Where is Dengue fever found?
Dengue fever is found in the tropical and subtropical regions of the world, including Southeast Asia, the Indian subcontinent, Africa, and the Americas. Dengue has been around since the 1780’s and has caused numerous global pandemics throughout these regions. Dengue epidemics result in thousands of fatalities annually. It is the most important mosquito-borne disease behind Malaria.
Southeast Asia has always been affected by Dengue fever epidemics. A large-scale pandemic broke out in Southeast Asia in the 1950’s and spread around the world. The more severe type of Dengue fever known as Dengue Haemorrhagic Fever (DHF) has become a frequent cause of illness and death among children in these regions. In 2007, Indonesia reported 160,000 cases of Dengue fever with over 1000 deaths. Other countries such as Cambodia, Malaysia, the Philippines, Thailand, and Vietnam each reported tens of thousands of cases in 2007.
Dengue fever has been sweeping through Latin America over the last several years as well. In 2002, an outbreak hit Rio de Janeiro and one million people were infected. In 2007 alone, Brazil reported over half a million cases, Colombia reported 42,000 cases, Venezuela reported 82,000 cases and Paraguay reported over 28,000 cases. The number of cases for 2008 is likely to be similar.
The situation in South America
Dengue’s emergence as a major public health problem in recent decades has been most remarkable in Central and South America. The dramatic increase in the incidence since the 1980s is in line with the situation previously observed in South East Asia. The Americas’ first major dengue fever epidemic (including a number of severe causes of infection) occurred in Cuba in 1981. By 2003, 24 countries in the region had reported confirmed cases of DHF . Most cases in this region occur between January and May, which corresponds to the rainy season in most of the affected countries .
This year, Brazil had reported over 245,000 dengue fever cases as of 2 June, compared with around 300,000 for the whole of 2006 and nearly 800,000 in 2002 . The Pan American Health Organization (PAHO), the WHO’s regional office for the Americas, will send a team of consultants to Brazil to analyse the dengue control measures there next month.
Paraguay has reported over 25,000 cases in 2007, including 52 cases of DHF and 13 deaths . This is a huge increase from previous years; by week 11 of 2006, 4,271 cases had been reported, which was itself close to a ten-fold increase on the same period in 2005 . As a result of the dengue situation, Paraguay declared a 60-day state of emergency in March, but the outbreak now seems to be subsiding .
The situation in South East Asia
Dengue fever is widespread in South East Asia, with eight of the region’s 11 countries reporting disease incidence to the WHO every year. According to the WHO’s Regional Office for South East Asia, 179,312 cases were reported in the region in 2005, over half of which were in Indonesia . The region has averaged over 100,000 cases annually since 1985 . However, dengue fever is widely considered to be under-reported, and accurate information about incidence in countries in this region is not always available through government sources. Official figures this year are scarce, but Indonesia had reported over 16,000 cases of dengue fever this year as of 12 February . Recent flooding in Jakarta has seen a spate of recent media reports quoting Health Ministry data that there have now been over 68,000 cases , but this is not yet visible in official documents.
India had reported 105 cases this year by 14 May, although this was a provisional figure and will almost certainly be raised, as over 12,000 cases were reported last year . Singapore had reported 1,308 cases of dengue fever as of 10 May, compared to 950 cases recorded during the same period last year, while Malaysia’s Ministry of Health has reported 208 confirmed cases this year, with another 500 or so suspected cases . An outbreak of dengue fever in the Cook Islands in May 2006 has so far seen 1,394 cases being reported but cases now appear to be dwindling.
The Philippines’ Department of Health has established a Dengue Control Program in light of the record high of 35,000 cases in the country last year. Crucial to this is the ‘Four O’Clock Habit’, a continuous and concerted effort to eliminate the breeding places of Aedes aegypti: people across the country are encouraged to clean their surroundings and drain water at 4 pm every day .
Recent media reports have claimed that a public health official from Thailand had announced 14 deaths and over 11,000 cases in that country so far this year, but again, this has not yet been confirmed in official documents .
Implications for Europe
Dengue fever does not naturally occur in the European Union (EU), and it should be underlined that in continental Europe conditions do not exist for further spread from patients returning with the infection from other countries. The disease is not statutorily notifiable in most Member States. It is of note that in several of the EU’s outermost regions and overseas territories cases of dengue fever have occurred. In recent decades, there have also been increasing reports of dengue infections in long-term expatriates, aid workers, military personnel and immigrants , and it has been frequently reported in travellers returning from South East Asia and the Indian subcontinent, increasingly from the Americas and the Caribbean , and occasionally from Africa. Cases in western travellers to tropical countries have become more common in the last decade , with fatalities very occasionally reported , however, the exact incidence in returning travellers is not well known.