Dengue06

The Geographical Distribution of Dengue Fever

Presently, around 2,5 billion people are at risk from dengue fever. It’s been estimated by the world health organization (WHO) that there might be around 50 million cases of dengue infection expected every year. More than 609,000 cases have been reported in the Americas in 2001 alone, double the number recorded in same region in 1995.


During the last few decades, the global prevalence of dengue fever has risen dramatically. Currently, dengue is endemic in over 100 countries. South-east Asia and the Western Pacific are most seriously affected.

Erythema_with_petechiae_on_patient_with_dengue_fever

A dengue patient with visible rashes.

Dengue is transmitted to via the bite of an infected mosquito of the species Aedes Aegypti. This mosquitoes species is uniquely adapted to living in and around human habitations, where it lays eggs in artificial containers, like fish water bowls, vases, and discarded plastic trash. Female mosquitoes acquire the virus by biting an infected humans. The infected mosquito can then transmit virus for the rest of its life.

The origin of dengue is still a still a matter of debate, but scientists have recently proposed that dengue originated in Asian forests in an infectious cycle involving mosquitoes and monkeys. An outbreak similar dengue was recorded in a Chinese medical encyclopedia as early as 992,. Epidemics of dengue-like illnesses were also reported in the French West Indies in 1635 and in Panama in 1699.

One of the major contributing factors to the spread of dengue is the geographic distribution of the four variations of dengue viruses and of their mosquito vectors. A rapid rise in urban populations is also another factor that caused the rising number of dengue cases, especially in areas that are favourable for mosquito breeding.

Global_DengueTransmission_ITHRiskMap

Dengue global distribution is centred in tropical regions.

 

Low level of reporting and difficulties in diagnosis of the disease where also factors that contributed to the spread of dengue. Thus, the true global burden of the disease and associated economic impact are still not clear. However, several researches have been conducted to map the global dengue incidence to better determine the population at risk.

 

Southeast Asia

Dengue is one of the leading causes of hospitalization and death in both children and adults in many Southeast Asian countries. The majority of dengue hemorrhagic fever cases were reported in Indonesia where large percent percentage of infected patients recorded in Jakarta and provincial areas. The disease has also became epidemic in Bangladesh. In the year 2000, 82% of hospitalized patients suffered from dangue fever.

In Singapore, there are around 4,000 to 5,000 reported cases of dengue or dengue haemorrhagic fever every year. Since 1980s, more than 50% of deaths in the country have occurred in adults (individuals older than 15 years).

In Malaysia, the number of dengue cases has risen 316% in 2014. According to the Health Ministry, dengue cases surpassed 76,079 with 50% of these cases reported in Selangor alone. That number is expected to be eclipse with that of the current year as 35,302 case have already been reported since Jan, 2015.

malasia-dengue-map

Dengue distribution in Malaysia showing Selangor as the state with the most reported cases.

 

The Americas

Over 1.6 million cases of dengue fever has been reported in the Americas in 2010 alone. 49,000 of these cases were associated with severe haemorrhagic fever. Currently, only two countries in South America have remained relatively, Chile and Uruguay, off the disease’s radar. According to locally acquired reports, dengue cases have also been reported in the US mostly in the southern region including particularly Puerto Rico.

Due to the growth of dengue and its vector in the Americas and other parts of the world, numerous health organizations launched an initiative targeting mosquito control and prevention. The Integrated Management Strategy for Dengue Prevention’ is striving to reduce the disease and economic burden that dengue places currently on many countries.

 

Africa

Although less widespread than malaria, an alarming rate of dengue cases has also been observed in many regions of Africa. However, surveillance is considered very poor and the disease under diagnosed leading to low level or awareness. Recent research estimates the burden of dengue infection in Africa to be similar to that of the Americas.

Between the year 2009 and 2012 thousands cases of dengue were reported mostly in West Africa countries including Cote d’Ivoire, Senegal and Gabon. In East Africa, the statistics came from Kenya, Djibouti and Sudan. Some of the cases were, even, reported in European travellers who had returned from these countries.

 

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