Outbreak of Nodding Syndrome Spreads

Yael Waknine

January 31, 2012 — The US Centers for Disease Control and Prevention (CDC) has issued recommendations geared toward controlling an outbreak of nodding syndrome in South Sudan. The permanent neurologic condition previously was reported in the neighboring countries of Uganda and Tanzania.
Nodding syndrome, which primarily affects children aged 5 to 15 years, is characterized by episodes of perpetual-motion head nodding that makes eating and drinking difficult. It is often accompanied by seizurelike activities such as nonresponsive staring spells and convulsions that can lead to injury or death.
Although its etiology and pathophysiology remain unknown, nodding syndrome has been linked to current infection with the nematode Onchocerca volvulus, which causes river blindness (onchocerciasis).
CDC recommendations include reinforcing mass ivermectin therapy to treat onchocerciasis and the antiepileptic management of seizures, as well as enhanced surveillance to enable identification of epidemiologic patterns. No recoveries have been reported among children and adolescents with nodding syndrome.
The report was published in the January 27 issue of the Morbidity and Mortality Weekly Report.
Investigation and Results
In May 2011, a team of CDC investigators responded to a request for assistance from the Sudanese Ministry of Health regarding a recent increase and geographic clustering of nodding syndrome cases.
After ascertaining that the clinical syndrome was the same as that observed in other East African countries, 38 case patients (mean age, 11.1 years; range, 7 - 16 years) were matched by age and location to 38 control patients (mean age, 10.6 years; range, 6 - 17 years).
All participants were recruited from clusters in the rural village of Witto (13 pairs) and the semiurban town of Maridi (25 pairs) in South Sudan's state of Equatoria.
Overall, the prevalence of current onchocerciasis, as diagnosed by skin snip, was significantly higher among case patients than control patients (76.3% vs 47.4%; matched odds ratio [mOR], 3.2; P = .02).
However, the increase was location-specific and driven by Maridi participants (88.0% vs 44.0%; mOR, 9.3; P = .001); no significant association with river blindness was found in Witto (53.8% vs 53.8%; mOR, 1.0; P = n/a).
Other Causes?
The cause of nodding syndrome and its mode of transmission remain unknown. Preliminary analyses of the collected data show no association with other risk factors, including exposure to munitions, parents' occupations, and demographic characteristics.
Additional analyses will explore the potential role of malnutrition, pending laboratory test results for certain vitamins (eg, A, B6, and B12). The presence of O volvulus antibodies, heavy metals, and genetic markers are also being evaluated.
According to the authors, enhanced surveillance is needed to identify new cases as they occur, their location, and patient age at onset. Further collaborative investigations may also help to identify the cause of nodding syndrome, as well as preventive measures and treatments.
Morb Mortal Wkly Rep.Full text  http://www.medscape.com/viewarticle/757813