Infectious Diseases
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Kuru
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PRION DISEASES

ID

Kuru

man with kuru photo

Classification(s):

  • Transmissible Spongiform Encephalopathy (TSE)

Environmental Triggers:

  • Deforestation
  • Habitat Conversion

History:

Kuru was first noted in the Fore tribe of the Eastern Highlands Province of Papua New Guinea as Australian administrators explored the area in 1953–1959. Kuru (Keru) was reported by W. T. Brown in Kainantu Patrol Report No 8 of 1953/54 (13 January 1954 - 20 February 1954.) .. "The first sign of impending death is a general debility which is followed by general weakness and inability to stand. The victim retires to her house. She is able to take a little nourishment but suffers from violent shivering. The next stage is that the victim lies down in the house and cannot take nourishment and death eventually ensues." The same reports described the cannibalism practised by the Fore people. It was in the late 1950s that the full extent of the disease was realized, after it had reached large infection rates in the South Fore of the Okapa Subdistrict, though the agent was unknown.

Awande Hospital was built in 1961 in the Eastern Highlands to accommodate kuru patients and research. Kuru was first noted in 1952-1953 by anthropologists R. M. and C. H. Berndt among the Fore, Yate, and Usanufa people. Charles O. Pfarr, Lutheran Medical Services was brought to the area by tribal persons and reported the disease to Australian authorities. Dr. Vincent Zigas, District Medical Officer began observation. Blood specimens and brain tissue were sent to Melbourne. In 1957, Dr. D. C. Gajdusek of the National Institute of Health joined Dr. Zigas at the research center. Sister Eva Hasselbusch of Germany joined the hospital in 1959 to take care of the patients. Sister Maria Horn of Germany was the first trained sister to work with the doctors to study the disease. By 1968 the hospital ceased to function as a Kuru hospital and was closed. (1886-1986, The Lutheran Church in Papua New Guinea by Herwig Wagner and Hermann Reiner)

The disease was researched by Daniel Carleton Gajdusek as part of an international collaboration with Australian doctor (now Professor) Michael Alpers.[4] In the mid-1960s Alpers collected post-mortem brain tissue samples from an 11-year-old Fore girl, Kigea, who had died of kuru. He took these samples to Gajdusek in the USA, who then injected two chimpanzees with the infected material. Within two years, one of the chimps, Daisy, had developed kuru, demonstrating that the unknown disease factor was transmitted through infected biomaterial and that it was capable of crossing the species barrier to other primates.

In 1976 Gajdusek, along with Baruch S. Blumberg, was awarded the Nobel Prize in Physiology or Medicine for showing that kuru was transmissible to chimpanzees. This was the first time that this group of encephalopathies had been demonstrated to be infectious and therefore a major step forwards in their investigation. As kuru is the only epidemic of human prion disease in known human history, it has provided important insights into the variant CJD.

Photo Source: wellesley.org

Creutzfeldt-Jakob Disease (CJD)

brain with CJD photo

Classification(s):

  • Transmissible Spongiform Encephalopathy (TSE)

Environmental Triggers:

  • Spontaneous Genetic Mutation
  • Mad Cow Disease
  • Animal Trafficking
  • Globalization of Travel and Trade

Epidemiology:

Although CJD is the most common human prion disease, it is still rare, occurring in about one out of every one million people every year. It usually affects people aged 45–75, most commonly appearing in people between the ages of 60–65. The exception to this is the more recently-recognised 'variant' CJD (vCJD), which occurs in younger people.

CDC monitors the occurrence of CJD in the United States through periodic reviews of national mortality data. According to the CDC:

  1. CJD occurs worldwide at a rate of about 1 case per million population per year.
  2. On the basis ofmortality surveillance from 1979 to 1994, the annual incidence of CJD remained stable at approximately 1 case per million persons in the United States.
  3. In the United States, CJD deaths among persons younger than 30 years of age are extremely rare (fewer than five deaths per billion per year.
  4. The disease is found most frequently in patients 55–65 years of age, but cases can occur in people older than 90 years and younger than 55 years of age.
  5. In more than 85% of cases, the duration of CJD is less than 1 year (median: four months) after onset of symptoms.

New Concerns:

In The Lancet (June 2006), a University College London team suggested that it may take more than 50 years for vCJD to develop, from their studies of kuru, a similar disease in Papua New Guinea. The reasoning behind the claim is that kuru was possibly transmitted through cannibalism in Papua New Guinea when family members would eat the body of a dead relative as a sign of mourning. In the 1950s, cannibalism was banned. In the late 20th century, however, kuru reached epidemic proportions in certain Papua New Guinean communities, therefore suggesting that vCJD may also have a similar incubation period of 30 to 50 years. A critique to this theory is that while mortuary cannibalism was banned in Papua New Guinea in the 1950s, that does not necessarily mean that the practice ended. 15 years later Jared Diamond was informed by Papuans that the practice continued. Kuru may have passed to the Fore people through the preparation of the dead body for burial.

These researchers noticed a genetic variation in some kuru patients that has been known to promote long incubation periods. They have also proposed that individuals who contracted CJD in the early 1990s represent a distinct genetic subpopulation, with unusually short incubation periods for Bovine spongiform encephalopathy (BSE). This means that there may be many more vCJD patients who have longer incubation periods, which may surface many years later.

In 1997 a number of Kentuckians developed CJD. It was discovered that all the victims had consumed squirrel brains, although a coincidental relationship between the disease and this dietary practice may have been involved.

Not So Fun Fact

Christina Warner's uncle passed away from vCJD in 2009.

Photo Source: health-healths.com

Mad Cow Disease

cow with BSE photo

Classification(s):

  • Bovine Spongiform Encephalopathy (BSE)

Environmental Triggers:

  • Defaunation
  • Global Warming
  • Cycles of Poverty
  • Factory Farming Pracitces
  • Animal Trafficking
  • Globalization of Travel and Trade

Epidemiology:

The tests used for detecting BSE vary considerably as do the regulations in various jurisdictions for when, and which cattle, must be tested. For instance, in the E.U. the cattle tested are older (30 months+), while many cattle are slaughtered earlier than that. At the opposite end of the scale, Japan tests all cattle at the time of slaughter. Tests are also difficult as the altered prion protein has very low levels in blood or urine, and no other signal has been found. Newer tests are faster, more sensitive, and cheaper, so it is possible that future figures may be more comprehensive. Even so, currently the only reliable test is examination of tissues during an autopsy.

It is notable that there are no cases reported in Argentina, Australia, Brazil, New Zealand, Uruguay, and Vanuatu where cattle are mainly fed outside on grass pasture and, mostly in Australia, non-grass feeding is done only as a final finishing process before the animals are slaughtered for meat.

As for vCJD in humans, autopsy tests are not always done and so those figures too are likely to be too low, but probably by a lesser fraction. In the United Kingdom anyone with possible vCJD symptoms must be reported to the Creutzfeldt-Jakob Disease Surveillance Unit. In the United States, the CDC has refused to impose a national requirement that physicians and hospitals report cases of the disease. Instead, the agency relies on other methods, including death certificates and urging physicians to send suspicious cases to the National Prion Disease Pathology Surveillance Center (NPDPSC) at Case Western Reserve University in Cleveland, which is funded by the CDC.

Photo Source: diseaseoftheweek.wordpress.com