Nearly 90 per cent of the people who have been diagnosed so far with
H5N1 strain of the avian flu virus were under age 40, a new analysis
from the World Health Organization shows.
And two British scientists suggest that as yet unexplained phenomenon
could be a clue that widespread immunity to infection with the virus
may exist in people aged 35 and older.
The age distribution of H5N1 human cases is "consistent with a
biological model of geographically widespread immunity to avian
influenza A (H5N1) in persons born before 1969," Matthew
Smallman-Raynor of the University of Nottingham and Andrew Cliff of the
University of Cambridge note in a letter to the March issue of the
journal Emerging Infectious Diseases.
They said such a model would account for:
- The similar rates of disease in younger people.
- The "sudden and pronounced reduction" of cases in patients over age 30-35.
- The age skew that "transcends the sociocultural and demographic contexts of countries and continents."
Different theories
It is not known why H5N1 seems to prefer the young and rarely infects the elderly, the age group hit hardest by seasonal flu.
Suggested theories have included that children and young people may
have closer exposure to poultry in countries where outbreaks are
occurring.
Another possibility could be that older people are actually being
infected but suffer such mild illness that they don't come to the
attention of health authorities.
The few studies that have looked for mildly symptomatic or
asymptomatic cases don't support this idea, but experts believe larger
studies need to be done before it could be ruled out.
Smallman-Raynor and Cliff, who teach analytical and theoretical
geography respectively, looked at ages of reported cases and compared
them to population figures for countries reporting human infections,
looking to see if the demographic compositions of those countries
provide some clues.
Their analysis showed that the imbalanced distribution of cases is seen
in both genders, throughout the duration of the ongoing H5N1 outbreak
(which began in late 2003) and across all countries which have had
enough human cases so that statistics could be crunched.
That suggests that the trend probably isn't due to local cultural or
geographic factors, argued Smallman-Raynor and Cliff, who said the idea
needs further study.
"If an element of immunity to avian influenza A (H5N1) does exist in
older populations, its possible association with geographically
widespread (intercontinental) influenza A events before the late 1960s
merits further investigation," they said.
52% of cases were younger than 20: WHO study
The WHO analysis, published in the agency's online journal the
Weekly Epidemiological Review, also argues that the higher proportion
of cases in younger age groups probably isn't just due to the fact that
young people make up a big part of the age structures of affected
countries.
The report, which covers the 256 laboratory confirmed cases that
occurred between Nov. 25, 2003 and Nov. 24, 2006, showed that the
median age of cases was 18 years old.
Fifty-two per cent of cases were younger than 20 years old and 89 per
cent were under age 40. Men and women made up virtually an equal number
of cases.
The death rate was highest among cases aged 10 to 19; 76 per cent of
cases in that group died. Cases aged 50 and over had the lowest death
rate (40 per cent) followed by children under age five (44 per cent)
and children aged five to nine (49 per cent).
The total case fatality rate was 60 per cent.
Cases have increased over time, the unnamed authors reported, with the
cases in the second year of the three-year period twice as high as
those recorded in the first year. From Year 2 to Year 3, the number of
cases rose by about 25 per cent.
A graph of cases showed that while there are definitely seasonal peaks
and troughs in human infections, there have been cases recorded every
month since November 2004.
Newer arthritis drug shows fewer side-effects
Last Updated: Friday, February 9, 2007 | 2:14 PM ET
CBC News
A newer arthritis drug leads slightly fewer stomach side-effects than older drugs, according to a new study.
People with arthritis often take non-steroidal anti-inflammatories or NSAIDS over a long term. A newer class of NSAIDS called COX-2 inhibitors cause fewer gastrointestinal side-effects such as ulcers and stomach bleeding than other NSAIDs such as Aspirin and ibuprofen.
In the Feb. 10 issue of the medical journal The Lancet, researchers analyzed the results of three clinical trials comparing Merck & Co.'s drug etoricoxib, sold as Arcoxia, to diclofenac, sold in Canada as Voltaren. Etoricoxib is not approved for use in Canada.
"Our results indicate that the rate of clinically important upper-gastrointestinal events was lower with the COX-2 selective inhibitor etoricoxib than it was with the traditional NSAID diclofenac," said Prof. Loren Laine of the University of Southern California Keck School of Medicine in Los Angeles.
The nearly 35,000 study participants had rheumatoid arthritis or osteoarthritis.
To mirror how the drugs are prescribed in real life, participants were encourage to take a proton pump inhibitor with the drugs to protect against gastrointestinal side-effects, and those with risk factors for heart disease were urged to take low-dose Aspirin.
Overall, there were fewer ulcers in people taking the new drug and more of those people continued to take the treatment, the researchers found.
Merck employees performed the statistical analysis, which was independently confirmed by the Frontier Science Foundation.
The trial was designed to address cardiovascular side-effects, not gastrointestinal ones, Joost Drenth and Freek Verheugt of Radboud University Nijmegen, Netherlands, said in an accompanying commentary.
"Though eterocoxib reduced upper-gastrointestinal events, the effect was only small, as 259 patients need to be treated to prevent one uncomplicated gastrointestinal event," the pair wrote.
The real question is whether a COX-2 inhibitor such as etoricoxib is safer than an NSAID when a proton pump inhibitor is added, Drenth and Verheugt said.
Taking an older NSAID with a proton pump inhibitor might be cheaper and potentially less harmful to the heart, although a randomized clinical trial is needed to test the idea.
Merck pulled Vioxx, an older COX-2 inhibitor, from the market in 2004, after studies suggested it doubled the risk of heart attack and stroke in people who took it for at least 18 months.
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More diabetics ending up with kidney failure: report
Last Updated: Wednesday, February 7, 2007 | 12:53 PM ET
CBC News
The number of people with diabetes diagnosed with end-stage kidney failure more than doubled from 1995 to 2004, according to a report released on Wednesday.
The number of new cases of kidney failure jumped 114 per cent, from just under 1,100 in the first year to more than 2,100 cases in 2004, says the Canadian Institute for Health Information, adding that the incidence of Type 2 diabetes jumped during the same period.
"Diabetes is the fastest growing cause of end-stage renal disease," said Margaret Keresteci, CIHI’s manager of clinical registries.
Diabetes is now a factor in more than 40 per cent of all registered patients with end-stage renal disease, up from 25 per cent a decade ago, Keresteci added.
In end-stage renal disease, the kidneys are permanently damaged and patients need regular dialysis to stay alive until they receive a kidney transplant.
Type 2 diabetes is linked to obesity, sedentary living and an aging population. Diabetes can result in scarring of the kidneys that can prevent them from working properly.
Over the study period, the number of end-stage kidney patients with Type 1 diabetes, or insulin-dependent diabetes, dropped from 526 in 1995 to 303 in 2004.
The reduction in kidney failure among people with Type 1 may be attributed to better treatments and interventions, Keresteci said.
People with Type 1 may be screened and treated for renal failure, but people may develop kidney problems without knowing they have Type 2 diabetes, said Dr. Joanne Kappel, director of chronic kidney disease program at St. Paul's Hospital in Saskatoon.
Kappel recommended that people over 40 be tested for Type 2 diabetes every three years. Those with other risk factors, such as people of aboriginal, Hispanic, Asian, South Asian or African descent, should be tested more often.
When people with kidney failure received transplants, the five-year survival rate was 19 per cent lower for those under 65 who also had diabetes, the report showed.
A potential explanation for the lower survival is that a transplant replaces kidney function, but the blood vessel complications of diabetes continue, Kappel said.
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New Brunswick doctors say outbreaks of the Norwalk virus, or Norovirus, seem to be peaking this year, and it's replacing influenza as the more common winter bug.
This week, St. Joseph's Hospital in Saint John had to shut down its seventh floor to outside residents due to several new cases of the virus — known commonly as stomach flu — which has been running rampant in hospitals and nursing homes all over the province for the past three months.
Saint John resident Debbie Donaldson says most of her family became violently ill with a Norwalk-like virus over the Christmas break.
"It was so violent that the little muscles between my ribs were so sore that it hurt to breathe the next day," Donaldson said. She says it took several days for her to recover from the illness.
Judith Rau, regional co-ordinator for infection prevention and control for the Atlantic Health Sciences Corporation, says the Norovirus is more prevalent this year, so much so that's it's replaced the regular flu outbreaks.
"Every once in a while you get an organism, such as Norovirus, that gives you a little bit more issue," Rau said. "Usually it's influenza, and you get at a higher percentage of influenza every once in a while, and so we're seeing that with Norovirus."
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Newer birth control pills raise clot risk, group warns
Last Updated: Tuesday, February 6, 2007 | 12:17 PM ET
CBC News
Some newer, low-dose birth control pills double the risk of potentially dangerous blood clots compared with older contraceptives and should be banned, a U.S. consumer group says.
Public Citizen filed a petition with the U.S. Food and Drug Administration on Tuesday to stop the sale of birth control pills containing a type of progestin called desogestrel.
"By banning third-generation oral contraceptives, the FDA will potentially save hundreds of young women a year from developing venous thrombosis and its disabling and sometimes fatal consequences," the petition read.
The newer contraceptives may lead to about 30 blood clots per 100,000 users, compared with 15 clots per 100,000 people taking "second generation" pills that contain estrogen and progestin.
In the U.S., the newer pills include a warning about the increased risk.
Several pharmaceutical companies sell third-generation oral contraceptives, including Johnson & Johnson's Ortho-Cept. Health Canada has approved sales of Ortho-Cept.
Public Citizen said there is no evidence that desogestrel pills offer improved clinical benefits.
"FDA will carefully review the petition," said agency spokeswoman Susan Cruzan.******************************************************************
People who are lonely may have a higher risk of developing Alzheimer's disease late in life compared with those who interact more socially, a new study suggests.
While social isolation has been linked to an increased risk of dementia, less is known about the effects of emotional isolation, that is, a feeling of loneliness rather than actually being alone.
"Humans are very social creatures," said study author Robert Wilson of Rush University Medical Center in Chicago. "We need healthy interactions with others to maintain our health.
"The results of our study suggest that people who are persistently lonely may be more vulnerable to the deleterious effects of age-related neuropathology."
Wilson and his colleagues studied the link between loneliness and dementia in 823 people with an average age of 81. Participants were tracked for up to 40 years.
In the February issue of the Archives of General Psychiatry, the team reported 76 people developed Alzheimer's during the study.
When the study began, the participants' overall average loneliness score was 2.3 from a scale of one (lowest) to five.
The risk of developing Alzheimer's increased about 51 per cent with each point of increase on the loneliness score such as those who reported "I feel like I don't have enough friends."
The results suggest that someone who scored 3.2 would be about 2.1 times more likely to develop Alzheimer's compared with someone with a score of 1.4, the researchers said.
Autopsies were done on 90 participants who died during the study. Loneliness during life was not linked to brain changes such as the presence of tangles that are associated with Alzheimer's, the team found.
How loneliness may be linked to Alzheimer's remains unclear.
Keeping emotionally connected to others may help protect the brain from the early onset of dementia or loneliness may be an early symptom.
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