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Public health

Through the wall

Viruses and bacteria propagatefreely on the frontier between United States and Mexico

CARLOS FIORAVANTIThere is the border between the United States and Mexico: a fence of green metal sheets of 4 meters in height and width, going as far as the eye can see. Two police vehicles constantly move along this barrier – imposing, but insufficient to maintain an effective separation between the two very different worlds on the edge of the Pacific. On one side, in California, one of the richest states of the United States, sprawls the city of La Jolla, with its broad and aseptic streets and open air shopping mall – an outlet – stuck to this barrier. The shoppers go in and out of the ample stores selling clothes, perfumes and shoes. They walk with their shopping bags under the strong July sun as if they saw neither the fence, nor, much less, the other side: the narrow streets and tiny houses that cover the hills of the neighboring city of Tijuana, one of Mexico’s largest. Living there temporarily – albeit for many years – are the immigrants expelled from the United States that have no money to go back to their land of origin, besides those that nourish the hope of entering into the richest country in the world.

Those who do not want to run the risk of dying by crossing through this moderate version of the Berlin Wall can go from one country to the other by showing their documents at any of the 20 border posts spread along the 3 thousand kilometers of barriers that cut across urban areas, rivers and deserts. The flow is intense. 350 million people a year – 1 million people a day, on average – cross through the posts from one side to the other, with authorization, to work, to leave their children at schools and to go shopping, to go to the doctor’s or to the movies. It is one of the busiest frontiers in the world, even without counting the illegal immigrants – roughly 1 million a year –, who try to pass by hiding in cars or digging tunnels under the fence, to challenge fate in the United States. When they succeed, like the characters in the America soap opera, shown last year by Globo TV, some immigrants spread out over more distant regions, others stay thereabouts. In California alone, one of the American states that border on Mexico, there must be 9 million foreign residents living, of which 1.5 million illegally.

It is through these same breaches that viruses and bacteria propagate openly in the region. The 100 kilometers strip to the north and to the south of the border shows many cases shows far more new cases of infectious diseases than in the interior of either of the two countries. Timothy Doyle and Ralph Bryan, researchers from the Centers for Disease Control and Prevention (CDC), reached impressive conclusions when comparing the occurrence of 22 obligatorily notifiable infectious diseases in three different areas of the United States. The first is the region closest to the border, where 9.8 million persons are currently living; the second consists of a strip that crosses the heart of the United States and is home to some 45 million persons; the third is the most distant, occupied by another 203 million. The western portion of the three strips includes land that one day belonged to Mexico – by means of agreements or wars, the United States took possession of 2 million square kilometers of the neighboring country, equivalent to one quarter of the Brazilian territory.

The contrasts in health are most marked between the region closest to the frontier with Mexico and the most distant region, which comprises mainly the states bordering on another country, Canada. In the American territory closest to Mexico, the percentage of people with brucellosis, a bacterial disease caused by contaminated meat or milk, is eight times greater, and of botulism, another ailment of bacterial origin, transmitted by means of industrially-processed food that is spoilt or consumed after the expiration date, seven times greater. The number of sufferers from leprosy is five times higher, from measles, four times higher, and with hepatitis A, 3.8 times higher.

From these comparisons between the inhabitants of two frontier regions of the United States emerges the least glamorous face of the richest nation in the world, poverty: 5 of the 14 poorest counties in the United States are to be found in the region of Texas that borders Mexico. The differences in the levels of diseases persisted even when ethnicity was adopted as a criterion for analysis. The levels of hepatitis A, for example, are twice as high amongst the inhabitants of Latin origin that amongst the non-Latinos. Not only the differentiated socioeconomic conditions, but also the cultural habits contribute to this result: the Latinos are more given to kissing and hugging – in short, physical proximity – than typical Americans are.

The high levels of infectious diseases on the border of the United States with Mexico denounce the lack of health professionals, hospitals and adequate medical attention, since many of these ailments could be avoided: the occurrence of diseases that could be prevented by means of vaccines, like measles, diphtheria and tetanus, is twice as high in the areas closest to Mexico and in those further away. In second place, the picture that emerges from this study, published in September 2000 in Journal of Infectious Diseases, is one of the most wide-ranging ever done, exposes the shortcomings in basic sanitation. There is no running water nor sewage network in the 2,500 informal settlements, known as colonies, established along the frontier, which bring together roughly 500 thousand persons. The underground water that circulates from one country to the other is contaminated with bacteria that cause infectious diseases.

The two sisters
“Although it is split by a frontier, this region is just one, from the biological, ecological and geological point of view”, comments Exequiel Ezcurra, the director of the San Diego Natural History Museum, while he watches a group of children taking apart and putting together models of dinosaurs that lived here millions of years ago. Tijuana and San Diego, the metropolitan region of California with which La Jolla has merged, are today sister cities that form an urban sprawl of almost 10 million inhabitants. It is the largest bi-national metropolitan area in North America, marked by economic contrasts: the average annual income of the inhabitants of San Diego is almost US$ 30 thousand, five times more than that of its neighbors from Tijuana.

San Diego is the most prosperous region along the frontier. It is a center of industries linked to telecommunications, agriculture and biotechnology, besides being a tourist center, with beautiful beaches, despite the always icy – and not always clean – water of the Pacific. Particularly after the heavy end-of-year rains, the Tijuana River, which bathes the north of Mexico and a part of California, spills into the sea a higher than normal load of residential sewage and industrial waste, darkening the waters that arrive at the beaches of neighboring California.

Urban planning, which could hold back the pollution, becomes more difficult because of Tijuana’s peculiarities. Of its almost 4 million inhabitants, at least 1 million are temporary, because they still dream of crossing the border, because they have not succeeded, and, again, because they have already been deported. People who live in Tijuana do not create roots – or it seems that they do not want to – because they do not feel a bond with the city, even after 20 or 30 years. The level of unemployment is nil, but the majority of the inhabitants work in factories that benefit from the abundant labor to pay low salaries. In spite of the precarious working conditions, the temporary inhabitants that work in the hundreds of electrical or medical equipment factories installed in the northern region of Mexico known as Baja California risk being fired if they dare to join a trade union.

Tijuana may be harrowing, sad, and violent, but never boring. The city of few buildings but many stores with colorful façades becomes even livelier with the annual music and sushi festivals. It is there that the Americans go in search of cheaper drinks, permitted in Mexican bars for those who are over 18 years old; in the United States, them age limit is 21 years of age. The majority of the bars also open their doors to minors, albeit at the risk of receiving heavy fines. Another motivation for going to Tijuana is to buy drugs or medicines, or even to undergo surgeries that in the United States would be far more expensive: the removal of a tumor would cost US$ 7 thousand in California, but less than US$ 3 thousand in Tijuana. Buying one thing and another, the American visitors leave about US$ 800 million a year over there.

The men of the frontier
Like the majority of frontier cities, Tijuana houses a predominantly male population. The immigrants arrive on their own and get involved with high risk sex with women or with other men. The result is that sexually transmissible disease, in particular Aids, spread freely. According to a study coordinated by Kimberly Brouwer, from the University of California in San Diego (UCSD), published this March in the Journal of Urban Health, one in every 125 inhabitants of Tijuana of between 15 and 49 years old is a carrier of HIV, the virus that causes Aids. The majority (70%) are men who have sex with men, followed by users of injectable drugs.

Epidemiologist María Luisa Zúñiga, from UCSD, coordinated a team that interviewed 354 male carriers of HIV who admitted having sex with other men. The first finding, which hampers the Aids prevention campaigns, is that they do not consider themselves homosexuals, but straights. “For them, homosexuality is a lifestyle that they do not identify themselves with”, María Luisa commented in July, during one of the conferences of the Jack Ealy scientific journalism program, organized by the Institute of the Americas in La Jolla. “Sexual behavior can be different from sexual identity”, she said. This distinction may help doctors to understand and to hold back the disease in the frontier region. According to this survey, almost half of these men go to San Diego or to Tijuana once or twice a month, diluted amongst the multitude of roughly 42 thousand people that cross the frontier every day.

As the inhabitants of Tijuana that show the greatest risk of contracting HIV are the immigrants, the Mexican government started a radio campaign to promote free HIV tests, with the purpose of identifying infected persons and starting treatment as early as possible. The campaign emphasizes “La prueba del VIH es para gente que piensa que no la necesita” (the HIV test is for people who think they don’t need it). But it has not been easy to make headway. Anyone who suspects that he may be a carrier of the virus knows that, if he really does have it, he may lose his job, his friends, and perhaps his very family. In the Mexican cities close to the United States, there is another reason for postponing the test: “When people discover that they have the virus, they may lose the permission to cross the frontier”, says María Luisa, one of the coordinators of a project that is trying to expand the access of people with HIV and Aids to the health services in San Diego and in Tijuana. Even in the United States, 40% of all those infected do not know that they have the virus.

Another problem is that the temporary inhabitants of Tijuana, not having the habit of using condoms, may contaminate their wives with HIV when they go back home. The virus spreads, covered up by silence and denial of the possibility of having contracted the disease, normally presented as or mistaken for anemia. The most common way out is to hide the disease until the last minute, when the contamination of many other persons may already have occurred.

Another peril runs through the air: the bacteria that cause tuberculosis, which is spreading all over the world in the wake of Aids and poverty. It is a disease that is endemic in Tijuana because of the very humid climate and of the numerous vast settlements, which house the temporary inhabitants. In addition, the migrants have many difficulties before reaching a doctor of the Social Security, the structure of medical assistance offered by the Mexican government, when they come from another state without an official identity document. While the United States records only 5 cases of tuberculosis for every 100 thousand persons, the Baja California region shows from 50 to 60 cases for each group of 100 thousand inhabitants. It is almost double the current Mexican average, which had fallen in the 1990’s and has started to grow again in recent years, as less attention was given to the campaigns for its prevention and treatment.

“Tuberculosis does not forgive”, comments the lung doctor Rafael Laniado-Laborín, from the Autonomous University of Baja California, in Tijuana. In a study published this May in the Infection Control and Hospital Epidemiology magazine, Laniado-Laborín and María Noemi Cabrales-Vargas report 18 cases of tuberculosis amongst the doctors and nurses who have been working for five years in a 140-bed hospital in Tijuana. The result represents an incidence 11 times more than in the population at large, and it is worrying because it is a place with an intensive circulation of sick people, more inclined to contract other infections. According to Laniado-Laborín, the hospital adopted some suggested administrative measures, but afterwards left them aside. In the same hospital, 17 new cases arose amongst the health professionals between November 2005 and June 2006.

Joint actions
On the other side of the frontier, tuberculosis is also a concern. A survey done two years ago with 571 immigrants and refugees that had installed themselves shortly before in San Diego showed that although only 7% of them had the active form of tuberculosis, 76% had the latent form and were potential transmitters of the bacillus that causes the disease. It is possible to contain this disease when the contaminated persons take the medicines rigorously during six months; it so happens that the treatment is usually interrupted when the symptoms disappear. That is when the more aggressive forms of the disease arise, caused by varieties of bacteria for which the medicines have become innocuous. Incidentally, three health professionals that were working in the hospital in Tijuana were infected with a multiresistant variety of M. tuberculosis. The resistance to the two drugs most adopted against tuberculosis was detected in 1% of the varieties of the bacillus that circulate in San Diego, and in 17% of the varieties isolated from patients from Baja California.

The specialists in health insist: both tuberculosis and other infectious diseases can only be held back by means of actions by the two countries to facilitate diagnosis and treatment. But it is not enough to train doctors to treat the Mexicans that live in California, or to give more attention to the inhabitants of Tijuana. The local realities have to be respected, warns Laniado-Laborín. “We cannot simply apply what comes from other countries”, he says, “because the situations and the cultures are distinct”.

* Carlos Fioravanti was in La Jolla at the invitation of the Institute of the Americas. Mariana Martinez Estens is a journalist with the Frontera daily newspaper, of Tijuana.