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Thursday 25 February 2010
Dengue spreads further in West Africa
Thousands of people affected as mosquito-borne disease hits new areas
The dengue virus is expanding its reach into new parts of West Africa, report medical scientists this month in Eurosurveillance. They warn that under-resourced laboratories in the region lack tools to track it.
?The first dengue outbreak in Cape Verde with more than 17,000 cases from September to December 2009 demonstrated that dengue virus is still expanding worldwide to new territories,? write Leticia Franco and colleagues.
Six people died during those months and thousands more became infected with the virus every week in what was the first outbreak of dengue fever to be reported on the island nation. Cases of infection were also picked up in neighbouring Senegal. The virus was likely introduced to the Cape Verde-Senegal region from another West African country, say the authors.
The outbreak was sparked by the dengue virus serotype 3 (DENV-3), which is one of four sub-strains. This virus first caused an outbreak of dengue fever in West Africa in 2008, in C?te d?Ivoire.i It was first spotted in Africa in 1984, when it appeared to be involved in an outbreak of febrile illness in the southeast African country of Mozambique. Signs of the virus then appeared in different parts of the continent: in Somalia in 1993, in three travellers returning to Europe from the West African countries of Cameroon in 2006 and Senegal in 2007, as well as in Eritrea in 2008.
With the recent arrival of DENV-3 to West Africa, all four serotypes have now been reported in the region since the mid-1960s, when the virus was first isolated from patients on the continent. Although historical reports suggest the first African dengue epidemic occurred even earlier, in 1927 in South Africa, scientists cannot say which serotype was responsible.
There are lingering questions over how widely any of the four dengue serotypes circulate on the continent, and how many people are affected by dengue fever each year. Many laboratories in West Africa lack the tools to test for the virus, and surveillance systems are not set up adequately to monitor viruses other than yellow fever and HIV, according to the authors.
The recent outbreaks show that laboratories in the region need diagnostic tools to detect the dengue virus, say Franco and colleagues.
In fact, the latest warning of the recent expansion of DENV-3 into West Africa came from Europe, when medics detected the virus in travellers returning from the area with signs of illness. These cases triggered an alert, prompting the countries the travellers had visited to look for the virus, explain the authors.
?As long as active dengue virus surveillance is poorly implemented in Africa, the study of febrile travellers returning to Europe could help to detect viral activity on the African continent,? they add.
A project of the European Centre for Disease Prevention and Control, dubbed ENVID-CLRN, will help monitor the dengue virus in Africa and across the world by recording cases of the disease imported into Europe, note the authors. It aims to map the global circulation of this and another mosquito-borne virus, chikungunya, and will include information about the distribution of different genotypes of these viruses.
1.
Franco L, Di Caro A, Carletti F, Vapalahti O, Renaudat C, Zeller H, et al. Recent expansion of dengue virus serotype 3 in West Africa. Euro Surveill 2010, 15. Article
World Health Organization information about dengue fever
Thursday 25 February 2010
Dengue spreads further in West Africa
Thousands of people affected as mosquito-borne disease hits new areas
The dengue virus is expanding its reach into new parts of West Africa, report medical scientists this month in Eurosurveillance. They warn that under-resourced laboratories in the region lack tools to track it.
?The first dengue outbreak in Cape Verde with more than 17,000 cases from September to December 2009 demonstrated that dengue virus is still expanding worldwide to new territories,? write Leticia Franco and colleagues.
Six people died during those months and thousands more became infected with the virus every week in what was the first outbreak of dengue fever to be reported on the island nation. Cases of infection were also picked up in neighbouring Senegal. The virus was likely introduced to the Cape Verde-Senegal region from another West African country, say the authors.
The outbreak was sparked by the dengue virus serotype 3 (DENV-3), which is one of four sub-strains. This virus first caused an outbreak of dengue fever in West Africa in 2008, in C?te d?Ivoire.i It was first spotted in Africa in 1984, when it appeared to be involved in an outbreak of febrile illness in the southeast African country of Mozambique. Signs of the virus then appeared in different parts of the continent: in Somalia in 1993, in three travellers returning to Europe from the West African countries of Cameroon in 2006 and Senegal in 2007, as well as in Eritrea in 2008.
With the recent arrival of DENV-3 to West Africa, all four serotypes have now been reported in the region since the mid-1960s, when the virus was first isolated from patients on the continent. Although historical reports suggest the first African dengue epidemic occurred even earlier, in 1927 in South Africa, scientists cannot say which serotype was responsible.
There are lingering questions over how widely any of the four dengue serotypes circulate on the continent, and how many people are affected by dengue fever each year. Many laboratories in West Africa lack the tools to test for the virus, and surveillance systems are not set up adequately to monitor viruses other than yellow fever and HIV, according to the authors.
The recent outbreaks show that laboratories in the region need diagnostic tools to detect the dengue virus, say Franco and colleagues.
In fact, the latest warning of the recent expansion of DENV-3 into West Africa came from Europe, when medics detected the virus in travellers returning from the area with signs of illness. These cases triggered an alert, prompting the countries the travellers had visited to look for the virus, explain the authors.
?As long as active dengue virus surveillance is poorly implemented in Africa, the study of febrile travellers returning to Europe could help to detect viral activity on the African continent,? they add.
A project of the European Centre for Disease Prevention and Control, dubbed ENVID-CLRN, will help monitor the dengue virus in Africa and across the world by recording cases of the disease imported into Europe, note the authors. It aims to map the global circulation of this and another mosquito-borne virus, chikungunya, and will include information about the distribution of different genotypes of these viruses.
1.
Franco L, Di Caro A, Carletti F, Vapalahti O, Renaudat C, Zeller H, et al. Recent expansion of dengue virus serotype 3 in West Africa. Euro Surveill 2010, 15. Article
World Health Organization information about dengue fever
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