Nodding disease or nodding syndrome is an unusual syndrome of unknown etiology characterized by nodding with or without meals and associated with generalized myoclonic type seizures, severe mental retardation, and physical growth impairment. It is affecting children mainly between 5 to 15 years. It is currently restricted to small regions in South Sudan, Tanzania, and northern Uganda. Prior to the South Sudan outbreaks and subsequent limited spread, the disease was first described in 1962 existing in secluded mountainous regions of Tanzania although the connection between that disease and nodding syndrome was only made recently.
Yet there was no confirmed cause for the Nodding syndrome, but it is believed to be connected to infestations of the parasitic worm Onchocercia volvulus, which is prevalent in all outbreak areas. O. volvulus is a nematode, carried by the black fly and causes river blindness. In 2004, most children suffering from nodding disease in South Sudan lived close to the Yei River, a hotbed for river blindness, and 93.7% of nodding disease sufferers was found to harbor the parasite a far higher percentage than in children without the disease. A link between river blindness and normal cases of epilepsy,as well as retarded growth, had been proposed previously, although the evidence for this link is inconclusive. The Syndrome is localized but River blindness is not only localized to those places. The CDC is investigating a possible connection with wartime chemical exposure. Deficiency of Vitamin B6 (pyridoxine), consumption of tainted monkey meat, as well as agricultural seeds provided by relief agencies were among the suspected causes of nodding syndrome.
The clinical features, the imaging findings and natural course of the syndrome are similar to post measles sub-acute sclerosingpanencephalitis, but measles is endemic in most parts of Sub Sahara Africa and not only localized to those geographic areas.
The symptoms of nodding disease are very peculiar. The growth of children affected by the syndrome is stunted completely and permanently. The growth of the brain is also stunted, leading to mental handicapping of the affected individuals. The disease is named nodding syndrome due to the characteristic, pathological nodding seizure. The seizure often begins when the children begin to eat, or sometimes when they feel cold. These seizures are brief and halt after the children stop eating or when they feel warm again. These seizures can manifest themselves with a wide degree of severity. Sub-clinical seizures have been identified in electroencephalograms, and MRI scans have shown brain atrophy and damage to the hippocampus and glia cells.
Diagnosis and treatment
Diagnosis is not very advanced and is based on the telltale nodding seizures of the victims. When stunted growth and mental handicap are also present, probability of nodding syndrome is high. As there is no known cure for the disease, treatment has been directed at symptoms, and has included the use of anticonvulsants such as sodium valproate and phenobarbitol. Administration of Pyridoxine is also recommended in some of the countries like Uganda; though pyridoxine was proven to help in control of other types of seizures too (so lacks specificity).
Nodding syndrome is progressive and debilitating both physically and mentally. Patients rarely survive more than few years though few children are said to have recovered from it.
Conclusion and recommendations:
Nodding syndrome is a mysterious health problem affecting children in localized areas in Eastern part of Africa. The problem is slowly progressive and fatal. The cause is yet to be known and hence there is no effective treatment for it. The problem is posing serious political and socioeconomic concerns in addition to its public health consequences. It is prudent to give a due attention for possible Infectious, Nutritional, Environmental or Genetic factors during further investigation of the causes.
Compiled by Mamude Dinkiye Ali (MD, MPH)
Juba, South Sudan