Why the world is just waking up to the power of immunisations to tackle this infectious disease and why we're learning more with every rainy season.
It's an unusually cool morning in early February in Lusaka in Zambia.
Terence Moyo* huddles into his jacket, leaning against the wall next to his small stationary stall. He loiters outside a cluster of mobile money booths on Lusaka's bustling Cairo Road.
It's the time of year when back-to-school supplies should be in high demand, but he hasn't made a sale all day.
No one has offered him 10 kwacha (less than one rand) for a pen or haggled for the price of a notepad. Part of the problem is that a passer-by wouldn't realise that he sells anything at all. But there's a good reason for that.
Nearby, a group of soldiers sit under the shade of a tree. Moyo's eyes dart nervously towards them, but the militias laugh and joke among themselves, showing him no interest.
Unknown to them, his stationery supply is hidden in a nearby abandoned money booth. He might not have any profit to take home to his six children tonight, but at least he has not been arrested.
Zambian traders and vendors gesture and chant slogans as they take part in a January 2018 protest in Lusaka following a ban on street trading amid the country's latest deadly cholera outbreak. (Dawned Salim, AFP)
On a normal day, Moyo's stationery table would be sandwiched between second-hand clothing laid out on the pavement and trestles bearing tomatoes and onions. But this morning there are no other vendors to compete with: the wind whips across open spaces as men wearing pinstripes and pleather hurry into office blocks.
"I was told that the last time we had it bad like this was in the Eighties," mumbles a university student walking past Moyo's hideout.
About seven months ago, a cholera outbreak hit Zambia - an event that has drastically changed the lives of Moyo and his colleagues.
Although easily treated, cholera can lead to severe diarrhoea, vomiting and dehydration in those who contract it, usually through water contaminated by infected faeces, the United States nonprofit the Mayo Clinic says on its website.
Zambia's cholera outbreak began in late September 2017. By February, there had been about 3200 cases of the bacterial infection and 74 deaths, according to the United Nations Children's Fund.
The Zambian government launched a huge effort to control the outbreak, forbidding public gatherings, including weddings, funerals and church meetings. Markets were shut down, as well as bars, nightclubs and other public places the government claimed "posed a risk of spreading cholera". In the badly affected township of Kanyama in Lusaka, a 6pm curfew was imposed. The country even postponed the start of the school year.
And the Zambian military enforced a ban on street vending in Lusaka.
The rub? Cracking down on street vendors such as Moyo, imposing curfews and even enacting quarantine zones don't work to control cholera, says the World Health Organisation (WHO) website, because they don't eradicate the source of outbreaks or stem transmission.
Reported instances in which police in Lusaka have bulldozed mobile money booths and used rubber bullets and tear gas to disperse tradespeople and worshippers are even further off the mark.
But they do make for an interesting show, says Landon Myer, the head of epidemiology and biostatistics at the University of Cape Town's School of Public Health. He says the Zambian government's harsh measures smack of attempts to use a national emergency such as an outbreak of disease as a false pretense to increase social, economic and even political control.
"As with any 'state of emergency', governments can use disease outbreaks - and the fear that they can cause - as an excuse to implement new policies with other aims. Perhaps that is what we are seeing here."
It's a political manoeuvre with a long history dating back to efforts to control and prevent tuberculosis and sexually transmitted infections in the first half of the 20th century and more recently to early responses to the HIV epidemic, he says.
Responses such as these often do more harm than good, diverting scarce resources and undermining public trust and co-operation.
The Zambian government did not respond to requests for comment.
But not all of the country's prevention and control efforts have been as bizarre and unscientific as curfews. Zambia has started to provide clean drinking water to people living in cholera-affected areas and is increasing household efforts to chlorinate water to stamp out the bacterium. It has also rolled out vaccines, and intend to vaccinate more than 74% of adults and children against the infectious disease, said Zambian health minister Chilufya Chitalu in a media statement released in mid-January.
"We have recorded in the last 24 hours ... a drastic reduction in numbers," he said. "Now we are [on] terra firma [feeling safe]."
A doctor tends to a woman at Lusaka's Heroes Stadium, which was converted into a temporary hospital to house mounting patient as cholera swept through the city earlier this year. (Dawood Salim, AFP)
Cholera is as familiar to most Zambians as the summer holidays. Its first major outbreak occurred in 1990 and lasted until 1993. Since then, the country has registered cholera cases almost every year. The number of people affected fluctuates from a few hundred cases to thousands admitted to hospital, according to the WHO.
Globally, no one knows exactly how many people contract cholera and die each year because most cases are never reported, a 2015 study published in the journal PLOS Neglected Tropical Diseases shows. But researchers estimate the bacterium infects 2.86-million people annually of whom 95 000 will die - mostly in Sub-Saharan Africa.
Vaccines such as those being used in Zambia may be a standard part of controlling cholera outbreaks now but this wasn't the case just a few years ago. And the world continues to find new ways of using vaccines to fight cholera with each new rainy season, it seems.
In many countries, from Haiti to Zambia, that fall prey to cholera its emergence is often heralded by the rains. This may be in part because heavy rains cause sewage to contaminate water pooling on the ground and beneath its surface that people use to drink, bath and wash clothes, 2013 research published in the journal Epidemics argues.
But in 2012, cholera came to Guinea before the rains, appearing in the town of Forécariah, about two hours outside the capital, Conakry. At the time, the West African country had not seen a cholera outbreak since 2007. Soon, hundreds of cases had appeared as cholera had made its way down the N4 highway from the mining town to the country's economic centre.
Figures for neighbouring Sierra Leone's outbreak were already in the tens of thousands, according to epidemiologists from the international medical humanitarian organisation Doctors Without Borders (MSF), quoted in a 2013 study also published in PLOS Neglected Tropical Diseases.
If cholera's early arrival in Guinea and the outbreak raging next door were not bad enough, the country's long spell without major epidemics meant many Guineans had never encountered the disease before and therefore lacked any natural immune defence to it, MSF doctors warned.
These, they said, were the signs of a looming major epidemic. That's when they decided to try something new.
As Guinea's ministry of health implemented standard responses to cholera, including providing clean water and educating people about the disease, it also began doing something no one in Africa had ever done before: widespread, reactive immunisations.
At the time, the WHO had approved two oral vaccinations to prevent and control the illness. But fear about how people would view the immunisations, their cost and how quickly they could be rolled out in an outbreak had prevented African countries from using them to contain an epidemic. Even the more affordable two-dose vaccine Sanchol still costs about R22 a dose, according to a 2016 study published in PLOS Neglected Tropical Diseases.
That is until Guinea. In partnership with the health department, MSF teams immunised at least adults and children older than one year with the two-dose vaccine, MSF said in a 2012 statement.
MSF's hunch worked. The vaccinations helped to stop new cases and, contrary to initial fears, people did not reject the prevention efforts.
In people who received both doses, Sanchol reduced their risk of contracting cholera by almost 87%, MSF researchers found in a 200-person study conducted during the outbreak. The research was published in 2014 in the New England Medical Journal.
In two towns, Boffa and Forécariah, where initial cases were first reported, at least 79% of those targeted by campaigns made sure they got both of the doses needed to provide the best protection against the bug, a study published in a 2013 edition of PLOS Neglected Tropical Diseases shows.
Watch: MSF doctors explain new vaccination techniques in this 2012 video
In Zambia, MSF piloted the same approach in the 2016 outbreak in Lusaka - the city's first in four year.
But there was a catch: because of a global cholera vaccine shortage, the organisation and health authorities could initially only provide about 500 000 people with just one of the vaccine's two doses. Additional doses were administered as more supplies became available.
Surprisingly, health workers found that a single dose was as effective in protecting people against cholera as two doses were, albeit for a shorter time, MSF argued in a February letter to the New England Medical Journal. This worked equally well whether people had been exposed to cholera previously or not, although more work will need to be done to prove this in young children.
"According to these results, people vaccinated can be protected against cholera a few days after receiving one dose. This is important in outbreaks when we need to protect people quickly," says Francisco Luquero with MSF's epidemiological research arm, Epicentre, in a statement.
Today, the WHO has approved four oral cholera vaccinations. But Luquero says Zambia's 2016 outbreak amid a worldwide shortage of such immunisations remains a stark warning.
"While the availability of vaccines has improved in recent years, the number is still far from being sufficient to tackle the large-scale outbreaks we are currently seeing, such as those currently ongoing in the Democratic Republic of Congo or Yemen."
But vaccines can't solve the real reason cholera continues to make regular appearances in Zambia.
"The single biggest intervention [to prevent cholera] ... is the provision of safe water accompanied by good sanitation. In the absence of that, you are always going to have a population that's at risk," says Karen Keddy, head of the centre of enterology at South Africa's National Institute for Communicable Diseases.
Most Lusaka neighbourhoods don't even have sewer lines, says Mweemba Siyankuku, an engineer for Zulu Burrow Development Consultants. The Lusaka-based company is working to provide clean drinking water and sanitation to more than 1.2-million Lusaka residents as part of a $355-million (R4.1-billion) US-funded project.
Part of this will include expanding Lusaka's sewer system.
"When someone moves on to the plot they build a pit latrine and also a shallow well. That shallow well will eventually be infected with faecal matter," Siyankuku says.
A second major aim is to rehabilitate old water lines, where leakages risk not only water loss but also allow contaminated groundwater to seep into drinking water.
But the new project brings its own problems, such as the interruption of trade.
When Siyankuku spoke to Bhekisisa, he was in the township of Gardens identifying which marketeers operated along the "construction corridor" of a new intended water pipe.
"We will need them to resettle," he explains. "They will be compensated but how much we will pay them depends on what they are selling. Most people have been co-operative, others are not."
Changes in the way Lusaka gets and uses its water may take time to get used to but it's the only way to protect Zambians in the long run.
"Even if you bring them clean water, some people will still go back to their old ways. People are swimming and throwing trash in the expensive drains we have built," Siyankuku says.
"In a few weeks' time, when the cholera cases go down to zero, you will see the government will do nothing again. It's about sanitation and drinking water; it's not about chasing street vendors."
*In the interest of Moyo's safety, his name has been changed