Jump to content

Nodding disease: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
Line 14: Line 14:
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.<ref name="NS" /> ''O. volvulus'', a [[nematode]], is carried by the [[black fly]] and causes [[Onchocerciasis|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.<ref>[http://web.archive.org/web/20060519084631/http://www.yaleph.com/archive/vol1no1/reg_focus.html 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</ref> A link between river blindness and normal cases of [[epilepsy]],<ref>{{cite journal |author=Druet-Cabanac M, Boussinesq M, Dongmo L, Farnarier G, Bouteille B, Preux PM |title=Review of epidemiological studies searching for a relationship between onchocerciasis and epilepsy |journal=Neuroepidemiology |volume=23 |issue=3 |pages=144–9 |year=2004 |pmid=15084784 |doi=10.1159/000075958}}</ref> as well as retarded growth,<ref>{{cite journal |author=Ovuga E, Kipp W, Mungherera M, Kasoro S |title=Epilepsy and retarded growth in a hyperendemic focus of onchocerciasis in rural western Uganda |journal=East African medical journal |volume=69 |issue=10 |pages=554–6 |year=1992 |pmid=1473507}}</ref> has been proposed previously, although the evidence for this link is inconclusive.<ref>{{cite journal |author=Marin B, Boussinesq M, Druet-Cabanac M, Kamgno J, Bouteille B, Preux PM |title=Onchocerciasis-related epilepsy? Prospects at a time of uncertainty |journal=Trends Parasitol. |volume=22 |issue=1 |pages=17–20 |year=2006 |pmid=16307906 |doi=10.1016/j.pt.2005.11.006}}</ref> 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".<ref name="NS" /> 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."<ref name="Nature" />
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.<ref name="NS" /> ''O. volvulus'', a [[nematode]], is carried by the [[black fly]] and causes [[Onchocerciasis|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.<ref>[http://web.archive.org/web/20060519084631/http://www.yaleph.com/archive/vol1no1/reg_focus.html 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</ref> A link between river blindness and normal cases of [[epilepsy]],<ref>{{cite journal |author=Druet-Cabanac M, Boussinesq M, Dongmo L, Farnarier G, Bouteille B, Preux PM |title=Review of epidemiological studies searching for a relationship between onchocerciasis and epilepsy |journal=Neuroepidemiology |volume=23 |issue=3 |pages=144–9 |year=2004 |pmid=15084784 |doi=10.1159/000075958}}</ref> as well as retarded growth,<ref>{{cite journal |author=Ovuga E, Kipp W, Mungherera M, Kasoro S |title=Epilepsy and retarded growth in a hyperendemic focus of onchocerciasis in rural western Uganda |journal=East African medical journal |volume=69 |issue=10 |pages=554–6 |year=1992 |pmid=1473507}}</ref> has been proposed previously, although the evidence for this link is inconclusive.<ref>{{cite journal |author=Marin B, Boussinesq M, Druet-Cabanac M, Kamgno J, Bouteille B, Preux PM |title=Onchocerciasis-related epilepsy? Prospects at a time of uncertainty |journal=Trends Parasitol. |volume=22 |issue=1 |pages=17–20 |year=2006 |pmid=16307906 |doi=10.1016/j.pt.2005.11.006}}</ref> 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".<ref name="NS" /> 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."<ref name="Nature" />


The CDC is investigating a possible connection with wartime [[chemical warfare|chemical]] exposure.<ref name="Nature" /> Another possible cause is tainted food such as spoiled plants or meats: tainted monkey-meat is one possible suspect.{{CN|date=December 2011}} People in the area have also admitted to eating seeds that were provided by relief agencies and were meant for planting and were covered in toxic chemicals.{{CN|date=December 2011}}
The CDC is investigating a possible connection with wartime [[chemical warfare|chemical]] exposure. The team is also investigating whether a deficiency in [[vitamin B6|vitamin B<sub>6</sub>]] ([[pyridoxine]]) could be a cause, noting the seizures of [[Pyridoxine-dependent epilepsy]] and this common deficiency in disease sufferers.<ref name="Nature" /> Another possible cause is tainted food such as spoiled plants or meats: tainted monkey-meat is one possible suspect.{{CN|date=December 2011}} People in the area have also admitted to eating seeds that were provided by relief agencies and were meant for planting and were covered in toxic chemicals.{{CN|date=December 2011}}


== Prevalence and epidemiology==
== Prevalence and epidemiology==

Revision as of 12:30, 25 December 2011

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]

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 disease since it causes pathological nodding. This is a seizure which begins when the victim begins to eat food, or when he/she feels cold.[4] As soon as either of these conditions is met, the afflicted will immediately begin to nod. These seizures are brief and halt after the child stops eating or when they feel warm again. However, this symptom 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. The seizures can be severe and cause the child to collapse, leading to further injury.[5] Sub-clinical seizures have been identified in electroencephalograms, and MRI scans have shown brain atrophy and damage to the hippocampus and glia cells.[6]

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.[7]

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.[4] 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.[7] 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.[8] A link between river blindness and normal cases of epilepsy,[9] as well as retarded growth,[10] has been proposed previously, although the evidence for this link is inconclusive.[11] 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".[7] 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."[6]

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.[6] Another possible cause is tainted food such as spoiled plants or meats: tainted monkey-meat is one possible suspect.[citation needed] People in the area have also admitted to eating seeds that were provided by relief agencies and were meant for planting and were covered in toxic chemicals.[citation needed]

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[12].

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.[6] 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.[6] 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.[7] Due to poor living conditions and poor healthcare in the regions where the disease is prevalent, little is known about the disease,[13] although neurological scans have been performed on some sufferers.

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. ^ "Nodding disease in East Africa". CNN. Retrieved 6 June 2011.
  4. ^ a b 'Nodding disease' hits Sudan Andrew Harding BBC News 23 September 2003, Accessed 19 October 2007
  5. ^ Bizarre Illness Terrifies Sudanese - 'Nodding Disease' Victims Suffer Seizures, Retardation, Death Emma Ross, CBS News, Jan. 28, 2004. Accessed 19 October 2007
  6. ^ a b c d e Wadman, Meredith (13 July 2011). "African outbreak stumps experts". Nature. Retrieved 25 December 2011.
  7. ^ a b c d Abraham, Curtis (23 December 2011). "Mysterious nodding syndrome spreading through Uganda". New Scientist. Retrieved 25 December 2011.
  8. ^ 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
  9. ^ 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)
  10. ^ 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)
  11. ^ 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)
  12. ^ Meredith Wadman (13 July 2011). "Box: A growing threat". Nature. Retrieved 11 July 2011.
  13. ^ Sudan A Hotbed Of Exotic Diseases - Country Has Unique Combination Of Worst Diseases In The World Emma Ross, Sudan, Feb. 3, 2004, CBS News. Accessed 19 October 2007
Retrieved from "https://en.wikipedia.org/w/index.php?title=Nodding_disease&oldid=467623500"