The border crossing that separates Tijuana, in Mexico, from San Diego, in the United States, is one of the busiest crossings in the world for drug trafficking and migration. A dynamic human corridor shaped by deportations, inequality, prostitution and marginalization that the authorities decided to close in 2020 to contain infections from one side to the other when the covid-19 pandemic broke out.
The blockade did not stop drug tourism between the two countries. And, instead of preventing the spread of disease, the authorities’ strategy led to an increase in HIV transmission. This is confirmed a study recently published in the journal The Lancet, a collaborative work between American scientists from the University of California in San Diego and Irvine that analyzed the spread of the virus through interviews with drug users and genetic data of the pathogen.
According to the investigation, blocking the passage between the two countries increased the spread of the infection, aggravating cross-border transmission. Closing the border during the pandemic, the work exposes, was a cause of structural risk that increased vulnerability to contracting HIV. “Injection drug use is one of the main determinants of acquiring it and mobility across geographic borders can increase the risk of exposure,” highlights one of the authors of the work, epidemiologist Britt Skaathun.
According to data his team collected, HIV prevalence among that population reached a rate of 16% in Tijuana, compared to 4% in San Diego. This shows how the geographical and social situation on the northern border of Mexico promotes vulnerability to exposure to infection in the population concentrated in that place.
To investigate the relationship between border closures, drug use and HIV transmission, scientists tracked more than 600 citizens, 74% of them men, living in Tijuana and San Diego and who, during the closure of the pass, they crossed from one side to the other to buy and consume narcotics.
The first phase of the research consisted of an interview in which respondents answered questions about their demographics, drug use, sexual, and border crossing behaviors. Every six months, the scientific team took blood samples and tested them for HIV and hepatitis C. To deepen their analysis, the researchers carried out molecular epidemiology techniques with the answers to the questionnaire. In order to find out how closely the viruses were genetically related, for each patient who tested positive for HIV, the agent was isolated, its RNA was sequenced, and the genetic diversity in the border region was analyzed.
Through phylogenetic techniques, trees were built to represent how the pathogens relate to each other to, once the evolutionary relationships of the viruses isolated in the participants were known, perform a molecular clock analysis. With this technique they estimated the moment of cross-border transmission of HIV. According to the results, the increase in transmission occurred just when the border was closed. Restricting passage without other measures to stop clandestine activities did not work as a public health strategy. “Efforts to build a higher wall or policies to stop immigration do not mitigate the spread of HIV,” says Tetyana Vasylyeva, assistant professor of Health and Disease Prevention at the University of Irvine and the lead author of the study.
To prevent viral spread, adds her colleague Skaathun, “better than trying to close a porous border is to establish programs to eliminate HIV transmission at the border, such as substance use treatment and harm reduction services.” “These interventions play a key role in reducing incidence, which is why it is necessary to ensure their financing. Combined with other services, they constitute a profitable tool to reduce the economic cost as well as the public health burden of HIV,” highlights Carlos Magis, professor of public health at the UNAM Faculty of Medicine and former director of Comprehensive Care at Censida between 2013. and 2019.
Since the nineties, the largest government institution in Mexico to combat HIV has developed various community and institutional strategies in Mexico to bring harm reduction services to people who inject drugs, “from deliveries of clean syringes, condoms or treatments for diseases associated,” explains the expert.
According to the expert, with more than 30 years of experience in the field, “thanks to harm reduction programs aimed at the population that injects drugs, between 2003 and 2017, more than 200 infections were avoided per year.” However, López Obrador’s decision to cut off public resources to intermediary organizations or foundations “put an end to this type of initiatives,” he laments.
“The reduction of support for syringe exchange programs with the intention of stopping corruption affected community organizations, causing them a great blow. They stopped having support to carry out harm reduction programs in the field,” warns Clara Fleiz, a researcher at the National Institute of Psychiatry specialized in the consumption of injected drugs on the country’s northern border.
As explained in a study that he coordinates and that aims to monitor the rate of infectious diseases among those who inject drugs in northern Mexico, new cases of HIV have increased in recent years. “If in 2019 the rate in Tijuana was 4.5%, now it is up to 12%,” says the researcher, for whom the Government cuts caused “the supplies to stop the spread of infections to be reduced, impacting the increase.” of risky practices, such as sharing needles, and increasing the number of infections.”
For this reason, maintains the former director of Censida, it is essential to “recover support for the programs.” In 2019, the US Department of Health and Human Services (HHS) launched a plan to reduce the incidence of HIV by up to 90% by 2030. The plan aims to capitalize on scientific advances in diagnosis, treatment and prevention in infection control. “We believe that Tijuana and the border region should be provided these funds to help unite efforts in the area,” says Skaathun.
“And we cannot forget the urgent need to address the social and environmental conditions that favor and accompany the increase in these infections,” adds Fleiz. In his opinion, to advance this fight “we need to respond to the determinants that force people to live in street conditions, without access to basic needs, such as food and a safe job, and improve access to health services.” that have worsened in the country”
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