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Nodding disease, also known as nodding syndrome, is a mentally and physically disabling disease that affects children aged 3 and above, continuing into adulthood. It was first described in 1962 in secluded mountainous regions of
Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...
, with sporadic outbreaks in the decades since in
South Sudan South Sudan (), officially the Republic of South Sudan, is a landlocked country in East Africa. It is bordered on the north by Sudan; on the east by Ethiopia; on the south by the Democratic Republic of the Congo, Uganda and Kenya; and on the ...
,
Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...
, and again in Sudan with its largest outbreak from 2016 to present. Since 2019 cases have been identified in the
Democratic Republic of the Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...
,
Central African Republic The Central African Republic (CAR) is a landlocked country in Central Africa. It is bordered by Chad to Central African Republic–Chad border, the north, Sudan to Central African Republic–Sudan border, the northeast, South Sudan to Central ...
and
Cameroon Cameroon, officially the Republic of Cameroon, is a country in Central Africa. It shares boundaries with Nigeria to the west and north, Chad to the northeast, the Central African Republic to the east, and Equatorial Guinea, Gabon, and the R ...
. Its cause is unknown, and no cure yet exists.


Signs and symptoms

Children affected by nodding disease experience a complete and permanent stunting of growth. The growth of the brain is also stunted, leading to intellectual disability. The disease is named for the characteristic, pathological
nodding A nod of the head is a gesture in which the head is tilted in alternating up and down arcs along the sagittal plane. In many cultures, it is most commonly, but not universally, used to indicate agreement, acceptance, or acknowledgement. To in ...
seizure A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...
, which often begins with the sight of food or dropping temperatures.'Nodding disease' hits Sudan
Andrew Harding BBC News 23 September 2003
These seizures are brief and halt after the children stop eating or when they feel warm again. Seizures in nodding disease span a wide range of severity. Neurotoxicologist Peter Spencer, who has investigated the disease, has stated that upon presentation with food, "one or two hildrenwill start nodding very rapidly in a continuous, pendulous nod. A nearby child may suddenly go into a tonic–clonic seizure, while others will freeze." Severe seizures can cause the child to collapse, causing injury. Sub-clinical seizures have been identified in
electroencephalogram Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The bio signals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neoc ...
s, and
MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...
scans have shown brain atrophy and damage to the
hippocampus The hippocampus (: hippocampi; via Latin from Ancient Greek, Greek , 'seahorse'), also hippocampus proper, is a major component of the brain of humans and many other vertebrates. In the human brain the hippocampus, the dentate gyrus, and the ...
and
glia Glia, also called glial cells (gliocytes) or neuroglia, are non-neuronal cells in the central nervous system (the brain and the spinal cord) and in the peripheral nervous system that do not produce electrical impulses. The neuroglia make up ...
cells. It has been found that no seizures occur when affected individuals are given an unfamiliar or non-traditional food, such as chocolate.


Causes

the cause of the disease was not known, but a link has been found between nodding syndrome, infestation by the parasitic worm '' Onchocerca volvulus'' prevalent in all outbreak areas, and exposure to black-fly bites which transmit it. A possible explanation involves the formation of antibodies against parasite antigen that are cross-reactive to leiomodin-1 in the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
. ''O. volvulus'', a
nematode The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
, is carried by the
black fly A black fly or blackfly (sometimes called a buffalo gnat, turkey gnat, or white socks) is any member of the family Simuliidae of the Culicomorpha infraorder. It is related to the Ceratopogonidae, Chironomidae, and Thaumaleidae. Over 2,200 s ...
and causes
river blindness Onchocerciasis, also known as river blindness, is a disease caused by infection with the parasitic worm ''Onchocerca volvulus''. Symptoms include severe itching, bumps under the skin, and blindness. It is the second-most common cause of blindne ...
. In 2004, most children with nodding disease lived close to the Yei River, a hotbed for river blindness, and 93.7% of those with nodding disease were found to harbour the parasite — a far higher percentage than in children without the disease. A link between river blindness and normal cases of
epilepsy Epilepsy is a group of Non-communicable disease, non-communicable Neurological disorder, neurological disorders characterized by a tendency for recurrent, unprovoked Seizure, seizures. A seizure is a sudden burst of abnormal electrical activit ...
, as well as retarded growth, had 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 he wormis 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
microfilaria The microfilaria (plural microfilariae, sometimes abbreviated mf) is an early stage in the life cycle of certain parasitic nematodes in the family Onchocercidae. In these species, the adults live in a tissue or the circulatory system of vertebr ...
e in epileptic or nodding children ranged from 70% to 100%. In 2011 the CDC was investigating a possible connection with wartime chemical exposure, and whether a deficiency in vitamin B6 (
pyridoxine Pyridoxine (PN) is a form of vitamin B6 found commonly in food and used as a dietary supplement. As a supplement it is used to treat and prevent pyridoxine deficiency, sideroblastic anaemia, pyridoxine-dependent epilepsy, certain metaboli ...
) could be a cause, noting the seizures of pyridoxine-dependent epilepsy and this common deficiency in those with the disease. 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.


Diagnosis

Diagnosis is not very advanced and is based on the telltale nodding seizures of the patients. When stunted growth and mental disability are also present, probability of nodding syndrome is high. In the future, neurological scans may also be used in diagnosis.


Management

no cure was known for the disease, so treatment has been directed at symptoms, and has included the use of anticonvulsants used to treat epilepsy such as sodium valproate and
phenobarbitol Phenobarbital, also known as phenobarbitone or phenobarb, sold under the brand name Luminal among others, is a medication of the barbiturate type. It is recommended by the World Health Organization (WHO) for the treatment of certain types of ...
. Anti-
malaria Malaria is a Mosquito-borne disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...
drugs have also been administered, to unknown effect. Nutritional deficiencies may also be present.


Prognosis

Nodding syndrome is debilitating both 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." Without epilepsy drugs, the condition worsens; seizures can cause accidents and even death. Long-term effects include brain damage, stunted growth and mental impairment. A few children are said to have recovered from the disease, but many have died.


Epidemiology

While the majority of 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 had become most prevalent in
South Sudan South Sudan (), officially the Republic of South Sudan, is a landlocked country in East Africa. It is bordered on the north by Sudan; on the east by Ethiopia; on the south by the Democratic Republic of the Congo, Uganda and Kenya; and on the ...
, where in 2003 approximately 300 cases were found in Mundri alone. By 2009, it had spread across the border to Uganda's
Kitgum Kitgum is a municipality in Kitgum District in the Northern Region, Uganda, Northern Region of Uganda. The town is administered by Kitgum Municipality Council, an urban local government. It is the largest metropolitan area in the district and th ...
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 Gulu is a city in the Northern Region of Uganda. It is the commercial and administrative centre of Gulu District. The coordinates of the city of Gulu are 2°46'54.0"N 32°17'57.0"E. The city's distance from Kampala, Uganda's capital and large ...
. More than 1000 cases were diagnosed in the last half of that year. There were further outbreaks in early 2012, in South Sudan, Uganda, and Tanzania. In the five years to 2024 cases have been identified in the Democratic Republic of the Congo, Central African Republic and Cameroon. The spread and manifestation of outbreaks may further be exacerbated due to the poor availability of health care in the region.


See also

* List of mystery diseases


References


External links

* {{DEFAULTSORT:Nodding Disease Ailments of unknown cause Health in Africa Health in Sudan Rare diseases Syndromes