Tag: Centers for Disease Control and Prevention

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What’s up with West Nile?

West Nile virus, that is. A widespread outbreak in the U.S. has attracted renewed attention to the virus, which acquired its name from West Nile, Uganda, although there is no evidence that it originated there. Unfair, isn’t it? The virus was first isolated in Omogo, West Nile district, Uganda, in 1937, by researchers at the Yellow Fever Research Institute, then based in Entebbe. According to a 1940 article by Smithburn et al. in the American Journal of Tropical Medicine and Hygiene:

In attempting to isolate virus numerous persons were seen who were suffering either from an illness suggesting yellow fever, or from pyrexia of unknown cause. From many such persons blood was drawn, and as soon as possible thereafter the serum was in oculated intracerebrally2 into mice. Subinoculations were done from mice which became ill. In this manner several transmissible infective agents were isolated.

The purpose of this paper is to report the isolation of one such agent, which we call the West Nile virus, and to describe some of its properties. Although this virus was isolated from the blood of a human being, the circumstances of its isolation were such that nothing is known regarding the illness produced by the virus in the human subject.

That the virus was identified in West Nile should, if anything, be a testament to the medical contributions that have been made from the region, but it is more likely to have inspired notoriety. West Nile virus outbreaks have occurred all over the world, but the virus was not identified in North America until 1999.

West Nile virus is carried by mosquitoes, which acquire the virus from infected birds. In rare cases (only about 1 in 150 cases), severe viral infection is characterized by “high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis“, according to the CDC. Up to 80% of those infected, however, do not experience any symptoms.

Current map of West Nile activity in the U.S.:

CDC surveillance of West Nile virus in the U.S., activity as of August 21, 2012
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Researching Nodding Disease

Nodding disease is a syndrome that was first reported in Tanzania in 1962, has been spreading in South Sudan and Uganda more recently. The number of cases in northern Uganda appear to have increased at a particularly fast clip in the last year. Nodding disease sounds made-up, but it is very real and often fatal, and is becoming a growing problem in the region. Most problematic is that the causes of nodding disease are still unclear, although there appears to be a connection with a parasitic infection from Onchocerca Volvulus, which causes river blindness.

Adult Onchocerca volvulus worms (WHO)

The Daily Monitor ran a story on December 23, 2011, quoting director of health services in Uganda, Dr. Jane Achieng, as saying that there are around 2,200 reported cases of nodding disease in Uganda (most in Acholi sub-region) and that the first case in the area had been reported in 2009.

A letter to the Daily Monitor written by Dr. Ddungu, of the Uganda Programme on Cancer and Infectious Diseases, notes that a similar phenomenon was studied in Kyarusozi sub-county as early as 1991. A 1992 study by E. Ovuga et al. on this topic was published in the East African Medical Journal.

Nodding disease appears to afflict children between the ages of 5 and 15 and is usually diagnosed by the characteristic nodding it produces in children. The head nodding (HN) is often triggered by eating or seeing familiar foods, or when a child becomes cold. Winkler et al. (2008) write:

HN represents a repetitive short loss of neck muscle tone resulting in a nodding of the head, sometimes associated with a short loss of muscle tone of the upper extremities. Loss or impairment of consciousness may be present, but not always. To date HN is not mentioned in any classification and it remains unclear whether it represents a seizure disorder and if so, whether it belongs to the group of generalized or partial seizures.

Nodding disease appears to be a growing problem that warrants serious attention from the government. The CDC and WHO have been involved in investigating its causes, but there has been relatively little information available to the public about this illness. I’ll be posting information on the published medical literature on nodding disease, as well as news updates and commentary as they become available.