2024 dengue outbreak in Latin America and the Caribbean

In the currently ongoing 2024 dengue outbreak in Latin America and the Caribbean, the number of reported infections surpassed historical records in several nations with a combined total of over 9.3 million suspected cases on 15 June 2024 and 4,500+ deaths. 7,983+ severe cases from epidemiological week (EW) 19 were reported on 31 May 2024, while the 8,140,210 suspected cases at EW 19 reflect a 226% increase compared to 2023's outbreak up to EW 19, and a 416% increase compared to the annual average number of cases of the last 5 years. Impacted countries include Brazil, Argentina, Paraguay, Uruguay, Peru, Ecuador, and Columbia in South America; Honduras, Nicaragua, Belize, Panama, El Salvador, Costa Rica, and Guatemala in Central America; and Mexico in North America.

Causes
A comprehensive multinational study published in Nature Communications found that climate change and increased human mobility were significant factors contributing to the rapid acceleration in the spread of dengue. Annual increases in temperatures, humidity levels, and rainfall amounts each provide more favorable conditions for the Aedes aegypti mosquito to breed and spread, and making it so previously unaffected regions gradually develop a climate more favorable for dengue spreading.

The study also stated that rapid urbanization and population growth in cities led to poor urban planning, waste management, sanitation, and access to clean water further help incubate mosquito spread.

Other studies indicate that the increased temperatures related to the El Niño weather pattern also contributed to the exceptionally high number of dengue fever cases and area covered.

Central America
Four dengue virus serotypes: DENV1, DENV2, DENV3 and DENV4, were found to be simultaneously circulating in all of the impacted countries in Central America aside from El Salvador, which currently only had DENV1, DENV2, and DENV3 confirmed.

Honduras
The number of reported infections rapidly escalated in February to March to reach epidemic classification. The continued increase in rate of infection led to the national government issuing an epidemiological national emergency on 31 May 2024. As of 24 May 2024, based on a report made by the World Health Organization, 20,563 dengue cases were reported, of which 266 (1.29%) were classified as severe infections, with 27 deaths of which 11 deaths were confirmed to have been directly caused by the infection. From EW 19, there was a 445% increase in reported cases compared to EW 19 in Honduras's dengue outbreak in 2023, and 193% compared to the average number of annual dengue infections in the past 5 years. The greatest concentration of cases are currently ongoing in the departments of Tegucigalpa, Cortés, San Pedro Sula, Bay Islands, Atlántida, and La Paz.

Reasons for the increase in cases from the prior year include logistical and personnel shortages in the national health secretariat, including shortages in chemical supplies, fumigation equipment, and vehicles. Another possible factor regards economic disparities in marginalized urban areas leading to delays in treatment allowing for the infection to spread in the densely populated environment. Poor waste management, water collection practices, and sanitation in part due to shortages of cleaning supplies prevented the disease from being contained.

Guatemala
From the beginning of 2024 to EW 14, 12,570 cases were reported in Guatemala, of which 1,086 were lab-confirmed cases and 20 were severe cases. The number of cases increased to 480% relative to EW 14 in 2023 and 599% compared to the annual average across the last 5 years. 9 deaths have been reported, with a fatality rate of 0.072%.

Panama
From the beginning of 2024 to EW 18, 5,882 dengue cases were reported, 4,141 (70%) were lab-confirmed, and 27 (0.45%) were severe cases. The number of cases increased to 155% relative to EW 18 in 2023, and 288% compared to the annual average across the last 5 years. 9 deaths have been reported, with a fatality rate of 0.153%.

Brazil
At EW 19 in Late May, Brazil made up the vast majority of cases of dengue fever reported in Latin America and the Caribbean in 2024, with 83% of suspected cases arising from Brazil, along with 79.4% of deaths. 6,803,727 cases were reported, and 2,897 deaths have been reported.

Reasons for why Brazil has such a high number of cases include long-term underinvestment in water and sanitation infrastructure especially in poorer urban slums, forcing citizens to store water in open tanks that provides standing water for mosquitos to lay eggs in.

In order to slow the spread of the disease and work to achieve herd immunity, Brazil preemptively purchased the entire global stock of Qdenga dengue two-dose vaccine made by the Japanese pharmaceutical company Takeda in January 2024. However, only six million doses were planned to be created for 2024, which would only be enough to vaccinate 1.5% of the population of Brazil.

Columbia
From the beginning of 2024 to EW 11, Colombia reported 69,837 cases, an increase of 262% relative to the annual average of cases up to EW 11 across the last 5 years. 9 deaths have been reported. The cumulative incidence rate was reported as 136 cases per 100,000 people.

Ecuador
From the beginning of 2024 to EW 11, Ecuador reported 13,075 cases, an increase of 277% relative to the annual average of cases up to EW 11 across the last 5 years, and a cumulative incidence rate was reported as 136 cases per 100,000 people. By EW 19, 31 deaths were reported.

Peru
79,741 cases were reported from EW 1 to EW 11, a 471% increase relative to the 5-year average at EW 11 with a cumulative incidence rate of 239 cases per 100,000 people.

Mexico
65,758 cases of dengue fever have been reported up to EW 19 in Mexico, accounting for 0.8% of total cases in Latin America and the Caribbean in 2024. 405 severe cases and 20 deaths have been reported so far in Mexico, with a fatality rate of 0.03%. DENV1, DENV2, DENV3 and DENV4 serotypes have been detected in Mexico. The states with the most cases were Guerrero, Tabasco, and Quintana Roo, as of EW 11.

Caribbean
From the beginning of 2024 to EW 19, 21,458 suspected cases were reported, 3,091 (14.4%) were lab-confirmed, and 111 (0.51%) were severe cases. The number of cases increased to 468% relative to EW 19 in 2023. DENV1, DENV2, and DENV3 serotypes have been proven to be circulating in the region.