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      The Threat of Zika Virus in Sub-Saharan Africa – The Need to Remain Vigilant

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          Abstract

          Background News of the recent outbreak of Zika virus (ZIKV) disease in South America, North America, and Europe has generated great interest in the scientific community and general public like (1, 2). The disease is caused by the Zika virus (ZIKV), a mosquito-borne Flavivirus transmitted mainly by Aedes aegypti and Aedes albopictus, mosquitoes that also transmit other viral infections, including dengue virus (DENV), chikungunya virus (CHIKV), and yellow fever virus (YFV) (2). Zika virus was isolated for the first time in Rhesus monkey in 1947 in Zika forest in Uganda and since then, evidence of seroprevalence of ZIKV infection in human has been documented in several African countries (3–5). However, to date, the virus has not been considered a serious threat in the region. Symptoms of Zika virus disease are very similar to those of dengue and chikungunya and include fever, rash, joint pain, or conjunctivitis (6). Furthermore, most of the infections remain asymptomatic; thus, majority of the cases are either misdiagnosed or not detected at all. Worryingly, the recent pandemic in South America has associated ZIKV infection with microcephaly, a condition that results in small heads and underdeveloped brains in infants and neurological complication (Guillain–Barré syndrome); yet, no specific treatment or vaccine for the disease exists (1, 7). The incidences of ZIKV infections are escalating at alarming rates in South, North America, and in Europe and potentially threatening countries in sub-Saharan Africa if migration might play a role in both directions. Increasing urbanization, poor urban planning, changes in climatic factors, and the availability of favorable microecological condition suitable for Aedes mosquitoes breeding in sub-Saharan Africa are among factors that escalate mosquito abundance. In the face of such potential threat, there is a need for vigilance and establishment of preparedness measures before a Zika pandemic hits the continent. Such a pandemic would pose overwhelming cost burdens to the health systems and potentially compromise the achievement of the sustainable development goals (SDGs). In this letter, we wish to highlight measures that we believe would be effective in setting up countries’ preparedness response and surveillance systems to address the potential Zika virus disease threat in sub-Saharan context. First, there is need for capacity strengthening with focus on the laboratory facilities and human resources to be able to implement epidemiological surveillance and disease control carry out accurate diagnosis and offer quality case management during outbreaks. The establishment of guidelines for all these aspects of disease management would need to be developed. There is need to support the setting up public health laboratories and strengthening of the existing ones to be able to conduct epidemiological surveillance and sophisticated molecular diagnosis that relies on polymerase chain reaction (PCR) or real-time PCR (RT-PCR) based assays. Currently, there is no ZIKV rapid diagnostic test available at the point of care. Therefore, it is important that health-care professionals are trained on case diagnosis and management approaches. This has to be in parallel with the improved capacity of laboratories to exclude other severe conditions, such as malaria and bacterial infection. Regional and cross-border networks, such as the East Africa Public Health Laboratory Networking (EAPHLNP), should be strengthened to fill the gaps and the model emulated in other African countries. In this era of increased mobility between countries, the need for regional coordination in sharing of virologic/serotype and vector surveillance data should be underscored. Additionally, there is a shortage of entomologists at regional and district levels to provide technical support in mosquito vector identification and dynamics, which is critical for vector surveillance and control. This shortage of qualified entomologists with technical field expertise is well documented (8). We therefore suggest that serious consideration be given to the training of entomologists so as to fill this gap. Second, there is a need to raise community awareness and to educate the public on measures that they can put in place to avoid mosquito bites and reduce mosquito breeding habitats. A. aegypti are container breeders and integrated approaches that require close community engagement are necessary for their effective control. Community awareness and education will contribute toward the adjustment of risky behavior, such as the failure to cover water storage containers that are in use and improper disposal of old water containers and used car tires. The media should be granted the opportunity by governments to take the lead in supporting community awareness and education efforts on all matters related to epidemiology and control of Zika virus disease more than is currently happening (2). Third, the role of global travel in the emergence and re-emergence of disease diseases cannot go unnoticed. There is already risk for transmission of Zika virus disease to sub-Saharan African countries in Cape Verde and other regions (3, 9). Expanding global travel and the shipping industry contribute significantly in the transportation of asymptomatic individuals (10). Strong incentives are needed for surveillance to prevent re-infestation of the Zika virus in sub-Saharan Africa. Attention is particularly needed in the main entry points such as the airports and seaports that are the main gateway from the infected areas. There is need for ministries of health and respective authorities to issue travel alerts and guidance to those visiting to ZIKV-risk countries. For example, pregnant women in any trimester should be advised to highly consider postponing travel and individuals who must visit such countries provided with guidelines and recommendations on the symptoms to look out for and immediately report to the health-care professional on the onset of such symptoms. Also, guidelines and recommendations on personal protection measures to avoid human–mosquito contact, such as the use of repellants and wearing long sleeve clothes, should be emphasized. Fourth, several key research issues need to be addressed. It will be important to evaluate the role of potential non-human primates in maintaining transmission and/or serving as ZIKV reservoirs. Other proposed routes of transmission, including sexual and maternal (Figure 1), also need further investigation as this will have implications for the epidemiology of the disease. In addition, given that there are no preventative or therapeutic vaccines and point of care diagnostic tests for Zika virus disease, it is important that financial resources to accelerate the discovery and clinical testing of these tools be urgently set aside and made available. With regard to vector control, strategies relevant to the local context are urgently needed to support effective preventive and control measures. The increasing role of climatic factors in relation to Aedes mosquito dynamics also needs further exploration as the changes in global temperatures and weather patterns could impact the transmission and spread of the virus. Possible consequences of coinfections between dengue serotypes (DENV 1–4) and ZIKV virus or coinfection between ZIKV and other prevalent infections in the continent, such as malaria and HIV, also need to be understood. Furthermore, the implication of different ZIKV serotypes in vulnerable groups’ particularly pregnant women and children are yet to be understood. With Africa increasingly opening up to the rest of the world due to human migration associated with tourism and business, it is imperative for countries to remain vigilant regarding the threat of the expanding arboviral infections. Figure 1 Zika virus is transmitted mainly by the Aedes aegypti mosquitoes, which is widespread in urban and peri-urban areas. The zoonotic is known to occur between human and non-human primates. The role of other reservoir and sexual transmission is still unconfirmed. The re-emergence and spread of arboviral infections could lead to devastating consequences on the human population, the health-care system and economic progress in the continent. It is crucial that countries establish harmonized and robust vector control and surveillance systems, which will include the setting up of regional preparedness plans in response to mosquito-borne viruses and investing in capacity building as well as creating community awareness. Investing in research in the development and validation of tools and strategies for the control of the viruses and in understanding of their epidemiology will also be critical. Author Contributions Both authors, VB and EK contributed equally to the drafting and approved the final manuscript for submission. Conflict of Interest Statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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          Zika Virus in Gabon (Central Africa) – 2007: A New Threat from Aedes albopictus?

          Introduction Zika virus (ZIKV) is a mosquito-borne flavivirus phylogenetically related to dengue viruses. Following its first isolation in 1947 from a sentinel monkey placed in the Zika forest in Uganda [1], serological surveys and viral isolations (reviewed in [2]) suggested that ZIKV (i) ranged widely throughout Africa and Asia, and (ii) circulated according to a zoonotic cycle involving non-human primates and a broad spectrum of potential mosquito vector species. In Africa, ZIKV has been isolated from humans in western and central countries such as Senegal, Nigeria, Central African Republic and Uganda [3]–[7]. Serological surveys (reviewed in [2]) suggested that its geographic range might extend not only to other West and Central African countries (Sierra Leone, Cameroon, Gabon), but also to eastern (Ethiopia, Kenya, Tanzania and Somalia) and northern Africa (Egypt). ZIKV has also been isolated from mosquitoes collected in Senegal, Ivory Coast, Burkina Faso, Central African Republic and Uganda [1], [6], [8], [9]. These mosquitoes mainly belonged to sylvan or rural species of the genus Aedes, and more precisely to the Aedimorphus, Diceromyia and Stegomyia subgenera. The virus has also been isolated in West Africa (Burkina Faso, Senegal and Ivory Coast) [6], [9] and Asia [10] from Aedes aegypti, a species being considered the main ZIKV epidemic vector outside Africa [11]. Moreover, Ae. aegypti was shown experimentally to be an efficient ZIKV vector [12]–[14]. Despite its apparent broad geographic distribution in Africa and Asia, only sporadic cases of human ZIKV infection have been reported. This virus received little attention until its sudden emergence in Yap Island (Micronesia) in 2007, which involved about 5000 persons [15], [16], revealing its epidemic capacity. Patients develop a mild dengue-like syndrome, including fever, headache, rash, arthralgia and conjunctivitis. This clinical similarity with other, more commonly diagnosed arboviral infections such as chikungunya (CHIKV) and dengue (DENV), might delay the diagnosis and/or lead to underestimation of ZIKV infections. Here, we report the first direct evidence of ZIKV epidemic activity in Central Africa, and its occurrence in an urban environment during concomitant CHIKV/DENV outbreaks in Libreville, the capital of Gabon, in 2007. We also report the first detection of ZIKV in the Asian tiger mosquito, Ae. albopictus. These findings, together with the global geographic expansion of this invasive species and its increasing importance as epidemic vector of arboviruses as exemplified by CHIKV adaptation, suggest that the prerequisites for the emergence and global spread of Zika virus may soon be satisfied. Materials and Methods Study In 2007 and 2010, Gabon recorded simultaneous outbreaks of CHIKV (genus Alphavirus) and DENV (genus Flavivirus) infections. The 2007 outbreaks primarily affected Libreville, the capital of Gabon, and subsequently extended northwards to several other towns [17], while the 2010 outbreaks occurred in the south-eastern provinces [18]. To detect other circulating arboviruses, we conducted a retrospective study based on molecular screening of 4312 sera from symptomatic patients presenting to healthcare centers; 24.7% of the samples were obtained during the 2007 outbreaks, 9.7% during the inter-epidemic period, and 65.5% during the 2010 outbreaks (data not shown). We also analyzed a collection of 4665 mosquitoes captured during the same period and split into 247 pools according to the species, date and sampling site (Table 1, see [18] and [19] for the details of the methodology used for mosquito trapping). 10.1371/journal.pntd.0002681.t001 Table 1 Mosquito collections screened for Zika virus. Libreville 2007 Franceville 2010 Total Species Pools Mos. Id. (No.) ZIKV CHIKV DENV Libreville suburb Pools Mos. Pools (%) Mos. Aedes albopictus 91 2130 T64 (21) + + − Nzeng-Ayong 46 571 137 (55.4) 2701 T713 (25) + + − Alenkiri T707 (25) − − + Alenkiri T717 (25) − − + Alenkiri T723 (25) − − + Alenkiri T724 (6) − + − Alenkiri T21 (25) − + − Avorembam T22 (25) − + − Avorembam T280 (1) − + − Bel-Air Aedes aegypti * 40 853 5 28 45 (18.2) 881 Aedes simpsoni complex 10 52 5 36 15 (6.1) 88 Anopheles gambiae * 8 72 8 (3.2) 72 Mansonia africana 6 86 6 (2.4) 86 Mansonia uniformis * 4 99 4 (1.6) 99 Culex quinquefasciatus 29 690 29 (11.7) 690 Culex spp. 1 22 1 (0.4) 22 Eretmapodites quinquevittatus * 2 26 2 (0.8) 26 Total 189 4004 58 661 247 4665 * Species in which Zika virus has previously been detected. (%) The percentage of each mosquito species in the collection is indicated in brackets. Mos.: Number of mosquitoes included in a pool. Id. (No.): Mosquito pool positive for ZIKV, CHIKV or DENV, followed by the total number of included mosquitoes in the pool indicated in brackets. Ethics statement The Centre International de Recherches Médicales de Franceville (CIRMF) and the Gabonese Ministry of Health cooperated in the 2007 and 2010 outbreak response and management, that included blood sampling for laboratory diagnostic and epidemiological survey. The study was approved by our Institutional review board (Conseil scientifique du CIRMF). Symptomatic patients presented to health care centers for medical examination. All patients were informed that blood sampling was required for laboratory diagnosis of suspected acute infections, such as malaria, dengue or chikungunya fever. During the two outbreaks, given the urgency of diagnosis, only oral consent was obtained for blood sampling and was approved by the institutional review board. However during the active surveillance study that was performed between the two outbreaks (described in reference [18]), written consent could be obtained. Virus identification and characterization Primary molecular screening was based on hemi-nested reverse-transcription PCR (hnRT-PCR) with the generic primers PF1S/PF2Rbis/PF3S targeting highly conserved motifs in the flavivirus polymerase (NS5) gene (280-bp) [20]. Yellow fever virus RNA (vaccinal strain 17D) was used as a positive control. A second screening was performed with a ZIKV-specific real-time PCR method using the primers-probe system ZIKV-1086/ZIKV-1162c/ZIKV-1107-FAM [16], also targeting a short sequence (160 bp) of the NS5 gene. Virus isolation was attempted on the Vero and C6/36 cell lines but was unsuccessful, presumably because of low viral titers (despite two patients presenting only 1 and 4 days after symptom onset), and unsuitable initial storage conditions. To further characterize the Gabonese ZIKV strains, partial envelope (E) (841 bp) and NS3 (772 bp) gene sequences were amplified by conventional nested RT-PCR with specific primers derived from published ZIKV sequences. The primer pairs targeting the E gene were ZIK-ES1 (TGGGGAAAYGGDTGTGGACTYTTTGG)/ZIK-ER1 (CCYCCRACTGATCCRAARTCCCA) and ZIK-ES2 (GGGAGYYTGGTGACATGYGCYAAGTT)/ZIK-ER2 (CCRATGGTGCTRCCACTCCTRTGCCA). The primer pairs for NS3 amplification were ZIK-NS3FS (GGRGTCTTCCACACYATGTGGCACGTYACA)/ZIK-NS3FR (TTCCTGCCTATRCGYCCYCTCCTCTGRGCAGC) and ZIK-X1 (AGAGTGATAGGACTCTATGG)/ZIK-X2 (GTTGGCRCCCATCTCTGARATGTCAGT). Phylogenetic analysis The E and NS3 sequences obtained from one Gabonese patient were concatenated and analyzed using a set of previously published ZIKV sequences. Phylogenetic relationships were reconstructed with the maximum likelihood algorithm implemented in PhyML [21] (available at http://www.atgc-montpellier.fr/phyml/) with best of NNI (Nearest Neighbor Interchange) and SPR (Subtree Pruning and Regrafting) criteria for tree topology searching, and the GTR model of nucleotide substitutions. The Gamma distribution of rate heterogeneity was set to 4 categories, with a proportion of invariable sites and an alpha parameter estimated from the dataset. Branch support was assessed from 100 bootstrap replicates. Tree reconstructions were also performed by Bayesian inference with MrBayes v3.2 [22] under the GTR+I+G model of nucleotide substitutions, and with the distance neighbor-joining method [23] implemented in MEGA5 [24] with confidence levels estimated for 1000 replicates. To test for phylogenetic discrepancies, tree reconstructions were also performed independently from the envelope dataset and the NS3 dataset with PhyML according to the parameters described above. The resulting trees were visualized with the FigTree software (Available at: http://tree.bio.ed.ac.uk/software/figtree/), and rooted on midpoint for clarity. The Genbank accession numbers for the Gabonese ZIKV strain are KF270886 (envelope) and KF270887 (NS3). Results Molecular screening The NS5 PCR products were sequenced, resulting in the first ZIKV RNA detection in a human sample (Cocobeach) and in two Ae. albopictus pools (Libreville) collected during the 2007 outbreaks. Real-time PCR was then performed, leading to the detection of four additional positive human samples, collected in 2007 in four suburbs of Libreville (Diba-Diba, Nzeng-Ayong, PK8, PK9) (Figure 1). No ZIKV was detected during the inter-epidemic period or during the 2010 outbreaks. 10.1371/journal.pntd.0002681.g001 Figure 1 Geographic distribution of Zika and chikungunya and/or dengue viruses infections in Gabon in 2007. The left-hand panel indicates Gabonese CHIKV and/or DENV cases in green circles and ZIKV cases in purple circles. The right-hand panel shows the location of Libreville suburbs where ZIKV-positive human sera (H) and mosquito pools (M) were detected. Clinical description Clinical information was available for only one ZIKV-positive patient, who had mild arthralgia, subjective fever, headache, rash, mild asthenia, myalgia, diarrhea and vomiting. No information was available on this patient's outcome. Cycle threshold values for human blood samples were high (>37 cycles), suggesting low viral loads (data not shown). Vector involvement Aedes albopictus was the predominant species collected, accounting for 55.4% of the mosquito pools, while Aedes aegypti accounted for 18.2% (Table 1). The other mosquito species consisted of members of the Aedes simpsoni complex, Anopheles gambiae, Mansonia africana, Mansonia uniformis, Culex quinquefasciatus, Eretmapodites quinquevittatus and unidentified Culex species. Positive mosquito pools were captured from two suburbs (Nzeng-Ayong and Alenkiri) where Aedes albopictus was the predominant species (Figure 1, Table 1). Sequences analysis As isolation on the Vero and C6/36 cell lines failed, the Gabonese ZIKV strain was further characterized by partial sequencing of the E and NS3 genes. Phylogenetic analysis was performed on concatenated E and NS3 sequences from one Cocobeach serum sample. The resulting tree topology (Figure 2) was similar to that previously obtained from the complete coding sequences, corroborating Asian and African distinct lineages [2]. The African lineage was further split into two groups, one containing the genetic variants of the MR766 strain (Uganda, 1947) and the second including West African strains (Nigeria, 1968; Senegal, 1984) and the new ZIKV sequence from Gabon, at a basal position. Phylogenetic trees derived from the E and NS3 partial sequences resulted in a similar topology, apart from the weakly supported branching pattern for the MR766 variant DQ859059, oscillating between the two African sister groups (Supporting Figure S1). The deletions in potential glycosylation sites previously reported for the Nigerian ZIKV strain and two variants of the Ugandan strain MR766 (sequences AY632535 and DQ859059) [2] were absent from the Gabonese ZIKV sequence. 10.1371/journal.pntd.0002681.g002 Figure 2 Phylogenetic relationships between concatenated sequences of the Zika virus envelope and NS3 genes. The tree was constructed with the maximum likelihood algorithm implemented in PhyML and rooted on midpoint. Bootstrap values are shown at the respective nodes, followed by bootstrap values resulting from NJ analysis and, finally, the posterior probability resulting from Bayesian analysis. The scale bar indicates the number of substitutions per site. The GenBank accession numbers for the 2007 Gabonese ZIKV isolate are KF270886 (envelope) and KF270887 (NS3). Discussion Evidence of human ZIKV infections in Central Africa is limited to one isolate from RCA in 1991 [6] and two serological surveys performed 50 years ago in Gabon [25], [26]. No report of human ZIKV infections was made in other countries of the Congo basin forest block, despite probable circulation through a sylvan natural cycle. We provide here the first direct evidence of human ZIKV infections in Gabon, as well as its occurrence in an urban transmission cycle, and the probable role of Ae. albopictus as an epidemic vector. Our phylogenetic results are in agreement with the tree topology previously obtained with complete coding sequences of ZIKV strains, showing an African lineage and an Asian lineage [2]. The branching pattern obtained here suggests that ZIKV emergence in Gabon did not result from strain importation but rather from the diversification and spread of an ancestral strain belonging to the African lineage. The identification of ZIKV in two different localities of Gabon (Cocobeach and Libreville) suggests that the virus was widespread rather than restricted to a single epidemic focus. The simultaneous occurrence of human and mosquito infections in Libreville also suggests that the virus circulated in 2007 in an epidemic cycle rather than as isolated cases introduced from sylvan cycles. Of note, ZIKV transmission occurred here in a previously undocumented urban cycle, supporting the potential for urbanization suggested in 2010 by Weaver and Reisen [27]. While some mosquito species (including Ae. aegypti) previously found to be associated with ZIKV, were captured and tested here, only Ae. albopictus pools were positive for this virus. Moreover, this species largely outnumbered Ae. aegypti in the suburbs of Libreville where human cases were detected, suggesting that Ae. albopictus played a major role in ZIKV transmission in Libreville. The ratio of ZIKV-positive Ae. albopictus pools is similar to that reported for DENV-positive pools, suggesting that these two viruses infect similar proportions of mosquitoes. The small number of recorded human ZIKV cases, by comparison with DENV cases, may be due to the occurrence of subclinical forms of ZIKV infections that did not required medical attention. Thus, an underlying ZIKV epidemic transmission might have been masked by concomitant CHIKV/DENV outbreaks. The natural histories of CHIKV and ZIKV display several similarities. Before the large Indian Ocean outbreaks in 2005–2007, chikungunya fever was a neglected arboviral disease. Both viruses are phylogenetically closely related to African viruses [28]–[30] suggesting they probably originated in Africa, where they circulated in an enzootic sylvan cycle involving non-human primates and a wide variety of mosquito species, human outbreaks presumably being mediated by Ae. aegypti [5], [31]. In Asia, both viruses are thought to circulate mainly in a human-mosquito cycle involving Ae. aegypti [11], [14], [31]. Together with the recent Yap Island outbreak, this prompted some researchers to re-examine the susceptibility of Ae. aegypti to ZIKV infection [14]. However, it must be noted that the vector of the Yap Island outbreak was not definitely identified since the predominant potential vector species Aedes hensilli remained negative [15], and that ZIKV has been isolated only once from Ae. aegypti in Asia [10], so that its vector status in natura is not confirmed. Additionally, a ZIKV enzootic transmission cycle involving non-human primates in Asia and sylvatic vectors cannot be ruled out as suggested by serologic studies carried on orangutang [32], [33]. Finally both CHIKV and ZIKV have shown their ability to adapt to a new vector, Ae. albopictus, upon introduction in an environment where their primary vector was outnumbered. This mosquito species being native to South-East Asia, our findings may help to explain human ZIKV transmission in Asia. Aedes albopictus was first introduced in Africa in 1991 [34] and detected in Gabon in 2007, where its invasion likely contributed to the emergence of CHIKV and DENV in this country [17]–[19], [35]. Multiple lines of evidence supporting its increasing impact as an arboviral vector have also been obtained during CHIKV outbreaks in the Indian Ocean region (2005–2007) and in Italy (2007) [36], [37] through viral evolutionary convergence of Ae. albopictus adaptive mutations [38]–[41]. Whether or not the transmission of ZIKV in Central Africa was also link to such an adaptative mutation of ZIKV to Ae. albopictus cannot be answered at this stage. Wong and colleagues [42] have just demonstrated experimentally that Ae. albopictus strains from Singapore were orally receptive to the Ugandan strain of ZIKV sampled in 1947, suggesting that this virus-vector association in Africa may have been previously prevented because the required ecological conditions did not yet exist. However, given the relatively low ZIKV viral loads previously reported in patients - with an order of magnitude of 105 copies/ml compared to 107 to 109 copies/ml for CHIKV [16], [18], [40] - the oral infectivity for Ae. albopictus may seem at least as critical as it was for CHIKV in establishing this new human-mosquito cycle. Why ZIKV has not yet been detected in the areas where DENV and CHIKV have already spread via Ae. albopictus is unclear, but it may be an ongoing process which we are just starting to detect. The spread of CHIKV reflects the ability of arboviruses to adapt to alternative hosts, and the resulting public health concerns in both developed and developing countries. Is ZIKV the next virus to succeed CHIKV as an emerging global threat? The increasing geographic range of Ae. albopictus in Africa, Europe, and the Americas [34], [36], [43], [44], together with the ongoing ZIKV outbreak in French Polynesia at the time of writing [45] suggest this possibility should be seriously considered. Analysis of sylvan and urban transmission cycles, together with viral genetics and vector competence studies, are now required to assess (i) how ZIKV is able to establish a sustainable transmission cycle involving this new vector in Central Africa, (ii) vector(s)-virus relationships in Asia, and (iii) the risk of importation and spread to new areas where Ae. albopictus occurs as well. Supporting Information Figure S1 Phylogenetic trees reconstructed from the E and NS3 datasets. Analyses were performed with the maximum likelihood algorythm implemented in PhyML and parameters set as described in the Methods section. Trees are rooted on midpoint. (TIF) Click here for additional data file.
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            Zika virus infection complicated by Guillain-Barre syndrome--case report, French Polynesia, December 2013.

            Zika fever, considered as an emerging disease of arboviral origin, because of its expanding geographic area, is known as a benign infection usually presenting as an influenza-like illness with cutaneous rash. So far, Zika virus infection has never led to hospitalisation. We describe the first case of Guillain-Barré syndrome (GBS) occurring immediately after a Zika virus infection, during the current Zika and type 1 and 3 dengue fever co-epidemics in French Polynesia.
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              Molecular characterization of three Zika flaviviruses obtained from sylvatic mosquitoes in the Central African Republic.

              Zika virus (ZIKV) is an emerging pathogen belonging to the Spondweni serocomplex within the genus Flavivirus. It has been isolated from several mosquito species. Two lineages of ZIKV have been defined by polyprotein homology. Using high-throughput sequencing, we obtained and characterized three complete genomes of ZIKV isolated between 1976 and 1980 in the Central African Republic. The three viruses were isolated from two species of mosquito, Aedes africanus and Ae. opok. Two sequences from Ae. africanus had 99.9% nucleotide sequence identity and 100% amino acid identity, whereas the complete genome obtained from Ae. opok had 98.3% nucleotide identity and 99.4% amino acid identity with the other two genomes. Phylogenetic analysis based on the amino acid sequence of the polyprotein showed that the three ZIKV strains clustered together but diverged from all other ZIKV strains. Our molecular data suggest that a different subtype of West African ZIKV strains circulated in Aedes species in Central Africa.
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                Author and article information

                Contributors
                Journal
                Front Public Health
                Front Public Health
                Front. Public Health
                Frontiers in Public Health
                Frontiers Media S.A.
                2296-2565
                31 May 2016
                2016
                : 4
                : 110
                Affiliations
                [1] 1Tanga Research Centre, National Institute for Medical Research , Tanga, Tanzania
                [2] 2Global Health Institute, Gouverneur Kinsbergen Centrum, University of Antwerp , Wilrijk, Belgium
                [3] 3Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute , Arusha, Tanzania
                [4] 4Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health and Allied Sciences , Mwanza, Tanzania
                Author notes

                Edited by: Jorg Heukelbach, Universidade Federal do Ceará, Brazil

                Reviewed by: Aimee Ferraro, Walden University, USA; Luciano P. G. Cavalcanti, Universidade Federal do Ceará, Brazil

                *Correspondence: Eliningaya J. Kweka, kwekae@ 123456tpri.or.tz

                Specialty section: This article was submitted to Infectious Diseases, a section of the journal Frontiers in Public Health

                Article
                10.3389/fpubh.2016.00110
                4885858
                27303663
                c69c6b46-e5de-42af-a41d-5a79cc8f9f97
                Copyright © 2016 Baraka and Kweka.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

                History
                : 08 April 2016
                : 16 May 2016
                Page count
                Figures: 1, Tables: 0, Equations: 0, References: 10, Pages: 3, Words: 1849
                Categories
                Public Health
                Opinion

                arboviral infections,zika virus,diagnosis surveillance and control,sub-saharan africa,commentary

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