It is the job of all doctors to pinpoint the source of a patient’s discomfort. To do so, it is necessary to do an auscultation and an interview to obtain all the basic elements for the diagnosis. Although one of the problems is that there are diseases with quite similar symptoms that complicate this work. Specific, Distinguishing cases of Covid-19 and dengue is complicated by the similarity in the symptoms of both in their initial stages.
Until a couple of years ago, the presence of intense headache, fatigue, fever and general malaise in inhabitants of tropical areas of the country was suspected of having dengue. Since the Covid-19 pandemic, work has been complicated in these regions, especially without precise tests, such as the molecular analysis to identify genetic traces of the virus, known as qRT-PCR.
Not all countries have laboratory tests to distinguish cases of Covid-19 and dengue
This situation led Rosa María del Ángel and student Juan Fidel Osuna Ramos, from the Department of Infectious Diseases and Molecular Pathogenesis of the Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav), in collaboration with Jesús Salvador Velarde Félix, from the General Hospital of Culiacán and José Manuel Reyes Ruiz, a researcher at UMAE Hospital de Especialidades No. 14, CMN“ARC” of the IMSS, to propose an alternative.
The objective was to have greater certainty in the diagnosis, especially since many regions affected by dengue coincide in lacking medical infrastructure or high-capacity laboratories to generate a high number of tests.
The proposal, recently published in the journal Tropical Medicine and Infectious Disease. It consists of performing simpler clinical tests, such as a blood count. Based on blood parameters, among which the neutrophil count stands out, it is possible to differentiate and distinguish between a case of dengue and one of Covid-19 with up to a sensitivity of 91.4 percent and a specificity of 89.1 percentage points. This suggests the possibility of using it as an efficient and low-cost diagnostic tool.
How does the test work?
Neutrophils are cells of the immune system, present in the blood that react to the presence of an infection. So it is common for them to be altered during a viral-type illness.
This is how from a Statistical study and samples from patients with Covid-19, the Cinvestav students analyzed the hematological parameters, finding notable differences. For example, in patients infected with SARS-CoV-2, both neutrophils and platelets are elevated. While when presenting dengue it is more common for them to decrease, especially platelets.
According to the candidate for Doctor of Sciences, Fidel Osuna Ramos, this differentiation in hematological parameters occurs mainly at the beginning of both diseases. In other words, during the first 12 days, which is the window when this diagnostic tool could be useful.
To reach these conclusions, researchers from Cinvestav and IMSS conducted an analysis of 288 patients. There were 105 with SARS-CoV-2 and the rest with data from dengue patients who arrived at the Culiacán General Hospital prior to the start of the pandemic.
“Having information on blood counts of patients with dengue, prior to the current pandemic, made it easier to compare and identify the difference in parameters. Therefore, when analyzing the samples with covid-19, we were able to differentiate the levels of platelets and neutrophils obtained from a blood count.”
A hematological analysis of a person with symptoms could help a doctor to diagnose, especially if he is in a region where he does not have the ideal laboratory tools, in this case molecular diagnosis (qRT-PCR).
Even one of the options on the part of the researchers is to make an application for smartphones. From a digital calculator, the parameters that the hematic biometry throws are incorporated and can give a probability of which disease is facing between Covid-19 and dengue.
The study was carried out in collaboration with Luis Adrián De Jesús González and Carlos Noe Farfán Morales, both PhD students in Infectomics and Molecular Pathogenesis at Cinvestav. Now they hope to continue with an analysis to validate this tool from a clinical study in which samples are taken during a situation where both diseases coexist.