Epidemic dengue 4 in the Yucatán, México, 1984

Abstract

An outbreak of dengue 4 occurred in the Yucatán, México in 1984. During the course of the outbreak, 538 of 5486 reported cases of dengue-like illness were studied; 200 were confirmed as dengue serologically and/or virologically. Dengue 4 virus was isolated from 34 patients and dengue 1 from one. Severe haemorrhagic symptoms were observed in 9 laboratory confirmed patients, including four deaths. Thus, the outbreak in Yucatán is the second dengue epidemic in the Americas after the Cuban epidemic in 1981 in which a number of patients suffered from haemorrhagic complications. It was notable that 5 of 9 hospitalized, severe cases were young adults and that only one met the WHO criteria of DHF, in contrast to primary pediatric nature of DHF in Southeast Asia. In this paper we describe clinical, serologic, and virologic studies conducted during the outbreak.

Genetic variation within the premembrane coding region of dengue viruses from the Yucatan peninsula of Mexico.

“…Both the earlier (1984) and the later (1994−1997) Mexican DEN-4 viruses, cluster in the second genotype with the 814669/Dominica81 isolate ( Figure 3D). The low divergence between the two subgroups of Mexican DEN-4 isolates (1.8-3.2%) is compatible with the rate of nucleotide substitution reported for this virus, 16 which suggests that the strain introduced in Yucatan in 1994 is the same virus that caused the 1984 outbreak, 22 and that both are derived from the original DEN-4 virus that appeared for the first time in the Americas in Dominica in 1981.…”

“…24 Some of the isolates were obtained from patients that had hemorrhagic manifestations, but only one met the complete DHF definition. 3,22 The virus collection was comprised of 23 DEN-1, 10 DEN-2, 62 DEN-3 and 45 DEN-4 isolates ( Table 1). Seventy-four (51%) of the viral isolates were obtained from patients from Merida, 51 (36%) were from other municipalities in the state of Yucatan, and 7 viruses (5%) were from patients from the states of Campeche and Quintana Roo in the Yucatan peninsula ( Figure 1).…”

“…The DEN-4 virus caused a major epidemic in 1984 with more than 5,000 reported cases but only one case met all World Health Organization criteria for DHF. 22 In 1991, DEN-2 was detected in Yucatan and 364 cases were confirmed. Dengue hemorrhagic fever appeared in epidemic form for the first time in 1996 23 and in 1997, 4,049 cases of DEN were reported in Yucatan with 163 cases of DHF (Sistema Nacional de Vigilancia Epidemiológica, Mexico, 1998).…”

Dengue seropositivity in a randomly selected sample from Yucatan analyzed in the context of dengue cases reported between 1996 and 2006

“…As municipalities include smaller population units called communities, for the 2006 serosurvey, the list of communities from the municipalities selected for the 1996 serosurvey was randomized, that means that the participating individuals in 1996 and 2006 belonged to the same municipalities that were selected for the 1996 serosurvey, but were not necessarily from the same community. The population from the randomized municipalities together account for 75.3% of the total state population (1,830,893 inhabitants, according to CONAPO estimates for 2006).…”

“…The serosurveys conducted during the 1980's decade showed a positivity close to 70% of the urban population, suggested a possible underreport of dengue cases at that time in Yucatan. [1][2][3] Since then, Denv has been associated in Yucatan with multiple fatal cases, Dengue Fever DF and DHF, becoming an endemic disease which had been favored by the abundance of Aedes aegypti, the main dengue vector in the region. [4,5] In Mexico, and particularly in Yucatan, experts have considered that the number of unreported DF cases were ten times more than reported by the epidemiological surveillance system.…”