Article

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

ABSTRACT

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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    • "This condition was first described by Spanish sailors visiting the southern coast of Tanzania during the 15 th Century[4,7,8]. In the 1823 and 1870, dengue was reported on Zanzibar Islands[3]. Since then, three epidemiological surveys have indicated that different areas of Tanzaniais the most important vector because of being highly domesticated, strongly anthropophilic, a nervous feeder and a discordant species[12]. "
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    ABSTRACT: Background: In 2010, 2012, 2013 and 2014 dengue outbreaks have been reported in Dar es Salaam, Tanzania. However, there is no comprehensive data on the risk of transmission of dengue in the country. The objective of this study was to assess the risk of transmission of dengue in Dar es Salaam during the 2014 epidemic. Methodology/principal findings: This cross-sectional study was conducted in Dar es Salaam, Tanzania during the dengue outbreak of 2014. The study involved Ilala, Kinondoni and Temeke districts. Adult mosquitoes were collected using carbon dioxide-propane powered Mosquito Magnet Liberty Plus traps. In each household compound, water-holding containers were examined for mosquito larvae and pupae. Dengue virus infection of mosquitoes was determined using real-time reverse transcription polymerase chain reaction (qRT-PCR). Partial amplification and sequencing of dengue virus genome in infected mosquitoes was performed. A total of 1,000 adult mosquitoes were collected. Over half (59.9%) of the adult mosquitoes were collected in Kinondoni. Aedes aegypti accounted for 17.2% of the mosquitoes of which 90.6% were from Kinondoni. Of a total of 796 houses inspected, 38.3% had water-holding containers in their premises. Kinondoni had the largest proportion of water-holding containers (57.7%), followed by Temeke (31.4%) and Ilala (23.4%). The most common breeding containers for the Aedes mosquitoes were discarded plastic containers and tires. High Aedes infestation indices were observed for all districts and sites, with a house index of 18.1% in Ilala, 25.5% in Temeke and 35.3% in Kinondoni. The respective container indices were 77.4%, 65.2% and 80.2%. Of the reared larvae and pupae, 5,250 adult mosquitoes emerged, of which 61.9% were Ae. aegypti. Overall, 27 (8.18) of the 330 pools of Ae. aegypti were positive for dengue virus. On average, the overall maximum likelihood estimate (MLE) indicates pooled infection rate of 8.49 per 1,000 mosquitoes (95%CI = 5.72-12.16). There was no significant difference in pooled infection rates between the districts. Dengue viruses in the tested mosquitoes clustered into serotype 2 cosmopolitan genotype. Conclusions/significance: Ae. aegypti is the main vector of dengue in Dar es Salaam and breeds mainly in medium size plastic containers and tires. The Aedes house indices were high, indicating that the three districts were at high risk of dengue transmission. The 2014 dengue outbreak was caused by Dengue virus serotype 2. The high mosquito larval and pupal indices in the area require intensification of vector surveillance along with source reduction and health education.
    Full-text · Article · Jan 2016 · PLoS Neglected Tropical Diseases
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    • "countries could be associated with dengue by sporadic outbreaks, cases of returning travelers, and several seroprevalence surveys (Amarasinghe et al., 2011). Moreover, Aedes aegypti, the principal vector of endemic/epidemic DENV, is also believed to originate in Africa and spread throughout tropical and sub-tropical regions of the world (Powell and Tabachnick, 2013). "
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    ABSTRACT: Dengue fever has become a worldwide public health concern, threatening an estimated 40% of the world's population. However, most resources and attention are still focused on malaria, while dengue statuses are poorly recognized in many African countries. In this serological survey, dengue virus (DENV) transmission was demonstrated by using serum samples collected from 78 pregnant women in the Democratic Republic of Sao Tome and Principe (DRSTP) during 2003 to 2004. Immunofluorescence assay was performed and 31 samples (39.74%) were found positive for DENV antibodies. Indirect enzyme-linked immunosorbent assay (ELISA) showed that 53 samples (67.95%) were positive for dengue E IgG, and 38 samples (48.72%) were positive for NS1 IgG. A prevalence of 35.9% was therefore determined for dengue IgG by considering samples that yielded positive results by all three tests. Cross-reactions with other flaviviruses were examined by indirect ELISA against Japanese encephalitis virus, West Nile virus, and yellow fever virus. Only one sample exhibited stronger absorbance against Japanese encephalitis virus and West Nile virus. Moreover, one sample was positive for dengue IgM. These results agreed with the previous researches in neighboring countries and suggested DENV exposure. The study contributes to raising public awareness of dengue and supporting future control strategies.
    Full-text · Article · Dec 2015 · Acta tropica
    • "Incidence of severe disease is more common in South-East Asian countries and children are the most affected, while the incidence of severe disease is less in India and young adults are the most affected (Halstead, 2006; Chakravarti et al., 2012; Gupta et al., 2012). In African populations in which both haplogroups A and B equally dominate, severe disease is rarely reported (Amarasinghe et al., 2011 ). Whether the varied frequency of KIR haplogroups A and B in different populations influence the rate of occurrence of severe disease needs further investigations. "
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    ABSTRACT: Killer cell immunoglobulin-like receptors (KIRs) regulate the activation of natural killer cells (NKs). Qualitative and quantitative differences in the type and the number of KIRs expressed on NK cells affect its activation which would influence the outcome of the disease. In this study, 114 hospitalized cases of dengue [82 dengue fever (DF) and 32 dengue haemorrhagic fever (DHF) cases] and 104 healthy controls (HC) without no known history of hospitalization for dengue-like illness were investigated for their KIR gene profile to find out the association of KIR genes with dengue disease severity. KIR gene profile was investigated using duplex sequence-specific priming polymerase chain reaction-based typing system. The results revealed a higher frequency of KIR3DL1 gene [P = 0.0225; odds ratio (OR) 4.1 95% confidence interval (CI) 1.1–14.8] and lower frequency of KIR3DS1/3DS1 genotype [P = 0.0225; OR 0.24 95% CI (0.068–0.88)] in DF cases compared to HC. Immunoglobulin-like receptor gene frequencies were not different between DHF and DF or HC. The results suggest that KIR3DL1/KIR3DS1 locus might be associated with the risk of developing DF.
    No preview · Article · Sep 2015 · International Journal of Immunogenetics
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