Co-circulation of Dengue Virus Serotypes 1 and 3 during the 2019 epidemic in Dar es Salaam, Tanzania

Abstract

22 23 *gaspary.mwanyika@sacids.org 24 25 26 27 PLOS Neglected Tropical Diseases 2 28 Abstract 29 Background 30 Dengue is an important mosquito-borne viral disease in tropical and sub-tropical 31 countries. In this study molecular characterization was carried out to determine 32 dengue viruses circulating among patients at health facilities during 2019 epidemic in 33 Dar es Salaam, Tanzania. 34 Methods 35 The study involved outpatients seeking care for febrile illness at four health facilities 36 in Kinondoni and Ilala Districts of Dar es Salaam City in Tanzania. A total of 45 sera 37 from the outpatients were confirmed dengue-positive for dengue virus (DENV) non-38 structural protein 1 (NS1) antigen and/or NS1-IgG/IgM antibodies using on-site rapid 39 test. The presence of the virus was detected by reverse-transcription polymerase 40 chain reaction (RT-PCR) method. Of the 45 sera, 20 samples were selected 41 randomly for identification of specific dengue virus serotypes using RT-PCR followed 42 by evaluation of resulting amplicons on agarose gel electrophoresis. 43 Findings and significance 44 Both Dengue virus serotypes 1 (DENV-1) and 3 (DENV-3) were detected in the 45 samples tested with the former being dominant. We present the first evidence of 46 dengue virus co-infection of DENV-1 and DENV-3 serotypes in Tanzania. The 47 emergence of DENV-1 indicates the possibility of importation of the virus to Tanzania 48 from endemic countries. Due to DENV serotype co-circulation, there is an increased 49 risk of severe dengue in future epidemics. Our findings advocate the importance of 50 genomic-based surveillance to provide rapid evidence of dengue virus 51 emergence/re-emergence and spread. 52 Author Summary 54 Dengue viruses are the most important mosquito-borne pathogens that pose a 55 serious global health threat. Tanzania has reported several dengue virus epidemics 56 since 2010 with the majority of the epidemics occurring in Dar-es-Salaam city. Until 57 August 2019, a total of 6,859 dengue cases have been confirmed in the country. We 58 performed molecular characterization of dengue viruses (DENV) circulating during 59 the 2019 epidemic phase. It was found that DENV-1 serotype was dominant during 60 the epidemic and two samples of the tested sera were co-infected by DENV-1 and 61

Knowledge, attitudes and bite prevention practices and estimation of productivity of vector breeding sites using a Habitat Suitability Score (HSS) among households with confirmed dengue in the 2014 outbreak in Dar es Salaam, Tanzania

“…Where did you travel to in the past two weeks before you had dengue fever? (Type II) [6] as well as locally reported cases in 2017 and 2019 [28]. However, knowledge among communities and about non-malaria febrile illnesses is extremely low and when attending health services, clinical diagnosis for febrile illnesses lacks specificity and has been reported to contribute to misdiagnosis and mistreatment of febrile patients [29].…”

“…While Dar es Salaam has in the recent past experienced dengue outbreaks, without adequate vector control it is certain that these will reoccur. Three dengue serotypes have now been observed circulating in the country [6,9] and 22 million people live in areas of Tanzania suitable for transmission of arboviruses [10].…”

Single blinded semi-field evaluation of MAÏA® topical repellent ointment compared to unformulated 20% DEET against Anopheles gambiae, Anopheles arabiensis and Aedes aegypti in Tanzania

“…This is especially important in the case of Ae. aegypti evaluations in areas of active dengue transmission, such as Tanzania [ 34 ]. Moreover, semi-field environments allow volunteers to be accessible to a known number of mosquitoes of known age, physiological status, and avidity, and minimize heterogeneity in the data, allowing a more precise estimation of true repellent efficacy.…”

MAÏA® Topical Repellent Ointment Provides Long-Lasting Protection Against Anopheles Gambiae s.s., Anopheles Arabiensis and Aedes Aegypti Under Semi-Field Conditions in Tanzania

“…This is especially important in the case of Ae. aegypti evaluations in areas of active dengue transmission such as Tanzania [35]. Moreover, semi-eld environments allow volunteers to be accessible to a known number of mosquitoes of known age, physiological status, and avidity and it minimizes heterogeneity in the data allowing a more precise estimation of true repellent e cacy.…”