Lisbon and Porto have the highest notification rates of sexually transmitted infections

The Metropolitan Areas of Lisbon and Porto are the areas in Portugal that have the highest notification rates of three sexually transmitted infections (STIs) – chlamydia, gonorrhea and syphilis.

This is the conclusion of a study by the Instituto de Saúde Pública da Universidade do Porto (ISPUP), which evaluated the geographical distribution of these three infections in the country, during the period between 2015 and 2017.

According to Cláudia Santos, the first author of the investigation, coordinated by Ana Isabel Ribeiro, “the work focused on the evaluation of these three infections, because, in addition to being the most reported mandatory STIs in our country, they are all preventable and curable, and therefore, if detected early, complications in neonatal and reproductive health can be avoided”, she says.

The researchers used data from the National Epidemiological Surveillance System (SINAVE), which has a record of all notifications of these infections in Portugal. During the three years analyzed in the study, 4819 cases of these three infections were reported. Half of the cases (51.5%) corresponded to syphilis, 33.2% to gonorrhea and 15.3% to chlamydia.

The study found that, from 2015 to 2017, there was an increase in the number of notifications of these STIs, with the most significant increase observed in cases of chlamydia. It should be noted that this increase occurred in the context of a change in the notification system.

With regard to the geographic distribution of pathologies, the Metropolitan Areas of Lisbon and Porto were found to be those that have the highest notification rates, standing above the national average, which makes them areas of higher risk. “The Metropolitan Area of Lisbon concentrates the majority of cases reported in the country: 70% of cases of chlamydia, 57% of cases of gonorrhea and 47% of cases of syphilis”, says Cláudia Santos.

The researchers also noted that, in Portugal, the typical patient of these three STIs is male, young and heterosexual.

Greater socioeconomic deprivation, urbanization and population density associated with STIs 

The study, published in the journal Sexually Transmitted Diseases, also found that reporting rates appear to be gradually increasing with a higher level of socioeconomic deprivation. In fact, the notification rates are higher in the most urbanized and densely populated municipalities, in comparison with the less urbanized and populated municipalities. This may be explained by the fact that there is a greater interaction between people among the former and they may come to have more sexual partners.

“Through this study, we can see that there are flaws in the degree of coverage of these records. We found almost five thousand reported cases, but this number is still far below that of the real cases. Therefore, the population needs to be sensitized to seek health services, in order to be able to diagnose STIs and move forward to treatment”, says the researcher. “The results of the work are also useful to help define the communities and groups that deserve priority intervention, and to develop public health programs suitable for these populations“.

Globally, sexually transmitted diseases are on the rise, representing an international threat to public health. Chlamydia, gonorrhea and syphilis are asymptomatic and, if left untreated, can lead to complications in the reproductive system and neonatal health. Considering this, the World Health Organization’s Global STIs Strategy foresees to reduce by 90% the incidence (number of new cases) of syphilis and gonorrhea by 2030.

The article is entitled Mapping Geographical Patterns and High Rate Areas for Sexually Transmitted Infections in Portugal: A Retrospective Study Bases on the National Epidemiological Surveillance System. The researcher Bernardo Gomes also participated in the study.

Image: Unsplash/Reproductive Health Supplies Coalition 


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