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Chikungunya: study indicates a revision of case classification


Fiocruz Bahia


A group of researchers made a critical analysis of the current system of clinical classification of chikungunya cases. According to the scientists, with the emergency of the chikungunya virus transmission in the Americas beginning in 2013, it became clear that the classification of cases as acute, sub-acute and chronic has been insufficient, as it does not include the classification needs presented in some patients. In addition, this classification does not contribute with early detection and handling of potentially serious cases.

According to researchers, the clinical spectrum of the chikungunya infection varies a lot and includes serious symptoms associated to a risk of death. These may include involvement of the central and peripheral nervous systems, such as Guillain-Barré syndrom and encephalitis, in addition to complications in other organs and systems.

For the researchers, current clinical guidelines focus on joint pain and duration of acute symptoms, but ignore atypical symptoms and the potentially more serious forms of the disease. The opinion article was published in The American Journal of Tropical Medicine and Hygiene and is signed by researchers of different teaching and research institutions in Brazil and in the USA. One of the authors is Guilherme Ribeiro, researcher of Fiocruz Bahia.

As the basis to suggest a revision of the classification, the authors warn that studies in Brazil and in the Caribbean have identified an increase in general mortality among the population during the months of chikungunya epidemics when compared to previous months without outbreaks. This temporal and spatial association between higher general mortality and the occurrance of chikungunyas epidemics suggests that higher mortality can be a consequence of chikungunya infections, even when a specific increase in the deaths caused by the disease has not been detected.

New dengue fever classification took decades

The article, titled Chikungunya Case Classification after the Experience with Dengue Classification: How Much Time Will We Lose?, wonders whether physicians and health policies agents will take decades to adopt a new classification for chikungunya, just as happened with dengue.

The dengue classification adopted in the 1980’s, which focused on identifying classic, hemorrhagic and shock forms, had limited uses for other severe forms of the disease, which involved specific organs (central nervous system, liver, lungs and heart). Neither did it allow for the early identification of patients at risk of developing acute complications. It was not until 2009 that a new classification for dengue cases was adopted, and it proved to have higher sensitivity and specificity when discriminating the more serious cases of the disease.

The study warns of the urgency of reviewing the classification of chikungunya cases, as the virus currently presents sustained circulation in three continents and has recently re-emerged in Asia and in some countries of southern Europe. A better classification of the disease collaborates with surveillance efforts to produce consistent reports on the early clinical presentation and on the evolution of cases. It will also allow for comparisons of the frequency of serious forms of the disease in different locations.

In addition, it will also work as a guide for surveillance actions during future epidemics and, more importantly, it will help standardize clinical management according to the complexity of the case, with potential impact on mortality by the disease.

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