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Nodding disease

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Nodding disease or nodding syndrome is a new, little-known disease which emerged in Sudan in the 1980s.[1] 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.[2][3] Prior to the South Sudan outbreaks and subsequent limited spread, the disease was first described in 1962 existing in secluded mountainous regions of Tanzania,[4] although the connection between that disease and nodding syndrome was only made recently.[3]

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 to mental 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.[5] 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."[6] Severe seizures can cause the child to collapse, leading to further injury.[7] Sub-clinical seizures have been identified in electroencephalograms, and MRI scans have shown brain atrophy and damage to the hippocampus and glia cells.[4]

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.[citation needed]

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[8] and phenobarbitol. Anti-malaria drugs has also been administered, to unknown effect.[6]

Prognosis

As the disease is not well known, little is known about the prognosis. It is thought to be a very debilitating disease physically and mentally. While a few children are said to have recovered from it, many have died from the illness.[5] 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.[8] 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.[9] A link between river blindness and normal cases of epilepsy,[10] as well as retarded growth,[11] has been proposed previously, although the evidence for this link is inconclusive.[12] 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".[8] 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."[4]

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 of Pyridoxine-dependent epilepsy and this common deficiency in disease sufferers.[4] 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.[5]

Prevalence and epidemiology

The map of South Sudan districts affected by nodding disease. Red district was already affected in 2001, yellow districts are prevalent in 2011 and in green districts there are only sporadic reports[13].

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.[4] 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 North to centre around Uganada's Kitgum district,[2] and the Ugandan ministry of health declared that more than 2000 children had the disease.[4] 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.[8] The spread and manifestation of outbreaks may further be exacerbated due to the poor health care of the region.[6]

References

  1. ^ Lacey M (2003). "Nodding disease: mystery of southern Sudan". Lancet neurology. 2 (12): 714. doi:10.1016/S1474-4422(03)00599-4. PMID 14649236.
  2. ^ a b UGANDA: Nodding disease or "river epilepsy"? IRIN Africa. Accessed 19 October 2010
  3. ^ a b "Nodding disease in East Africa". CNN. Retrieved 6 June 2011.
  4. ^ a b c d e f Wadman, Meredith (13 July 2011). "African outbreak stumps experts". Nature. Retrieved 25 December 2011.
  5. ^ a b c 'Nodding disease' hits Sudan Andrew Harding BBC News 23 September 2003, Accessed 19 October 2007
  6. ^ a b c Ross, Emma (3 February 2004). "Sudan A Hotbed Of Exotic Diseases". CBS News. Rumbek, Sudan. Retrieved 25 December 2011.
  7. ^ Bizarre Illness Terrifies Sudanese - 'Nodding Disease' Victims Suffer Seizures, Retardation, Death Emma Ross, CBS News, Jan. 28, 2004. Accessed 19 October 2007
  8. ^ a b c d Abraham, Curtis (23 December 2011). "Mysterious nodding syndrome spreading through Uganda". New Scientist. Retrieved 25 December 2011.
  9. ^ When Nodding Means Dying: A baffling new epidemic is sweeping Sudan. Lekshmi Santhosh The Yale Journal of Public Health Vol. 1, No. 1, 2004. Accessed 25 December 2011
  10. ^ Druet-Cabanac M, Boussinesq M, Dongmo L, Farnarier G, Bouteille B, Preux PM (2004). "Review of epidemiological studies searching for a relationship between onchocerciasis and epilepsy". Neuroepidemiology. 23 (3): 144–9. doi:10.1159/000075958. PMID 15084784.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Ovuga E, Kipp W, Mungherera M, Kasoro S (1992). "Epilepsy and retarded growth in a hyperendemic focus of onchocerciasis in rural western Uganda". East African medical journal. 69 (10): 554–6. PMID 1473507.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ Marin B, Boussinesq M, Druet-Cabanac M, Kamgno J, Bouteille B, Preux PM (2006). "Onchocerciasis-related epilepsy? Prospects at a time of uncertainty". Trends Parasitol. 22 (1): 17–20. doi:10.1016/j.pt.2005.11.006. PMID 16307906.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ^ Meredith Wadman (13 July 2011). "Box: A growing threat". Nature. Retrieved 11 July 2011.
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