Dengue Outbreaks

Dengue Outbreaks 2024

According to the World Health Organization (WHO) and numerous health agencies, Dengue is a viral infection spread to humans by mosquitoes of the Aedes genus. According to its dashboard, it is endemic in about 125 countries, including the United States. As of December 2024, the WHO has classified Dengue as a grade 3 emergency, with an estimated 4 billion people at risk globally. Dengue's four subviruses are usually spread to people through the bites of infected Aedes species mosquitoes. However, women infected with Dengue during pregnancy can pass the virus to their fetuses.

On October 3, 2024, the WHO launched the Global Strategic Preparedness, Readiness, and Response Plan to tackle Dengue and other Aedes-borne arboviruses. This WHO plan aligns with the Global Vector Control Response 2017-2030, a global strategy to strengthen vector control worldwide, and the Global Arbovirus Initiative.

According to an editorial published by The Lancet, 2024 has been the worst year on record for dengue infections. A study published in 2024 found that the equatorial tropical and subtropical zones spanning much of Sub-Saharan Africa, Southeast Asia, and northern South America experienced the most significant increases in climate suitability over the past 40 years. As of December 2024, the European Centre for Disease Prevention and Control (ECDC) reported over 13 million dengue cases, and 8,500 dengue-related deaths have been reported this year.

Dengue Outbreak Travel Advisories

The U.S. Centers for Disease Control and Prevention (CDC) reissued a Global Travel Health Notice on November 15, 2024, regarding Dengue outbreaks in 26 countries in the Americas, Africa/Middle East, and Asia/Pacific Islands. The CDC has not issued travel advisories for cities in the U.S. reporting local dengue outbreaks, such as Los Angeles, CA, and Miami, Florida. The U.K. Health Security Agency (UKHSA) says that dengue fever does not occur in the United Kingdom but has been acquired from traveling to dengue-endemic areas. 

Where Are Travelers Infected With Dengue

An analysis published in July 2024 included 5,958 travelers with confirmed or probable Dengue. The most frequent regions of dengue infection acquisition were Southeast Asia (50.4%), South Central Asia (14.9%), the Caribbean (10.9%), and South America (9.2%). The median age was 33 years, and tourism was the most frequent reason for travel (67.3%). Mosquitoes that spread Dengue usually live below 6,500 feet elevation; therefore, chances of getting Dengue while in high altitudes are very low. As of 2024, HealthMap published dengue case maps. 

Dengue Outbreak United States

The U.S. CDC reported that 52 jurisdictions, led by California, Florida, New Jersey, New York, and Puerto Rico, had reported 7,858 dengue cases as of December 2024. In June 2024, the CDC updated a Health Alert Network Health Advisory, notifying healthcare providers, public health authorities, and the public of an increased risk of dengue virus infections in the United States. The CDC says clinicians should consider Dengue in patients with fever who live in or recently traveled to areas with risk of Dengue. In 2023, 52 U.S. jurisdictions reported 6,164 dengue cases to the CDC.

As of December 2024, the Florida Health Department (FDH) reported over 803 travel-associated and 66 locally acquired dengue cases throughout the state this year.

The Texas Department of State Health Services (DSHS) says mosquitoes that transmit dengue fever are found in Texas. As of November 25, 2024, there have been (106) imported dengue cases, one local case (Cameron County), and one related fatality in 23 Texas counties, led by Travis (14),  Collin (9), Dallas (13), Denton, and Ft. Bend. Texas reported 79 travel-related dengue cases in 2023 and one locally acquired case in Val Verde County.

In California, the San Bernardino County Public Health Department reported (1) a locally-acquired dengue case in San Bernardino on November 7, 2024. The Los Angeles County Department of Public Health has reported 12 locally acquired dengue cases in the San Gabriel Valley in the cities of Baldwin Park (8), El Monte (2), Hollywood Hills (1), and Panorama City (1) in 2024. In San Diego, Escondido and Visa reported dengue cases in 2024. In total, over 360 dengue cases were confirmed in California in 2024. California reported wo locally acquired cases (Long Beach and Pasadena) and 250 travel-related cases in 2023.

Dengue Outbreak U.S. Territories

The CDC says the Dengue virus is endemic in the U.S. territories of Puerto Rico, American Samoa, the U.S. Virgin Islands (163), the Federated States of Micronesia, the Republic of Marshall Islands, and the Republic of Palau. In 2024, Puerto Rico's Department of Health confirmed Dengue was endemic in the greater San Juan area, with 4,467 cases. Of American Samoa school-aged children, the estimated seroprevalence among those aged 7–16 years was 59% (95% CI = 47%–71%) and was 60% (95% CI = 48%–72%) among those age-eligible for vaccination.

Dengue Outbreaks Africa

According to the Africa CDC Epidemic Intelligence Report of October 2024, over 74,000 dengue cases have been reported this year from Burkina Faso, Cameroon, Cabo Verde, Central African Republic, Chad, Cote d Ivoire, Ethiopia, Ghana, Kenya, Mali, Mauritius, Sao Tome and Principe, Senegal, Sudan and Togo. The CDC reported in 2024 that travelers visiting these African countries may be at increased risk for Dengue: Burkina Faso, Cape Verde, Côte d'Ivoire, Ethiopia, Mali, Senegal, and Sudan. The U.K. Foreign Office issued health advice for those traveling to Cape Verde after a dengue fever outbreak in 2024. In 2023, 171,991 dengue cases and 753 deaths were reported in African countries. Dengue circulation has been detected in more than 30 African countries. The U.S. CDC issued a Travel Health Notice in 2023, confirming Dengue is an ongoing risk in Africa.

Dengue Outbreaks Region of the Americas

The first suspected dengue-like epidemics were reported in 1635 in Martinique and Guadeloupe. The Pan American Health Organization (PAHO) issued an Epidemiological Alert in 2024. As of December 2024, 43 countries and territories have reported over 12,576519 Dengue cases and 7,656 related deaths in the Americas this year. In 2023, 4,617,108 Dengue cases were reported in the Americas.

According to Argentina's Epidemiological Bulletin week #35, posted on September 9, 2024, 764,901 dengue cases were reported nationwide, with 56,435 in the City of Buenos Aires this year. Argentina's Ministry of Health published a Comprehensive Preparedness and Response Plan for Dengue Epidemics 2024-2025.

Over the past 25 years, nearly 18 million Brazilians have been infected with the dengue virus. As of October 2024, Brazil's Ministry of Health weekly Arboviruses reports indicate over 9.6 million dengue cases and 5,441 related deaths. The Brazilian Ministry of Health reported dengue cases among pregnant women reached 5,151 in the first six weeks of 2024, compared to 1,157 in the same period in 2023. In 2023, Brazil reported about  2.9 million patients, a one-year increase of 20%. In 2023, Rio de Janeiro reported 22,959 dengue cases.

According to the Republic of Costa Rica Health Surveillance Directorate, 1,076 dengue cases were reported in 2024. Costa Rica confirmed over 24,000 dengue cases in 2023, with the Huetar Caribe and Central Sur regions presenting the most cases. As of August 4, 2023, all four dengue serotypes were registered.

In French Guyana, over 8,000 confirmed dengue cases have been reported since the beginning of 2024.

The U.S. CDC includes Mexico in its global Level 1 Dengue Travel Health Advisory. In October 2024, Mexico reported (Epidemiological Week 40) more than 358,000 cases of Dengue and 180 related fatalities. The Mexican states reporting the most cases were Quintana Roo (Cancun), Tabasco, and Guerrero. A May 2024 model predicted that the percentage of municipalities affected by Dengue will rise from 55 to 91% in Mexico. Dengue was reported in 28 of 32 Mexican states in 2023, and transmission has been documented in Yucatan since 1979. All four DENV serotypes have been found in Mexico for decades.

DENV was reintroduced in Panama in 1993 after a 35-year absence of autochthonous transmission. The increase in the number of total dengue cases has been accompanied by an increase in severe and fatal cases, with the highest case fatality rate recorded in 2011. All four serotypes were detected in Panama. An analysis published in 2024 suggests that Panamanian strains were related to viruses from different regions of the Americas, suggesting a continuous exchange of viruses.

Peru issued an Alert in November 2024, notifying public and private health facilities of the increased risk of dengue infections. On November 23, 2024, a dengue vaccination program was launched in 16 districts of Loreto, Piura, Tumbes, and Ucayali regions.

As of 2024, the PAHO reported continuing widespread transmission of dengue fever in the Caribbean. On August 16, 2024, the Republic of Trinidad and Tobago confirmed 825 cases of Dengue Fever and eight (8) laboratory-confirmed deaths. The Caribbean reported over 62,000 dengue cases in 2023, a significant increase from 20,349 cases in 2022. Jamaica's Ministry of Health declared a dengue outbreak on September 23, 2023. 

Dengue Outbreaks Asia and Pacific Islands

Dengue has become an annual epidemic in many parts of Southeast Asia. In 2024, the U.S. CDC reported that the countries listed in the WHO Western Pacific Region are reporting higher-than-usual dengue cases, and travelers visiting these countries may be at increased risk: Cambodia, Malaysia, Nepal, the Philippines, Singapore, Sri Lanka, and Thailand. The governments of the Philippines (Aklan), Bangladesh (Balochistan), Pakistan, Nepal, and Singapore health departments have declared dengue outbreaks in 2024. In Singapore, the female Aedes aegypti mosquito is the primary vector of Dengue, and it transmitted the virus to 9,939 people in 2023. In Bangladesh, 421 Dengue-related deaths were reported in 2024, and 1,705 people lost their lives due to Dengue in 2023, the deadliest year ever.

The WHO Western Pacific Region published Dengue Situation Update #708 on October 3, 2024.

Dengue Outbreaks Eastern Mediterranean Region

Dengue and severe dengue epidemics were first reported in the WHO's Eastern Mediterranean Region in 1998. Dengue outbreaks have occurred in all nine endemic countries: Afghanistan, Djibouti, Egypt, Oman, Pakistan, Saudi Arabia, Somalia, Sudan, and Yemen. On July 17, 2024, the WHO reported 12 autochthonous (local) cases of Dengue documented in Iran. Dengue screening at the Iranian border was launched in August 2024.

Dengue Outbreaks Europe

In Europe, dengue viruses, transmitted by Aedes albopictus mosquitoes, are primarily associated with infections acquired in endemic countries. Local transmission remains rare, with only sporadic or small-scale outbreaks documented. The ECDC has reported locally acquired dengue cases in France, Italy, and Spain in 2024. In 2023, 130 locally acquired dengue cases were reported in the EU/EEA. Imported dengue cases in Europe increased from 1,572 in 2022 to about 4,900 in 2023.

In 2024, France reported 82 locally transmitted dengue fever cases and over 4,042 imported cases. In 2023, France reported nine dengue outbreaks that produced 45 autochthonous infections. In 2022, France reported 65 locally acquired dengue cases.

The Italian National Public Health Authority reported 213 locally acquired dengue cases in 2024 and 82 locally acquired dengue cases in 2023. In Fano, a small coastal city in the Marche Region, Eurosureliiance reported 138 confirmed and 61 probable cases of DENV-2 were notified by October 28, 2024. Travel-related dengue cases have reached 472 in 2024. Non-travel-associated dengue cases have been reported in Italy since 2020 (10 cases).

Spain reported eight locally acquired dengue cases in the Camp de Tarragona area of the Catalonia region in 2024, and the Catalonia region reported three local cases in 2023.

Dengue Outbreaks India

As of September 2024, dengue cases in India are increasing, especially in Karnataka, Kerala, and Tamil Nadu. Dengue cases in India generally peak in October. According to data from the National Centre for Vector-Borne Diseases Control Program, India reported 289,235 dengue cases and 485 related deaths in 2023. In the Democratic Socialist Republic of Sri Lanka, the cocirculation of multiple dengue virus genotypes was reported in October 2024 to be associated with increased cases.

Dengue Outbreaks Indonesia

In September 2024, the WHO reported that dengue outbreaks in Indonesia (E000099) are at level 4. Dengue virus (DENV) infection is a major cause of acute febrile illness in Indonesia, a DENV-endemic region that has experienced a 700-fold increase in incidence over the past 45 years. As of July 2024, 149,866 confirmed cases of Dengue and 884 deaths had been reported from 465 districts across 38 provinces of Indonesia in 2024.

Dengue United Kingdom

As of December 2024, the UKHSA reported 459 travel-related dengue cases had been reported in England, 11 in Wales, and 4 in Northern Ireland. The largest proportion of English cases (40%) were reported in London. This data represents a 201% increase compared to the same period in 2023, which saw 157 cases. In 2024, travel history was known for 441 out of 473 cases in the U.K., with the majority of these reporting travel to Barbados (125, 28%), followed by Brazil (67, 15%) and Indonesia (54, 12%).

Dengue Carrying Mosquitoes

Mosquitoes bites cause more human suffering than any other organism. The spread of Dengue throughout the world can be directly attributed to the proliferation and adaptation of these mosquitoes. In the U.S., there are 176 species. A recent study published by the Royal Society indicates that dengue-carrying mosquitoes are expanding their range by an average of 6.5 meters of elevation and have moved polewards by 4.7 km annually.

Dengue Disease

Dengue is a disease caused by a virus spread through mosquito bites. The disease can take up to 2 weeks to develop, with illness generally lasting less than a week. Without treatment, severe Dengue can become fatal. New research has identified pre-existing anti-DENV IgG antibodies responsible for Dengue's increased deadliness upon second exposure. 

Severe Dengue

About 5% of infections lead to severe Dengue, a life-threatening disease. Promptly initiating intensive supportive therapy can reduce the risk of death among patients with severe Dengue. The extent and duration of viremia often appear to be associated with clinical disease severity. A study published in October 2024 concluded that secondary dengue infections with different dengue virus serotypes after two years have been linked to an increased risk of severe Dengue. 

Dengue Viruses

There are four Dengue Viruses. A study published in October 2024 concluded that the cocirculation of multiple genotypes is associated with increased cases, highlighting the importance of continuous surveillance. This study identified 2 DENV-3 genotypes (I and III) cocirculating. DENV-3 genotype III strains shared a common ancestor with a sequence from India collected in 2022, while DENV-3 genotype I, was found to share a common ancestor with DENV-3 sequences from China. DENV-3 genotype III was detected by the modified Centers for Disease Control and Prevention DENV-3 primers, whereas genotype I evaded detection due to key mutations at forward and reverse primer binding sites. We identified point mutations C744T and A756G in the forward primer binding sites and G795A in the reverse primer binding sites, which were not identified in DENV-3 genotype III. Furthermore, our Sri Lankan DENV-3 strains demonstrated a high root-to-tip ratio compared to the previous DENV-3 sequences, indicating a high mutation rate during sampling (2017 to 2023).

Dengue Virus Blood Transfusion-Transmission 

Emerging evidence published in November 2024 suggests a potentially concerning route of blood transfusion-transmitted dengue virus (TT-DENV), which poses a critical threat, especially in endemic countries like Brazil. In May 2024, a RESEARCH ARTICLE found dengue virus transmission was a risk in blood donation in Thailand. In March 2016, Transfusion-Transmitted Dengue and Associated Clinical Symptoms During the 2012 Epidemic in Brazil was published.

Dengue Infection Immune-Mediated Enhancement

In this study published on October 31, 2024, researchers demonstrate that the expression of a DENV-specific B cell receptor (BCR) renders cells highly susceptible to DENV infection, with the infection-enhancing activity of the membrane-restricted BCR correlating with the ADE potential of the IgG version of the antibody. In addition, they observed that the frequency of DENV-infectible B cells increases in previously flavivirus-naïve volunteers after a primary DENV infection. These findings suggest that BCR-dependent infection of B cells is a novel mechanism for immune-mediated enhancement of DENV infection. This observation suggests that BCR-dependent infection of DENV-specific B cells may be a complementary mechanism of immune-mediated enhancement of DENV infection that expands upon and complements existing models of antibody-dependent enhancement.

Dengue Outbreak Discrepancy Research 2024

In October 2024, a study published by The Lancet Infectious Diseases provides novel insights into serotype-specific epidemiological patterns and disease outcomes of primary DENV infections by revealing the hidden contribution of inapparent infections. This indicates that case surveillance skews the perceived epidemiological footprint of Dengue's four viruses. On October 25, 2024, these researchers wrote, 'While inapparent infections are often overlooked and do not require immediate medical attention, we have assumed that they account for up to 88% of all dengue virus (DENV) transmission events'. A study published in May 2024 revealed substantial discrepancies between estimates and reported dengue cases. A study published by the journal Nature in January 2024 uncovered variations in antibody composition that contribute to miscounting primary and secondary prior infection.

Dengue Virus Pregnant Women

The CDC confirms a pregnant woman already infected with Dengue can pass the virus to her child during pregnancy, and there has been one documented report of Dengue spread through breast milk. A study published in the American Economic Journal: Applied Economics in April 2024 confirmed robust evidence for the negative effect of dengue infections on birth weight and documented increases in children's hospitalizations and medical expenditures for up to three years after birth.

Dengue and Zika Virus

The journal Science Translational Medicine published a study on May 29, 2024, finding that primary ZIKV infection increased the risk of disease caused by DENV3 and DENV4 but not DENV1. This finding was also factual for tertiary infections when individuals were previously infected with DENV and ZIKV but not when previously infected with ZIKV and DENV.

Dengue Vaccines

Information on dengue vaccines (Qdenga) and vaccine candidates can be found at PrecisionVaccinations.com.