Science in the time of cholera (and nodding syndrome)

Published online January 11, 2012.

In August 1854 a terrible illness tore through a London neighborhood, killing hundreds in a matter of days. The terrifying disease emptied the body of fluid until vital organs shut down, after which point the petrified soul would succumb to the illness. Death often arrived less than twelve hours after the first signs of an upset stomach. Londoners of the day had a name for this illness, but did not understand its cause. They called it cholera.

Though cholera outbreaks had hit London before the mid-1800s, the Broad Street Pump outbreak of 1854 is now perhaps the best known. It was during this scourge that physician John Snow was able to demonstrate that cholera was not an airborne disease, as was the popular and professional opinion at the time, but rather a waterborne disease. This insight proved critical to improving public health in London and beyond. Londoners had been emptying their waste into the Thames, often just upstream of intake pipes for water companies. Their water and city stunk. But because disease was thought to be airborne, they doused smelly sidewalks in chloride of lime in attempt to purify the air. They made few attempts to purify the water so obviously contaminated with their own waste.

When cholera inevitably struck, they applied all manner of remedies, most of them useless at best. Castor oil, opium, and leeches were all espoused to treat cholera, not just by ordinary folks, but also by doctors. Worse still were treatments such as laxatives or bleeding. The extreme dehydration facilitated by cholera was often “treated” by attempts to further remove fluids from the body.

In hindsight, both the cause and the treatments for cholera are straightforward, if not obvious. Cholera is a waterborne illness that spreads when one person ingests the cholera-infected waste of another person. The treatment for the extreme dehydration that ensues is most fundamentally rehydration – consuming copious amounts of fluid to replace those that are lost. Yet at its emergence, a series of facts and observations did not at first fit together in a single theory about the cause of cholera. When cholera struck a household, sometimes it struck everyone, sometimes just a single person. In a neighborhood, some homes would be hard hit, while others escaped untouched. Whether you survived or not seemed random.

So it is with another illness in our midst – nodding disease. Nodding disease sounds like a folksy and tabloid-inspired syndrome. Its name describes the telltale symptoms of the disease, a rhythmic head nodding in children. The fact that unlike many diseases its name does not betray anything about its likely causes demonstrates just how little we know about its transmission. For example, HIV (human immunodeficiency virus) is named for the virus that causes AIDS. The name malaria comes from the Italian mala aria, meaning “bad air”, so named because the illness we now know is caused by a parasite was originally thought to be airborne.

But despite its odd name, nodding disease is far from folksy or fake. It is often fatal. First reported in Tanzania in 1962, nodding disease has since spread throughout what is now South Sudan, and has been rapidly spreading in northern Uganda as well.

The pattern of incidence of nodding disease and its symptoms are puzzling, as were those of cholera in the early nineteenth century. First, the onset of nodding disease appears to occur almost exclusively in children between the ages of 5 and 15.

Second, nodding is reportedly often triggered by the presence or eating of familiar foods, or when a child becomes cold. Unfamiliar foods, such as chocolate candy bars, do not induce nodding. Third, when untreated, those with nodding syndrome cease developing both physically and mentally. They are often stunted and experience mental retardation. Fourth, most children affected come from very poor families. There are now thousands of children in South Sudan and northern Uganda who experience symptoms of nodding disease, and the incidence of the syndrome appears to be increasing.

Several theories regarding the cause of the syndrome have been mooted, but none proven. For the past several years, teams of experts from the U.S. Centers for Disease Control (CDC) and World Health Organization (WHO) have travelled to South Sudan and northern Uganda in an attempt to better understand the causes of nodding disease, and possible treatments. Their work suggests that nodding disease is a new epilepsy syndrome, and that the characteristic head nodding is caused by seizures that lead to temporary lapses in neck muscle tone.

A vast majority of children experiencing symptoms of nodding disease are also infected with a parasite called Onchocerca volvulus, which causes river blindness. The high prevalence of this parasite in victims of nodding disease means that the most plausible (published) theory about the cause of nodding disease links the syndrome to O. volvulus, but how and why remain unclear. Moreover, there are a number of children both in and outside the region who are infected with the parasite and do not acquire nodding disease, so the link between the two is not straightforward.

So far, therefore, we have accumulated a series of facts about the mysterious syndrome, which have yet to be pieced together in a coherent theory. We have many more tools at our disposal than did the Londoners of the 1800s, but answers to pressing medical and public health questions do not usually come without time and resources. Nodding disease is a terrifying prospect for those living in South Sudan and northern Uganda not only because of the debilitating effect it has on children, but also because families and communities do not understand why their children are falling ill in the first place. A confusing array of facts, theories, and observations are unnerving both to those in the midst of the outbreak, but also those who see its spread as a very serious health issue for the region.

Misunderstanding the causes of nodding disease can have disastrous consequences, as was the case with cholera some 150 years ago. So far, anti-epilepsy treatments appear to be helping children experiencing nodding disease, but supplies of these treatments are often scarce, and determining the ultimate cause of epilepsy in these children should be a high priority for health officials. Cases of epilepsy are often documented at high rates in hospitals in the region, and there is thought to be a link between epilepsy and cerebral malaria as well. In Arua Regional Referral Hospital, in northwestern Uganda at the border with Sudan and DRC, 7 percent of all outpatient children over age 5 in April 2009 were diagnosed with epilepsy. In 2004/05, 74 percent (nearly 4500) of all cases in the Mental Ward were diagnosed as epilepsy.

Clearly, epilepsy, whether nodding disease or otherwise, is a condition that deserves the utmost attention from public health and medical professionals. The sooner we understand the causes of this new breed of epileptic seizures, the sooner we can take steps to both treat it and prevent its spread. In the absence of a compelling theory about its cause, however, fear and futile treatments are likely to ensue.

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