Dengue cases set to break records in 2019
Dengue fever has become the fastest growing mosquito-borne disease worldwide, now present in over 100 countries compared to only nine before 1970. This year, the number of dengue cases and outbreaks worldwide have surged further compared with 2018, with numbers in many countries set to break records.
Compared to the same time periods in 2018, data for dengue infections so far in 2019 shows substantial increases, prompting several countries across continents to declare national emergencies. Outbreaks have also been identified in previously dengue-free areas, with for example the Cook Islands declaring a dengue outbreak for the first time in a decade earlier this year.
In the beginning of this year, the World Health Organisation had listed dengue among ten diseases as a potential threat for 2019. According to Dr. Raman Velayudhan from the World Health Organisation, present trends confirm this observation and dengue epidemics tend to have seasonal patterns, with transmission often peaking during or after rainy seasons. There are several factors contributing to this increase and they include high mosquito population levels, susceptibility to circulating serotypes, favorable air temperatures, precipitation, and humidity all of which affect the reproduction and feeding patterns of mosquito populations, as well as the dengue virus incubation period.
In Asia, more than twelve countries have so far declared an outbreak the first half of 2019, including in Thailand, Singapore, Cambodia, and Vietnam. Dengue cases in the Philippines soared to 100,000 representing an increase of 85% compared to estimates for the same period in 2018 – this has led to more than 450 fatal cases this year. Cases in some localised areas such as the city of Zamboanga are up 200% from the previous year, prompting authorities to declare a “national dengue alert”.
Similarly, the number of dengue cases in Bangladesh in the year-to-date has already soared well above 2018 levels, with about 10,000 dengue hospitalisations by the end of July 2019. Total number of cases are in fact so high that 2019 is set to break all-time records in terms of dengue outbreaks. This is leaving healthcare facilities highly overburdened whilst governments endeavour to control mosquito populations, particularly in the hard-hit capital city Dhaka, by stepping up vector control interventions including fumigation.
Dhaka, Bangladesh-July 28, 2019: Dengue patients lying on floor outside the Mugda Hospital admission. Public hospital’s medicine ward has run out of beds amid an increased number of dengue patients. Photo: Sk Hasan Ali.
In Latin America, Honduras is another example: this year, at least 28,000 people so far have been infected and dozens have died in the country’s worst dengue outbreak in over half a century. As a result, a national state of emergency has been declared but despite substantial resource mobilisation by the government, including fumigation being stepped up nation-wide, the healthcare system and a majority of hospitals remain completely overwhelmed with the number and requirements of dengue patients. With the rainy season about to begin, the situation could also further deteriorate.
The incidence of dengue is also rapidly increasing in the African continent. Tanzania is currently fighting a dengue outbreak, the worst since 2014, and the government has offered free diagnosis services following four fatalities.
Responsive governments, implementing effective mosquito eradication programs including vector-control interventions, the building of community awareness and participation and the increase in resources to the healthcare systems, can trigger significant declines in the number of cases of dengue. After several years of increases in cases including a major outbreak in 2016, Jamaica also declared a dengue outbreak early in 2019 after cases exceeded the epidemic threshold; effective monitoring and prevention strategies have brought numbers down with authorities reporting in July a major decline in cases.
Dengue fever remains endemic across continents putting over 400 million individuals at risk; although most cases are asymptomatic or mild, over 22,000 people continue to die of severe dengue a year. International cooperation on surveillance, data sharing, public information, control of both the disease and the vectors which transmit it, as well as effective prevention including through vaccination remain crucial in preventing this fast-spreading global disease. These are the principles brought together under the global movement for a World Dengue Day, an initiative to accelerate the international collaborations needed to coordinate prevention and control on dengue and vector-borne diseases worldwide.
For more information about dengue fever, please visit the World Health Organisation website.
Please click here for more information about the World Dengue Day petition and initiative.