Introduction
Dengue is an alarming health concern for Africa, as disease outbreaks continue to grow in the continent. Although previous programs tailored to study the epidemiology of dengue in Africa proved imperfect, the World Health Organization, Regional Office for Africa (WHO-AFRO), through its Ministry of Health and Social Welfare, initiated a preventive program to manage and evaluate the disease in 2008 (Mmbuji et al., 2011).
Although the results of the program are underway, identifying the epidemiology of the disease remains complex. However, there is increased knowledge of the wide distribution of the Aedes spp mosquito as a vector of the dengue virus (DENV) that combines with the growing population, interregional travels, and unplanned urbanization to transmit DENV rapidly across Africa (Mosha et al., 2011). Research is needed to identify the possible dispersion patterns of the disease and to change laxity in prevention before the disease continues spreading. In addition, people need better ways of defining the appropriate treatment methods for the disease. The present study estimates the widespread nature of DENV infection by reviewing literature as well as reports on the disease.
Search methods
The literature used in this study is picked from various databases using the keywords “Dengue” and “Africa.” The review includes publications from MEDLINE and EMBASE electronic databases. The study reviews references in all the articles to find epidemiologic, entomologic, and virologic data on DENV in Africa. The comprehensive literature review offers innovative and valuable theoretical as well as empirical evidence to policymakers and researchers in the healthcare sector. Gathered evidence helps shed light on public healthcare aspects of dengue, including healthcare delivery, vaccination, and prevalence.
Reports of Dengue in Africa
Out of the 34 African countries, 22 reports local DENV disease transmission. In addition, twenty countries report laboratory experiment cases while two clinical report cases. The last twelve countries have never reported the disease locally. The unavailable data on incidences of dengue outbreaks make it hard to compare DENV infection in studies on Africa with other dengue-endemic regions of Asia and America (Jaenisch et al., 2014). The small sample sizes and the non-comparative studies hinder universalizing the results to other regions.
Underreported incidence of Dengue in Africa
Over 70% of the endemic malaria regions presume that febrile illnesses are malaria, without appropriate laboratory diagnoses or examination (Amarasinghe, Kuritsky, Letson & Margolis, 2011). Given that malaria is endemic to Africa as compared to other febrile illnesses, the possibility of misdiagnosing malaria is real. Researchers document over-diagnosis of malaria, thereby complicating the diagnosis of dengue.
Other areas overestimate the clinical diagnosis of malaria and do not give preference to dengue. Most African fevers are designated as unknown or malarial without proper diagnosis, even in instances where patients fail to respond to anti-malarial drugs (Amarasinghe et al., 2011). Studies show that dengue cases have increased considerably from 1960 to 2010, creating a need for in-depth research on the prevalence of the disease.
Factors affecting the transmission of Dengue
Vector efficiency
Aedes aegypti is the principle DENV vector, while other species such as the Ae albopictus and the Ae Africanus are potential DENV vectors for the African region (Amarasinghe et al., 2011). The Aedes species of mosquitoes have spread majorly due to urbanization. Mosquito densities in African regions such as Ghana and Kenya provide an environment suiting dengue mosquitoes (Rolle, Pearson, & Nsubuga, 2011).
The increasing urban population facilitates the spread of mosquitoes, especially through the widespread non-biodegradable human-made containers. Each species of the Apes mosquito either increases or decreases vector competence, making it important to study the roles of each species in transmitting the dengue virus.
Virus infectivity and host susceptibility
Four genetically related but antigenetically different virus types cause dengue. Although the virus has its origins in Africa, the recent outbreaks are linked to virus introductions from Southeast Asia or western Pacific regions (Amarasinghe et al., 2011). Studies suggest that evolutionary changes, as well as natural selection patterns, have a distinct similarity in endemic as well as Sylvatic DENVs that help explain the variability in susceptibility to DENV infection.
Host genetic factors also help explain the spread of dengue, given how the disease expresses itself in other races. Studies (Amarasinghe et al., 2011; Rolle, Pearson, & Nsubuga, 2011) document a dengue resistant gene among blacks in regions such as Cuba. The decreased susceptibility in the severity of the disease among blacks shows that genomic differences in the race are DENV risk factors. This explains why the DENV virus is reported across Africa (Bhatt et al., 2013).
Moreover, diseases such as tuberculosis and HIV shed light on the minimal prevalence of dengue in Africa. The cross-protection from the endemic flavivirus associated with these infections may explain the low DENV infections.
SWOT on Dengue in Africa
The following are the strengths, weaknesses, opportunities, and threats that the dengue disease faces in Africa.
Strengths
Dengue has several common symptoms ranging from joint pain, muscle and bone pain, rash, and mild bleeding to internal bleeding, vomiting, abdominal pain, respiratory problems, and potential circulatory failure that could make its diagnosis easy (Figueiredo et al. 2010). Disease control programs should not ignore this strength of diagnosis.
Weaknesses
A significant weakness of DENV concerns the costs of treating, preventing and vaccinating the disease. Were (2012) gives evidence of the complexity in managing and maintaining the disease, which has done little to help prevent the disease from spreading further. The dengue virus lacks comprehensive treatment or prevention regimens, thereby exacerbating its negative impact on the economic standing of people and the society greatly.
Opportunities
Wilson et al., (2007) state that the potential vaccinations for dengue present new opportunities for controlling the prevalence of the disease. Evidence shows that the attenuated recombinant tetravalent vaccine is an effective vaccination with few side effects. Good reporting is another opportunity that disease control initiatives should focus on if the routine disease surveillance and reporting systems in Africa are to help in tailoring effective prevention efforts.
Threats
Cases of the deadly dengue hemorrhagic fever occur more frequently today, as compared to the past. The complex nature of the disease is increasingly a threat to the management of the dengue virus. According to Schmidt et al. (2011), urbanization is another threat of the dengue fever that is on the increase.
In sum, the need to understand the dengue virus arises out of its growing severity and ineffective methods of preventing the disease. The increase of thirty percent in reported dengue cases shows that the strategies implemented in controlling mosquitoes in high incidence areas of Africa are ineffective. Moreover, their costly nature and complexity in maintenance have done little to help prevent the disease from spreading.
The dengue virus has no treatment or prevention regimens, thereby exacerbating its negative impact on the economic standing of people and the society greatly. Increased care costs and insufficient productivity associated with the continent have affected how people seek and get medical care. Vector control, which is the primary method of preventing the transmission of the Dengue virus, has proven costly, ineffective, and time-consuming.
The method has introduced unintended consequences, for instance, reduction in herd immunity. The method has increased the risks of massive outbreaks across African regions with poor access to the treatment regimens. Re-introduction also links to the numerous cases of dengue found in adults. Studies, however, show that Dengue causes few cases in children and more in adults. Although the vector method remains the only effective means of controlling the dengue virus, it will remain applicable as the attenuated recombinant tetravalent vaccine picks up.
Better information on Dengue incidences will help trace the spread patterns of the disease and tailor prevention methods to prone areas. In addition, data on the number of hospital visits will illuminate the impact of dengue on societies in Africa. The data is central to estimating the costs of Dengue incidences as well as the benefits of maximization. The following research paper gathers evidence on the burden of the disease, the cost of the illness, and the impact of immunizations.
However, a major concern that needs redress is the under-reporting of Dengue disease. It is important that health care stakeholders initiate routine disease surveillance for the region if they are to curb the spread of the disease. Instituting reporting systems across Africa will help in gathering data on the disease to tailor effective prevention and vaccination efforts.
References
Amarasinghe, A., Kuritsky, J. N., Letson, G. W., & Margolis, H. S. (2011). Dengue virus infection in Africa. Emerging Infectious Diseases, 17(8), 1349-1354.
Bhatt, S., et al. (2013). The global distribution and burden of dengue. Nature, 497(20), 504-507.
Figueiredo, M. et al. (2010). Allergies and diabetes as risk factors for dengue hemorrhagic fever: Results of a case control study. PLoS Neglected Tropical Diseases, 4(6), 1-6.
Jaenisch, T. et al. (2014). Dengue expansion in Africa: Not recognized or not happening? Emerging Infectious Diseases, 20(10). Web.
Mmbuji, P. et al. (2011). The Tanzania field epidemiology and laboratory training program: Building and transforming the public health workforce. PanAfrican Medical Journal, 10(1), 9.
Mosha, F. et al. (2011). Public health laboratory systems development in East Africa through training in laboratory management and field epidemiology. PanAfrican Medical Journal, 10(1), 14.
Rolle, I. V., Pearson, M. L., & Nsubuga, P. (2011). Fifty-five years of international epidemic- assistance investigations conducted by CDC’s disease detectives. American Journal of Epidemiology, 174(11), 97-112.
Schmidt, W. et al. (2011). Population density, water supply, and the risk of dengue fever in Vietnam: Cohort study and spatial analysis. PLoS Medicine, 8(9), 1-10.
Were, F. (2012). The dengue situation in Africa. Pediatrics and International Child Health, 32(1), 18-21.
Wilson, M. E. et al. (2007). Fever in returned travelers: Results from the Geosentinel Surveillance Network. Clinical Infection Diseases, 44, 1560-8.