Dengue Virus Infection in Africa

Pediatric Dengue Vaccine Initiative, International Vaccine Institute, Seoul National University Research Park, Kwanak-gu, Seoul, South Korea.
Emerging Infectious Diseases (Impact Factor: 6.75). 08/2011; 17(8):1349-54. DOI: 10.3201/eid1708.101515
Source: PubMed


Reported incidence of dengue has increased worldwide in recent decades, but little is known about its incidence in Africa. During 1960-2010, a total of 22 countries in Africa reported sporadic cases or outbreaks of dengue; 12 other countries in Africa reported dengue only in travelers. The presence of disease and high prevalence of antibody to dengue virus in limited serologic surveys suggest endemic dengue virus infection in all or many parts of Africa. Dengue is likely underrecognized and underreported in Africa because of low awareness by health care providers, other prevalent febrile illnesses, and lack of diagnostic testing and systematic surveillance. Other hypotheses to explain low reported numbers of cases include cross-protection from other endemic flavivirus infections, genetic host factors protecting against infection or disease, and low vector competence and transmission efficiency. Population-based studies of febrile illness are needed to determine the epidemiology and true incidence of dengue in Africa.

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Available from: Ananda Amarasinghe, Sep 19, 2014
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    • "It is estimated that over 50% of the world population lives in areas that are at risk of transmission of at least one of the four serotypes of Dengue virus (DENV) and in the presence of one or more vector species (Kyle and Harris, 2008). On the African continent, there has been an expansion of dengue in recent years (Amarasinghe et al., 2011; Franco et al., 2010). In the Republic of Cabo Verde, a country comprising 10 archipelago islands located along the West African coast, A. aegypti was first described in 1931 on the island of São Vicente and was subsequently described on other islands (Alves et al., 2010; Ribeiro et al., 1980). "
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    ABSTRACT: In 2009, Cabo Verde diagnosed the first dengue cases, with 21,137 cases reported and Aedes aegypti was identified as the vector. Since the outbreak, chemical insecticides and source reduction were used to control the mosquito population. This study aimed to assess the susceptibility of Ae. aegypti populations from Santiago, Cabo Verde to insecticides and identify the mechanisms of resistance. Samples of Ae. aegypti eggs were obtained at two different time periods (2012 and 2014), using ovitraps in different locations in Santiago Island to establish the parental population. F1 larvae were exposed to different concentrations of insecticides (Bacillus thuringiensis var israelensis (Bti), diflubenzuron and temephos) to estimate the lethal concentrations (LC90) and calculate the respective rate of resistance (RR90). Semi-field tests using temephos-ABATE® were performed to evaluate the persistence of the product. Bottle tests using female mosquitos were carried out to determine the susceptibility to the adulticides malathion, cypermethrin and deltamethrin. Biochemical and molecular tests were performed to investigate the presence of metabolic resistance mechanisms, associated with the enzymes glutathione S-transferases (GSTs), esterases and mixed-function oxidases (MFO) and to detect mutations or alterations in the sodium channel and acetylcholinesterase genes. Ae. aegypti mosquitoes from Santiago exhibited resistance to deltamethrin, cypermethrin (mortality <80%) and temephos (RR90 = 4.4) but susceptibility to malathion (mortality ≥98%), Bti and diflubenzuron. The low level of resistance to temephos did not affect the effectiveness of Abate®. The enzymatic analysis conducted in 2012 revealed slight changes in the activities of GST (25%), MFO (18%), α-esterase (19%) and β-esterase (17%), but no significant changes in 2014. Target site resistance mutations were not detected. Our results suggest that the Ae. aegypti population from Santiago is resistant to two major insecticides used for vector control, deltamethrin and temephos. To our knowledge, this is the first report of temephos resistance in an African Ae. aegypti population. The low level of temephos resistance was maintained from 2012 to 2014, which suggested the imposition of selective pressure, although it was not possible to identify the resistance mechanisms involved. These data show that the potential failures in the local mosquito control program are not associated with insecticide resistance.
    Acta tropica 08/2015; 152. DOI:10.1016/j.actatropica.2015.08.013 · 2.27 Impact Factor
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    • "The prevention and control of dengue outbreaks mainly depend on the epidemiological surveillance of cases and mosquito vectors [19] [20]. Dengue is likely underrecognized and underreported in Africa because of low awareness by health care providers, other prevalent febrile illnesses, and lack of diagnostic testing and systematic surveillance [18]. Dengue morbidity can be reduced by implementing improved outbreak prediction and detection through coordinated epidemiological and entomological surveillance [3]. "
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    ABSTRACT: to investigate the presence of dengue vectors in discarded tires and artificial water containers in houses and peridomestic areas. Methods. A cross-sectional immature stage survey was done indoors and outdoors in 301 houses. Mosquito larval sampling was conducted using pipette or dipper depending on container types. Larvae were identified morphologically and larval indices were also calculated. Results. A total of 750 containers were inspected, and of these 405 were positive for mosquito larvae. A total of 1,873 larvae were collected and morphologically identified as Aedes aegypti (í µí±› = 1580: 84.4%) and Culex (í µí±› = 293: 15.6%). The larval indices, house index, container index, and breteau index, varied from 33.3 to 86.2, from 23.2 to 73.9, and from 56.5 to 188.9, respectively. Conclusion. Aedes aegypti is breeding in a wide range of artificial containers. To control these mosquitoes, the integration of different methods should be taken into consideration.
    Interdisciplinary Perspectives on Infectious Diseases 08/2015; 2015(1). DOI:10.1155/2015/706276
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    • "Dengue NS1 is produced during viral replication and can be detected shortly after dengue infection (1–9 days after onset of fever) prior to IgM seroconversion positioning this antigen as an ideal marker for diagnosis of acute dengue infection (Kassim et al., 2011). Although the first isolated case of dengue was in Nigeria in the 1960s (Amarasinghe et al., 2011; Carey et al., 1971), dengue is not a reportable disease with most cases often undiagnosed, misdiagnosed as malaria or labeled as fever of unknown cause. The unfortunate consequence is the persistent over prescription of anti-malarias and antibiotics. "
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    ABSTRACT: We conducted a dengue seroprevalence survey among febrile patients positive or negative for malaria in Ibadan, Nigeria. Dengue IgG and NS1 seroprevalence of 73% and 35% respectively was observed, and 43% of those with malaria had acute dengue infection (NS1 determination). On the other hand, all participants with malaria were IgG dengue seropositive consistent with the endemicity of both arthropod-borne infections in the region. These data indicate that dengue is emerging as a major cause of fever in Nigeria.
    Virus Research 07/2014; 191(1). DOI:10.1016/j.virusres.2014.07.023 · 2.32 Impact Factor
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