Friday, June 14, 2024

ARGENTINA | 27-03-2023 15:18

Growing concern over rise in dengue and chikungunya cases across Argentina

Epidemiological authorities note dengue cases are doubling week-by-week, with almost 9,400 cases across 13 provinces recorded in latest medical update. Chikungunya cases are also on the rise, with both viruses surging in provinces of Tucumán, Salta and Santa Fe.

There is no rest from pathogenic viruses. As soon as SARS-CoV-2 takes a breather and its case and mortality figures drop to the point of the dilution levels of other infectious pathologies such as influenza, another disease returns to sound the alarm. 

At a medical event held last Tuesday, Carlos Giovacchini, the coordinator of the National Epidemiology Directorate at the National Health Ministry, revealed that – in the last few days – recorded cases of dengue fever have doubled. In the most recent registry, the agency noted 9,389 cases of dengue (type 1 and 2) from 63 localities located across 13 provinces nationwide. For comparison, in the same preceding period – the second week of March – the figure was 4,828 cases across 12 provinces.

This recent increase in infections is not so surprising. In National Epidemiological Bulletin No. 10, published in early March, authorities wrote that  "in the last three weeks there has been a marked increase compared to the same period of the previous two years: 683 percent compared to the average recorded for the same time of the year in 2022 and 159 percent compared to the same period in 2021".

Another interesting fact to emerge from the latest epistemological annotations is that  the provinces most affected by dengue cases are Tucumán, Salta and Santa Fe, while Buenos Aires City ranks in sixth. Finally, the age group most affected by the virus is young adults.

According to public health experts, this is part of a trend. Although this pathology has been endemic for decades in most countries in the region, over the last two years both dengue and chikungunya have been "expanding" their reach, both in terms of the number of cases and their increasing arrival in new geographical areas that were previously untouched by transmission. Figures from the Pan American Health Organisation suggest that the "triad" of mosquito-borne diseases in this family of viruses is as follows: dengue accounts for almost 90 percent of cases, the other 10 percent are chikungunya and one percent are cases of Zika virus infection.

In the case of "chikun," as it’s often referred to locally, the most up-to-date figures indicat4e sustained growth: 528 cases, ranging from five different provinces. While the magnitude of these cases is 20 times smaller than dengue, it is also a worrying situation because previously there had only been records of chikungunya diagnoses in two provinces: Salta and Jujuy, with a total of around 120 cases. For the first time, local circulation of the virus has also been confirmed in Argentina –  those identified as affected were part of "autochthonous" outbreaks (i.e. – they were infected locally and are patients with no history of travel to areas with confirmed viral circulation).

Ninety-nine per cent of the chikungunya cases are reported in the Southern Cone, of which almost three-quarters occurred in Paraguay. There are already more than 47,000 patients affected by this pathology in the country, and some 50 people have died.

It is worth remembering too that this is not an issue that Argentina is indifferent to, given its shared borders and the intense flow of people who cross them daily. Not only is the geographical proximity to the northern provinces of Argentina considered, but it should also be noted that many people come and go directly from Paraguay to the Buenos Aires Metropolitan Area, increasing the chances of transmission. 

Experts also fear that there is "co-circulation" of two different dengue serotypes in the same geographical areas, a chain of events that has already been observed in Brazil in recent years. This is no small matter as it means that the chances of a person being re-infected with another subtype of the same virus are increasing. 

"This situation exponentially increases the risk of contracting severe or haemorrhagic dengue, a potentially fatal complication of the disease," said Diego Flichman, a researcher with the CONICENT national scientific research council and professor of virology at the University of Buenos Aires.

With regards to dengue, although there are historical precedents, from the public health point of view, the "key" year for contagion data was 1998. Since then, there have been three major outbreaks: in 2009, 2016 and 2020.

Beyond these "peaks," annual trend observation by experts shows that the at-risk areas have been progressively encroaching into new territories and regions, especially more southerly latitudes, a progression facilitated by global warming and climate change. Alongside this, areas of increased "co-circulation" of the different dengue serotypes have also been recorded in several countries, increasing the risk of further complications for people who do become reinfected.

Enrique Garabetyan

Enrique Garabetyan

Redactor especializado en Ciencia, Salud & Tecnología.


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