The Dengue Situation in Africa

Dengue outbreaks and epidemics have been reported

By Fred Were


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Dengue Risk Areas and Epidemic Activity in Africa

Aedes aegypti mosquitoes – the primary vector for dengue transmission - are known to be present in all but five countries (Western Sahara, Morocco, Algeria, Tunisia and Libya), for which data are not available.

Available data suggest that dengue is endemic to 34 countries across all regions of Africa.

More detailed epidemiological data are required to assess the impact and the reliable information of dengue in the continent.


Factors Influencing transmission of Dengue Virus

Vector efficiency

It is known that African strains of A. aegypti and A. albopictus have shown uniformly lower susceptibility to all four subtypes of DENV in laboratory settings and it may explain the apparent lower dengue transmission than expected prevalence in Africa.

Viral infectivity

The enzootic forms of DENV became less infective in Africa, however there is still a potential for the virus to emerge from Asia and the Western Pacific due to travel.

Host Vulnerability

Given race differences, genetic polymorphism in cytokines and coagulation proteins has been proposed as a potential mechanism conferring resistance to black individuals.

Age is also a key factor which is proved by the increasing incidence of dengue hemorrhagic fever in older age groups.

Environmental Factors

Recent reports are showing an increase in rural epidemics especially in Africa, which states it is not certain whether urbanization is related to the shift of the vector nearer to settlements.


Recent epidemics and Dengue Prevention in Africa

Dengue epidemics have occurred in all regions of Africa in 5 years between 2006 and 2011.

Current dengue prevention strategies in Africa focus on vector control, however the primary aim of such efforts is the typical prevention of malaria and the preventive measures are not practiced


Conclusions

Many dengue outbreaks in Africa are not properly identified owing to the poor surveillance infrastructure and under-recognition of the disease.

In order to understand in more detail the factors involved in differences in vulnerability to dengue across Africa, further research is required to characterize the epidemiology of dengue.