Dengue is a febrile illness caused by any of the four dengue virus types (DENV-1 to -4, genus
Dengue, the most prevalent arthropod-borne viral disease in the world, is an acute, febrile disease caused by any of the four dengue virus types (DENV-1 to -4, genus
DENV can also be transmitted by transfusion of blood and blood components and by solid organ transplants containing infectious virus [
Approximately, 50–100 million cases of dengue were calculated to occur each year around the globe [
The mosquitoes that serve as DENV vectors have been able to reach sub-tropical and temperate regions, including North America and countries in Europe [
The scope of this review is to provide an analysis of the epidemiology of dengue in the United States and its territories, with emphasis on the changes in dengue activity in the last decade and on aspects on the molecular epidemiology of currently circulating DENV.
Dengue is thought to have been present in the USA since the end of the 18th century, when Dr. Benjamin Rush, a physician and signatory of the US Declaration of Independence, described a disease resembling dengue fever in Philadelphia during 1780 [
Dengue activity in the continental USA between 1780 and 2013.
Year(s) | Activity reported | References |
---|---|---|
1780 | Dengue suspected in Philadelphia, PA | [ |
1826 | USA ports report 1st dengue outbreak | [ |
1827-1828 | Epidemic in Southern USA | [ |
1845 | Dengue reported in St. Louis, MO | [ |
1850-1851 | 1st report of dengue epidemic inland (including GA and MS), epidemic in Southern USA, New Orleans, LA, and along South Coast | [ |
1870–1872 | Epidemic in Southern USA | [ |
1873 | Dengue reported in LA, AL, and MS; |
[ |
1879-1880 | Epidemic in Southern USA | [ |
1885-1886 | Dengue in gulf ports of TX, dengue in Austin, 16,000 estimated cases of 22,000 inhabitants | [ |
1897–1903 | Epidemic in Southern USA, TX most heavily affected | [ |
1904 | Dengue reported in FL and TX | [ |
1916 | Fatal case of possible DHF reported in TX | [ |
1922 | Dengue epidemic, 500,000 to 600,000 cases in TX, 30,000 in Galveston, and 7,561 in LA | [ |
1923 | 1,376 dengue infections reported in LA | [ |
1924 | 1 dengue case in LA | [ |
1941–1944 | Texas and gulf states involved in epidemic | [ |
1945 | Last continental epidemic of dengue reported in LA | [ |
1980 | 1st indigenous dengue cases in USA since 1945 (Brownsville, TX), DENV-1 isolated | [ |
1981 | DENV-4 cases reported, 1st isolation of DENV-4 in the USA | [ |
1982 | 1st reports of DENV-2 in the USA | [ |
1983 | 1st reports of DENV-3 in the USA | [ |
1986 | DENV-1 reported in TX | [ |
1987 | Autochthonous dengue reported in TX | [ |
1990 | DENV-1, -2, and -3 isolated in the USA, reports of 102 dengue cases | [ |
1991 | DENV-1 and DENV-3 isolated in the USA, 25 dengue cases reported | [ |
1994 | 91 cases of dengue, DENV-2 and -3 isolated in the USA | [ |
2005 | First case of autochthonous DHF case reported in TX | [ |
2009–2011 | Autochthonous dengue transmission in FL, DENV-1 isolated. DENV-1 isolated from a blood donor from Key West, FL in 2010 | [ |
2012 | 4 DENV cases reported in FL, 2 of them in Miami-Dade | [ |
2013* | No indigenous dengue cases reported | [ |
Adapted from [
AL: Alabama, FL: Florida, GA: Georgia, LA: Louisiana, MO: Missouri, MS: Mississippi, PA: Pennsylvania, and TX: Texas.
The continental USA comprises the 48 contiguous states and the District of Columbia, and the non-contiguous states of Alaska in North America and Hawaii in the Pacific Ocean and a number of unincorporated territories including Puerto Rico and the US Virgin Islands (USVI) in the Caribbean and American Samoa, Guam, and the Northern Mariana Islands in the Pacific Ocean [
Autochthonous dengue has been reported sporadically in the Mexico-Texas border, where indigenous cases of dengue reappeared in 1980 after more than 30 years of absence. Since then, most dengue cases reported in the USA have been imported, brought by infected travelers returning from visits to endemic countries or places experiencing dengue epidemics. Dengue has also been present in the state of Hawaii, the US territories in the Pacific (American Samoa, Guam, and Northern Mariana Islands) and the territories of Puerto Rico and USVI. In 2009, after over 70 years of absence, autochthonous dengue reappeared in the state of Florida (Figure
Timeline of selected recent dengue activity in the U.S. and its territories, 1998–2013. U.S.: United States; representing the states of Florida (FL), Hawaii (HI) and Texas (TX), P.R.: Puerto Rico, V.I.: U.S. Virgin Islands, A.S.: American Samoa, M.P.: Northern Mariana Islands. Numbers shown represent dengue reported cases.
In all those instances, dengue outbreaks were facilitated by the presence of the mosquito vector, the favorable climatic conditions for its subsistence, and the presence of susceptible individuals. The dengue mosquito vectors
Map of the U.S. showing the areas at risk of dengue outbreaks, based on the approximate distribution of dengue mosquito vectors
The first autochthonous case of dengue reported in the USA since 1945 occurred in Brownsville, Texas in 1980 when DENV-1 was isolated from a 5-year-old girl that did not have history of travel outside Brownsville (Table
Subsequently, surveillance studies reported 63 additional dengue cases (all caused by DENV-1) that were laboratory confirmed in Texas, 52 of which occurred in counties contiguous to the Mexico-Texas border [
In 2005, a woman who had not traveled to Mexico in the months before the onset of dengue symptoms developed DHF, and this was the first case of autochthonous DHF reported in Texas. During that year, a large dengue epidemic developed in the neighboring Mexican state of Tamaulipas with more than 1,200 dengue cases of which 223 (18%) were classified as DHF. Meanwhile, 25 dengue cases were reported in Brownsville, of which at least three were locally acquired [
After 75 years without reports of dengue activity in Florida, a case was identified in 2009 in a New York patient who had traveled to Key West (Table
According to the Florida State Department of Health, between 2009 and 2012, a total of 103 autochthonous dengue cases have been reported in Florida including those from the outbreak of 2009. Of these, 27 were reported in 2009 in Key West (Monroe county), 65 during 2010 (Broward, Miami-Dade, and Monroe counties), 7 in 2011 (Hillsborough, Martin, Miami-Dade, and Palm Beach counties) and 4 in 2012 (Miami-Dade, Seminole, and Osceola counties) [
Imported and autochthonous cases of dengue reported in the state of Florida, USA, 2009–2013 (as of April 27, 2013).
Year | Number of imported cases | Countries visited* (number of cases) | Number of autochthonous cases | Florida counties |
---|---|---|---|---|
2009 | 36 | BO (2), BR, CO (2), DO (3), GT (2), HT(10), HN (2), IN (3), MY, MX, NI, PA (3), PH, PR (3), SR | 27 | Monroe (27) |
2010 | 133 | BD, BR, KY, CO (8), CR (4), CU, DO (13), EC, SV, GH, GD (4), GT (2), HT (6), HN (6), JM (5), MQ (2), MV, MX, NI (13), PK, PH, PR (36), TH, TT, VE (16), VI (3), MY/AE/BD**, PA/VE** | 65 | Broward (1), Miami-Dade (1), and Monroe (63) |
2011 | 61 | AW, BS (14), BD (3), BR (3), CO, CR, CU (5), DO, GD, GY, HT (2), IN, JM (2), NI (2), PK, PA (2), PR (11), LC (2), TT (4), TC, VE, VN | 7 | Hillsborough (1), Martin (1), Miami-Dade (3), and Palm Beach (2) |
2012 | 135 | BR, CO, CU (29), DO (17), EC (4), |
4 | Miami-Dade (2), Seminole (1), and Osceola (1) |
2013 | 27 | AO, BB, BR, CO (2), DO (3), GT, HT, ID, JM (3), NG, PH, PR (8), MF | 0 | — |
| ||||
Total | 392 | 103 |
Source: Florida State Department of Health [
DENV-1 was detected in mosquito pools collected in Key West [
Phylogeny of DENV-1 in the USA and Puerto Rico. A consensus phylogenetic tree (50% majority rule) was obtained by Bayesian phylogenetic analysis (Mr. Bayes, v. 3.2.) based on the envelope protein gene. Analysis included sequences of strains from Hawaii (2001-2002)
The dengue outbreak of 2009-2010 has been linked to
In addition to the autochthonous cases, an important number of dengue imported cases (392) from travelers to countries in Central and South America, the Caribbean, Africa, the Middle East, and South and Southeast Asia have been reported in Florida since 2009 [
The first large dengue epidemic on record occurred in Hawaii in the mid-19th century. Another large epidemic occurred in 1903 with approximately 30,000 cases reported [
A DENV-1 epidemic occurred in Hawaii from 1943 to 1944, with almost 1,500 cases reported [
Dengue activity in the state of Hawaii and the Territories of American Samoa, Guam, and Northern Mariana Islands, 1840s–2010.
Year(s) | Activity reported | References |
---|---|---|
Late 1840s | First large dengue epidemic recorded in HI, associated with |
[ |
1903 | Large dengue epidemic in HI, |
[ |
1943-1944 | DENV-1 epidemic in HI, |
[ |
1944 |
|
[ |
<1950 | Dengue cases were reported in AS and GU before 1950, no dengue epidemics reported in GU in recent times | [ |
1995 | Possible dengue infection in German visitors to HI | [ |
1972 | Dengue epidemic in AS (DENV-2) | [ |
1975 | Dengue epidemic in AS (DENV-1) | [ |
1995-1996 | Dengue epidemic in AS (DENV-3) | [ |
1997 | Reports of dengue cases in AS | [ |
1998 | Dengue seropositive individuals reported in Saipan (MP) during 1998, DENV-2 implicated in epidemic activity | [ |
2001 | More than 1,600 dengue cases reported in AS (DENV-1), 3 deaths | [ |
Dengue outbreak in the MP, >1,400 cases reported | [ | |
2001-2002 | Autochthonous transmission of dengue in HI, 122 confirmed cases, DENV-1 isolated, and |
[ |
2007 | 63 dengue cases confirmed in AS, 23 cases hospitalized | [ |
2008 | Dengue activity reported in AS | [ |
2009 | Outbreak of |
[ |
2010 | Dengue cases reported in AS. Serosurvey conducted in 2010 revealed >95% of the tested individuals as seropositive for dengue | [ |
AS: American Samoa, GU: Guam, HI: Hawaii, and MP: Northern Mariana Islands.
However, in 2001, following 56 years without reports of autochthonous dengue cases, an epidemic occurred in the island of Maui. A total of 122 laboratory-confirmed dengue cases were reported between 2001 and 2002, 92 of which occurred in Maui, 26 in Oahu, and 4 in Kauai. DENV-1 was the type identified in viral isolates obtained from 15 cases from Hawaii, and the mosquito vector implicated in this epidemic was
Molecular epidemiologic studies suggest that at least two distinct DENV-1 strains were introduced in Hawaii during the 2001-2002 epidemics, although most of the isolates analyzed belong to the “Pacific subtype” (genotype IV) of DENV-1, and cluster together with Tahitian DENV-1 strains, suggesting that Tahiti was the source of these strains. In contrast, the same study reported a single DENV-1 isolate from Hawaii obtained during 2001 from a traveler to Samoa that clustered outside the Tahitian cluster and that closely associated with a DENV-1 isolate previously obtained from another traveler to Samoa [
Dengue was reported in American Samoa and Guam before 1950 [
Conversely, American Samoa had dengue epidemics in 1972 (DENV-2), 1975 (DENV-1), and 1995-1996 (DENV-3) [
In 2010, less than 100 dengue cases were reported for an incidence of 77/100,000 inhabitants [
There are reports indicating that individuals from the Northern Mariana Islands, without travel history, were seropositive for DENV (IgM and IgG) in 1998 in the island of Saipan [
Dengue has been endemic in the USVI since at least 1924, when the first documented dengue epidemic in the Caribbean is thought to have started in the USVI [
Phylogeny of DENV-4 in Puerto Rico and the US Virgin Islands (USVI). A consensus phylogenetic tree (50% majority-rule) was obtained by Bayesian phylogenetic analysis (Mr. Bayes, v. 3.2.) based on the envelope protein gene. Analysis included sequences of strains from USVI (1994)
Forty dengue cases were reported in the island of St. Thomas in 2004. In 2005, a DENV-2 epidemic was reported in St. Croix, with 331 suspected cases of which 37% were laboratory-confirmed [
During November 2012, 27 dengue cases were reported in the island of St. Croix, some of which were later laboratory confirmed. A serosurvey found that around 20% of the students and staff from a school in the island were positive for IgM antibodies to dengue; four students were positive for DENV-1 or DENV-4 RNA by PCR [
Dengue is endemic in Puerto Rico, and cases have been reported every year for more than 50 years (Table
Dengue activity in Puerto Rico and the USA Virgin Islands, 1915–2013.
Year(s) | Activity reported | References |
---|---|---|
1915 | Dengue epidemic reported in PR | [ |
1924 | 1st recorded epidemic of dengue in the Caribbean-Gulf-Atlantic region begun in the VI | [ |
1941–1946 | Dengue epidemic reported in PR | [ |
1963 | Epidemic of |
[ |
1968-1969 | DENV-2 (only) epidemic, 1st report of DENV-2 in PR, 16,665 cases | [ |
1970–1974 | Sporadic DENV-2 cases reported in PR | [ |
1975 | DHF suspected among 3 serologically confirmed dengue cases, shock seen in 1 patient in PR - DHF described for the 1st time in the Western Hemisphere | [ |
1977-1978 | DENV-1 outbreak in PR, |
[ |
1978 | DENV-1 outbreaks in VI | [ |
1981–1983 | DENV-1 and DENV-4 outbreaks in PR, 1st reports of DENV-4 in both PR and the Americas | [ |
1985 | 2 DHF cases associated with DENV-4 in PR | [ |
1986 | Dengue epidemic in PR associated with DENV-4, 10,659 cases, 31 DHF cases, 3 deaths | [ |
1987 | 17 DHF cases in PR, 1 death | [ |
1988 | 8 DHF cases in PR | [ |
1989 | DENV-1, -2, and -4 cases reported in PR, including 12 DHF cases, 5 deaths | [ |
Dengue cases reported in the VI | [ | |
1990 | 6 DHF cases in PR, 1 death | [ |
Dengue cases reported, DENV-1, -2, and -4 involved in outbreaks, 1st report of DENV-4 in the VI | [ | |
1991 | 14 DHF cases in PR, 1 death | [ |
1994 |
|
[ |
1998 | >17,000 dengue cases reported in PR, 173 DHF cases, 9 deaths, all 4 serotypes isolated | [ |
1999 | All 4 serotypes reported present in PR, 34 DHF cases (6 deaths), 4,993 dengue cases | [ |
2000 | DENV-1, -2 and -3, isolated in PR, 24 DHF cases, 2,433 dengue cases | [ |
2005 | Dengue reported in blood donors from PR, DENV-2 and DENV-3 isolated | [ |
Dengue epidemic reported in St. Croix, VI | [ | |
2007 | Epidemic caused by DENV-3, -2, -1, and -4 (in order of frequency) in PR, more than 10,000 cases, 227 DHF cases, 40 deaths. Dengue reported in blood donors from PR | [ |
2010 | Largest epidemic in PR history, DENV-1, -4, -2, and -3 isolated (in order of frequency), 26,766 cases reported, 448 DHF cases, 128 deaths. Dengue reported in blood donors from PR, DENV-1, DENV-4, and DENV-2 isolated | [ |
2012 | Dengue epidemic in PR, 12,877 cases reported, DENV-1 and -4 isolated | [ |
Dengue epidemic in the VI | [ | |
2013* | Dengue epidemic in PR, >5,000 cases reported, DENV-1 and -4 isolated | [ |
Adapted from [
A large epidemic of DENV-3 involving approximately 27,000 individuals was reported in 1963-1964 [
The following year (1978), another dengue outbreak was reported, this time caused primarily by DENV-1 [
In 1994-1995, approximately 24,000 cases of dengue were reported in Puerto Rico, with circulation of DENV-2, DENV-4 and DENV-1 (in order of frequency of detection) [
In 1999, all four DENV types co-circulated in the island resulting in 4,993 reported cases. The 2000 epidemic had co-circulation of DENV-1, DENV-2, and DENV-3 and resulted in 2,433 dengue cases reported [
In 2007, a large epidemic (10,508 suspected dengue cases, with 227 fulfilling criteria for DHF) occurred after an interepidemic period of almost ten years; this epidemic was the second outbreak to have co-circulation of all DENV types, after the 1998 epidemic. During the 2007 dengue epidemic, 2,175 individuals tested positive for DENV RNA, of which 62% was infected with DENV-3, 31% with DENV-2, 6% with DENV-1, and 1% with DENV-4. DENV-1, and DENV-4 reappeared after approximately 9 years of absence (Table
The largest epidemic of dengue in Puerto Rico’s history occurred during 2010, with almost 27,000 suspected dengue cases, of which more than 12,000 individuals (about 47% of tested cases) were laboratory-positive; more than 1,300 cases were classified as severe dengue, and there were 40 dengue-associated deaths (Table
In 2012, an epidemic resulted in 12,877 suspected cases reported, of which 5,652 (44%) were laboratory confirmed. DENV-1 and DENV-4 were the predominant types detected, similar to the 2010 epidemic [
Because DENV can be transmitted by blood transfusion [
A study performed in asymptomatic blood donors from Puerto Rico during the inter-epidemic year 2005 reported that 0.7% (12 out of 16,521) blood donations tested positive for DENV RNA. Of these, three donors were identified by TaqMan as infected with DENV-2 and one with DENV-3, which were the DENV types circulating in the island during that year (Figure
Study of DENV strains circulating in 2010 performed in blood donors [
Dengue has emerged and re-emerged in many locations around the world, including countries in Europe (e.g., France and Croatia) [
Although the primary mosquito vector for dengue is
In the case of the USA, both dengue vector species are widely distributed in the southern parts of the country (Figure
Many large cities in the US are important hubs for air travel and therefore receive a high number of individuals potentially infected with pathogens that cause asymptomatic disease, including several arboviruses (e.g., dengue viruses, Japanese Encephalitis virus and Chikungunya virus). Thus, there is an increasing risk of introduction of these “exotic” pathogens to urban conglomerates where mosquito vectors are present or have the potential to become established (e.g., Miami, Atlanta, Baltimore/Washington, D.C., and New York City in the East Coast, and Los Angeles and San Francisco in the West Coast).
Despite the current economic and budgetary constraints, strict mosquito control policies and activities, that may include both traditional and biological vector control strategies, must be implemented and maintained in localities that have the potential to become the port of entry for these viruses and become the focus for another dengue epidemic in the USA.
The authors want to thank Dr. Celso Bianco for his critical reading, comments, and suggestions on the paper.