Results
During 2010–2020, a total of 30,903 cases were reported to ArboNET from American Samoa, Guam, Puerto Rico, and the USVA. 21,705 (70.2%) were confirmed and 9,198 (29.8%) were probable (Table 1). The highest incidence of dengue occurred among people aged <20 years, accounting for approximately half (15,640). [50.6%]) reported cases. The majority of cases occurred in males, accounting for 16,808 (54.4%) of all cases. Approximately 2% (584) of all cases were classified as severe dengue. A total of 10,037 (32.4%) dengue patients were hospitalized, and 68 (0.2%) died. Travel to a country with local dengue transmission in the 2 weeks prior to symptom onset was reported in 28 (0.1%) cases.
Puerto Rico
In 2010–2020, the majority (29,862 [96.6%]Dengue cases have been reported from Puerto Rico (Figure 1). Annual incidence per 1,000 population was highest during the two epidemics in 2010 and 2013, 2.9 and 2.6, respectively.Figure 2). Of all cases reported from Puerto Rico, 20,675 (69.2%) were confirmed and 9,187 (30.8%) were probable; 54.6% of dengue cases were in men. In Puerto Rico, 50% of reported cases occurred among persons <20 years of age, with the 10–19-year age group accounting for 37.3%. The highest incidence and hospitalization rates also occurred in children aged 10–14 and 15–19 years.Figure 3). In Puerto Rico, 32.6% of dengue patients were hospitalized and 68 dengue-related deaths were reported in 2010–2020. The highest number of deaths (n = 10) occurred in people over 70 years of age, although 6 (8.8%) of the deaths occurred in people <20 years of age.Figure 4). Almost all (>99%) dengue cases in Puerto Rico are locally acquired.
American Samoa
In 2010–2020, American Samoa accounted for 660 (2.1%) of all reported cases in US territories (Figure 1). The annual incidence per 1,000 population was highest in 2017, reaching 10.2 per 1,000 population (Figure 2). All dengue cases were confirmed and 50.3% were in women. The highest case numbers and rates occurred among people aged <20 years. 68.0% of the reported cases occurred in people aged <20 years, and 45.9% occurred in people aged 10-19 years. The number of dengue cases in American Samoa (45.5%) is similar to Puerto Rico (Table 1); The highest incidence and hospitalization rates occurred in the 10-14 and 15-19 age groups (Figure 5). No dengue-related deaths have been reported, and one travel-related case has been reported.
US Virgin Islands
In the year In 2010–2020, the USVI accounted for 353 (1.1%) of all reported cases in US states (Figure 1). In the year During the 2012–2013 epidemic, the annual incidence per 1,000 population was high, with 1.6 annual events in 2013 (Figure 2). In the USVI, almost all (96.9%) reported cases were confirmed, and 53.3% were in women. One-third of reported cases occurred among children and adolescents <20 years of age, with the majority (21.5%) occurring in the 10–19-year age group. The 20-29 year age group is the second most affected age group with 15.0% of cases. Three (0.8%) dengue patients were hospitalized, and no dengue-related deaths were reported. The highest incidence occurred in children aged 10–14 years (Figure 6). All reported cases were locally acquired.
Guam
In the year In 2010–2020, Guam accounted for 28 (0.1%) of all reported cases in US territories. All cases are verified and occurred in 2019 and 2020. However, about half of the reported cases (13 [46.4%]) were related to travel. More than half (60.7%) of the cases were in men. Similar to other US states, the 10-19-year-old age group is most affected, with approximately 25% reported. Unlike the other states, the next most affected age group was 30-39 year olds, accounting for 21.4% of cases. Thirty-two percent of dengue patients were hospitalized, and no dengue-related deaths were recorded (Table 1).
Serotype Distribution in Puerto Rico, USVI, and American Samoa
A total of 21,329 confirmed cases from Puerto Rico (21,194), the USVI (119), and American Samoa (16) had DENV serotype data reported or processed by the CDC dengue branch laboratory.Table 2). In Puerto Rico, the majority (72.9%) of DENV-1, followed by DENV-4 (24.1%), were associated with large dengue outbreaks in 2010-2013.Figure 7). In the year The overall number of dengue cases declined from 2015 to 2019, with the outbreak of chikungunya in 2014 and Zika in 2016, with all four DENV serotypes circulating at low levels. In the year Dengue activity increased slightly in 2019 and 2020, with all locally acquired cases identified as DENV-1, plus more travel-associated DENV-2 and DENV-3. In the 2012–2013 outbreaks in the USVI, DENV-1 and DENV-4 were the two circulating dengue serotypes, with DENV-1 accounting for 80.7% of the serotypes. In American Samoa, although DENV-2 (n = 2) and DENV-3 (n = 14) cases were reported, limited serotype information was available.