Dengue fever, a tropical disease transmitted by mosquitoes, is predicted to become endemic in parts of the US, Europe, and Africa within the next decade as a result of climate change and urbanization, according to World Health Organization (WHO) Chief Scientist Jeremy Farrar. He warns that the disease will “take off” in these regions as mosquitoes carrying the virus migrate to areas that were previously unsuitable for their survival.
Farrar emphasizes the need for proactive discussions about dengue and preparations for the additional pressure it will bring to many big cities in the future. Dengue fever has long been endemic in Southeast Asia and Latin America, causing approximately 20,000 deaths annually. Cases of dengue have increased eightfold since 2000 due to climate change expanding the habitat of the dengue-carrying mosquitoes and the rapid urbanization of cities providing more opportunities for the insects to thrive.
The WHO’s concerns are exemplified by the current outbreak of dengue in Bangladesh, with over 208,000 cases and 1,000 deaths reported since the beginning of the year. Europe has also witnessed a spike in locally acquired dengue cases last year, surpassing the number of cases recorded in the entire previous decade. Isolated cases have even been reported in parts of the US, such as Florida and Texas.
The dengue virus is primarily transmitted by Aedes aegypti mosquitoes, which bite both during the day and night and can be found both indoors and outdoors. Unlike the Anopheles mosquitoes that transmit malaria, Aedes aegypti mosquitoes are more adaptable to urban settings. Symptoms of dengue include fever, muscle spasms, nausea, and in severe cases, joint pain so intense that the disease is nicknamed “bone-break fever.” While most patients recover within two weeks, less than 1% of cases are fatal. Currently, there are two vaccines available, including Dengvaxia, which requires previous exposure to the virus, and Qdenga, approved in several countries.
The WHO fears that a surge in dengue cases could overwhelm healthcare systems in poorer countries, especially in sub-Saharan Africa, where resources and medical staff are already limited. Farrar points out that the clinical care required for dengue is intensive, with a high ratio of nurses to patients. This raises concerns about the capacity of healthcare facilities to handle an increase in cases.
The rise in global temperatures linked to climate change is a significant factor contributing to the spread of dengue. The Earth’s surface is currently 0.86 ° Celsius warmer than the 20th Century average, and the ten warmest years on record have all occurred since 2010. As temperatures continue to rise, the habitats suitable for dengue-carrying mosquitoes expand, enabling the disease to establish itself in new regions.
In conclusion, the increasing prevalence of dengue fever in regions not historically affected by the disease is a concerning consequence of climate change and urbanization. Governments and health organizations must address this issue proactively to prepare for the additional pressure on healthcare systems and implement preventive measures to control the spread of the virus.