Dengue virus type 4 arrives in the state of Rio de Janeiro: a challenge for epidemiological surveillance and control

Abstract

EditorialDengue virus type 4 arrives in the state of Rio de Janeiro: a challenge for epidemiological surveillance and control Dengue virus type 4 (DENV-4) re-emerged in the state of Roraima (RR), a remote state in the extreme Northwest of Brazil, in July 2010 at the height of the rainy season. This serotype had not been detected in the country for almost 30 years, when DENV-4 and DENV-1 caused a limited outbreak in RR's capital city Boa Vista in [1981][1982] with 11,000 reported cases. The reinvasion of DENV-4 in July 2010 was not followed by an epidemic in RR; less than 20 cases of DENV-4 were confirmed in this state throughout the second half of 2010. The first cases, which were considered to have been the result of the virus spreading from RR, were not registered until January 2011. First, the virus reached two states of the Northern Region, Amazonas and Pará, in January. In March, the virus was subsequently detected in the Northeast Region, first in the state of Piauí and later in the states of Pernambuco, Bahia and Ceará, and in the Southeast Region, in the states of Rio de Janeiro (RJ) and São Paulo. The arrival of this serotype in RJ eight months after its resurgence in RR, almost 5,000 km away, has important and particular epidemiological significance. Furthermore, its early detection during the course of a DENV-1 epidemic reveals the efficiency of an epidemiological surveillance.RJ is a hub for many tourist activities and is therefore connected to a large and busy roadway and railway system that allows access to the most populous part of the country. In addition, the local Aedes aegypti populations are highly susceptible to dengue virus and are generally found in high densities throughout most of the state's territory. As a result, the state is known as the most important point for the introduction and dissemination of the dengue virus in Brazil. Indeed, RJ was where the introduction and dispersion of the first cases of DENV-1 (1986; the previous invasion in 1981 was limited to Boa Vista), DENV-2 (1990) and DENV-3 (2000) took place. The recent introduction of DENV-4 in this state is of great concern because of its potential to spread to the rest of Brazil.The first cases of DENV-4 detected in RJ occurred in the Cafubá neighbourhood, in the oceanic region of the municipality of Niterói (22°52′S 43°06′W; 487,327 inhabitants), which is located in the metropolitan region of RJ, only 15 km away from the capital city. The tourist sector is one of the most promising sectors, and the water supply reaches almost all of the households in the neighbourhoods' urban areas in Niterói. However, the sewage system does not coincide with the extension of the water supply networks. A considerable portion of the Niterói population is represented by the elderly, and the aging index is the highest in the state.Curiously, the first two cases of DENV-4 in RJ were detected in two young sisters, 22 and 23 years of age, who first began to show symptoms on March 6, 2011 during a DENV-1 outbreak in the state. Both presented fever,...

Potential impact of a presumed increase in the biting activity of dengue-virus-infected Aedes aegypti (Diptera: Culicidae) females on virus transmission dynamics

“…The absolute number of infections was greater, and most strikingly, the annual pattern of epidemics changed, with more severe biennial epidemics being observed. This pattern of biennial epidemics more closely resembles the observed multi-annual cycle of dengue epidemics in endemic countries, including the pattern observed in Brazil (Nogueira et al 2007, Nogueira & Eppinghaus 2011. In agreement, other studies have shown the importance of the parameters related to the vector-host interaction, including the biting rate, in determining the seasonal and multi-annual cycle of dengue (Hay et al 2000, Bartley et al 2002.…”

Temporal analysis of the relationship between dengue and meteorological variables in the city of Rio de Janeiro, Brazil, 2001-2009

“…Another limitation was the lack of reliable information in each time period on the specific incidence rates for each serotype (among the circulating serotypes) 36 . Some authors claim that the entry of a new serotype into a non-immune population entails a risk of explosive epidemics, even while the succession of serotypes can result in epidemics with more severe cases 10,18,37 . The role of the exposed human populations, the effect of immunity to the virus in the at-risk population, and infestation by the mosquito vector are decisive factors in maintaining the virus in circulation.…”

Dengue virus type 4 in Niterói, Rio de Janeiro: the role of molecular techniques in laboratory diagnosis and entomological surveillance

“…In RJ, the first DENV-4 cases that were detected occurred in the Cafubá neighbourhood. Cafubá is located in the oceanic region of the municipality of Niterói which is located in the metropolitan region of RJ, Brazil (Nogueira & Eppinghaus 2011). The entomological surveillance of DENV in adult and immature mosquito stages is an important tool for the early prediction of dengue epidemics.…”

“…The first two confirmed cases were two sisters who lived in the Cafubá neighbourhood of Niterói. Both experienced an onset of symptoms on March 6 2011 (Nogueira & Eppinghaus 2011). We investigated nine other suspected cases of individuals who experienced an onset of symptoms from March 23 2011-April 11 2011 and who lived in Cafubá, São Francisco, São Domingos and Engenho do Mato (Fig.…”