presence of dengue viremia during 4 years of surveillance (2014–2017) among children with febrile illness in Kenya. Acutely ill febrile children were recruited from 4 clinical sites in western and coastal Kenya, and 1,022 participant samples were tested by using a highly sensitive real-time reverse transcription PCR. A complete case analysis with genomic sequencing and phylogenetic analyses was conducted to characterize the presence of dengue viremia among participants during 2014–2017. Dengue viremia was detected in 41.9% (361/862) of outpatient children who had undifferentiated febrile illness in Kenya. Of children with confirmed dengue viremia, 51.5% (150/291) had malaria parasitemia. All 4 dengue virus serotypes were detected, and phylogenetic analyses showed several viruses from novel lineages. Our results suggests high levels of dengue virus infection among children with undifferentiated febrile illness in Kenya.

Genomic investigation of a dengue virus outbreak in Thiès, Senegal, in 2018

Dengue virus is a major and rapidly growing public health concern in tropic and subtropic regions across the globe. In late 2018, Senegal experienced its largest dengue virus outbreak to date, covering several regions. However, little is known about the genetic diversity of dengue virus (DENV) in Senegal. Here we report complete viral genomes from 17 previously undetected DENV cases from the city of Thiès. In total we identified 19 cases of DENV in a cohort of 198 individuals with fever collected in October and November 2018. We detected 3 co-circulating serotypes; DENV 3 was the most frequent accounting for 11/17 sequences (65%), 4 (23%) were DENV2 and 2 (12%) were DENV1. Sequences were most similar to recent sequences from West Africa, suggesting ongoing local circulation of viral populations; however, detailed inference is limited by the scarcity of available genomic data. We did not find clear associations with reported clinical signs or symptoms, highlighting the importance of testing for diagnosing febrile diseases. Overall, these findings expand the known range of DENV in Senegal, and underscore the need for better genomic characterization of DENV in West Africa.

Mosquito-Associated Viruses and Their Related Mosquitoes in West Africa

Mosquito-associated viruses (MAVs), including mosquito-specific viruses (MSVs) and mosquito-borne (arbo)viruses (MBVs), are an increasing public, veterinary, and global health concern, and West Africa is projected to be the next front for arboviral diseases. As in-depth knowledge of the ecologies of both western African MAVs and related mosquitoes is still limited, we review available and comprehensive data on their diversity, abundance, and distribution. Data on MAVs’ occurrence and related mosquitoes were extracted from peer-reviewed publications. Data on MSVs, and mosquito and vertebrate host ranges are sparse. However, more data are available on MBVs (i.e., dengue, yellow fever, chikungunya, Zika, and Rift Valley fever viruses), detected in wild and domestic animals, and humans, with infections more concentrated in urban areas and areas affected by strong anthropogenic changes. Aedes aegypti, Culex quinquefasciatus, and Aedes albopictus are incriminated as key arbovirus vectors. These findings outline MAV, related mosquitoes, key knowledge gaps, and future research areas. Additionally, these data highlight the need to increase our understanding of MAVs and their impact on host mosquito ecology, to improve our knowledge of arbovirus transmission, and to develop specific strategies and capacities for arboviral disease surveillance, diagnostic, prevention, control, and outbreak responses in West Africa.

Aedes-borne disease outbreaks in West Africa: A call for enhanced surveillance

Arboviruses transmitted by Aedes mosquitoes are a growing global concern; however, there remain large gaps in surveillance of both arboviruses and their vectors in West Africa. We reviewed over 50 years of data including outbreak reports, peer-reviewed literature, and prior data compilations describing Zika, dengue, and chikungunya, and their vectors in West Africa. Large outbreaks of dengue, Zika, and chikungunya have recently occurred in the region with over 27,000 cases of Aedes-borne disease documented since 2007. Recent arboviral outbreaks have become more concentrated in urban areas, and Aedes albopictus, recently documented in the region, has emerged as an important vector in several areas. Seroprevalence surveys suggest reported cases are a gross underestimate of the underlying arboviral disease burden. These findings indicate a shifting epidemiology of arboviral disease in West Africa and highlight a need for increased research and implementation of vector and disease control. Rapid urbanization and climate change may further alter disease patterns, underscoring the need for improved diagnostic capacity, and vector and disease surveillance to address this evolving health challenge.

Field evaluation of a mobile biosafety laboratory in Senegal to strengthen rapid disease outbreak response and monitoring

Background

Past and recent outbreaks have highlighted the vulnerability of humans to infectious diseases, which represent serious economic and health security threats. A paradigm shift in the management of sanitary crises is urgently needed. Based on lessons from the 2014 Ebola outbreak, the Praesens Foundation has developed an all-terrain mobile biosafety laboratory (MBS-Lab) for effective field diagnostics capabilities.

Objective

The aim of the study was to train African teams and run a field evaluation of the MBS-Lab, including robustness, technical and operational sustainability, biosafety, connectivity, turn-around times for testing and result delivery.

Methods

The MBS-Lab was deployed in Senegal in October 2017 for a six-month field assessment under various ecological conditions and was mobilised during the dengue outbreaks in 2017 and 2018.

Results

The MBS-Lab can be considered an off-grid solution that addresses field challenges with regard to working conditions, mobility, deployment, environment and personnel safety. Blood (n = 398) and nasal swab (n = 113) samples were collected from 460 study participants for molecular screening for acute febrile illnesses and respiratory infections. The results showed that malaria (particularly in Kédougou) and upper respiratory tract infections remain problematic. Suspected dengue samples were tested on board during the dengue outbreaks in 2017 (882 tests; 128 confirmed cases) and 2018 (1736 tests; 202 confirmed cases).

Conclusion

The MBS-Lab is an innovative solution for outbreak response, even in remote areas. The study demonstrated successful local ownership and community engagement. The MBS-Lab can also be considered an open mobile healthcare platform that offers various opportunities for field-deployable, point-of-care technologies for surveillance programmes.

Spatial Assessment of Contact Between Humans and Anopheles and Aedes Mosquitoes in a Medium-Sized African Urban Setting, Using Salivary Antibody-Based Biomarkers

BACKGROUND

Anarchic and poorly controlled urbanization led to an increased risk of mosquito-borne diseases (MBD) in many African cities. Here, we evaluate the spatial heterogeneity of human exposure to malaria and arboviral disease vectors in an urban area of northern Senegal, using antibody-based biomarkers of exposure to Anopheles and Aedes mosquito bites.

METHODS

A cross-sectional study was undertaken during the rainy season of 2014 in 4 neighborhoods of Saint-Louis, a city in northern Senegal. Among children aged 6-59 months in each neighborhood, the dried blood spot technique was used to evaluate immunoglobulin G (IgG) responses to both gSG6-P1 (Anopheles) and Nterm-34-kDa (Aedes) salivary peptides as validated biomarkers of respective mosquito bite exposure.

RESULTS

IgG response levels to gSG6-P1 and Nterm-34-kDa salivary peptides varied significantly between the 4 neighborhoods (P < .0001). The level of exposure to Aedes bites also varied according to household access to sanitation services (P = .027), whereas that of exposure to Anopheles bites varied according to insecticide-treated bed net use (P = .006). In addition, spatial clusters of high contact between humans and mosquitoes were identified inside 3 neighborhoods.

CONCLUSIONS

Antibody-based biomarkers of exposure to Anopheles and Aedes mosquito bites could be helpful tools for evaluating the heterogeneity of exposure to malaria and arboviral disease vectors by national control programs.

Chikungunya fever in Africa: a systematic review

Since the identification of chikungunya virus (CHIKV), sporadic cases and outbreaks were reported in several African countries, on the Indian subcontinent, and in south-east Asia. In the last 20 years, there is a growing number of reports of CHIKV infections from African countries, but the overall picture of its circulation at the continent level remains ill-characterized because of under-diagnosis and under-reporting. Moreover, the public health impact of the infection in Africa is generally poorly understood, especially during outbreak situations. Our work has the aim to review available data on CHIKV circulation in Africa to facilitate the understanding of underlying reasons of its increased detection in the African continent.

Guaroa Virus and Plasmodium vivax Co-Infections, Peruvian Amazon

During April–June 2014 in a malaria-endemic rural community close to the city of Iquitos in Peru, we detected evidence of Guaroa virus (GROV) infection in 14 febrile persons, of whom 6 also had evidence of Plasmodium vivax malaria. Cases were discovered through a long-term febrile illness surveillance network at local participating health facilities. GROV cases were identified by using a combination of seroconversion and virus isolation, and malaria was diagnosed by thick smear and PCR. GROV mono-infections manifested as nonspecific febrile illness and were clinically indistinguishable from GROV and P. vivax co-infections. This cluster of cases highlights the potential for GROV transmission in the rural Peruvian Amazon, particularly in areas where malaria is endemic. Further study of similar areas of the Amazon may provide insights into the extent of GROV transmission in the Amazon basin.

Possible influence of Plasmodium/Trypanosoma co-infections on the vectorial capacity of Anopheles mosquitoes

Objective

In tropical Africa, trypanosomiasis is present in endemic areas with many other diseases including malaria. Because malaria vectors become more anthropo-zoophilic under the current insecticide pressure, they may be exposed to trypanosome parasites. By collecting mosquitoes in six study sites with distinct malaria infection prevalence and blood sample from cattle, we tried to assess the influence of malaria-trypanosomiasis co-endemicity on the vectorial capacity of Anopheles.

Results

Overall, all animal infections were due to Trypanosoma vivax (infection rates from 2.6 to 10.5%) in villages where the lowest Plasmodium prevalence were observed at the beginning of the study. An. gambiae s.l. displayed trophic preferences for human-animal hosts. Over 84 mosquitoes, only one was infected by Plasmodium falciparum (infection rate: 4.5%) in a site that displayed the highest prevalence at the beginning of the study. Thus, Anopheles could be exposed to Trypanosoma when they feed on infected animals. No Plasmodium infection was observed in the Trypanosoma-infected animals sites. This can be due to an interaction between both parasites as observed in mice and highlights the need of further studies considering Trypanosoma/Plasmodium mixed infections to better characterize the role of these infections in the dynamic of malaria transmission and the mechanisms involved.

Mechanisms of inter-epidemic maintenance of Rift Valley fever phlebovirus

Rift Valley fever phlebovirus (RVFV) is an arthropod-borne virus that has caused substantial epidemics throughout Africa and in the Arabian Peninsula. The virus can cause severe disease in livestock and humans and therefore the control and prevention of viral outbreaks is of utmost importance. The epidemiology of RVFV has some particular characteristics. Unexpected and significant epidemics have been observed in spatially and temporally divergent patterns across the African continent. Sudden epidemics in previously unaffected areas are followed by periods of long-term apparent absence of virus and sudden, unpredictable reoccurrence in disparate regions. Therefore, the elucidation of underlying mechanisms of viral maintenance is one of the largest gaps in the knowledge of RVFV ecology. It remains unknown whether the virus needs to be reintroduced before RVF outbreaks can occur, or if unperceived viral circulation in local vertebrates or mosquitoes is sufficient for maintenance of the virus. To gain insight into these knowledge gaps, we here review existing data that describe potential mechanisms of RVFV maintenance, as well as molecular and serological studies in endemic and non-endemic areas that provide evidence of an inter- or pre-epidemic virus presence. Basic and country-specific mechanisms of RVFV introduction into non-endemic countries are summarized and an overview of studies using mathematical modeling of RVFV persistence is given.

Pathogenic Th1 responses in CHIKV-induced inflammation and their modulation upon Plasmodium parasites co-infection

The induction of polyarthritis and polyarthralgia is a hallmark of arthritogenic alphavirus infections, with an exceptionally higher morbidity observed with chikungunya virus (CHIKV). While the mechanisms underlying these incapacitating acute symptoms remain partially understood, the progression to chronic conditions in some cases remains unanswered. The highly pro‐inflammatory nature of alphavirus disease has suggested the involvement of virus‐specific, joint‐infiltrating Th1 cells as one of the main pathogenic mediators of CHIKV‐induced joint pathologies. This review summarizes the role of cell‐mediated immune responses in CHIKV pathogenesis, with a specific focus on pro‐inflammatory Th1 responses in the development of CHIKV joint inflammation. Furthermore, due to the explosive nature of arthritogenic alphavirus outbreaks and their recent expansion across the world, co‐infections with other highly prevalent pathogens such as malaria are likely to occur but the pathological outcomes of such interactions in humans are unknown. This review will also discuss the potential impact of malaria co‐infections on CHIKV pathogenesis and their relevance in alphavirus control programs in endemic areas.

Malaria Coinfections in Febrile Pediatric Inpatients: A Hospital-Based Study From Ghana

Background

The epidemiology of pediatric febrile illness is shifting in sub-Saharan Africa, but malaria remains a major cause of childhood morbidity and mortality. The present study describes causes of febrile illness in hospitalized children in Ghana and aims to determine the burden of malaria coinfections and their association with parasite densities.

Methods

In a prospective study, children (aged ≥30 days and ≤15 years) with fever ≥38.0°C were recruited after admission to the pediatric ward of a primary hospital in Ghana. Malaria parasitemia was determined and blood, stool, urine, respiratory, and cerebrospinal fluid specimens were screened for parasitic, bacterial, and viral pathogens. Associations of Plasmodium densities with other pathogens were calculated.

Results

From November 2013 to April 2015, 1238 children were enrolled from 4169 admissions. A clinical/microbiological diagnosis could be made in 1109/1238 (90%) patients, with Plasmodium parasitemia (n = 728/1238 [59%]) being predominant. This was followed by lower respiratory tract infections/pneumonia (n = 411/1238 [34%]; among detected pathogens most frequently Streptococcus pneumoniae, n = 192/299 [64%]), urinary tract infections (n = 218/1238 [18%]; Escherichia coli, n = 21/32 [66%]), gastrointestinal infections (n = 210 [17%]; rotavirus, n = 32/97 [33%]), and invasive bloodstream infections (n = 62 [5%]; Salmonella species, n = 47 [76%]). In Plasmodium-infected children the frequency of lower respiratory tract, gastrointestinal, and bloodstream infections increased with decreasing parasite densities.

Conclusions

In a hospital setting, the likelihood of comorbidity with a nonmalarial disease is inversely correlated with increasing blood levels of malaria parasites. Hence, parasite densities provide important information as an indicator for the probability of coinfection, in particular to guide antimicrobial medication.

Prevalence and laboratory analysis of malaria and dengue co-infection: a systematic review and meta-analysis

Background

A clear understanding of the epidemiology of malaria and dengue co-infection is essential for informed decisions on appropriate control strategies for dengue and malaria. This systematic review synthesized evidence on the relationship of malaria and dengue co-infection and related it to alterations in platelet, hemoglobin, hematocrit, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels when compared to malaria mono-infection.

Methods

A systematic review in accordance with PRISMA guidelines was conducted. All published articles available in PubMed and Web of Science (ISI) databases before October 21, 2017 were recruited. All epidemiological studies except case reports on the prevalence or incidence of malaria and dengue co-infection among patients visiting hospitals with febrile illness were included. Studies that involved conference abstracts, protocols, systematic reviews, only mono-dengue or mono-malaria infections, and only animal or in vitro studies were excluded after screening the titles, abstracts, and body texts. Studies were additionally excluded after full text review when they lacked epidemiologic data on malaria and dengue co-infection. Two reviewers independently screened, reviewed, and assessed all the studies. Cochrane Q (Chi-square) and Moran’s I² were used to assess heterogeneity, and the funnel plot was used to examine publication bias. The summary odds ratio (OR) and 95% confidence intervals (CI) were estimated using a fixed-effects model. Thirteen cross-sectional and two retrospective studies were eligible to be included in the systematic review and meta-analysis.

Results

Out of the 2269 citations screened, 15 articles were eligible to be included in the systematic review and meta-analysis. The 15 studies involved 13,798 (10,373 cases with malaria and 3425 with dengue) patients in 9 countries. Thirteen studies compared the incidence and odds of Plasmodium sp. infection, five studies compared the odds of mean platelet, three studies compared Plasmodium parasite density, and four studies compared the odds of hemoglobin, hematocrit, AST, and ALT levels among co-infected groups and single-malaria-infected groups.

Conclusions

This study showed that dengue and malaria co-infection was associated with decreased odds of malaria infection, malaria parasitemia, AST, and ALT levels when compared to malaria mono-infection. However, malaria and dengue co-infection was associated with increased odds of platelet and hemoglobin levels when compared to malaria mono-infection.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7488-4) contains supplementary material, which is available to authorized users.

Case Report: Typhoid Fever and Spotted Fever Group Rickettsiosis Presenting Concomitantly in an Indian Immigrant

We present a rare case of an Indian immigrant suffering from concomitant infection of Salmonella typhi and spotted fever group Rickettsia. We discuss the scarce reports of dual infections from the developing world and the related diagnostic challenges.

Prevalence of Zika and malaria in patients with fever in secondary healthcare facilities in south-eastern Nigeria

We describe the frequency of Zika and malaria among patients presenting with fever to secondary health facilities in Cross River State, Nigeria. Using a cross-sectional, stratified survey design, we randomly selected nine facilities and consecutively recruited 100 participants (aged ≥ 1 year) who presented with fever. On testing blood samples using Biocan qualitative lateral flow immuno-chromatographic cassettes for Zika IgG and IgM, 10% were seropositive for Zika virus (ZIKV) IgM, 12% for ZIKV IgG and 20% for ZIKV IgM, IgG or both. Following microscopy of thick films stained with Giemsa for malaria parasites, 55% were positive for malaria and 15% were positive for both malaria and ZIKV IgM, IgG or both. A moderately negative association between urban and rural household location and seropositivity for ZIKV IgM or IgG was found on logistic regression. Our results clearly indicate a high rate of probable ZIKV and malaria co-incidence in Cross River State. Given the high risk of serious fetal outcomes following ZIKV infection, further epidemiological research and surveillance systems for ZIKV are clearly required.

Multinomial Logistic Model for Coinfection Diagnosis Between Arbovirus and Malaria in Kedougou

In tropical regions, populations continue to suffer morbidity and mortality from malaria and arboviral diseases. In Kedougou (Senegal), these illnesses are all endemic due to the climate and its geographical position. The co-circulation of malaria parasites and arboviruses can explain the observation of coinfected cases. Indeed there is strong resemblance in symptoms between these diseases making problematic targeted medical care of coinfected cases. This is due to the fact that the origin of illness is not obviously known. Some cases could be immunized against one or the other of the pathogens, immunity typically acquired with factors like age and exposure as usual for endemic area. Thus, coinfection needs to be better diagnosed. Using data collected from patients in Kedougou region, from 2009 to 2013, we adjusted a multinomial logistic model and selected relevant variables in explaining coinfection status. We observed specific sets of variables explaining each of the diseases exclusively and the coinfection. We tested the independence between arboviral and malaria infections and derived coinfection probabilities from the model fitting. In case of a coinfection probability greater than a threshold value to be calibrated on the data, long duration of illness and age are mostly indicative of arboviral disease while high body temperature and presence of nausea or vomiting symptoms during the rainy season are mostly indicative of malaria disease.

Serological Data Shows Low Levels of Chikungunya Exposure in Senegalese Nomadic Pastoralists

The chikungunya virus (CHIKV) is spread by Aedes aegypti and Ae. albopictus mosquitos worldwide; infection can lead to disease including joint pain, fever, and rash, with some convalescent persons experiencing chronic symptoms. Historically, CHIKV transmission has occurred in Africa and Asia, but recent outbreaks have taken place in Europe, Indonesia, and the Americas. From September to October 2014, a survey was undertaken with nomadic pastoralists residing in the northeast departments of Senegal. Blood dried on filter paper (dried blood spots; DBS) were collected from 1465 participants of all ages, and assayed for Immunoglobulin G (IgG) antibodies against CHIKV E1 antigen by a bead-based multiplex assay. The overall seroprevalence of all participants to CHIKV E1 was 2.7%, with no persons under 10 years of age found to be antibody positive. Above 10 years of age, clear increases of seroprevalence and IgG levels were observed with increasing age; 7.6% of participants older than 50 years were found to be positive for anti-CHIKV IgG. Reported net ownership, net usage, and gender were all non-significant explanatory variables of seropositivity. These data show a low-level historical exposure of this pastoralist population to CHIKV, with no evidence of recent CHIKV transmission in the past decade.

Surveys of Arboviruses Vectors in Four Cities Stretching Along a Railway Transect of Burkina Faso: Risk Transmission and Insecticide Susceptibility Status of Potential Vectors

Background: A severe outbreak of dengue occurred in Burkina Faso in 2016, with the most cases reported in Ouagadougou, that highlights the necessity to implement vector surveillance system. This study aims to estimate the risk of arboviruses transmission and the insecticide susceptibility status of potential vectors in four sites in Burkina Faso.

Methods: From June to September 2016, house-to-house cross sectional entomological surveys were performed in four cities stretching along a southwest-to-northeast railway transect. The household surveys analyzed the presence of Aedes spp. larvae in containers holding water and the World Health Organization (WHO) larval abundance indices were estimated. WHO tube assays was used to evaluate the insecticide susceptibility within Aedes populations from these localities.

Results: A total of 31,378 mosquitoes' larvae were collected from 1,330 containers holding water. Aedes spp. was the most abundant (95.19%) followed by Culex spp. (4.75%). Aedes aegypti a key vector of arboviruses (ARBOV) in West Africa was the major Aedes species found (98.60%). The relative larval indices, house index, container and Breteau indexes were high, up to 70, 35, and 10, respectively. Aedes aegypti tended to breed mainly in discarded tires and terracotta jars. Except in Banfora the western city, Ae. aegypti populations were resistant to deltamethrin 0.05% in the other localities with low mortality rate under 20% in Ouagadougou whereas they were fully susceptible to malathion 5% whatever the site. Intermediate resistance was observed in the four sites with mortality rates varying between 78 and 94% with bendiocarb 0.1%.

Conclusions: This study provided basic information on entomological indices that can help to monitor the risks of ARBOV epidemics in the main cities along the railway in Burkina Faso. In these cities, all larval indices exceeded the risk level of ARBOV outbreak. Aedes aegypti the main species collected was resistant to deltamethrin 0.05% and bendiocarb 0.1% whereas they were fully susceptible to malathion 5%. The monitoring of insecticide resistance is also important to be integrated to the vector surveillance system in Burkina Faso.

Zika viruses of African and Asian lineages cause fetal harm in a mouse model of vertical transmission

Congenital Zika virus (ZIKV) infection was first linked to birth defects during the American outbreak in 2015/2016. It has been proposed that mutations unique to the Asian/American-genotype explain, at least in part, the ability of Asian/American ZIKV to cause congenital Zika syndrome (CZS). Recent studies identified mutations in ZIKV infecting humans that arose coincident with the outbreak in French Polynesia and were stably maintained during subsequent spread to the Americas. Here we show that African ZIKV can infect and harm fetuses and that the S139N substitution that has been associated with the American outbreak is not essential for fetal harm. Our findings, in a vertical transmission mouse model, suggest that ZIKV will remain a threat to pregnant women for the foreseeable future, including in Africa, Southeast Asia, and the Americas. Additional research is needed to better understand the risks associated with ZIKV infection during pregnancy, both in areas where the virus is newly endemic and where it has been circulating for decades.

Asymptomatic Plasmodium vivax infections among Duffy-negative population in Kedougou, Senegal

Background

In the southeastern Senegal, the report of Plasmodium vivax infections among febrile patients in Kedougou constitutes a new emerging health problem.

Methods

Samples from 48 asymptomatic schoolchildren sampled twice a year over 2 years were used to explore the reservoir of P. vivax parasite infections in this region. Both Duffy genotyping and Plasmodium species diagnostic assays were performed.

Results

PCR assays detected Plasmodium genomic DNA in 38.5% (74/192) of samples. Pure P. falciparum and P. vivax infections were identified in 79.7% (59/74) and 20.3% (15/74) of samples, respectively. All schoolchildren were classified as Duffy-negative by genotyping. P. vivax infections were detected in five children: in two children during both years, in one child in 2010 and on May 2011, and only in 2010 for the remaining two children.

Conclusions

This unexpectedly high proportion of P. vivax infections in asymptomatic Duffy-negative children highlights to consider vivax malaria as an emerging problem in Senegal.

Chikungunya virus infection prevalence in Africa: a contemporaneous systematic review and meta-analysis

OBJECTIVES

The (re)emergence of chikungunya virus (CHIKV) in Africa requires better knowledge on the epidemiology of CHIKV infection in the continent for efficient public health strategies. We aimed to describe the epidemiology of CHIKV infection in Africa, a neglected tropical disease (NTD).

STUDY DESIGN

This was a systematic review with meta-analysis of studies reporting CHIKV infection prevalence. We searched Embase, PubMed, Africa Journal Online and Global Index Medicus to identify observational studies published from January 2000 to September 2017.

METHODS

We used a random-effect model to pool the prevalence of CHIKV infections reported with their 95% confidence interval (CI). Heterogeneity was assessed via the Chi-squared test on Cochran's Q statistic. Review registration is in PROSPERO CRD42017080395.

RESULTS

A total of 39 studies (37,881 participants; 18 countries) were included. No study was reported from Southern Africa. Thirty-two (82.0%), seven (18.0%) and no studies had low, moderate and high risk of bias, respectively. Outside outbreak periods, the pooled immunoglobulin M (IgM) and immunoglobulin G (IgG) seroprevalence was 9.7% (95% CI 3.0-19.6; 16 studies) and 16.4% (95% CI 9.1-25.2; 23 studies), respectively. The IgM seroprevalence was lower in Northern Africa, and there was no difference for IgG prevalence across regions in Africa. The IgM and IgG seroprevalences were not different between acute and non-acute febrile participants. The seroprevalence was not associated with GPS coordinates (latitude, longitude and altitude).

CONCLUSIONS

Although considered a NTD, we find high prevalence of CHIKV infection in Africa. As such, chikungunya fever should deserve more attention from healthcare providers, researchers, policymakers and stakeholders from many sectors.