Since late September 2017, Zambia has been dealing with an outbreak of cholera—believed to have originated in the crowded capital city of Lusaka. Zambia’s Minister of Health reported more than 3,200 cases and 74 deaths on January 14, and the Ministry of Health is collaborating with the WHO to initiate a mass oral cholera vaccination campaign.

The International Federation of Red Cross and Red Crescent Societies’ Emergency Plan of Action for the outbreak noted that it began before Zambia’s rainy season, which is an atypical occurrence. The document also notes that a water scarcity in the summer months led some to seek out alternative water sources, which if contaminated with cholera, could have contributed to the onset of the outbreak. Zambia typically faces sporadic cases of cholera during their 5-month rainy season—from November to March—but there is concern that the impending rain will exacerbate the current situation, as it has in previous outbreaks. Some research suggests that heavy rain may stir up sediments in water and lead to an accumulation of fecal microorganisms, including waterborne pathogens such as Vibrio cholerae, which could increase exposure in populations that utilize untreated water sources. While the initial cases are thought to be a result of consuming water from contaminated shallow water wells, transmission has also been linked to contaminated food and infected food handlers.

Facing the prospect of a worsening outbreak, the Zambian government has taken what some have viewed as extreme measures in an attempt to gain control of the outbreak, and some of these measures have been met with resistance from the affected communities. The current situation in Zambia highlights, in addition to impacts on the public’s health, the significant social and economic impacts that infectious disease outbreaks can cause.

What is Cholera?

Cholera, the topic of several previous Outbreak Thursday reports, is an acute diarrheal infection caused by ingestion of food or water contaminated with the Vibrio cholerae bacterium. Labeled a disease of inequity by the WHO, it predominantly affects populations that, for the most part, suffer from malnutrition and have poor access to safe, clean drinking water and the public health and healthcare services necessary to prevent and treat infection. Symptoms can manifest in as little as 5 hours after infection—typically within 2-3 days—and include diarrhea and vomiting that can quickly result in dehydration and associated complications. Severe symptoms occur in approximately 10% of individuals, which can lead to the rapid loss of bodily fluids and death within hours if not adequately treated. Standard treatments include replacement of lost fluids and salts and antibiotics, and cholera can be prevented with two doses of an oral cholera vaccine administered 10-15 days apart.

Government Response

The Zambian government has been active in attempting to curb the spread of cholera. In collaboration with the WHO, the UN, and the Global Alliance for Vaccines and Immunizations (GAVI), Zambia has initiated a mass cholera vaccination campaign with the goal of vaccinating one million people living in high-risk areas. The first round of immunization began on January 10, while the second dose is scheduled to be administered sometime in February. Additionally, Zambian President Edgar Lungu directed the military to assist with clean-up operations in market areas suspected of spreading the disease, including clearing blocked drains. A recent study found that inefficient drainage systems can lead to flooding and effectively spread waterborne pathogens through runoff.

On January 7, the Zambian government instituted a seven-day curfew and travel restrictions into and out of Lusaka as well as a ban on all public gatherings—including street vending, church services, and schools—in an attempt to prevent the spread of cholera. The curfew and street vending ban has led to serious backlash from those affected, many of whom live in slums and whose livelihood depends on their sales for the day. Several riots over these bans erupted this past weekend, resulting in the use of tear gas and the arrest of 55 individuals.

The market closures, bans on public gatherings, travel restrictions, and curfew have been met with resistance among the public due to their socio-economic effects, and it is unclear what contribution these measures will have with respect to interrupting transmission. Theoretically, measures that curb or limit public exposure to contaminated food or water should help to limit transmission of the disease. If there is considerable concern that food markets are contributing to the spread of cholera, then limiting public access to them could help stop further transmission.

In addition to the health benefits, health officials must carefully consider secondary effects of all disease control strategies. Sometimes, measures aimed at stopping the spread of disease can exacerbate the toll of an outbreak. For example, one study reports that implementing a curfew during an oral cholera vaccination campaign restricted and delayed vaccination operations—clearly, an undesirable outcome.

Another important factor to consider is whether public health interventions support or undermine community engagement and public trust, both of which are essential to implementing effective outbreak response measures. Community engagement is critical to improving water and sanitation/hygiene efforts, which can not only bring existing outbreaks under control, but also prevent future outbreaks. Public trust depends on regular, transparent, and comprehensive communication that balances the risks and benefits of public health interventions.

This past Sunday (January 14), Zambia began relaxing some restrictions, announcing that schools and some marketplaces would reopen. Additionally, Zambia did permit some bars to continue to operate for limited hours to mitigate the negative economic impact, but this was paired with increased hygiene and sanitation inspections to reduce the risk of cholera transmission at these establishments. Hopefully, these efforts will help to ease the tension and allow for outbreak response to run more smoothly.

Fortunately, health officials in Zambia have reported that the number of new cholera cases seem to be declining. Nonetheless, the situation in Zambia is a reminder that outbreaks, and their associated public health interventions, can have profound social and economic consequences in addition to the direct health impact of the disease. Even those interventions that are based on scientific evidence can have significant negative consequences for the affected population. Public officials have the responsibility to ensure the public’s health and safety, and they must be able to anticipate the second- and third-order effects of planned interventions in order to determine the best course of action for everyone. It is critical, particularly in these types of situations, to proactively engage the public and provide them with transparent and honest assessments of the relative risks, benefits, and consequences of these efforts in order to encourage adherence to the official guidance.


Photo: Vibrio cholerae colony growth in agar; courtesy of CDC.

Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly in near-real time to allow others to learn from these experiences in order to improve global outbreak response capabilities.