"The continued arrival of refugee families from Sudan, where measles and meningitis outbreaks are ongoing," is fuelling the surge in meningitis and measles cases in border areas of eastern Chad, said MSF. "In the camps, overcrowding, limited access to water and healthcare, and malnutrition facilitate rapid transmission and increase the risk of severe complications, particularly among children under five." The organisation said that in Adre, near the border, measles cases had gone up from 16 in January to 371 in March, with 161 cases recorded in the first two weeks of April.

Meningitis cases have gone from 18 in January to 109 in March and 101 by mid-April. "Every day, we see children arriving with severe measles, often complicated by pneumonia, requiring urgent hospitalisation," said Isabelle Kavira, MSF's medical activity manager in Adre. "At the same time, bed occupancy for meningitis is close to 100 percent, saturating our capacity and compromising care for other conditions."

The medical charity said that over three weeks, Chad's health ministry, with MSF support, had carried out the emergency vaccination of more than 95,500 children against measles and 337,800 people against meningitis. However, disruptions in the refrigeration needed to preserve vaccine doses and gaps in routine immunisation "leave entire populations exposed", MSF warned. Without strengthening routine vaccination, "reactive campaigns alone will not be sufficient", it said. Nearly 1,400 kilometres (870 miles) long and located in a desert region, the border between Chad and Sudan is porous and difficult to control.