Top stories this week are likely to include: Dilma Rousseff in Washington; Sixth Summit of the Americas on Saturday; Chávez possibly seeking treatment in Brazil; Maras and Zetas reportedly joining forces; and Boudou under investigation.

Dilma in Washington: Brazilian President Dilma Rousseff begins a three-day visit to Washington today, where she will meet with her U.S. counterpart Barack Obama. This is Rousseff’s first visit to the U.S. since taking office in January 2011. Aside from meetings at the White House, Rousseff will speak at the U.S. Chamber of Commerce later today, and give a public speech at Harvard University tomorrow. In the Financial Times, Moisés Naim calls for the two countries to agree to a trade deal as a tangible outcome. Adds AQ Editor-in-Chief, Christopher Sabatini, “There will be plenty to discuss, from improving bilateral commerce and investment, Brazil’s recent flurry of legislation favoring local content and business, Iran, and—I hope—the upcoming presidential elections in Venezuela.”

Summit of the Americas on Saturday: Cartagena, Colombia, will host this weekend the Sixth Summit of the Americas, the regional conference of heads of state organized under the aegis of the Organization of American States. This year’s theme is “Connecting the Americas: Partners for Prosperity.” But will the summit yield any significant results? Notes Sabatini: “While this will be a great opportunity to show off how far Colombia has come in the 18 years since the summit process started, there is really very little the summit can accomplish beyond speeches and vague promises.”

Chávez May Seek Treatment in Brazil: Although Venezuelan President Hugo Chávez landed in Havana on Sunday to receive his latest round of radiotherapy, Brazilian media has been reporting that Chávez may seek further treatment at Sírio-Libanês hospital in São Paulo. This is the same hospital where former Brazilian President Luiz Inácio Lula da Silva last year successfully recovered from cancer surgery. Specifically, O Globo has reported—citing anonymous sources—that Chávez’ cancer has metastasized and may spread to his liver. Although the Venezuelan embassy in Brasília has denied the reports, pay attention to how this story develops over the coming days.

Maras-Zetas Alliance: Guatemalan authorities this weekend reported that the deadly Mara Salvatrucha gang, which dominates Central America’s Northern Triangle, has formed a pact with the equally dangerous Zetas group in Mexico for control of key drug transit routes from South America to the United States. In an already violence-plagued Central America, the alliance spells bad news for counternarcotics officials and may bolster the positions of Guatemalan President Otto Pérez Molina—a proponent of drug legalization—at this weekend’s Summit of the Americas. “An alliance between two of the region’s most feared criminal networks yet again reinforces the critical need for a real regional approach to reducing insecurity. The drug traffickers don’t respect borders and neither should counternarcotics efforts,” notes AQ Senior Editor Jason Marczak.

Future of Boudou: Argentine Vice President Amado Boudou  is now under investigation by federal authorities for his actions as economy minister—in the two years prior to assuming the vice-presidency—specifically that he helped printing company Ciccone Calcográfica get out of bankruptcy. Boudou has denied the charges and still has the full support of President Cristina Fernández de Kirchner and her administration. After a raid of Boudou’s apartment last week, there may be new developments this week on the ongoing investigation.

Trained as a criminologist and a sociologist, Maria Mourani, a Montreal Member of Parliament (MP) with a special interest in street gangs in Canada, thought she had seen it all.

But when she delved into the universe of the

Through contacts, Mourani was able to meet with members of two rival gangs in El Salvador (the Mara Salvatrucha, or MS13, and the Pandilla 18), take pictures of their tattoos and visit prominent members in overcrowded prisons. This provided a rare insight into a culture of violence unlike anything she had seen before. [Photographs of gang members and their tattoos can be seen here.]

She calls these gangs “by far the most violent and most dangerous gangs in the world.”

In her newly-published book released in French, Gangs de rue Inc. (Street Gangs Inc), Mourani describes her foray in 2008 into El Salvadorbarrios controlled by gangs who deal in drugs, girls, arms, and assassinations.

She was shocked by what she found: cruel and violent initiation rites, young pregnant women proudly displaying the MS13 tattoos, children learning hand signals and a drive by gangs to “export” their “sub-culture” of violence wherever it gains a foothold.