|
EHJ June 2002
Some unexpected and unwelcome threats to human health
have cropped up in the past 50 years - from parasites in animals'
guts, from proteins mutating into prions and from bacteria
flourishing in water droplets in spas and heating systems.
Also, some well-known pathogens have cropped up in new forms.
|
 |
1963
Campylobacter was classified as a genus of bacteria. Under different
names, campylobacter had been known as a veterinary problem since
the early years of the century. In the 1970s, campylobacter jejuni
and campylobacter coli were established as major causes of diarrhoeal
illness, surpassing salmonella in some countries. All kinds of the
bacteria are killed by cooking and pasteurisation but they can survive
in chilled conditions.
1968
Norwalk virus was named following an outbreak of gastro-enteritis
in schoolchildren in Norwalk, Ohio. They are small round structured
viruses, causing diarrhoea and vomiting lasting for up to 48 hours.
Symptoms include projectile vomiting, which can assist the spread
of the illness. The infectious dose is not known.
1969
Lassa fever virus was isolated. In severe forms, the viral haemorrhagic
fever causes fluid in the lungs, haemorrhage and seizures. Fifteen
per cent of hospitalised patients die. It occurs in Guinea, Liberia,
Sierra Leone and Nigeria and is transmitted by wild rodents. A suspected
case was reported in the UK in 2000.
1976
Cryptosporidiosis was identified in a three-year-old girl from Tennessee.
The gastro-intestinal disease is caused by infection through water-borne
Cryptosporidium parasites, called oocysts. Found in water supplies,
oocysts are not killed by normal levels of chlorination. Cryptosporidiosis
can be fatal in immuno-compromised people. In 1989, the first large-scale
UK outbreak was identified in Swindon.
1976
Legionnaire's disease gained its name from an illness affecting
American ex-servicemen (legionnaires) who attended a reunion in
a Philadelphia hotel in 1976. It is an airborne infection caused
by the bacterium Legionella pneumophilia, which lives in water.
The mortality rate is 12 per cent. The disease is not spread from
person to person.
1976
Ebola haemorrhagic fever was first recognised when large outbreaks
occurred in southern Sudan and neighbouring northern Zaire in 1976.
Person to person spread was common in local hospitals, but also
caused many cases in the community. Mortality rates were as high
as 80-90 per cent in some patients giving rise to extreme concern
both in the original outbreaks and in case of export of the disease
to non-endemic areas.
1981
Listeria monocytogenes was identified as transmissible by food in
an outbreak in Canada. Coleslaw was implicated, from cabbage contaminated
with droppings on a farm. The bacteria, which can multiply at low
temperatures, were first described in 1926. It is associated with
soft cheeses and delicatessen meats, and can be fatal in humans.
1982
Vero cytotoxin producing Escherichia coli O157 (VTEC O157) first
manifested itself in the early 1980s. The effects of this organism
range from mild gastrointestinal symptoms, through severe bloody
diarrhoea (haemorrhagic colitis) and intense stomach pains, to life-threatening
conditions such as haemolytic uraemic syndrome. Commonly thought
of as a food poisoning organism, due to several large outbreaks,
including the Lanarkshire outbreak in 1996 in which 20 elderly people
died and more than 500 other people were affected. There are however,
other equally important routes of infection, ie person to person
spread and direct or indirect animal contact. The majority of VTEC
O157 infections in the UK are sporadic and so the routes of transmission
for most infections remain largely unknown.
1995
vCJD, a new form of Creutzfeldt-Jakob disease, was diagnosed in
Britain. It is a human spongiform encephalopathy, a fatal brain
disorder, caused by prions probably originating in infected tissue
from cattle. Prions are an abnormal form of proteins called PrP.
The majority of cases have been in young people.
1999
West Nile virus was first isolated from a febrile adult woman in
the West Nile district of Uganda in 1937. West Nile-like virus first
appeared in the Western hemisphere in New York during 1999 and has
so far killed nine people and affected 55 others. This potentially
fatal viral disease is carried by mosquitoes and attacks the central
nervous system causing inflammation of the brain. Outbreaks were
feared from pools of water sprayed by firemen following the terrorist
attacks on the United States on 11 September 2001.
|
