Re: Veracruz a?n es primer lugar en casos de dengue
Re: Veracruz a?n es primer lugar en casos de dengue
http://www.medscape.com/viewarticle/417334_7
Emergence of Dengue Hemorrhagic Fever in the Americas
from Infections in Medicine ?
Emergence of DHF in the Americas
Before 1981, there were no known DHF outbreaks in the Americas despite the circulation of dengue viruses in parts of the region during the 1960s and 1970s. A small number of suspected cases of DHF or severe fatal dengue were reported before then, but only a few of them fulfilled the WHO case definition for DHF/DSS, and the majority lacked laboratory confirmation.[37]
Cuba. A milestone in the emergence of DHF in the Americas was the major DHF epidemic that affected Cuba in 1981.[9] This epidemic was first detected in late May 1981 and peaked during July and August; the last cases were diagnosed in October. A total of 344,203 cases of dengue and DHF/DSS were reported, 10,312 of which were determined to be grades II to IV of the WHO classification for DHF severity (Table I). There were 158 fatalities, 101 of which occurred in children younger than 15 years. Over a 3-month period, a total of 116,143 persons were hospitalized. This outbreak was short-lived, thanks to a vigorous and effective A aegypti control program implemented by the Cuban authorities, which virtually eradicated the mosquito from the island. Cuba became free of dengue virus until 1997, when another epidemic occurred in Santiago province. A total of 2946 cases of dengue were reported in that outbreak, including 205 DHF cases and 12 deaths, all of them in adults.[47]
Venezuela. Since 1981, DHF cases or epidemics have been reported in 25 countries of the Americas every year except for 1983 (Fig. 1). Small outbreaks were reported in El Salvador, Mexico, Nicaragua, and Puerto Rico between 1982 and 1988.[39] In 1989, however, the second major epidemic of DHF/DSS in the Americas occurred in Venezuela.[11] The first cases were diagnosed in October; the epidemic peaked in January 1990 and then declined sharply. From December 2, 1989, through April 17, 1990, a total of 3108 DHF cases were reported, with 73 deaths. Approximately two thirds of the cases occurred in children under 14 years of age, and a similar age distribution was observed in fatal cases. Cases of DHF were reported from 17 of 20 states, the Federal District, and 1 of the 2 Venezuelan Federal Territories. Most DHF reports originated in the Federal District and from the states of Aragua, Barinas, Carabobo, Falcon, Miranda, and Zulia. Dengue viruses isolated during the epidemic belonged to serotypes 1, 2, and 4, but dengue-2 was predominant. However, none of these isolates came from fatal cases. Immunohistochemical studies with formalin-fixed tissues of fatal cases found dengue-2 antigen in the liver of 4 patients.[11] The end of the epidemic was officially declared in mid-April 1990, but it re-emerged later in the year. Outbreaks of DHF have been reported in Venezuela every year since then. The largest outbreak occurred in 1997, when 6300 cases with 43 deaths were reported.
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http://www.medscape.com/content/1998/00/41/73/417334/art-m3365.fig1.jpg
Figure 1. (click image to zoom) Dengue hemorrhagic fever in the Americas. Provisional as of February 6, 1998. Data from country reports to PAHO/WHO.
Brazil. In Brazil, 4 cases of primary infection with dengue-1 virus were identified in 1986-1987.[39] In 1990-1991, the country experienced its first outbreak of DHF in the state of Rio de Janeiro.[12] This outbreak was associated with dengue-2, but it was preceded in 1986-1987 by outbreaks of dengue-1-associated fever.[48] That dengue-1 serotype was introduced into Brazil in 1986 after several decades during which no cases of dengue were reported. This sequence of events was similar to the Cuban outbreak of 1981. However, the number of cases in Rio de Janeiro was much smaller. Only 462 DHF cases and 8 deaths were reported. A second outbreak affected the state of Ceara in 1994.[34,49] This outbreak was also associated with dengue-2 and resulted in 24 DHF cases and 11 deaths.
Other countries. During the 1990s, 3 other American countries--Colombia, Mexico, and Nicaragua--reported significant outbreaks of DHF.[8] Between 1990 and 1994, Colombia reported small outbreaks each year, but since 1995 this country has recorded over 1000 DHF cases each year. Prior to 1994, Mexico had reported 14 DHF cases between 1984 and 1991. A small outbreak occurred in 1994, and since 1995 there has been a sharp increase in the incidence of DHF. During the 1995 outbreak in Mexico, dengue-2 virus was isolated from 20 DHF cases and dengue-1 from an additional 5 cases, but dengue-3 and -4, which were also circulating in the country, were recovered only from non-DHF cases.[50] In Nicaragua, outbreaks have occurred since 1992, the 2 largest ones in 1993 and 1995.
All cases. As seen in Figure 2, between 1981 and 1997 a total of 54,248 cases of DHF and 689 deaths were reported by 25 countries in the Americas (provisional figures at February 6, 1998). Figure 2 shows that most of the reported cases (28,470, or 52.5%) and deaths (250, or 36%) originated in Venezuela. In addition to Venezuela, 4 other countries--Colombia, Cuba, Mexico, and Nicaragua--reported more than 1000 cases each, and the remaining 20 countries reported between 1 and 706 DHF cases.
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http://www.medscape.com/content/1998/00/41/73/417334/art-m3365.fig2.jpg
Figure 2. (click image to zoom) Number of reported cases and deaths (indicated in parentheses) of dengue hemorrhagic fever in the Americas by country, 1981-1998. Provisional as of February 6, 1998. Data from country reports to PAHO/WHO.
The age distribution observed for DHF cases in the Americas is different from that in Asia. During the outbreaks that occurred in Cuba in 1981 and in Venezuela in 1989, about one third of the deaths were among children over 14 years of age, whereas in Asia, cases of DHF/DSS and associated deaths occurred among children aged under 14 years. In the 1997 Cuban outbreak, however, all of the deaths were among adults. In Brazil, an age range of 31 to 45 years was seen in patients who fulfilled the WHO criteria.[51] In Puerto Rico, two thirds of the cases reported in 1986 were in children under 15 years old,[52] but in 1990-91 the mean age of the patients was 38 years.[31] In contrast, in Southeast Asia, young children are predominantly affected. However, a marked increase in the number of DHF cases in individuals over 15 years of age has been seen in Malaysia and the Philippines during recent years.[53] In Asia, females are at higher risk than males for developing DHF/DSS. During the 1981 Cuban outbreak of DHF/DSS, the frequency of DHF/DSS was higher in female adults,[41] but no significant female predominance was evident among fatal cases.[9] This observation contrasts with findings reported in Asian countries.
DHF/DSS in the Americas continues to occur in both children and adults, but it is not clear if this is due to the genetic background of populations, epidemiological events, or other unknown factors.
The overall case-fatality rate (CFR) of DHF/DSS in the Americas is 1.4%,[8] but a large variation among countries has been observed. In countries reporting over 100 cases, the CFR ranged from below 1.0% (Colombia, Nicaragua, and Venezuela) to 11.9% (Puerto Rico). The reasons for this variation are not clear, but could be due to reporting criteria, viral virulence, host genetic factors, case management, or other unidentified factors.
