AS OMENS go, it is not a good one. In Kinama, a district in north-east Bujumbura, the cobble-stoned capital of Burundi, residents found the body of a man floating in a field of rice on May 8th. His head was missing; his heart had been torn out. Stuck to his chest was a message written in Kirundi, the language of most Burundians: “Traitors are punished.”

Violence has broken out in Burundi ahead of a referendum on May 17th to change the constitution to allow Pierre Nkurunziza, a former rebel who has been president since the end of the civil war in 2005, to stand for office again in 2020. On May 11th, 26 people were killed in the north-west of the country in an attack by rebels who crossed in from the neighbouring Democratic Republic of Congo. Three days later an opposition activist who had been campaigning against the change was murdered in the street by a crowd of young pro-government militiamen.

Many Burundians expect the constitutional amendment to pass comfortably (no matter which way they actually vote). Having named himself “Supreme Eternal Guide” of the country in March, Mr Nkurunziza could then stay in office until 2034. The referendum in Burundi highlights the steady erosion of term limits in recent years across central Africa (see map). Over the past decade half a dozen countries have ignored or revoked laws limiting presidents to no more than two terms in office.

It also represents the final death of the Arusha accords that ended the civil war, created a blueprint for democracy and mandated power-sharing between Hutus and Tutsis, the two main ethnic groups, whose fighting has torn Burundian politics apart since independence in 1962.

Burundi’s latest crisis began in earnest in 2015, when Mr Nkurunziza decided to run for a third term. His party, the CNDD, which is descended from the Hutu rebel group he led during the civil war, argued that under the constitution his first term did not count. He had been appointed by parliament, not elected, you see. Two months before he was re-elected, his government was briefly overthrown in a coup while he was on a trip to neighbouring Tanzania. In the year afterwards, Burundi was shaken by violence. Opposition supporters (or those merely suspected of being so) were arrested or went missing. Almost half a million people have fled to neighbouring countries. Rights groups say 456 were assassinated in 2017 alone.

Gunshots and grenades are a rarer sound in Bujumbura than they were two years ago, say residents. But repression continues. “Many citizens today live in fear, even if they do not say so aloud,” says Monseigneur Joachim Ntahondereye, president of the Burundian Council of Bishops. The church is one of the few institutions to have spoken out against the constitutional change. Independent journalism has been all but banned; this month, the BBC and Voice of America transmitters were shut down. Most foreign publications have been denied accreditation.

Particularly worrying is the gradual ethnic polarisation of the army. It had been rebuilt under the Arusha accords with quotas for Hutus and Tutsis at all levels of its officer corps, to win the trust of both groups. Yet many of the officers who dominated before 2005, most of them Tutsi, have been forced to retire or posted abroad on peacekeeping missions in places such as Somalia and the Central African Republic. Some officers have been murdered. Meanwhile, rebels who served in Mr Nkurunziza’s force—mostly Hutus—have risen up the ranks. The constitutional amendment opens up the possibility of doing away with ethnic quotas, allowing Mr Nkurunziza to make the army and police completely dominated by Hutus.

The economy has been crushed. GDP per person has fallen every year since 2015, even as the population has risen by around 10% to about 11m. Almost three-fifths of Burundians are “chronically malnourished”, according to the UN’s World Food Programme. Hunger has worsened of late, as the government has increased taxes to pay for the referendum. The only growing industry has been smuggling gold from Congo, where Mr Nkurunziza is said to have allies in the remnants of the genocidal Hutu militias that fled Rwanda after the massacres there in 1994. Fears are growing that a proxy war between Burundi and Rwanda (whose president, Paul Kagame, is a Tutsi) is reigniting in Congo.

There is little hope of outside intervention halting the crisis. The Tanzanian government played midwife to the Arusha accords. Yet today Tanzania itself is sliding into authoritarianism. Its president, John Magufuli, an ally of Mr Nkurunziza, has tried to force Burundian refugees back to their original country. Without regional support, foreign powers such as the European Union are unable to do much. They have already played their strongest card by cutting most aid.

Democracy is struggling in other parts of the region, too. In Congo Joseph Kabila will probably stand as his party’s candidate in presidential elections this year, despite having finished his second and supposedly final term in 2016. In Rwanda Mr Kagame was re-elected last year after changing the constitution to let him stay in power until 2034. In Uganda Yoweri Museveni, who has run the place for 31 years, first abolished term limits in 2005; last year, the 73-year-old also abolished a presidential age limit of 75. That will allow him to run for a sixth presidential term in 2021.

The erosion of term limits bodes ill. Where they have been observed, they are generally associated with a sharp decline in armed conflict, according to the Africa Centre for Strategic Studies, a think-tank in Washington funded by the American government. Where they are ditched, the opposite may prove to be the case. Presidents should be temporary, not eternal.