Two teenaged sisters from Kerala were among five persons who tested positive for swine flu
today, taking the total number of those
affected with the virus to 134 in the country. Out of the five cases, three are from Kerala and two from Delhi.

"Five new cases of swine flu have been reported. Two cases each were reported from Delhi and Kozhikode and one was reported from Kochi. The total number of cases has now risen to 134," a Health Ministry official said.

Out of the 134 people affected with swine flu, the official said, 99 have been discharged while the rest remain admitted to various hospitals across the country.

The cases in Kozhikode were of two teenaged girls, aged 16 and 19, whose parent had earlier been detected with swine flu. "All of them had travelled from Abu Dhabi and they reached Kozhikode on June 27," the official said.

The third case in Kerala was that of a 35-year-old man, who travelled from Cayman Island in United Kingdom, and reached Kochi on June 29.

Out of the two cases in Delhi, one is that of the 34-year-old mother of a positive case reported July three. They had reached Delhi from New Jersey on June 29. The other case is that of a 30-year-old man, who travelled from Botswana and reached Delhi on June 30.

Video from portable cameras is analysed to calculate the distance of obstacles and predict the movements of people and cars. This information is then transformed and relayed to a blind person as a three-dimensional 'picture' of sound.

The concept is apparently simple and two prototypes have been successfully tested. Laser and digital video cameras become the eyes for the blind man and see the objects and activity going on around him.

Researchers from the University of Bristol have developed powerful real-time image processing and some clever algorithms to then identify objects and obstacles, such as trees, street furniture, vehicles and people. The system uses the stereo images to create a "depth map" for calculating distances. The system can also analyse moving objects and predict where they are going.

So much for the image processing, but how do you present this visual information to a blind person? Technology developed at the University of Laguna in Spain makes it possible to transform spatial information into three-dimensional acoustic maps.

A blind person wears headphones and hears how sounds change as they move around. The stereo audio system makes it possible to place sounds so that the brain can interpret them as a point in space. Sounds get louder as you walk towards objects, quieter as you move away. Objects to your right are heard on your right, and if you move your head the sound moves too. And if something is heading right for you, you'll hear it coming, with a tone that tells you to get out of the way.

The full picture

The EU-funded CASBLiP project was conceived to integrate the image processing and acoustic mapping technologies into a single, portable device that could be worn by blind people and help them to navigate outdoors.

The University of Laguna worked to adapt its acoustic mapping system and the University of Bristol refined its image processing algorithms. The device also incorporates a gyroscopic sensor developed by the University of Marche, Italy. This component, called the head-positioning sensor, detects how the wearer moves his head. It feeds back the position of the head and the direction it is facing, so that the relative position of the sounds being played to the wearer also move as expected. For example, if you turn your head towards a sound on the right, the sound must move left towards the centre of the sound picture.

Vision for the future

After three years, the consortium has produced two prototype devices mounted on a helmet. They have been tested successfully in trials by blind people in several real-world environments, including busy streets. Two blind institutions (the German Federation of the Blind and Partially Sighted and the Francesco Cavazza Institute, Italy) were heavily involved in the testing programme.

The first design (M1) uses a laser sensor developed by Siemens and originally intended to detect passengers in cars. It can calculate the distance to objects within 0 to 5m in a 60º field of view. The system is mounted inside glasses and cannot be seen by others because it uses infrared light. The M1 has been extensively tested by blind users who are able to recognise items, such as chairs and trees, from the sound picture they receive.

A second version (M2) adds two digital video cameras to either side of a helmet. It can detect moving objects and predict their path.

Few people changed their behaviour in the early stages of the swine flu outbreak, finds a study published on bmj.com. But the results do support efforts to inform the public about specific actions that can reduce the risks from swine flu and to communicate about the government's plans and resources.

Encouraging the public to undertake specific behaviours related to hygiene has proved useful in containing previous outbreaks of infectious disease, but motivating the public to adopt such behaviours can be difficult.

So researchers at Institute of Psychiatry King's College London and the Health Protection Agency set out to assess whether perceptions of the swine flu outbreak predicted changes in behaviour among members of the public England Scotland and Wales.

They conducted a telephone survey of 997 adults between 8 and 12 May 2009. Participants were asked nine questions about recent behaviours.

Six related to avoidance of places or activities, behaviours that had not been recommended by the government. Three related to activities that had been recommended - namely, increased cleaning or disinfecting of surfaces, washing hands with soap and water more often than usual, and discussing with a friend or family member what to do if either person caught swine flu.

The results suggest that, in the face of intense media coverage and a major government advertising campaign, public responses to swine flu were muted.

Anxiety about the outbreak was low, with only 24% of participants reporting any anxiety and only 2% reporting high anxiety. Behaviour changes were also limited.

Most people reported that they had not changed the frequency of their hand washing (72%), increased the amount that they cleaned or disinfected things (83%), or discussed plans with a "flu friend" (85%). In fact most people (62%) had done none of these things.

And fewer than 5% of people reported that they had avoided people or places as a result of the outbreak.

Factors associated with an increased likelihood of making these changes included perceptions that swine flu is severe, the risk of catching it is high, the outbreak will continue for a long time, the authorities can be trusted, and people can control their risk. In contrast, being uncertain about the outbreak and believing that it had been exaggerated were associated with a lower likelihood of change, say the authors.

Our results largely endorse the current policy of providing the public with clear, consistent information, which focuses on the practical things that people can do to reduce their risk and which maintains trust by explicitly discussing the current level of knowledge, preparation, and resources available to tackle the outbreak, conclude the authors. Tackling the perception that the outbreak has been "over-hyped" may be difficult but also worthwhile, they add.

Mental stress causes carotid artery dilation and increases brain blood flow. A series of ultrasound experiments, described in BioMed Central's open access journal Cardiovascular Ultrasound, also found that this dilatory reflex was absent in people with high blood pressure.

Tasneem Naqvi and Hahn Hyuhn from the University of Southern California and Cedars-Sinai Medical Center evaluated carotid artery reactivity and brain blood flow in response to mental stress in 10 healthy young volunteers (aged between 19 and 27 years), 20 older healthy volunteers (aged 38 to 60 years) and in 28 patients with essential hypertension (aged 38 to 64 years). They found that in healthy subjects, mental stress caused vasodilation. This was accompanied by a net increase in brain blood flow. In hypertensive subjects, mental stress produced no vasodilation and no significant change in brain blood flow.

During the experiments, the volunteers were set a series of tasks designed to provoke mental stress, including reading, arithmetic and anger recall tests. The researchers used ultrasound imaging to measure the effects of this activity on the carotid artery and an artery within the brain, while also measuring blood pressure and heart rate.

According to Naqvi, "Inappropriate vasoconstriction, or lack of dilation in response to mental stress in stable coronary heart disease, contributes to the genesis of myocardial ischemia and confers an increased risk in patients with coronary artery disease. It will be interesting to see whether the lack of mental stress induced dilation we found defines subjects at increased risk of future cerebral events". Lack of required blood flow increase to the brain during mental activities may potentially affect cognition and cerebral performance during complex cerebral tasks.

Scientists in the US and the Netherlands discovered what most doctors already suspected: the new H1N1 swine flu virus causes more severe infection than seasonal flu, but the two groups disagreed on how easily it spreads, with one finding that it spreads easily while the other finding it does not.

The two studies are published in the 2 July online issue of Science.

In the first study, scientists from the Massachusetts Institute of Technology (MIT) in Cambridge and from the US Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, assessed the severity of the new swine flu strain against seasonal flu strains and compared their ability to transmit from infected to non-infected ferrets via respiratory droplets.

Lead MIT author Dr Ram Sasisekharan, the Edward Hood Taplin Professor and director of the Harvard-MIT Division of Health Sciences and Technology (HST) and senior microbiologist at the CDC Dr Terrence Tumpey had already discovered that the severity of a flu infection depends on the ability of the hemagglutinin protein in the virus to bind to a particular type of receptor on the surface of human respiratory cells.

For this study, they compared the new swine flu strain to several seasonal flu strains, including some mild ones and the extremely severe 1918 strain that killed millions worldwide.

As expected, they found that the new swine flu strain was able to bind to the human respiratory tract umbrella-shaped alpha 2-6 glycan receptor. They reported that:

"In contrast to seasonal influenza H1N1 virus, 2009 A(H1N1) viruses caused increased morbidity, replicated to higher titers in lung tissue, and were recovered from the intestinal tract of intranasally inoculated ferrets."

But, binding efficiency also depends on how well the virus can attach to the human respiratory tract receptor, and here they found that the receptor binding site in the hemagglutinin protein of the new swine flu virus was not as effective at binding to the human receptor as the other flu viruses.

Sasisekharan said:

"While the virus is able to bind human receptors, it clearly appears to be restricted."

The weak or restricted binding ability, together with a genetic variation in the H1N1 RNA polymerase enzyme PB2 that MIT scientists reported in Nature Biotechnology nearly a month ago, explains why the virus does not spread as readily as seasonal flu, he added.

(A virus uses RNA polymerase to control replication once it has infected a host. The MIT group found that new H1N1 strain does not have the version of the PB2 gene necessary for efficient transmission).

But this is no reason to be relaxed, since we know that flu viruses can mutate quickly, and one such mutation may improve ability of the new swine flu virus to attach to the human respiratory tract receptor. If that happens, then it will spread much more easily.

"We need to pay careful attention to the evolution of this virus," says Sasisekharan.

To test how easily the new strain spreads, Sasisekharan and colleagues put ferrets in close contact with each other and also kept apart. In close contact the virus particles spread from ferret to ferret easily, for instance when they touched each other. When they were kept further apart, so that transmission could only be via airborne respiratory droplets, the infection spread less readily.

Sasisekharan said this was consistent with what we have seen in humans, where most outbreaks have occurred in limited clusters, such as in a family or school, but not much further outside of that.

Another reason to keep an eye on the evolution of this new virus is that the MIT researchers working on the PB2 study also found that the virus is only one mutation step away from a version that would interact weakly with the antiviral Tamiflu (oseltamivir), raising the possibility that Tamiful resistant strains of swine flu may easily emerge.

In the second study, Dr Ron. A M Fouchier a virologist with the Erasmus Medical Center, Rotterdam, the Netherlands, and colleagues also found, using ferrets, that the new A(H1N1) virus was more pathogenic than a seasonal A(H1N1) virus, "with more extensive virus replication occurring in the respiratory tract".

However, when they looked at transmission from ferret to ferret, they found that transmission via aerosol or respiratory droplets was equally efficient in the new swine flu virus as the seasonal flu virus, which differs markedly from the result of the other study.

They concluded that:

"These data suggest that the 2009 A(H1N1) virus has the ability to persist in the human population, potentially with more severe clinical consequences."