Scientists have identified new drug-resistant strains of the parasite that causes malaria.

They found malaria-causing parasites in western Cambodia that are genetically different from other strains around the world.

These parasites could also withstand treatment by artemisinin - a frontline drug in the fight against malaria, the researchers found.

Reports of drug resistance in the area first emerged in 2008. The problem has since spread to other parts of South East Asia.

"All the most effective drugs that we have had in the last few decades have been one by one rendered useless by the remarkable ability of this parasite to mutate and develop resistance," the BBC quoted Dr Olivo Miotto, of the University of Oxford and Mahidol University in Thailand as saying.

As part of the study, published in the journal Nature Genetics, scientists sequenced the genomes of 800 malaria-causing parasites (Plasmodium falciparum) collected from around the world.

"When we compared the DNA of the parasites in Cambodia, they seem to have formed some new populations that we have not really seen elsewhere," Dr Miotto said.

The international team found three distinct groups of drug-resistant parasites present in the area.

The researchers said they did not yet understand what genetic mutations had occurred that enabled the parasites to withstand artemisinin treatment.

But they said that understanding their genetic fingerprint would help them to quickly spot and track these strains if they spread further.

A study by Loyola University Medical Center physicians have found that about one-third of patients suffer depression following a stroke, and depression in turn increases the risk of stroke.

Antidepressant medications known as SSRIs, such as fluoxetine ( Prozac), sertraline ( Zoloft ), and escitalopram (Lexapro), are effective when given to stroke patients as a preventive measure, the physicians said.

Murray Flaster, MD, PhD, who specializes in stroke care, and psychiatrists Aparna Sharma, MD, and Murali Rao, MD, who specialize in depression are authors of the study.

Mental disorders are common after stroke. They include anxiety, irritability and agitation, uncontrollable crying, apathy, delusions and hallucinations. But the most common disorder is depression, either major or minor.

Some patients recover over time, while others move in and out of depression. For some patients, depression doesn`t develop until up to two years after the stroke.

Post-stroke depression (PSD) is linked to worse functional outcomes and increased risks of suicide and mortality.

Women are more likely to suffer PSD. Other risk factors include living alone and away from family members, higher levels of education, changes in lifestyle or marital status and degree of functional impairment. Depression, in turn, is a risk factor for stroke and stroke recurrence, even after controlling for other risk factors.

Given the severe effects of PSD, doctors should take an aggressive approach. Timing of medication may be crucial, with early treatment perhaps advantageous.

In addition to helping relieve depression, antidepressants also have been shown to improve cognitive and functional recovery. Recent evidence also shows that SSRIs are helpful in motor recovery (improved movement and coordination).

"Taken together, the available data make a strong case for the prophylactic use and effectiveness of antidepressants post stoke," the researchers said.

The finding was reported in the journal Topics in Stroke Rehabilitation.

Regular exercise may help reduce the chance of developing liver cancer, a study has said.

The research involved two groups of mice that were fed a control diet and a high fat diet, which were then divided into separate exercise and sedentary groups.

The exercise groups were made to run on a motorised treadmill for 60 minutes per day, five days a week.

After 32 weeks of regular exercise, 71 percent of mice on the controlled diet developed tumours larger than 10mm versus 100 percent in the sedentary group.

The mean number and volume of HCC tumours per liver was also reduced in the exercise group compared to the sedentary group.

EASL`s Educational Councillor Prof. Jean-Francois Dufour said that the data showed significant benefit of regular exercise on the development of HCC and exercise reduced the level of non-alcoholic fatty liver disease in mice receiving a high-fat diet.

Dufour said "The results could eventually lead to some very tangible benefits for people staring down the barrel of liver cancer and I look forward to seeing human studies in this important area in the future.

"The prognosis for liver cancer patients is often bleak as only a proportion of patients are suitable for potentially curative treatments so any kind of positive news in this arena is warmly welcomed," he added.

University of Guelph researchers have created the first-ever vaccine for gut bacteria common in autistic children that may help control some autism symptoms.

Brittany Pequegnat and Guelph chemistry professor Mario Monteiro developed a carbohydrate-based vaccine against the gut bug Clostridium bolteae.

C. bolteae is known to play a role in gastrointestinal disorders, and it often shows up in higher numbers in the GI tracts of autistic children than in those of healthy kids.

More than 90 per cent of children with autism spectrum disorders suffer from chronic, severe gastrointestinal symptoms. Of those, about 75 per cent suffer from diarrhea, according to current literature.

"Little is known about the factors that predispose autistic children to C. bolteae," said Monteiro.

Although most infections are handled by some antibiotics, he said, a vaccine would improve current treatment.

"This is the first vaccine designed to control constipation and diarrhea caused by C. bolteae and perhaps control autism-related symptoms associated with this microbe," he said.

Autism cases have increased almost six fold over the past 20 years, and scientists don`t know why. Although many experts point to environmental factors, others have focused on the human gut.

Some researchers believe toxins and/or metabolites produced by gut bacteria, including C. bolteae, may be associated with symptoms and severity of autism, especially regressive autism.

Pequegnat, a master`s student, and Monteiro used bacteria grown by Mike Toh, a Guelph PhD student in the lab of microbiology professor Emma Allen-Vercoe.

The new anti- C. bolteae vaccine targets the specific complex polysaccharides, or carbohydrates, on the surface of the bug.

The vaccine effectively raised C. bolteae -specific antibodies in rabbits. Doctors could also use the vaccine-induced antibodies to quickly detect the bug in a clinical setting, said Monteiro.

The vaccine might take more than 10 years to work through preclinical and human trials, and it may take even longer before a drug is ready for market, Monteiro said.

But this is a significant first step in the design of a multivalent vaccine against several autism-related gut bacteria, he said.

The groundbreaking study appeared this month in the journal Vaccine.

International experts probing China`s deadly H7N9 bird flu virus said Wednesday it was "one of the most lethal influenza viruses" seen so far as Taiwan reported the first case outside the mainland.

China has confirmed 108 cases and 22 deaths since the first infections were announced on March 31 and Taiwan Wednesday confirmed its first infection in a man who had recently returned from working in eastern China where most cases have been reported.

"This is definitely one of the most lethal influenza viruses we have seen so far," said Keiji Fukuda, one of the leading flu experts for the World Health Organization, which has led a team on a week-long visit to China to study H7N9.

Fukuda told a news conference that the H7N9 virus was more easily transmissible than the more common H5N1 strain of bird flu. Experts had previously remarked on the "affinity" of H7N9 for humans.

"We think this virus is more transmissible to humans than H5N1," he said, referring to the strain the WHO estimates has killed more than 360 people globally since 2003.

"When we look at influenza viruses this is an unusually dangerous virus," he said, but he added: "We are really at the beginning of our understanding."

Taiwanese health authorities said their first case, a 53-year-old man who had been working in the eastern Chinese city of Suzhou, showed symptoms three days after returning to Taiwan via Shanghai.

Health Minister Chiu Wen-ta told reporters the patient said he had not been in contact with poultry or eaten under-cooked birds or eggs while staying in Suzhou.

The WTO team, however, said poultry were the likely source of the H7N9 outbreak as chickens, ducks and pigeons from markets had tested positive, but nevertheless warned over the potential for human-to-human transmission.

"So far no migratory birds or their habitats have tested positive for H7N9," said team member Nancy Cox, director of the influenza division at the US Centers for Disease Control and Prevention.

"At least we can now understand that the likely source of infection is poultry, the virus originates from poultry," she said.

Experts have previously said the animal reservoir for H7N9 appeared to be unspecified birds.

There are worries over the prospect of such a virus mutating into a form easily transmissible between humans, which could then have the potential to trigger a pandemic.

But a statement released by the team, which includes Chinese experts, repeated that no human-to-human transmission has been discovered.

"No sustained person to person transmission has been found," it said. "What remains unclear is whether the virus could gain the ability to become transmissible between people."

A WHO official said last week more than 50 percent of those with the virus had remembered coming into contact with birds, raising questions over how the remaining cases became infected.

Chinese health officials have acknowledged so-called "family clusters", where members of a single family have become infected, but have so far declined to put it down to human-to-human transmission.

Such cases could be examples of what health officials call limited human-to-human transmission, in which those in close contact with the ill become infected, as opposed to widespread, or "sustained", transmission.

So far most H7N9 cases have been confined to the commercial hub Shanghai and nearby provinces in eastern China.

But the number of reported new cases in Shanghai has seen a "dramatic slowdown", Cox said, calling the reduction in the frequency of new cases "very encouraging".

Tuesday marked the fourth consecutive day where no new cases were reported in Shanghai.