At a camp in Mexico, migrants weigh the prospect of a second Trump term 

Ricardo Santiago, who heads MSF’s operations in southern Mexico, anticipates more migrants and asylum seekers like Ramirez will race to reach the border over the next month, before Trump takes office.

That would mean a reversal of current trends. September saw a four-year low in apprehensions at the US border, according to government figures. Still, Santiago said he has observed the numbers of migrants climbing again.

“The caravans are becoming larger and larger,” Santiago told Al Jazeera. “If in September and October they were made up of a few hundred people, now they are made up of thousands.”

Hundreds have sought medical attention from his 16-person MSF team in Santiago Niltepec, as a "migrant caravan" passed through the city in November.

Perez and his family were part of the recent caravan, which Santiago estimated to comprise 2,000 people.

Caravans began forming in 2018 as hundreds of migrants and asylum seekers banded together for safety. The groups offered an alternative to the human traffickers who charged thousands of dollars for safe transit to the US border.

Members of November's caravan estimated they walked between 30 and 40 kilometres per day — between 19 and 25 miles — often travelling by night to avoid scorching daytime temperatures.

Still, experts say the groups often disintegrate before reaching their destination. And the caravans, no matter their number, are still vulnerable to unscrupulous authorities and Mexican drug cartels that use violence to demand bribes and ransoms.

"There has been a notable increase in patients who have experienced violent attacks in November," Santiago told Al Jazeera.

Sometimes, members of the caravan get into fights among themselves, he explained. But the principal danger comes from outside groups like the cartels.

Santiago said he has heard reports of "attacks against young people, boys, girls, women and men of all ages who are exposed to kidnappings, extortion and sexual violence".