Pan American Health Organization

Health Status of the Population

Vector-transmitted diseases

  • Chikungunya
  • Dengue
  • Malaria
  • Zika virus
  • References
  • Full Article
Page 1 of 5

Chikungunya

In December 2013, the health authorities of Saint Martin (French territory) confirmed the autochthonous transmission of chikungunya virus for the first time in the Americas. The virus spread rapidly from this focus in the Caribbean to the northern coast of South America and Central America (Figure 1). In 2015, transmission was documented in 44 countries and territories of the Region, with an average cumulative incidence of 73.28 cases per 100,000 inhabitants. During 2016 (up to epidemiological week 52), 361,312 cumulative suspected cases (cumulative incidence rate of 51.96 per 100,000 inhabitants) were reported in the Region and 157,288 were confirmed (Table 1).

Figure 1. Countries and territories with chikungunya autochthonous transmission in the Americas, 2014–2016

Source: Cases reported by IHR national focal points to PAHO/WHO and/or through Member State websites or official news publications. Cases reported by CARPHA for Non-Latin Caribbean countries, unless other source specified.

Although most of the patients recover fully and serious complications in the past were rarely documented, the recent outbreak in the Region has been characterized by a high number of uncommon manifestations and an unusual severity rate of 440 fatal cases in total that were directly or indirectly associated with chikungunya during 2013ndash;2016, and a total case fatality rate of 0.018% (2013–2016).

Table 1. Number of reported cases of chikungunya fever in the Americas, by country or territory, 2016 (to week noted) – Cumulative cases (updated as of 17 February 2017)

Country/territory Epidemiological weeka Autochthonous transmission casesb Imported cases Incidence ratec Deathsd Populatione
Suspected Confirmed X 1,000
North America  
Bermudaf Week 24 3 0 0 4.2 0 71
Canada           36,286
Mexico Week 52   757 0 0.59 0 128,632
United States of America > Week 52     164 0.0 0 324,119
Subtotal   3 757 164 0.16 0 489,108
Central American Isthmus
Belizef 58 1 0 16.1 0 367
Costa Rica Week 52 3,430 0 0 70.62 0 4,857
El Salvador Week 52 6,071 0 0 98.78 0 6,146
Guatemala Week 52 5,125 177 0 31.80 0 16,673
Honduras Week 32 14,325 0 0 174.91 0 8,190
Nicaragua Week 26 4,675 682 0 87.11 1 6,150
Panama Week 52 3,545 6 5 89.00 0 3,990
Subtotal   37,229 866 5 82.15 1 46,373
Latin Caribbean              
Cuba Week 52   0 0 0.0 0 11,393
Dominican Republic Week 30 112 0 0 1.05 0 10,649
French Guiana Week 44 921 18 0 340.22 0 276
Guadaloupe# Week 49 41 2 0 9.13 0 471
Haitig Week 16 2 1 0 0.03 0 10,848
Martinique Week 49 22         396
Puerto Ricog Week 52 0 178 0 4.84 0 3,681
Saint Barthelemy# Week 49 4 0 0 44.94 0 9
Saint Martin (French part)# Week 49 20 1 0 58.84   36
Subtotal   1,122 200 0 3.50 0 37,759
Andean Area              
Bolivia Week 52 20,785 1,190 2 201.83 0 10,888
Colombia Week 52 19,357 209 0 40.21 12 48,654
Ecuador& Week 52 280 1,860 3 13.06 0 16,385
Peru Week 52 141 131 1 0.87 0 31,374
Venezuela Week 52 3,471 355 0 12.14 0 31,519
Subtotal   44,034 3,745 6 34.42 12 138,820
Southern Cone              
Argentina* Week 52 3,394 322 91 8.47 0 43,847
Brazil^ Week 52 271,824 151,318 0 201.91 159 209,568
Chile Week 50 0 0 4 0.00 0 18,132
Paraguay Week 51 881 38 0 13.67 0 6,725
Uruguay           344
Subtotal   276,099 151,678 95 153.54 159 278,616
Non-Latin Caribbean              
Anguillaf Week 24 9 1 0 58.82 0 17
Antigua and Barbudaf Week 24 38 2 0 42.55 0 94
Arubaf Week 47 929 8 0 821.93 0 114
Bahamasf Week 20 75 1 0 19.34 0 393
Barbadosf Week 20 86 0 0 29.55 0 291
Cayman Islandsf Week 24 48 0 0 84.21 0 57
Curacaof           149
Dominicaf Week 24 269 2 0 366.22 0 74
Grenadaf Week 20 103 0 0 92.79 0 111
Guyanaf Week 16 149 0 0 19.33 0 771
Jamaicaf Week 24 204 1 0 7.31 0 2,803
Montserratf Week 24 5 0 0 100.00 0 5
Saint Kitts and Nevisf 28 0 0 53.85 0 52
Saint Luciaf Week 24 114 0 0 69.51 0 164
Saint Vincent and the Grenadinesf Week 24 154 1 0 151.96 0 102
Sint Maarten (Dutch part)h Week 52 12 2 0 34.15 0 41
Surinamef 3 0 0 0.55 0 548
Trinidad and Tobagof 575 15 0 43.22 0 1,365
Turks and Caicos Islandsf Week 24 22 0 0 43.14 0 51
Virgin Islands (UK)f Week 24 2 9 0 32.35 0 34
Virgin Islands (US)           103
Subtotal   2,825 42 0 39.1 0 7,339
TOTAL   361,312 157,288 270 51.96 172 998,015

Notes: Only accumulated cases for the year 2016 are presented.
a Epidemiological week for which information is available. Changes in the data from week to week should be interpreted by taking into account the differences in surveillance systems. The case count differences in this report are related to reporting delays and are not a reflection of any newly identified cases.
b Suspected case: patient with acute onset of fever >38°C (101°F) and severe arthralgia or arthritis not explained by other medical conditions, and who resides or has visited epidemic or endemic areas within two weeks prior to the onset of the symptoms. Confirmed case: a suspected case with any specific chikungunya test (viral isolation, RT-PCR, Ig M, or four-fold increase of chikungunya specific antibodies titers) – PAHO/CDC confirmed case definition available at www.paho.org/chikungunya.
c Incidence rate (autochthonous suspected + autochthonous confirmed) / 100,000 population.
d Deaths directly or indirectly related to chikungunya.
e Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, World Population Prospects: The 2015 Revision, http://esa.un.org/unpd/wpp/index.htm, July 2015.
International Programs Center, Population Division, U.S. Census Bureau. IDB Release Date: December 2013.
Population source for Saint Barthélemy and Saint Martin available at: Populations légales 2011 des collectivités d’outre-mer http://www.insee.fr/fr/ppp/bases-de-donnees/recensement/populations-legales/france-departements.asp?annee=2011
. Population source for Bonaire, Saint Eustatius, and Saba available at: Caribisch Nederland; bevolkingsontwikkeling, geboorte, sterfte, migratie – 12 augustus 2015 http://statline.cbs.nl/StatWeb/publication/?DM=SLNL&PA=80539ned&D1=0-1,9-10&D2=a&D3=a&HDR=T&STB=G1,G2&CHARTTYPE=1&VW=T.
f Department of Health data: http://www.salud.gov.pr/Estadisticas-Registros-y-Publicaciones/Pages/Informe-Arboviral
g Source: CARPHA 2016 Chikungunya Report. 21 July 2016.
h The two confirmed cases were reported for EW 22 and 23 of 2016.
# Confirmed cases from 2015 EW47 to 2016 EW16, as in http://www.invs.sante.fr/fr/Publications-et-outils/Points-epidemiologiques/Tous-les-numeros/Antilles-Guyane/2016/Surveillance-des-arboviroses-en-Guadeloupe-et-Iles-du-Nord.-Point-au-28-avril-2016.
& Suspected cases for EW17 and only from Esmeraldas, Manabi, and Santo Domingo provinces, as in http://www.salud.gob.ec/wp-content/uploads/2016/04/11_Boletin-DNVE-del-06-05-2016-1 .
* Confirmed cases by lab test or epidemiological nexus.
^ Confirmed cases by lab testing or epidemiological nexus, as in http://portalsaude.saude.gov.br/images/pdf/2016/maio/17/2016-016—Dengue-SE16-publica—-o.pdf.
> Total number of reported cases in USA. Source: Notifiable Diseases and Mortality Weekly Report (MMWR), available at: http://www.cdc.gov/mmwr/volumes/65/wr/mm6524md.htm?s_cid=mm6524md_w.
Data Source: Cases reported by IHR NFPs to PAHO/WHO and/or through Member States’ websites or official news publications. Cases reported by CARPHA for Non-Latin Caribbean countries, unless other source specified.

Since 2010, PAHO, together with regional partners and WHO Collaborating Centers, has helped the countries to prepare for the possible introduction of chikungunya in the Region. Thanks to this continuous technical support, it has been possible to strengthen the diagnostic capacity and clinical management of the disease. However, its impact on health systems and the (short- and medium-term) economic burden on countries still remain to be evaluated.

Dengue

Dengue is the arboviral disease that is the most widespread and significant for public health in the Americas. The infection caused by the dengue virus (DEN-1, DEN-2, DEN-3, and DEN-4) () is transmitted from human to human by the Aedes aegypti mosquito, which is present in all countries and territories of the Americas, except Canada. In April 2016, the vector was found in the Arica region in northern continental Chile, a country that had not reported its presence since the 1950s.

All four dengue serotypes are present in the Americas and circulate simultaneously in several countries and territories, increasing the risk of epidemics, severe cases, and deaths from the disease (). In 2013, in one of the Region’s largest dengue epidemics (Figure 2), 11 countries and territories reported simultaneous circulation: Argentina, Brazil, Colombia, French Guiana, Guadeloupe, Guatemala, Martinique, Mexico, Nicaragua, Peru, and Venezuela.

Dengue epidemics occur cyclically every 3 to 5 years in the Region, with each epidemic surpassing the number of cases in the previous one. Between 2011 and 2015, two major epidemics were recorded: one in 2013, with 2,386,836 cases, and another in 2015, with 2,430,278 reported cases. In the different countries, sufficient evidence was found to determine that this shortening of the epidemic cycle was due to over-reporting of the number of suspected cases of dengue due to the introduction of two new arboviral diseases in the Americas that have clinical manifestations similar to dengue: the chikungunya virus (December 2013) and Zika virus (February 2014) ().

Figure 2. Number of dengue cases and trend, per year, Region of the Americas, 1980–2015

a Exponential estimate of the trend based on the number of dengue cases.
The red bar represents the first epidemic year of the 5-year period 2011-2015. The yellow bar represents the second epidemic year in the period, which shows a shortening in the epidemic cycles due to the over-reporting of dengue cases with the introduction of the chikungunya and Zika viruses in the Americas.
Cumulative cases of dengue per 5-year period: 2001–2005 (2.9 million cases), 2006–2010 (5.2 million cases), and 2011–2015 (8.2 million cases).
Source: PAHO/WHO Regional Dengue Program.

In the period 2011–2015, the number of dengue cases in the Americas trended upward—as has been the case over the last 30 years (Figure 2). However, it is important to recognize the efforts and achievements of countries and territories in terms of improving their epidemiological surveillance systems, enabling them to systematically report cases as they occur.

Between 2011 and 2015, more than 45 countries and territories reported 8,207,797 cumulative cases of dengue. Of these, 118,837 (1.4%) were severe cases that resulted in 5,028 deaths (0.06%) (Table 2). This represents an increase of 58% in the number of cases and 93% in the number of deaths. In turn, these figures show a 22% drop in the number of severe cases over the previous 5-year period (2006–2010), when 5,194,657 cases of dengue were reported, including 151,437 severe cases and 2,599 deaths. Despite the increase in the number of deaths, case fatality has declined 45%, from a rate of 0.069% in 2010 (the close of the previous 5-year period) to 0.038% at the end of the current period (2015) (Table 2). This reduction in case fatality has been achieved following implementation of the new classification of dengue severity published in 2009 by the World Health Organization (WHO) () and implemented in the Americas starting in 2010 through various training processes for health workers. It focuses on patient care at the first level of care, to identify warning signs and thus prevent progression to severe forms of the disease, thereby preventing deaths.

Table 2. Number of cases, incidence per 100,000 population, number and percentage of severe cases, number of deaths, and case-fatality rate of dengue per year, Region of the Americas, 2011–2015

  2011 2012 2013 2014 2015
Number of cases 1,093,252 1,120,902 2,386,836 1,176,529 2,430,278
Incidence per 100,000 populationa 208.8 214.1 455.9 194.4 385.5
Number of severe cases 19,455 32,748 37,898 16,238 12,498
% severeb 1.78 2.92 1.59 1.38 0.51
Number of deaths 763 784 1,318 798 1,365
Case-fatality ratec 0.070 0.070 0.055 0.068 0.056

a Number of cases of dengue divided by the at-risk population per 100,000 population.
b Number of severe cases of dengue divided by the total number of dengue cases, as a percentage.
c Number of deaths from dengue divided by the total number of dengue cases, as a percentage.
Source: PAHO/WHO Regional Dengue Program.

The Southern Cone subregion has reported the most dengue cases in the Americas (50–70%). In the current 5-year period (2011–2015), the subregion reported the equivalent of 65% of cases and 59% of deaths from dengue in the Americas (Table 3). Two of the five countries with the greatest burden of cases and deaths from dengue are in this subregion. Brazil reported the equivalent of 94% of dengue cases in the Southern Cone and 61% of cases in the Americas, as well as 86% of reported deaths in the subregion and 51% of reported deaths in the Americas (Table 4). The epidemiological situation of dengue in Paraguay during 2011–2015 made it one of the five countries with the greatest burden of dengue and deaths from this disease. In 2013 alone, Paraguay reported 144,539 cases of dengue (a figure surpassed only by Brazil and Mexico) and 251 deaths (Tables 4 and 5).

The Mexico and Central America subregion reported 19.1% of all dengue cases and 12% of all deaths from this disease in the Americas. Mexico had the second highest number of cases in the Region, accounting for 52% of cases in the subregion and 10% of cases in the Americas (Tables 3 and 4). The number of deaths reported by Mexico represented 66% of deaths in the subregion and 8% of those in the Americas. Among Central American countries, Nicaragua had the most cases (204,232, representing 13% of the subregional total). Guatemala, in turn, had the highest death toll in Central America in the period 2011–2015 (56 cases), equivalent to 9% of deaths in the subregion.

The Andean subregion reported 13% of all dengue cases and 20% of all deaths. Colombia reported 11% of the Regional total and 39% of cases in the subregion (Tables 3 and 4). Colombia had the second highest number of deaths from dengue in the Region (Table 5). Venezuela ranks fifth in the Americas in terms of disease burden (Table 4).

The Spanish-speaking Caribbean and non-Spanish-speaking Caribbean (English, French, and Dutch) subregions reported 105,069 and 113,905 cases, respectively (Table 3). While the Caribbean subregions account for only 2.7% of dengue cases in the Americas, the reported incidence is high (Table 2), which translates into greater risk of infection. This high incidence with a relatively low number of cases is due to the small geographical and population size of these countries and territories. The number of deaths in these subregions totals 381 cases, of which 93% (353) are in the Dominican Republic—the highest number of deaths in the two subregions (Table 5) and fifth highest in the Americas. Furthermore, the Dominican Republic has the highest dengue case-fatality rate in the Americas, at 0.625% at the close of 2015. Other countries that at the end of the 5-year period (2011–2015) reported a case-fatality rate higher than the average for the Americas were Barbados (0.255%), Brazil (0.052%), Colombia (0.161%), Guatemala (0.050%), Panama (0.119%), Peru (0.145%), Trinidad and Tobago (0.178%), and Venezuela (0.131%).

The North America subregion (Canada and the United States of America) has no indigenous transmission of the disease. A total of 1,957 imported cases were reported between 2011 and 2015 in this subregion.

Table 3. Number of cases, incidence per 100,000 population, number of deaths, and case fatality from dengue, by subregion, per year, Region of the Americas, 2011–2015

  2011 2012 2013 2014 2015
Mexico and Central America subregion
Number of cases (incidence per 100,000 population)b 129,709
(87.1)
288,046
(191.0)
444,478
(294.5)
298,763
(179.6)
407,408
(237.0)
Number of deaths (case-fatality rate %)c 70
(0.054)
185
(0.064)
173
(0.039)
109
(0.036)
81
(0.020)
Andean subregion
Number of cases (incidence per 100,000 population) 128,908
(125.8)
187,647
(183.2)
231,458
(225.9)
238,591
(173.6)
270,350
(194.2)
Number of deaths (case-fatality rate %)c 128
(0.099)
152
(0.081)
198
(0.086)
209
(0.088)
305
(0.113)
Southern Cone subregion
Number of cases (incidence per 100,000 population) 807,191
(332.9)
604,881
(249.4)
1,622,745
(669.2)
604,390
(234.7)
1,722,487
(628.2)
Number of deaths (case-fatality rate %)c 544
(0.067)
354
(0.059)
796
(0.049)
415
(0.069)
868
(0.050)
Spanish-speaking Caribbean subregion
Number of cases (incidence per 100,000 population) 7,993
(33.7)
22,542
(95.1)
36,252
(153.0)
17,676
(71.2)
20,606
(80.6)
Number of deaths (case-fatality rate %)c 5
(0.063)
78
(0.346)
123
(0.339)
62
(0.351)
107
(0.519)
English-, French-, and Dutch-speaking Caribbean subregion
Number of cases (incidence per 100,000 population) 19,444
(244.8)
17,786
(223.9)
51,360
(646.6)
16,639
(87.4)
8,676
(44.7)
Number of deaths (case-fatality rate %)c 16
(0.082)
15
(0.084)
28
(0.055)
3
(0.018)
4
(0.046)

a The North America subregion (Canada and United States of America) reported a total of 1,957 imported cases in the 5-year period, with no reported deaths.
b Number of dengue cases divided by the at-risk population per 100,000 population.
c Number of deaths from dengue divided by the total number of dengue cases, as a percentage.
Source: PAHO/WHO Regional Dengue Program.

Table 4. Countries with the greatest dengue burden (number of cases), per year, Region of the Americas, 2011–2015

  2011 2012 2013 2014 2015
Brazil 764,032 565,510 1,468,873 591,080 1,649,008
Mexico 67,918 164,947 231,498 124,943 219,593
Colombia 33,207 49,361 127,219 105,356 96,444
Paraguay 42,945 39,063 144,539 10,010 68,652
Venezuela 31,551 49,044 63,726 75,020 68,389

Source: PAHO/WHO Regional Dengue Program.

Table 5. Countries with the greatest burden of deaths from dengue (number of deaths), per year, Region of the Americas, 2011–2015

  2011 2012 2013 2014 2015
Brazil 482 284 545 410 863
Colombia 42 51 161 166 155
Dominican Republic 2 71 111 62 107
Mexico 36 153 104 76 42
Paraguay 62 70 251 5 5

Source: PAHO/WHO Regional Dengue Program.

Malaria

In the Americas, the number of malaria cases declined by 62% (from 1,181,095 cases to 451,242 cases) between 2000 and 2015 (Figure 3). In the same period, malaria-related deaths declined by 76% (410 in 2000 to 98 deaths in 2015). An estimated 7.2 million cases and 3,200 deaths were averted during 2001–2015, assuming the rates from 2000 remained constant. Despite the many achievements, an estimated 100 million people remain at risk for malaria in the Americas, of whom at least 25 million are classified as being at high risk.

Figure 3. Number of cases and deaths due to malaria in the Region of the Americas, 2000–2015



Source: Annual country reports to PAHO.

There are currently 21 malaria-endemic countries and territories in the Americas; by the end of 2015, however, all of these countries (except for Haiti and Venezuela) had reduced malaria morbidity compared to 2000 (Figure 4). Twelve of the endemic countries reported no deaths related to malaria in 2015. Brazil (31.7%), Venezuela (30.2%), and Peru (14.8%) together accounted for 76.7% of malaria cases in the Americas in 2015. Brazil also accounted for 38% of malaria-related deaths. However, reporting discrepancies exist for mortality data, especially from earlier years in the 2000–2015 period.

Figure 4. Change in cases by country in the Region of the Americas, 2000–2015



Source: Annual country reports to PAHO.

In 2015, the number of reported cases of malaria increased in Colombia, the Dominican Republic, Ecuador, Guatemala, Honduras, Nicaragua, Peru, and Venezuela as compared to 2014. In Colombia, reported cases increased in the department of Choco between 2014 and 2015 and currently account for 53% of all cases reported in Colombia. The Dominican Republic had a 33% increase in the number of cases between 2014 and 2015, mostly due to a local outbreak in Santo Domingo. In Ecuador, the increase in cases is partially due to outbreaks in areas of the Amazon rainforest; this increase also coincides with the reorganization of the national malaria program, which may have led to decreased attention to case management and preventive interventions between 2014 and 2015. Furthermore, an increase in reported cases along the Pacific coast in South America was influenced by the El Niño Southern Oscillation phenomenon (). In Guatemala, 67% of cases in 2015 were reported in the department of Escuintla due to local outbreaks related to agricultural workers in sugarcane and other plantations living in precarious conditions and prone to mosquito bites. Similar living conditions for workers involved in the harvesting of jellyfish contributed to a local outbreak in the Moskitia area of Honduras in 2015. In the adjoining Moskitia area in Nicaragua, an outbreak was reported in 2015 related to the internal migration of people due to social disturbances caused by changes in land ownership as well as the precarious living conditions of agricultural workers in palm and cacao plantations and artisanal miners. This outbreak led to almost double the amount of cases compared to 2014 (from 1,163 to 2,307 cases) in Nicaragua. In Peru, 96% of cases were reported in the region of Loreto. Located in the Amazon Basin, Loreto is the largest and least populated region of Peru and has had high rates of malaria in the past few years. In Venezuela, cases have increased annually since 2008. Between 2014 and 2015, cases increased by 50% from 90,708 to 136,402. In 2015, Venezuela reported more cases than in any of its previous 50 years. If this trend continues, by 2016 Venezuela could report the most cases of all countries in the Americas. The situation is worsening mainly due to the poor economic conditions, increased mining activities, and decreased vector control interventions, especially in the Sifontes municipality of the Bolivar state.

Plasmodium vivax is the main species found in the Americas (72% of cases in 2015). Belize, El Salvador, Mexico, and Panama report cases caused exclusively by P. vivax. On the other hand, cases in Haiti and the Dominican Republic are almost exclusively caused by P. falciparum. P. malariae is also prevalent in the Americas, but accounts for less than 0.1% of all cases.

Throughout the Americas, approximately 58% of all cases in 2015 occurred in men. This trend has been consistent throughout the years, with malaria mostly affecting males between the ages of 15–24 years. Females are most affected during the ages of 5–14; however, the number of cases in this age group is still less than their male counterparts. In 2015, approximately 1% of the total cases reported in the Region occurred among pregnant women. In Haiti, pregnant women were at significantly higher risk (relative risk = 1.58; 95% confidence interval 1.49–1.68) of having malaria than nonpregnant women in 2011–2012. An estimated 9% of all cases in 2015 occurred in children under 5 years of age. Brazil, Colombia, Haiti, Panama, and Peru reported particularly high numbers of malaria cases (>10% of total cases) in children <5 years, suggesting that malaria transmission occurs within households. Adjusting for age, Guyana had an incidence of 2,324 cases per 100,000 men in 2014, 2.9-fold higher than that in women, while in Venezuela the rate was 2.5-fold higher. Malaria is associated with outdoor occupational activities such as mining and agricultural work, which predominately employs young males, a condition prevalent in both aforementioned countries.

Resistance to anti-malarials has occurred in the Americas in the past, and more recently, in 2012 there were reports of decreased sensitivity to artemisinin in the Guiana Shield area. Further studies in this area have not shown decreased sensitivity, yet the threat of development of resistance is real and needs attention. In addition, as many as 11 countries have reported information on insecticide surveillance for Anopheles mosquitoes during 2012–2015. Although all of these countries (except Haiti and Suriname) have reported resistance to pyrethroids, the resistance is limited to some areas of each country.

The majority of funding for malaria in the Americas comes from domestic governmental sources (90% in 2015). At least US$ 16 million came from external funding sources in 2015; the Global Fund alone provided US$ 13.5 million and has supported the Americas since 2003. Total domestic funding in countries of the Americas increased between 2014 and 2015 by 19% (from US$ 134.4 to 159.5 million) despite having decreased between 2013 and 2014 (US$ 180.1 to 134.4 million).

Malaria risk is dependent on interactions with epidemiologic factors: host, vector, parasite, and environment. The Americas has a diverse set of challenges involving interactions among these epidemiologic factors. The most important challenges currently being faced have evolved from those of the past and are related to social determinants, occupation, geography, environment, and various other issues. Social determinants mostly stemming from race, ethnicity, and cultural distinctions regarding ethnic diversity are major issues in key malaria-endemic areas of the Americas. Some of the ethnic/indigenous populations at risk include Miskitos in Honduras and Nicaragua, Guna Yala in Panama, Embera-Wounaans in Colombia and Panama, and Yanomamis in Venezuela and Brazil, to name a few. Many of these distinct groups of people live in poverty, lack access to health care, and face cultural barriers inhibiting proper diagnosis and treatment. Cases originating from ethnic/indigenous populations were only reported by 9 of the 21 endemic countries in the Americas in 2015. In Guyana, ethnic groups (also known as Amerindians) were at a 5-fold higher risk of malaria during 2014 compared to the rest of the population (6,052 cases per 100,000 people compared to 1,152 cases per 100,000 people). Unfortunately, similar information is not available from other countries, making it difficult to measure specific risks by ethnicity, track disease trends, implement proper interventions, and make sound cases for policy change.

Another current challenge is malaria’s association with occupations in high-risk areas, particularly those related to mining, logging, and agriculture. Miners in all countries comprising the Guiana Shield are at risk of malaria with limited intervention or control methods available to them. Problems such as Haiti’s weak surveillance system and the surge of cases in Venezuela due to a challenging political and economic situation add to the prevailing malaria concerns in the Americas.

Zika virus

Zika virus is a flavivirus primarily transmitted to humans through the bite of infected Aedes mosquitoes. Its transmission was documented in the Americas for the first time in February 2014. Subsequently, between late 2014 and February 2015, clusters of rash illness were detected in northeastern Brazil (). After conducting field investigations, on 15 May 2015, the Ministry of Health of Brazil announced the country’s first autochthonous cases of Zika virus disease, in the northeastern states of Bahia and Rio Grande do Norte (). Since then, up to December 2016, autochthonous transmission of the virus was identified in 48 countries and territories in the Americas. In addition to transmission by Aedes mosquitoes, non-vector-borne modes of transmission were identified: cases of sexually transmitted Zika virus infection () were detected in five countries (Argentina, Canada, Chile, Peru, and the United States of America).

Although Zika virus often causes no symptoms or mild illness, infection during pregnancy can lead to microcephaly and other congenital anomalies. Zika virus has also been associated with Guillain-Barré syndrome (GBS) and other neurological complications.

Between 15 May 2015 and 31 December 2016, a total of 712,167 autochthonous cases of Zika virus disease, including 18 deaths, were reported from 48 countries and territories in the Americas. During the same period, 2,525 total cases of microcephaly and other central nervous system (CNS) malformations potentially associated with Zika virus infection were detected in 21 countries and territories in the Region. Moreover, 20 countries and territories reported increases in the incidence of GBS, with at least one GBS case confirmed following Zika virus infection.

Figure 5. Reported cases of Zika in the Americas, per 100,000; October 2015, January 2016, and November 2016



Source: Cases reported by the IHR National Focal Points to the WHO IHR Regional Contact Point for the Americas and through the Ministry of Health websites, 2016.

In general, cases of Zika virus disease reported in the Americas began to increase in October 2015 and peaked in February 2016 (Figure 5), coinciding with the introduction of mandatory reporting of cases of Zika virus disease in Brazil. Since then, a progressive decline in reported cases was observed. Overall trends, however, mask the heterogeneous case rates and transmission patterns observed within each country and among the various subregions (Figure 6 and Table 6). In the Andean, Central America, and Southern Cone subregions, numbers of reported cases were on a downward trend since February 2016. In the Caribbean, however, peak incidence was recorded in June and high incidence rates continued to be registered until August. In North America, case incidence remained generally low.

Figure 6. Incidence rate of Zika by subregion of the Americas, per 100,000, October 2015–November 2016



Source: Cases reported by the IHR National Focal Points to the WHO IHR Regional Contact Point for the Americas and through the Ministry of Health websites, 2016.

A number of factors may have contributed to the emergence and rapid spread of Zika virus in the Americas: the high density of Aedes mosquitoes, the immunologically naive status of the affected populations, and the occurrence of ecological conditions optimal for the transmission of the virus (). Variation in these same elements could partly explain the observed subregional differences in the incidence and spread of the infection.

Table 6. Zika cases and congenital syndrome associated with Zika virus reported by countries and territories in the Americas, 2015–2017 (cumulative cases as 5 January 2017)

Country/territory Autochthonous casesa Imported cases Incidence rateb Deaths among Zika casesc Confirmed congenital syndrome associated with Zika virus infectiond Populatione
per 1,000
Suspected Confirmed
North America
Bermuda 0 0 5 0.00 0 0 71
Canada 0 0 421 0.00 0 1 36,286
United States of America1 0 217 4,618 0.07 0 41 324,119
Subtotal 0 217 5,044 0.06 0 42 360,476
Latin America and the Caribbean
Latin America
Mexico 0 7,475 15 5.81 0 0 128,632
Central American Isthmus
Belize 756 68 0 224.52 0 0 367
Costa Rica 5,221 1,614 32 140.72 0 2 4,857
El Salvador2 11,434 51 0 186.87 0 4 6,146
Guatemala3 3,343 788 0 24.78 0 15 16,673
Honduras 31,936 298 0 393.58 0 2 8,190
Nicaragua 0 2,053 3 33.38 0 2 6,150
Panama4 2,663 676 42 83.68 0 5 3,990
Subtotal 55,353 5,548 77 131.33 0 30 46,373
Latin Caribbean
Cuba 0 3 30 0.03 0 0 11,393
Dominican Republic5 4,908 333 0 49.22 0 22 10,649
French Guiana6 9,700 483 10 3,689.49 0 16 276
Guadeloupe6 30,845 379 0 6,629.30 0 6 471
Haiti 2,955 5 0 27.29 0 1 10,848
Martinique6 36,680 12 0 9,265.66 0 18 396
Puerto Rico 0 36,326 1 986.85 5 10 3,681
Saint Barthélemy6 975 61 0 11,511.11 0 0 9
Saint Martin6 3,115 200 0 9,208.33 0 0 36
Subtotal 89,178 37,802 41 336.29 5 73 37,759
Andean Area
Bolivia (Plurinational State of) 741 156 4 8.24 0 14 10,888
Colombia7 96,753 9,799 0 219.00 0 75 48,654
Ecuador8 2,680 875 15 21.70 0 0 16,385
Peru 1,570 388 19 6.24 0 0 31,374
Venezuela (Bolivarian Republic of)9 59,235 2,380 0 195.49 0 0 31,519
Subtotal 160,979 13,598 38 125.76 0 89 138,820
Brazil10 211,770 109,596 0 153.35 9 2,289 209,568
Southern Cone
Argentina11 1,821 26 29 4.21 0 1 43,847
Chile 0 0 33 0.00 0 0 18,132
Paraguay12 555 14 0 8.46 0 2 6,725
Uruguay 0 0 1 0.00 0 0 3,444
Subtotal 2376 40 63 3.35 0 3 72,148
Non-Latin Caribbean
Anguilla13 24 18 1 247.06 0 0 17
Antigua and Barbuda 465 14 2 509.57 0 0 94
Aruba 676 28 7 617.54 0 0 114
Bahamas 0 22 3 5.60 0 0 393
Barbados 699 46 0 256.01 0 0 291
Bonaire, St Eustatius, and Saba14 0 85 0 340.00 0 0 25
Cayman Islands 211 30 10 422.81 0 0 57
Curacao 0 820 0 550.34 0 0 149
Dominica 1150 79 0 1,660.810 0 0 74
Grenada15 316 111 0 384.68 0 1 111
Guyana 0 37 0 4.80 0 0 771
Jamaica 7,052 186 0 258.22 0 0 2,803
Montserrat 2 5 0 140.00 0 0 5
Saint Kitts and Nevis 549 33 0 1,119.23 0 0 52
Saint Lucia 822 50 0 531.71 0 0 164
Saint Vincent and the Grenadines 508 83 0 579.41 0 0 102
Sint Maarten (Dutch part)16 168 62 0 560.98 0 0 41
Suriname 2,760 723 0 635.58 4 2 548
Trinidad and Tobago 0 643 1 47.11 0 1 1,365
Turks and Caicos Islands 179 17 3 384.31 0 0 51
Virgin Islands (UK) 74 52 0 370.59 0 0 34
Virgin Islands (US) 1,028 877 0 1,849.51 0 0 103
Subtotal 16,683 4,021 27 281.15 4 4 7,364
TOTAL 536,339 178,297 5,305 71.38 18 2,530 1,001,140


Source: Cases reported by the IHR National Focal Points to the WHO IHR Regional Contact Point for the Americas and through the Ministry of Health websites, 2016.
Notes: Data is shared in an effort to transparently disseminate available information reported by Member States. Any subsequent interpretation and analysis of this data should consider differences in surveillance systems and reporting requirements. Information may change as Member States review and integrate retrospective data.
a PAHO/WHO case definitions for suspected and confirmed Zika cases are available at: https://www.paho.org/hq/index.php?option=com_content&view=article&id=11117&Itemid=41532&lang=en.
b Incidence rate (autochthonous suspected + autochthonous confirmed) / 100,000 population.
c Deaths among Zika cases do not include deaths related to Guillain-Barré syndrome (GBS) or congenital malformations associated with Zika virus infection. As of 12 May 2016, previously reported deaths related to GBS were removed from this total.
d Confirmed congenital syndrome associated with Zika virus infection case definition: Live newborn who meets the criteria for a suspected case of congenital syndrome associated with Zika virus AND Zika virus infection was detected in specimens of the newborn, regardless of detection of other pathogens. Case definitions for congenital syndrome associated with Zika virus infection is available at: https://www.paho.org/hq/index.php?option=com_content&view=article&id=11117&Itemid=41532&lang=en.
e Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, World Population Prospects: The 2015 Revision, http://esa.un.org/unpd/wpp/index.htm, July 2015. Processed and revised by PAHO.
Core Basic Indicators 2016. https://www.paho.org/data/index.php/en/indicators/demographics-core/106-cat-data-en.html. Accessed on 16 August 2016.
International Programs Center, Population Division, U.S. Census Bureau. IDB Release Date: December 2013.
https://www.paho.org/data/index.php/en/indicators/demographics-core/106-cat-data-en.html Accessed on August 16, 2016.
Population source for Saint Barthelemy and Saint Martin available at: Populations légales 2011 des collectivités d’outre-mer http://www.insee.fr/fr/ppp/bases-de-donnees/recensement/populations-legales/france-departements.asp?annee=2011#com. Accessed on August 16, 2016.
Population source for Bonaire, Sint Eustatius, and Saba available at: Caribisch Nederland; bevolkingsontwikkeling, geboorte, sterfte, migratie – 12 augustus 2015 . http://statline.cbs.nl/StatWeb/publication/?DM=SLNL&PA=80539ned&D1=0-1,9-10&D2=a&D3=a&HDR=T&STB=G1,G2&CHARTTYPE=1&VW=T. Accessed 16 August 2016.
1 Confirmed cases in the United States of America includes one laboratory acquired case. Available at: http://www.cdc.gov/zika/geo/united-states.html.
2 After retrospective review, laboratory-confirmed cases were adjusted by the El Salvador IHR National Focal Point as of 25 August 2016.
3 On 24 October, the Guatemala IHR National Focal Point provided an update indicating that there were 15 laboratory-confirmed cases of microcephaly associated with Zika virus infection. They have explained that the retraction of two cases is due to erroneous information posted by the Ministry of Health where two of the mothers who tested positive for Zika virus had been included in the total count, but no samples were obtained of the two infants with microcephaly. For this reason, the total was changed by Guatemala to 15.
4 After retrospective review, laboratory-confirmed cases were re-classified as imported cases by the Panama Ministry of Health as of 25 August 2016.
5 As of 6 October, suspected Zika cases were adjusted by the Dominican Republic Ministry of Public Health after retrospective review. As of 20 October, confirmed Zika cases were adjusted by the Dominican Republic Ministry of Public Health after retrospective review.
6 Per the Cire Antilles Guyane Bulletin the epidemiological situation is classified in four levels: Level 1, absence of autochthonous circulation; Level 2, initial autochthonous transmission; Level 3, epidemic; and Level 4, end of epidemic and results. In the instance that a territory reaches Level 3, the data on all confirmed cases are no longer included in the epidemiological bulletin. Martinique was classified as Level 3 since 20 January 2016. Parts of French Guiana were classified as Level 3 on 22 January 2016 and 1 April 2016. Guadeloupe was classified as Level 3 since 28 April 2016.
7 On 9 December a joint publication between the National Institute of Health of Colombia, the US-CDC National Center on Birth Defects and Developmental Disabilities, and the Colombia Ministry of Health reported that between 31 January and 12 November 2016, a total of 147 microcephaly cases in fetuses and infants had laboratory evidence of Zika virus infection by real-time reverse transcription–polymerase chain reaction (rRT-PCR) or immunohistochemistry.
8 After retrospective review by the Ecuador Ministry of Public Health, only laboratory-confirmed cases were included in the confirmed Zika cases for Ecuador; previously reported non-laboratory-confirmed cases were included in the suspected Zika cases as of 18 August. Data are consistantly modified as Ecuador reviews and integrates retrospective data.
9 After retrospective review, laboratory-confirmed cases were adjusted by the Venezuela (Bolivarian Republic of) IHR National Focal Point as of 25 August 2016.
10 The Brazil Ministry of Health case definition for confirmed cases of congenital syndrome associated with Zika virus infection includes confirmed and probable cases per PAHO’s case definition. As of EW 50 of 2016, 469 cases were confirmed for Zika virus by laboratory criteria. Information on suspected and confirmed Zika cases is available at: http://portalsaude.saude.gov.br/images/pdf/2016/outubro/18/2016-029-Dengue-publicacao-n-34.pdf. As of 11 November, suspected Zika cases were adjusted by the Brazil Ministry of Public Health after retrospective review.
11 As of 23 December 2016, two cases of congenital syndrome in Argentina, whose mothers acquired the Zika infection in Bolivia, were initially classified as confirmed cases by the Argentina Ministry of Health and then reclassified as probable cases. < a target="_blank"href="http://www.msal.gob.ar/images/stories/boletines/boletin_integrado_vigilancia_N338-SE48.pdf">http://www.msal.gob.ar/images/stories/boletines/boletin_integrado_vigilancia_N338-SE48.pdf.
http://www.msal.gob.ar/images/stories/boletines/boletin_integrado_vigilancia_N339-SE50.pdf.
12 As of 29 December 2016, the number of suspected cases decreased based on the modification by the Paraguay Ministry of Health.
13 As of 29 December 2016, the number of suspected cases decreased based on the modification by the Anguilla Ministry of Health and Social Development.
14 The data provided herein is the sum of cases reported for Bonaire (60), Sint Eustatius (16), and Saba (9).
15 After retrospective review, suspected cases were adjusted by the Grenada Ministry of Health as of 13 October 2016.
16 Per information shared by the Netherlands IHR NFP to PAHO/WHO, the confirmed Zika cases were adjusted for Sint Maarten.
Report Production: PAHO/WHO.
Suggested citation: Pan American Health Organization / World Health Organization. Zika suspected and confirmed cases reported by countries and territories in the Americas: Cumulative cases, 2015-2017. Updated as of 5 January 2017. Washington, D.C.: PAHO/WHO; 2017; Pan American Health Organization • www.paho.org • © PAHO/WHO, 2017

Detailed information about gender and age distribution of reported cases of Zika virus disease is available from five countries (Bolivia, Colombia, Dominica, the Dominican Republic, and Panama) for a total of 100,858 cases. Of these, 67,137 cases (67%) were female. The highest incidence was in persons aged 20–39 years (245 cases per 100,000 population). It is unclear why more cases were reported among women compared with men. This could be due to differential vector exposure, health care seeking—behavior, testing strategy, or physiology. Nevertheless, the high incidence of cases among women of childbearing age is a major concern because of the causal link between Zika virus infection during pregnancy and adverse pregnancy and birth outcomes.

Zika virus emerged at a time when countries in the Americas were building capacity for the potential occurrence of an outbreak of Ebola virus disease. The public health response to Zika was particularly challenging. This was due to the lack of knowledge surrounding the virus, its vectors, modes of transmission, and potential complications, alongside the difficulties in implementing effective vector control measures. The nonspecificity of the symptoms—which are mild and akin to those of dengue and chikungunya—may have resulted in misdiagnosis. Limiting movement or contact of people was not a viable option for containing Zika virus as its main vectors of transmission were mosquitoes. The absence of antiviral drugs and vaccines further complicated response efforts. As the development of an effective vaccine is still ongoing, countries and territories in the Americas should continue to be vigilant for cases of Zika virus, implement vector control measures, and strengthen the capacity for the laboratory diagnosis of Zika virus and other arboviruses.

References

1. Yung C-F, Lee K-S, Thein T-L, Tan L-K, Gan VC, Wong JG, et al. Dengue serotype-specific differences in clinical manifestation, laboratory parameters and risk of severe disease in adults, Singapore. American Journal of Tropical Medicine and Hygiene 2015;92(5):999–1005.

2. Guzman MG, Halstead SB, Artsob H, Buchy P, Farrar J, Gubler DJ, et al. Dengue: a continuing global threat. Nature Reviews Microbiology 2010;8:S7–S16.

3. Guzmán MG, Kourí G, Valdés L, Bravo J, Vázquez S, Halstead SB. Enhanced severity of secondary dengue-2 infections: death rates in 1981 and 1997 Cuban outbreaks. Revista Panamericana de Salud Pública 2002;11(4):223–227.

4. Guzmán MG, Kouri G. Dengue: an update. The Lancet Infectious Diseases 2002;2(1):33–42.

5. Soo K-M, Khalid B, Ching S-M, Chee H-Y. Meta-analysis of dengue severity during infection by different dengue virus serotypes in primary and secondary infections. PLoS ONE 2016;11(5):e0154760.

6. Reich NG, Shrestha S, King AA, Rohani P, Lessler J, Kalayanarooj S, et al. Interactions between serotypes of dengue highlight epidemiological impact of cross-immunity. Journal of the Royal Society Interface 2013;10(86):20130414.

7. Cardoso CW, Paploski IA, Kikuti M, Rodrigues MS, Silva MM, Campos GS, et al. Outbreak of exanthematous illness associated with Zika, chikungunya, and dengue viruses, Salvador, Brazil. Emerging Infectious Diseases 2015;21(12):2274.

8. Van Bortel W, Dorleans F, Rosine J, Blateau A, Rousset D, Matheus S, et al. Chikungunya outbreak in the Caribbean region, December 2013 to March 2014, and the significance for Europe. Eurosurveillance 2014;19(13):20759.

9. World Health Organization. Dengue: guidelines for diagnosis, treatment, prevention and control. New edition. Geneva: WHO; 2009. Available from: http://www.who.int/tdr/publications/documents/dengue-diagnosis.pdf.

10. Carter KH, Singh P, Mujica OJ, Escalada RP, Ade MP, Castellanos LG, et al. Malaria in the Americas: trends from 1959 to 2011. American Journal of Tropical Medicine & Hygiene 2015;92(2):302–316.

11. Ministry of Health of Brazil. SVS monitora casos de doença exantemática no Nordeste [Internet]; 2015. Available from: http://portalsaude.saude.gov.br/index.php/o-ministerio/principal/secretarias/svs/noticias-svs/17524-svs-monitora-casos-de-doenca-exantematica-no-nordeste.

12. Ministry of Health of Brazil. Confirmação do Zika Vírus no Brasil [Internet]; 2015. Available from: http://portalsaude.saude.gov.br/index.php/o-ministerio/principal/secretarias/svs/noticias-svs/17702-confirmacao-do-zika-virus-no-brasil.

13. Brooks RB, Carlos MP, Myers RA, White MG, Bobo-Lenoci T, Aplan D, et al. Likely sexual transmission of Zika virus from a man with no symptoms of infection – Maryland, 2016. Morbidity and Mortality Weekly Report 2016;65(34):915–916.

14. Lessler J, Chaisson LH, Kucirka LM, Bi Q, Grantz K, Salje H, et al. Assessing the global threat from Zika virus. Science 2016;353(6300):aaf8160.

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Reference/Note:

1. Suspected case: patient with acute onset of fever >38°C (101°F) and severe arthralgia or arthritis not explained by other medical conditions, and who resides or has visited epidemic or endemic areas within two weeks prior to the onset of the symptoms. Confirmed case: a suspected case with any specific chikungunya test (viral isolation, RT-PCR, Ig M, or four-fold increase of chikungunya-specific antibodies titers); PAHO/CDC confirmed case definition available from www.paho.org/chikungunya.

2. Source: PAHO/ WHO Chikungunya Statistical Data. Available from: https://www.paho.org/hq/index.php?option=com_topics&view=readall&cid=5932&Itemid=40931&lang=es.

3. High-risk areas are those with an annual parasite index of 10 or more cases per 1,000 inhabitants.

4. Deaths due to GBS or other neurological complications not included in this value.

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