Study shows dengue virus can lower sperm production in men

By Dr. Tomislav Meštrović, MD, Ph.D.Reviewed by Aimee MolineuxMay 16 2022

A recent study published in the journal Emerging Infectious Diseases supports the notion that the dengue virus can be sexually transmissible for a short period after acute dengue illness and that it can also cause alterations in sperm production.

Background

Dengue is a viral disease transmitted by mosquitoes that is common in regions with tropical climates around the world. Since it is endemic in more than one hundred countries, the World Health Organization (WHO) considers it one of the salient global health issues.

Most individuals infected with the dengue virus are asymptomatic or present with a mild form of the disease with signs and symptoms akin to influenza (e.g., fever, headache, muscle and joint pains, nausea, fatigue). Nonetheless, in a small number of affected people, the disease can become serious and even fatal.

But mosquitoes are not the only way how the virus can be transmitted. For example, vertical transmission from pregnant women to their fetuses has been described, which results in higher rates of preterm births and miscarriages.

Furthermore, the transmission can occur via blood products, needlestick injury or blood transfusion. However, more controversial topic is potential sexual transmission that has been recently hinted in medical literature. By using this route, would the virus exert an additional impact on reproductive health?

A group of scientists, led by Dr. Joffrey Mons from the Groupe Hospitalier Sud Réunion in St. Pierre (France), aimed to address one of these pertinent questions by appraising the effects of acute dengue infection on sperm and viral clearance in body fluids of affected men.

Appraising spermatozoids and hormones

In a nutshell, this prospective study shows results from a longitudinal appraisal of various biologic samples (such as whole blood, urine, and semen) and reports the characteristics of semen and reproductive hormones following the acute infection with dengue virus in men.

The researchers have also documented the detection and clearance of viral genetic material in different fractions of the semen, as well as the presence of replicative virus (including in motile spermatozoids). Samples were collected 7, 15, 30, 60, and 90 days after disease symptoms have started in ten infected volunteers on Réunion Island.

Semen samples have been analyzed for dengue virus with the use of reverse transcription-polymerase chain reaction (PCR), and also examined for dengue virus ribonucleic acid (RNA) by virus isolation in Vero E6 cell cultures established from kidney epithelial cells of the African green monkey.

Lower sperm production, but no RNA in motile sperm cells

In this study, the researchers have found that sperm production in the context of dengue infection actually diminished approximately thirty days after symptom onset. Moreover, even though there were no significant disturbances in reproductive hormone levels, a substantial decrease in the testosterone/LH ratio might point to subtle dysfunction of Leydig cells found in the testes.

Spermatozoids, non-sperm cells, and seminal plasma from patients included in the study have been positive for dengue virus RNA, but not motile spermatozoa cell fractions. This implies that either the dengue virus has not been associated with motile spermatozoa, or the viral load was well below the detection threshold.

This is a rather important finding, as sperm processing methods that are employed for assisted reproductive technology seem to be effective for isolating spermatozoa free of dengue virus, as is the case for several other notable viruses.

Implications

In conclusion, the genetic material of the dengue virus has been found in semen up to thirty days after symptom onset; however, it was not associated with motile sperm cells. Of course, there are some study limitations, such as, low number of patients, no control group, mild symptoms, but these insights are quite valuable.

These findings emphasize the need for further studies in this field and also have implications for public health policy, such as contributing to increased diagnostic efficiency and limiting sexual transmission of dengue virus”, said study authors.

“Finally, our findings provide information relevant to counseling dengue virus-infected patients and couples who wish to conceive a child”, they added.

As the body of knowledge addressing the interactions between the dengue virus and the reproductive tract is still in its infancy, research endeavors like this one undoubtedly shed the light on what role viruses transmitted by mosquitos can actually play within the human reproductive tract.