Dengue, although marginally, is circulating throughout the country in this summer of 2022-2023. According to Health Surveillance data, until week 12 of the current year, all the country's Departments reported cases of DEN1 or DEN2. In some, both serotypes co-circulate, in addition to the virus that this time predominates: Chikungunya ¹. But let's remember that Dengue has been causing major epidemics in Paraguay for over 20 years until it was finally declared endemic in 2009. The four serotypes in various opportunities have circulated simultaneously. However, each has dominated almost in turn in the great waves of significant epidemics of the last decades. During the great epidemic from 2006-2007 it was DEN3, in 2011-2012 it was DEN2, during 2015-2016 DEN1 and in the years 2019-2020, it was the DEN4. This means few cohorts of populations are susceptible to some of the four serotypes today. Inferring from this way, even if they circulate permanently throughout the national territory (as it is now), the next great epidemic wave of Dengue should only occur when a serotype that makes good weather does not circulate massively. In this case, it would be when the DEN3 returns. If this occurs, it should affect the younger cohorts born after that great epidemic of 2006-2007. Fortunately, none of the neighboring countries has a significant circulation of this serotype, but given the great global mobility, you always have to stay alert.

After the last major DEN4 epidemic at the beginning of 2020, the quarantines of coronavirus abruptly cut off this previous epidemic. Due to the start of the quarantines as the coronavirus pandemic began SARS-CoV2 did not have significant outbreaks in the country because of no arboviruses until the Chikungunya epidemic began. This The Chikungunya epidemic is among the largest reported in the Americas, which has alerted all the region's countries ².

The first record of Chikungunya circulation in Paraguay was between 2015 and 2016, in outbreaks concentrated in the Central Department and Asuncion. The sequencing of the viral RNA carried out by the Central Laboratory of Public Health was described as a lineage belonging to the Asian genotype but from Brazil.

In those years, to a considerable extent, there was also co-circulation of other arboviruses, such as Zika and DEN1. During the month of April In 2018, another critical outbreak was described again in the north of the country, in the city of Pedro Juan Caballero. In this outbreak, the presence of another genotype was also described from Brazil: the genotype known as East-Central-South-Africa (ECSA). This outbreak in our border city with the Brazilian city of Punta Porâ showed us for the first time more clearly the great diversity and severity of clinical manifestations of the disease in its different phases: acute, subacute, and chronic ³.

The current Chikungunya epidemic began as an outbreak in mid-2022 between the cities of Mariano Roque Alonso and Limpio in the metropolitan area of Asunción. When the rainy season began (October-November) began the considerable increase in cases, massively surpassing Dengue. It's the ECSA genotype again, too, coming from lineages of Brazil, but this time disseminating to a great speed, beginning in the metropolitan area of Asunción, to later expanding to the different urban areas of the country ¹.

The great epidemic of Chikungunya is the result, on the one hand, of introducing a practically new virus in a population that has suffered several cycles of dengue epidemics. But this time, two more related elements were added to the vector, which is very important for the mixture to be finally explosive. First is the start of the outbreak during the beginning of the rainy season. This makes it easier for the epidemic to be active every month during the season of rains, generally until before the onset of winter of the year following. The second is that the outbreak begins in the metropolitan area of Asunción, where approximately 3 million inhabitants gather.

Equivalent to 40% of the national population. It is the region with the highest density of people of the country, and therefore with the highest risk of an epidemic.

According to SENEPA reports, no urban district in the country has rates of acceptable infestation for at least one month of the year. The rainy seasons multiplied by the rates of infestation ⁴. In this way, the density of mosquitoes practically defines the rate of contagiousness or rate of transmissibility (RT) of any arbovirosis, and in this case for Chikungunya, making it explosive if it also develops in a sea of individuals fully susceptible to the virus.

According to the literature, the Chikungunya virus has prolonged immunity, and reinfections are unlikely ⁵. Seroprevalence studies should be carried out to correctly estimate the proportion of the population that has passed the disease, at least in our most important cities, because this will tell us what next summer will be like and what is the need to acquire or be part of the development of a vaccine for Chikungunya. But we will likely have a break of this virus for some time after this epidemic. This experience should alert us that we are exposed to a diversity of viruses transmitted by the real enemy, the Aedes Aegypti. In At the time, Dengue was transmitted to us with its different serotypes, now it is Chikungunya can also be Zika, the Mayaro virus, and Yellow Fever. It is time that before we face each disease in turns again almost infinite, let's go to the root of the problem because if we control the mosquito, we contain a variety of diseases ⁶. In addition, we must do something different from what we have been doing for more than 20 years, and let us now concentrate our efforts on public policies that go beyond what the Ministry of Health does.

The efforts of SENEPA, Surveillance, and Health Services, which are the that ultimately save lives; let us add education to the solutions to this evil in all levels, let us improve waste management in our large cities, and let’s work towards healthy urbanism