Dengue Virus Dynamic and Persistence in Body Fluids of Infected Patients in Italy, 2018-2023

Abstract

Dengue, a mosquito-borne disease caused by the dengue virus (DENV), is constantly expanding worldwide. We investigated the presence and persistence of DENV RNA in the bloodstream and other body fluids to describe the viral kinetics in the human host. We longitudinally collected serum (n = 118), plasma (n = 110), whole blood (n = 90), urine (n = 118), oral swabs (n = 68), saliva (n = 42), semen (n = 23), and vaginal fluids (n = 49) from 42 DENV patients. We measured DENV RNA for a median of 28 (range 1-63) days from symptom onset (DSO). We estimated the probability of viral detection applying a generalized linear model, and the duration of viremia using Monte Carlo-Markov Chain approach. In the bloodstream, the highest rate of positivity, levels of DENV RNA, and persistence were observed in whole blood. The estimated probability of a positive test dropped below 5% after 12.5, 20.7, and 35.4 DSO for plasma, serum, and whole blood, respectively. The average duration of viremia was estimated to be 19.9 DSO. Saliva and oral swabs showed 76.2% and 58.8% of DENV RNA positivity during the first week of symptoms while the longest persistence was observed in urine (39 DSO). DENV was revealed in 20% cervicovaginal (up to 11 DSO) and 30% seminal (up to 35 DSO) fluids. Whole blood represents the preferential specimen for dengue molecular detection and the correct estimation of viremia duration which have clear implications for onward transmission and public health countermeasures. Blood, urine, and oral samples can be assayed according to time from disease onset, severity, and screening purposes.

Keywords: arboviruses; dengue virus; laboratory diagnosis; viral shedding; viremia duration.

Figure 1

DENV‐RNA shedding during the acute phase of infection. DENV RNA levels (Ct value) in serum, plasma, whole‐blood, urine, oral swabs, and saliva during the first (A) and the second (B) week from symptom onset. The number of samples tested, and the percentage of positive samples are indicated in the donut graphs. (C) Kinetic of viral DENV RNA levels (Ct value) in serum, plasma, whole‐blood, urine, oral swabs, and saliva during 4 weeks from symptom onset, w = week. The Kruskal–Wallis test was used to compare Ct values.

Figure 2

Estimated probability of a positive test result at different DSO. Each panel represents a different compartment. On the x‐axis the DSO, on the y‐axis the probability of a positive test result as obtained with the GLM model. The solid line represents mean estimates; the shaded area is the 95% confidence interval. Points represent the proportion of tests that resulted positive in the data. The dashed lines highlight the day when the estimated likelihood for a positive test result reaches 50% and 5%.

Figure 3

Distribution of DENV viremia duration from symptom onset in the blood compartments. The dark blue line represents the distribution of viremia duration as obtained by using the mean posterior values of the estimated parameters of the Gamma distribution. Dashed lines represent the 95% credible intervals. The horizontal boxplot summarizes the 2.5, 25, 50, 75, and 97.5 percentile of the estimated distribution.

Figure 4

Kinetic of viral RNA in genital samples from DENV patients. (A) DENV RNA levels (Ct value) in vaginal swabs and seminal fluids during 4 weeks from symptom onset. w = week. (B) Estimated probability of a positive test result on different DSO. On the x‐axis the DSO, on the y‐axis the probability of a positive test result as obtained with the GLM model. The solid line represents mean estimates; the shaded area is the 95% confidence interval. Points represent the proportion of tests that resulted positive in the data. The dashed lines highlight the day when the estimated likelihood for a positive test result reaches 50% and 5%.