Dengue Outbreaks

Dengue Outbreaks 2023

According to the U.S. Centers for Disease Control and Prevention (CDC), Dengue is a vaccine-preventable, vectorborne infectious disease caused by four dengue viruses (DENV). The U.S. CDC recently issued Travel Health Notices regarding dengue outbreaks in the Americas (September 25, 2023), Africa/Middle East (October 18, 2023), Costa Rica, and Asia/Pacific Islands (July 25, 2023). According to the World Health Organization (WHO), Dengue is endemic in about 125 countries and is present in Asia, Brazil, the Pacific Islands, the Americas, and Africa. In addition, the Pan American Health Organization (PAHO) and the WHO issued various dengue travel advisories in 2023. As of November 2023, the European Centre for Disease Prevention and Control (ECDC) confirmed over 4.5 million dengue cases and about 4,000 deaths globally. In 2023, over 100 non-travel-associated dengue cases have been reported from Italy (72), France (41), and Spain (3).

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. As of November 2023, HealthMap published dengue case maps. 

Dengue Outbreaks Africa

The U.S. CDC, Africa CDC, and the ECDC stated in November 2023 that Dengue is an ongoing risk in many parts of Africa, such as Chad, Egypt, São Tomé and Príncipe, Somalia, and Sudan. And Ethiopia has had nearly annual dengue outbreaks since 2013. In addition, there has been an ongoing dengue fever outbreak in the Afar region in northeastern Ethiopia since April 2023. The World Health Organization (WHO) reported on October 16, 2023, that a dengue outbreak was declared by the Ministry of Public Health and Prevention in Chad. There have been 1,342 suspected cases, and one death was reported. Abéché health district in Ouaddaï province is the current epicenter of the dengue outbreak. The Africa Region reported on May 29, 2023, a total of 1,638 suspected and confirmed dengue cases and nine associated deaths (case fatality ratio 0.5%) in Logia and Mille districts in the Region from April 4 through May 10, 2023. The U.S. CDC issued a Travel Health Notice on July 21, 2023, confirming Dengue is an ongoing risk in Mauritius. Dengue cases have also been reported in 2023 in Réunion and French Guyana, where the activity remains high.

Dengue Outbreaks Region of the Americas

As of November 2023, the WHO/PAHO assessed the risk of dengue outbreaks in the Americas as high at the regional level due to the widespread distribution of the Aedes spp. Mosquitoes. The highest number of dengue cases were reported in Brazil, with over 2.5 million cases, an increase of 20% when compared to 2022., followed by Peru. Among the severe dengue cases reported in 2023, the highest number was reported in Brazil, with 1,396 severe cases, followed by Colombia, Peru, Bolivia, and Mexico. Countries with severe dengue cases included Cuba, Honduras, Colombia, Panama, Paraguay, the Dominican Republic, Guatemala, Grenada, Puerto Rico, the U.S. Virgin Islands, and the British Virgin Islands (9.09%). The WHO reported 2.8 million dengue cases from 46 countries with a case fatality rate (CFR) of 0.047%) in the Americas Region in 2022.

According to the Republic of Costa Rica Health Surveillance Directorate, 18,194 dengue cases were reported in mid-October 2023, with the Huetar Caribe and Central Sur regions presenting the most cases. As of August 4, 2023, all four dengue serotypes were registered.

Dengue has been reported in 28 of 32 Mexican states in 2023. Quintana Roo (Cancun) is the leading state reporting dengue cases in 2023. Mexico's Health Ministry reported 30,320 confirmed dengue cases between January and October 7, 2023, a 337% year-over-year increase.

In 2022, the PAHO reported 36,926 cases throughout Mexico and 53 dengue deaths (Sonora confirmed 14 deaths, Oaxaca 13 deaths). In addition, dengue transmission has been documented in Yucatan, Mexico (Cancun) since 1979. The recent increase in dengue cases in Mexico has been partly attributed to the genetic diversification of DENV serotypes and the emergence of new genotypes across Latin America (Hernández-García et al., 2020). 

Jamaica's Ministry of Health declared a dengue outbreak on September 23, 2023. To date, there have been 1,060 confirmed dengue infections in Jamaica. All parishes have recorded dengue cases, with Kingston and St. Andrew, St. Thomas, St. Catherine, Portland, and St. James recording the most confirmed cases.

The Republic of Colombia health officials reported as of the week ending September 23, 2023, the total number of dengue cases this year is 83,138.

Dengue Outbreaks Asia

In 2023, Dengue fever is hyperendemic in several Southeast and South Asian countries. Dengue is an ongoing risk in many parts of Asia, such as Bangladesh, Cambodia, India, Laos, Malaysia, Maldives, Myanmar, Pakistan, Sri Lanka, Thailand, Taiwan, and Vietnam. Dengue cases have steadily increased in the last 50 years in East Asian countries such as India.

As of October 30, 2023, Taiwan's CDC recorded 20,363 domestic dengue cases, 17,962 of which were in Tainan and 1,208 in Kaohsiung. The Taipei Times reported the third vertical transmission of dengue fever in 2023.

As of November 15, 2023, Bangladesh has reported over 290,000 dengue cases and 1,500 related deaths this year. The WHO published Dengue Situation Report #8 on October 16, 2023, confirming that 16,050 new cases were reported in Bangladesh during the reporting week, a 7.1% decrease compared to the previous week. 

Dengue is endemic in India with an overall seroprevalence of 48·7 % (95 % CI 43·5–54·0). Over a hundred thousand dengue cases are diagnosed in India annually, and about half of the country's population carries dengue virus-specific antibodies. Since 2000, genotype III of DENV-1, the cosmopolitan genotype of DENV-2, genotype III of DENV-3, and genotype I of DENV-4 have dominated India. Moreover, the DENV-4-Id is drifting towards DENV-1 and DENV-3 clades, suggesting the role of cross-reactive antibodies in its evolution. The observed emergence of the non-Indian lineage of DENV-2 in Bhopal, which again is the first report from the area, coincides with the gradual increase in DENV cases in Bhopal since 2014. As of June 11, 2023, Mumbai has reported 386  dengue cases, accounting for 31% of all registered cases in 2023. The WHO published Dengue Situation Report # 1 on August 28, 2023, confirming Dengue is endemic in Bangladesh, with yearly increases and peaks reported around the monsoon season. Save the Children reported in October 2023 that about 225,000 cases have been reported in the current outbreak, more than 38,000 of them children, with at least 113 pediatric deaths reported.

According to Bangladesh's Directorate General of Health Services, of these dengue cases, 63% of patients and 62% of deaths were reported in July 2023. The WHO reported that from January to August 7, 2023, the dengue case fatality rate (CFR) was 0.47%. As of December 2022, a total of 274 related fatalities (CFR 0.44%) were reported by the Ministry of Health & Family Welfare of Bangladesh in 2022. According to a Bangladesh Sangbad Sangstha report in 2019, 179 deaths were reported.

Sri Lanka's National Dengue Control Unit Director, Dr. Nalin Ariyaratne, reported 66,500 dengue cases with 39 related deaths in 2023.

Dengue Outbreaks Caribbean Islands

Jamaican health officials on the Caribbean island nation reported in 2023, there have been 1,060 (132 confirmed) dengue cases and the first dengue-related death. Among the confirmed cases, DENV2 predominates. In 2023, Kingston & St. Andrew, St. Thomas, St. Catherine, Portland, and St. James recorded the most confirmed dengue cases. In the French Antilles, Martinique and Guadeloupe have entered an epidemic phase. According to the ECDC epidemiologic report published in October 2023, Saint-Martin and Saint-Barthélemy are showing an increasing trend, and the epidemiological situation is characterized as one having the potential to evolve.

Dengue Outbreaks Europe

The European CDC reported in November 2023 autochthonous/non-travel-associated dengue cases in Europe in Italy (72), France (41), and Spain (3). From May through October 2023, Public Health France reported 36 indigenous cases of dengue fever. According to Santé Publique France, these cases were recorded in Paca, Occitanie, and particularly in Auvergne Rhône-Alpes. As of October 30, 2023, 68 confirmed locally transmitted dengue cases have been reported in Italy, in the province of Lodi (2 cases), and in sections of the metropolitan city of Rome. And 230 travel-related dengue cases have also been reported.

Dengue Outbreaks United States

Provisional data published by the U.S. CDC as of November 8, 2023, indicates that 48 jurisdictions have reported about 1,716 dengue cases in 2023. In addition, the CDC says Dengue is endemic in the U.S. territories of Puerto Rico, American Samoa, the U.S. Virgin Islands, the Federated States of Micronesia, the Republic of Marshall Islands, and the Republic of Palau. 

On November 1, 2023, Long Beach, California, reported its first locally acquired and fifth travel repeated dengue cases. On October 20, 2023, the Pasadena Public Health Department reported a case of Dengue in a California resident who did not travel outside the U.S. This is the first confirmed case of Dengue in California not associated with travel. In 2023, California reported 38 travel-related dengue cases.

As of November 18, 2023, the Florida Health Department reported 458 travel-associated dengue cases (Miami-Dade) and 142 locally acquired dengue cases confirmed as week #46 in 2023. Both Miami-Dade and Broward Counties remain under a mosquito-borne illness alert. In 2022, 903 travel-associated and 68 locally-acquired dengue cases were reported. In 2022, the Florida Department of Health in Miami-Dade County confirmed  (DENV-3) cases. FlHealthCharts displays the previous year's dengue case totals.

In November 2023, 155 dengue cases were confirmed in New York (New York City), and 56 patients were confirmed in New Jersey.

As of November 2023, Puerto Rico's Department of Health Arboviral Disease Week #44 report indicates about 864 probable dengue cases. In 2022, 929  confirmed dengue cases and three related fatalities were reported. From 2010 to 2020, approximately 95% of locally acquired dengue cases in the U.S. (n = 31,289) occurred near San Juan, Puerto Rico (n = 29,779). The estimated dengue seroprevalence among persons nine years of age was approximately 40%. During 2010–2020, Puerto Rico reported the highest number of dengue cases (29,862 [96.6%]), followed by American Samoa (660), USVI (353), and Guam (28). A recent CDC study stated that the cost-effectiveness of dengue vaccinations in PR depends on the seroprevalence, which is lower for younger age groups.

Dengue Outbreaks Western Pacific Region

Various countries in the WHO Western Pacific Region have reported dengue cases in 2023. As of October 26, 2023, the cumulative number of dengue cases in Australia was 783. Dengue outbreaks can occur annually in north and central Queensland and Victoria, and residents need to be vigilant to ensure dengue mosquitoes are not breeding on their property. Dengue is an ongoing risk in many parts of the Pacific Islands, such as the Philippines and Taiwan, as of July 25, 2023. The WHO published Update #664 on the Dengue situation in the Western Pacific Region. As of 2023, countries like Vietnam, Singapore, the Philippines, Thailand, Taiwan,  and Malaysia experienced dengue outbreaks. Thailand's Bureau of Epidemiology, Department of Disease Control, reported through epidemiology week #20 that there have been 16,650 dengue cases, including 14 deaths, in 2023. The Dengvaxia and Qdenga vaccines are commercially available in Thailand in 2023. As of October 10, 2023,  there have been over 17,500 local dengue cases in Taiwan, with 14,017 cases in Tainan City and 32 deaths. Taiwan CDC physician Lin Yung-ching stated on October 17, 2023, that a case of mother-to-infant transmission of Dengue was confirmed last week, affecting a five-day-old boy, the second such case this year and the third ever in Taiwan.

Dengue Disease

New research has identified pre-existing anti-DENV IgG antibodies responsible for Dengue's increased deadliness upon second exposure. "We definitively proved that it's not the presence of dengue antibodies that are a problem, but the quality of those antibodies," says Stylianos Bournazos, a research associate professor in the laboratory of Jeffrey Ravetch, the Theresa and Eugene M. Lang Professor at Rockefeller University in New York. "Now that we know the pathway these antibodies use, we can develop therapeutics against it." 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.

On June 30, 2023, a study concluded higher environmental temperature shortens the DENV extrinsic incubation period in mosquitoes, increases human transmission, and plays a critical role in dengue outbreak dynamics. Dr. Easwaran Sreekumar, who led the research team, commented, "The body temperature of mosquitoes is not constant as in higher animals, and it increases or decreases as temperatures change. 

Dengue Vaccines

Authorized dengue vaccines (Qdenga and Dengvaxia) and vaccine candidates' information can be found at PrecisionVaccinations.com.