Three-quarters of people with cholera will show little or no signs of disease, which means Zimbabwe may have thousands more people infected with cholera than the 9 000 cases that have reportedly been identified clinically.
But these people will still be infectious and able to spread the cholera bacterium if their faeces contaminate drinking water or through poor hygiene, especially when preparing food. And with people crossing into South Africa in search of medical care — or food and work — there is a risk of the epidemic spreading to neighbouring countries.
Dr Karen Keddy, head of the enteric diseases reference unit at the National Institute of Communicable Diseases in Johannesburg, says cholera epidemics stop when enough people have developed immunity to the disease to cause it to burn out. Rapid public health responses to prevent transmission are another important factor.
The best response to an outbreak such as that seen on South Africa’s border with Zimbabwe is a full-scale and rapid response — of the kind triggered by Minister of Health Barbara Hogan. It involves treating everyone who may have the disease and a mass and rapid education campaign.
Cholera is a waterborne disease caused by a comma-shaped bacillus, Vibrio cholerae, which attaches itself to the lining of the small intestine. In severe cases the bacteria produces a toxin that causes water to flood out of the body into the small intestine at such a rate that the large intestine is unable to absorb it fast enough. The result is diarrhoea, with stools becoming liquid. Patients can lose up to 20 litres of water a day.
Without treatment the patient becomes steadily more dehydrated. Eventually there will be insufficient water in the body for the organs to function and the victim will die of organ failure.
Cholera, which can kill its victims within hours, is a sign of poor water quality and is particularly notorious for outbreaks in disaster areas and refugee camps. The most vulnerable victims are children, who can die swiftly, as their body pours out the so-called “rice water” stools. But adults can also succumb quickly, some dying within hours.
Malnourished and HIV-positive people are at particular risk.
Outbreaks of cholera can occur in developed countries with proper water and sewerage systems.
The World Health Organisation (WHO) describes cholera as an indicator of social development, and one of the major threats to public health.
The cholera epidemic of 1854 in London was a catalyst for the development of proper sanitary systems in developed countries.
Famously, a doctor, John Snow, linked the outbreak to one particular water well. After he removed the pump handle, the number of new cases dropped.
Dr David Coetzee, director of the infectious disease epidemiology unit at the University of Cape Town, says patients get sick 24 to 72 hours after being infected and usually recover within 48 hours.
The treatment is basic: a steady supply of fluids and electrolytes such as salt and sugars to keep the body hydrated.
It takes between five and seven days for a patient to develop immunity to the disease, so epidemics are self-limiting if patients can be kept alive.
Since 1817 there have been seven cholera pandemics across the world — the last one is considered ongoing — and the experts say the disease is endemic in many parts of the world, including Africa.
There are two strains of the bacterium, the Classic and the El Tor.
Such outbreaks are usually linked to raw food, especially shellfish, that have been living in water infected by the bacillus. Similarly, raw food that has been washed in contaminated water is a source of infection.
For a healthy individual a large number of cholera bacilli need to be ingested, since most of the pathogens will be wiped out by the stomach acid.
The cholera bacterium has the ability to go dormant and then to reactivate, but scientists are still unclear about what triggers these changes.
The disease shows a seasonal pattern, with outbreaks more likely to occur during warmer months, and it is thought that temperature plays a role in activating the pathogen.
There are vaccines against cholera, but they confer only a short-term protection and do not help during outbreaks.
The vaccine takes about two weeks to stimulate a protective immune response and, given that cholera reproduces rapidly, people can become sick even after exposure, before vaccine-dependent immunity has developed.
Boiling water for at least three minutes or putting a capful of bleach in a bucket of water and leaving it for a few hours will kill cholera.
Proper handwashing before and after using the toilet or touching food will also limit its spread.
‘Cholera is part of life here’
For the residents of Matapi, a cluster of rundown blocks of flats in Mbare — Zimbabwe’s oldest township — cholera has always been a part of daily life.
The ground floor of one of the blocks now lies abandoned, taken over by sewage flowing freely from burst pipes on the top floors. Waste cascades down the stairwell from the second floor, where vendors line the dim corridors selling anything from tomatoes to fresh fish.
The flats, owned by the council, have long been abandoned by the authorities. Rentals are paid to local kingpins, there are dodgy power connections, little running water and crime is so rife residents joke about keeping your soap in your mouth when using the common shower for fear that it may be stolen.
Last week two members of one family living in the flats died of the disease. But residents there said cholera deaths are not unusual.
“It’s surprising to hear people talking about cholera only now. We have been trying for years to get government to listen to us, to realise that these conditions were always going to breed a real crisis,” said Aleck Mwale, a community organiser at the flats.
The cholera crisis has its roots in Robert Mugabe’s economic management and his attempts to whittle down the influence of opponents in urban areas.
Mugabe began deploying his strategy to neutralise the influence of the Movement for Democratic Change (MDC) in urban areas three years ago after electoral defeats.
Part of his strategy was to seize control of water and sewage systems from MDC-controlled local councils and hand them to the Zimbabwe National Water Authority. This poorly funded state company had previously been in charge only of running the country’s natural water sources.
As Zimbabwe’s economic crisis worsened the water authority found it increasingly difficult to source funding to import water- treatment chemicals and to repair its ageing water-treatment plants. These plants constantly break down and frequently have to shut down because of power outages.
There has been virtually no investment in new sewerage systems since independence in 1980, and the ageing urban water and sewer network is now collapsing under the strain of booming urban populations.
In the past two months, as the cholera crisis began to spin out of control, the Reserve Bank has ploughed more than R20-million into the water authority. But health experts said the emergency funding came too late.
Thabiso Moyo, mayor of Zimbabwe’s second city, Bulawayo, told the Mail & Guardian on Tuesday that his city had less than a month’s supply of water-treatment chemicals. “We cannot pump untreated water. Until the money for chemicals arrives, we will have to shut down supply,” Moyo said.
Health Minister David Parirenyatwa, who has been more candid than most of his colleagues about the crisis, said this week that the outbreak “scared” him. Cholera would be hard to contain without clean running water, he said.
But other senior officials in the Mugabe administration remain defiant, with a meeting of the Zanu-PF politburo this week saying there was no need to classify the outbreak as a national emergency. The party blames Western powers for the crisis, saying their blockade of Zimbabwe has left the country unable to import water-treatment chemicals and parts with which to refurbish old equipment.
There are fears that with the rain it will be harder to contain the outbreak. “Delay is not an option as this crisis could rapidly spread with the rainy season looming,” said Charles Abani, regional director for aid agency Oxfam. — Jason Moyo