Sindato, C. | bioRxiv Science

bioRxiv2019

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

BackgroundDengue is an important mosquito-borne viral disease in tropical and sub-tropical countries. In this study molecular characterization was carried out to determine dengue viruses circulating among patients at health facilities during 2019 epidemic in Dar es Salaam, Tanzania.\n\nMethodsThe study involved outpatients seeking care for febrile illness at four health facilities in Kinondoni and Ilala Districts of Dar es Salaam City in Tanzania. A total of 45 sera from the outpatients were confirmed dengue-positive for dengue virus (DENV) non-structural protein 1 (NS1) antigen and/or NS1-IgG/IgM antibodies using on-site rapid test. The presence of the virus was detected by reverse-transcription polymerase chain reaction (RT-PCR) method. Of the 45 sera, 20 samples were selected randomly for identification of specific dengue virus serotypes using RT-PCR followed by evaluation of resulting amplicons on agarose gel electrophoresis.\n\nFindings and significanceBoth Dengue virus serotypes 1 (DENV-1) and 3 (DENV-3) were detected in the samples tested with the former being dominant. We present the first evidence of dengue virus co-infection of DENV-1 and DENV-3 serotypes in Tanzania. The emergence of DENV-1 indicates the possibility of importation of the virus to Tanzania from endemic countries. Due to DENV serotype co-circulation, there is an increased risk of severe dengue in future epidemics. Our findings advocate the importance of genomic-based surveillance to provide rapid evidence of dengue virus emergence/re-emergence and spread.\n\nAuthor SummaryDengue viruses are the most important mosquito-borne pathogens that pose a serious global health threat. Tanzania has reported several dengue virus epidemics since 2010 with the majority of the epidemics occurring in Dar-es-Salaam city. Until August 2019, a total of 6,859 dengue cases have been confirmed in the country. We performed molecular characterization of dengue viruses (DENV) circulating during the 2019 epidemic phase. It was found that DENV-1 serotype was dominant during the epidemic and two samples of the tested sera were co-infected by DENV-1 and DENV-3 serotypes. These findings emphasize the importance of genomic-based surveillance of dengue viruses in Tanzania to guide strategies for appropriate interventions.

genomics↗

bioRxiv2019

Seroprevalence of human Brucellosis and associated risk factors among high risk occupations in Mbeya Region of Tanzania

BackgroundBrucellosis is an infectious zoonotic disease that affects humans, livestock and wildlife.\n\nMethodsA cross-sectional study was conducted in Mbeya region between November 2015 and January 2016 to investigate the seroprevalence of human brucellosis and identify associated risk factors among individuals in risky occupations in Mbeya Region. A total of 425 humans from six occupational categories were serially tested for Brucella antibodies using the Rose Bengal Plate Test (RBPT) and competitive Enzyme Linked Immunosorbent Assay (c-ELISA), for screening and confirmation, respectively. A questionnaire survey was administered to participants collect epidemiological data.\n\nResultsThe overall seroprevalence among the high risk occupational individuals was 1.41% (95% CI: 0.01-0.03). Seroprevalence among the different occupations were as follows: shepherds 1.33% (95% CI: 0.14-0.22); butcher men 5.26% (95% CI: 0.10-0.17) and abattoir workers 1.08% (95% CI: 0.39-0.49). Seroprevalence was noted to vary according to occupation type, milk consumption behaviour, age and sex. Butcher men recorded the highest seroprevalence (5.0%) while individuals who consumed unboiled milk had a higher seroprevalence (1.56%) compared to those who drunk boiled milk. High seropositivity (2.25%) was observed among the age group of 1-10 years while male individuals had a higher seroprevalence (1.41%) than females (0%). Butcher men were at higher risk of exposure compared to other professions.\n\nConclusionOur findings show the presence of brucellosis in occupationally exposed individuals in Mbeya region. There is need to sensitize the exposed individuals in order to reduce the risk of acquiring Brucella infections from animals and animal products This also calls for public health awareness about the disease, and implementation of control measures that will prevent further spread of brucellosis within and outside the study area..\n\nAuthor summaryBrucellosis is a bacterial zoonosis that has evolved to establish itself as an occupational and food-borne disease Worldwide. It is responsible for huge economic losses incurred by livestock keepers and poses a public health risk to humans in most developing countries. In Tanzania, which has the 3rd highest cattle population in Africa, many studies that have been done show that brucellosis exists in livestock, especially in cattle and wildlife. However, very few studies have reported on human brucellosis. The disease has been reported to occur in humans who have direct exposure to cattle or cattle products like livestock farmers, abattoir workers, veterinarians, shepherds and farm workers in many developing countries. A few studies in Tanzania have reported seroprevalences among these high-risk occupations; however, the disease has not been fully described in Mbeya region. This study was therefore aimed at filling these information gaps and contributing to the existing body of knowledge.

epidemiology↗