TRIVIA: THE MYSTERY OF NODDING DISEASE

Nodding disease or nodding syndrome is a new, little-known disease which emerged in Sudan in the 1960s. It is a fatal, mentally and physically disabling disease that only affects young children typically between the ages of 5 and 15. It is currently restricted to small regions in South Sudan, Tanzania and 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.

Symptoms

The symptoms of nodding disease are very peculiar. When a child is affected by it, his/her growth appears to be completely and permanently stunted. The growth of the brain is also stunted, leading tomental retardation of the victim. The disease is named nodding syndrome since it causes pathological nodding. This is a seizure which often begins when the victim begins to eat food, or sometimes when he/she feels cold. These seizures are brief and halt after the child stops eating or when they feel warm again. These seizures can manifest themselves with a wide degree of severity.Neurotoxicologist Peter Spencer, who has investigated the disease has stated that upon presentation with food, "one or two [children] will start nodding very rapidly in a continuous, pendulous nod. The child next door will suddenly go into a grand-mal seizure, others will freeze." Severe seizures can cause the child to collapse, leading to further injury. Sub-clinical seizures have been identified inelectroencephalograms, and MRI scans have shown brain atrophy and damage to the hippocampus and glia cells.

The nodding is very unusual as the victims don't appear to suffer from seizures when they are given an unfamiliar food, for example a candy bar.

Diagnosis and treatment

Diagnosis is not very advanced and is based on the telltale nodding seizures of the victims. Stunted growth and mental retardation along with the seizures means there is a high probability that the disease is present. Neurological scans may also be used in attempts to diagnose symptoms of the disease in the future. As there is no known cure for the disease, treatment of the symptoms has included the use of anticonvulsants such as sodium valproate and phenobarbitol. Anti-malaria drugs have also been administered, to unknown effect.

Prognosis

Nodding syndrome is thought to be a very debilitating disease physically and mentally. In 2004, Peter Spencer stated: "It is, by all reports, a progressive disorder and a fatal disorder, perhaps with a duration of about three years or more." While a few children are said to have recovered from it, many have died from the illness. The seizures, as mentioned before, could also cause children to collapse and further injure themselves or die, for example, by falling into an open fire.

Possible causes

It is currently unknown what causes the disease, however it is believed to be connected to infestations of the parasitic worm Onchocerca volvulus, which is prevalent in all outbreak areas. O. volvulus, a nematode, is carried by the black fly and causes river blindness. In 2004, most children suffering from nodding disease lived close to the Yei River, a hotbed for river blindness, and 93% of nodding disease sufferers were found to harbor the parasite--far more than disease-sufferers without it. A link between river blindness and normal cases of epilepsy, as well as retarded growth, has been proposed previously, although the evidence for this link is inconclusive. Of the connection between the worm and the disease, Scott Dowell (the lead investigator into the syndrome for the US Centers for Disease Control and Prevention (CDC)) stated: "We know that [Onchocerca volvulus] is involved in some way, but it is a little puzzling because [the worm] is fairly common in areas that do not have nodding disease". Andrea Winkler, the first author of a 2008 Tanzanian study has said of the connection: "We could not establish any hint that Onchocerca volvulus is actually going into the brain, but what we cannot exclude is that there is an autoimmune mechanism going on." In the most severely affected region of Uganda, infection with microfilariae in epileptic or nodding children ranged from 70% to 100%.

The CDC is investigating a possible connection with wartime chemical exposure. The team is also investigating whether a deficiency in vitamin B₆ (pyridoxine) could be a cause, noting the seizures ofPyridoxine-dependent epilepsy and this common deficiency in disease sufferers. Older theories include a 2002 toxicology report that postulated a connection with tainted monkey meat, as well as the eating of agricultural seeds provided by relief agencies that were covered in toxic chemicals.

Prevalence and epidemiology

While occurrences of the disease known as "nodding syndrome" have been relatively recent, it appears that the condition was first documented in 1962 in southern Tanzania. More recently, nodding syndrome was previously most prevalent in South Sudan, where in 2003 approximately 300 cases were found in Mundri alone. By 2009, it had spread across the border to Uganda's Kitgum district, and the Ugandan ministry of health declared that more than 2000 children had the disease. As of the end of 2011, outbreaks were concentrated in Kitgum, Pader and Gulu. More than 1000 cases were diagnosed in the last half of that year. The spread and manifestation of outbreaks may further be exacerbated due to the poor health care of the region. 

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