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Human papillomaviruses (HPV for Human Papilloma Virus) are very common viruses that can infect the skin and mucous membranes. There are more than 150 types of papillomavirus, of which about 40 can infect the genitals of both men and women. Most of papillomavirus infections do not give any lesions: in 90% of cases, the infection is transient and resolves naturally within one to two years after sexual contamination. In 10% of cases, the infection persists and can lead to abnormalities (lesions) in the lining of the cervix. We speak then precancerous lesions, which can progress to cancer 10 to 15 years after infection with the virus.
The most common human papillomaviruses are HPV 16 and HPV 18. These so-called “oncogenic” HPVs can also affect other mucous membranes, and in particular cause anal or oropharyngeal cancers. A new study led by researchers from the University of Montreal, reveals that a persistent infection by these two types of HPV in pregnant women could increase the risk of preterm labor. These conclusions are potentially very important, since it is according to the High Authority of Health (HAS) the most frequent sexually transmitted infection, and that a high portion women carrying the virus is of childbearing age.
Study the genotype to better understand
“Our study shows that persistent infection with HPV type 16 or 18 up to the third trimester of pregnancy is associated with a risk of preterm delivery. Knowing that preterm births remain a major cause of perinatal mortality and morbidity, these results are worrying, ”emphasizes Helen Trottier, lead author of the study. But the researchers believe that this discovery, the results of which are published in “JAMA Network Open”, is in fact hopeful, since a preventive vaccine which protects against certain papillomaviruses including types 16 and 18 is available, which would prevent premature births related to this infection.
“Among all the known types of HPV, around XNUMX infect the genital area. Although most of them are harmless, some types are associated with serious diseases like cervical cancer, ”they add. The research team drew on the data collected with 899 pregnant women recruited through the HERITAGE cohort between 2010 and 2016 in three hospitals in Quebec. She then took vaginal samples during the first and third trimesters of pregnancy in order to perform genotyping tests in order to identify the precise types of HPV present: its presence was detected in 378 participants.
The importance of prevention: which test is the most effective?
It turns out that compared to uninfected women, the risk of premature labor has been found to be tripled in pregnant women with persistent HPV 16 or 18 infection. Very often, those infected have no noticeable symptoms or lesions. This is why the researchers recall in their conclusion the fact that “vaccination remains the best means of protection against HPV infections and its complications and should ideally take place before the first sexual intercourse. ”. The next step in their research will be to determine the frequency and the short- and long-term consequences of a transmission. virus from mother to child.
Currently, the prevention of cervical cancer involves the prevention of sexually transmitted infections (condoms, examinations for the partner) and especially by routine cervical smear in women. There are two types of screening tests performed on a sample of cells from the cervix: cytological examination and HPV-HR test. The first involves examining cells in the cervix under a microscope, looking for abnormalities to detect possible precancerous lesions. Unlike the cytological examination which is concerned with the morphology of cells, the HPV-HR test looks for the presence of high-risk HPV virus DNA.
Highly recommended papillomavirus screening
In France, it is recommended to get screen by the HPV-HR test, considered “more effective than screening by cytological examination” according to the HAS, from the age of 30. In its new “guidelines for the screening and treatment of precancerous lesions of the cervix” “, which it has just published, the WHO also recommends it as first-choice screening method. “Tests based on human papillomavirus DNA are more efficient than tests based on cytology because they are less prone to quality issues. They allow a diagnosis that leaves no room for interpretation of the results. ”, She says. Finally, “they are more profitable and suitable for all contexts, regions and countries. », She concludes.