Nodding disease: The unanswered questions

I wish to make a few comments on the story ‘Nodding Syndrome; parasite discovered’, that appeared in the Daily Monitor of April 15. We, as the department of Pathology, Mulago Hospital/Makarere University of Health Sciences, were mandated by the Ministry of Health in 2012 to carry out postmortem examinations on children with the Nodding syndrome who died.

To date we have carried out more than 25 of these postmortem examinations. We have also observed over a period of time some of the children living with the disease and noted that the children with the Nodding syndrome are those who were mainly born between 1995 and 2005. The disease is basically limited to specific areas of Kitgum, Pader and Lamwo.

There is no doubt that the Nodding syndrome is a chronic neurodegenerative disease of children. This, we have established by examining, under the microscope, the brains of the children who have died of the disease. The signs and symptoms exhibited by the children living with the disease are also classical of a neurodegenerative disease.

It is, therefore, vital to find out the cause of this devastating disease as well as the mechanism by which the causative agent brings about the disease. This is important to prevent further tissue damage as well as offer treatment options and map out preventive measures.

It should be noted that measures to control the black fly, the vector for the worm that causes river blindness, in the epicentres of the nodding syndrome, were initiated in 2013. However, there are hardly any children born between 2005 and 2013, who have shown features of the disease. This implies that whatever initiated or triggered the disease ceased shortly after 2005. That we have no new cases of the disease can, therefore, not be attributed to the spraying of the black fly in 2013.

The nodding syndrome is a disease of children and whatever was responsible for the disease, therefore, was most likely limited to or affected children. Yet, it is a well established fact that the worm that causes river blindness, affects both children and adult. The question is, therefore, why the disease is not manifested in adults.

River blindness has been in Uganda for a very long time and has affected many areas. Why have we not seen cases of nodding syndrome all this time? Why now? And why is the disease not in other areas such as Bunyoro Sub-region or Moyo District where river blindness and the black fly exist? Or even in other parts of Africa where Onchocercaisis is rampant?

The clinical features of infection with the worm that causes river blindness are well documented. These include intense itching of the skin, swellings under the skin, with associated inflammation, skin atrophy, loss of pigmentation and blindness. A question that begs an answer is why the children with Nodding syndrome do not have these signs and symptoms of Onchocerciasis?

That the nodding syndrome occurs in areas in which the black fly exits is not in question. The question is, however, whether this co-existence is coincidental or not. There are certainly still many more unanswered questions in respect of the Nodding syndrome and much more objective scientific research is needed to answer these questions.

Dr Sylvester Onzivua,
Consultant Pathologist