The Northwest monsoons can lead to food and water borne diseases…:

Hepatitis A occurs mostly during rainy weather

By Carol Aloysius

The heavy rains currently being experienced islandwide, has resulted in many areas of the country being flooded, with thousands of families displaced from their homes and forced to take shelter in schools, church halls, temples and camps.

Health officials have warned that lack of safe drinking water, hygienically cooked food which is often lacking in such temporary shelters, and poor personal hygiene could lead to an outbreak of contagious diseases.

Of these, the most virulent is perhaps Hepatitis A, which as in the case of most other infectious diseases at this time, can be prevented with simple healthy practices, that even a child could follow.

The Sunday Observer spoke to the Chief Medical Officer of the Dehiwala - Mt Lavinia, Municipality Division, Dr INDIKA ELLAWELA. He says several patients in the area have been admitted with symptoms of food and water borne diseases following the rains. “This could have been avoided if they had followed the simple instructions which the Health Ministry has given to prevent such diseases”, he laments, adding that patients attending most outdoor patient clinics in high risk areas are advised on how to protect themselves against infectious diseases during rainy weather. He shares some of this advice focussing mainly on Hepatitis A which is among the commonest food and water borne diseases at this time of the year.

Excerpts…

Q. The North West monsoon is now in full swing and expected to continue through October to December. Is it correct that heavy rains are often associated with an outbreak of food and water borne diseases?

A. Yes. Usually we see an outbreak of diseases such as diarrhoea, dysentery and Hepatitis at this time of the year due to the rains.

Q. How does rainy weather lead to these diseases?

A. Because when it rains, it is difficult to access safe drinking water and food. Furthermore, many people living in overcrowded areas or in temporary shelters, do not follow good personal hygienic practices.

Q. Of the common water and food borne diseases that occur during this period, what in your opinion is perhaps the most dangerous or virulent?

A. Hepatitis A.

Q. What is this disease? How is it caused?

A. Hepatitis A is a liver disease caused by the hepatitis A virus.

Hepatitis A occurs sporadically and in epidemics worldwide, with a tendency for cyclic recurrences. Every year there are an estimated 1.4 million cases of hepatitis A worldwide.

Q. Is it infectious?

A. Yes, all forms of the Hepatitis virus are infectious but mode of transmission differs according to the type of Hepatitis.The Hepatitis A virus is one of the most frequent causes of food borne infection.

The disease is closely associated with unsafe water, inadequate sanitation and poor personal hygiene.

Q. How does the virus spread?

A. The virus is primarily spread when an uninfected (and unvaccinated) person ingests food or water that is contaminated with the faeces of an infected person.

Water-borne outbreaks, though infrequent, are usually associated with sewage-contaminated or inadequately treated water.

Other risk factors for the disease include injecting drugs, living in a household with an infected person, being a sexual partner of someone with acute Hepatitis A infection and travelling to areas of high endemicity without being immunised.

Q. Who are most at risk of getting it in Sri Lanka?

A. Evidence has shown that Hepatitis A is most common in children and young adults in Sri Lanka.

Q. How long does it take for symptoms to present after the virus enters the body?

A. Signs and symptoms of the disease will usually appear following a period of 14 to 28 days after the entry of the virus into the body.

Q. What are the most visible symptoms?

A. The symptoms range from mild to severe. They can include fever, malaise, loss of appetite, diarrhoea, nausea, abdominal discomfort, dark-coloured urine and jaundice (a yellowing of the skin and whites of the eyes). Not everyone who is infected will have all of the symptoms. Cases of Hepatitis A are not clinically distinguishable from other types of acute viral hepatitis.

Q. Then how do you identify and diagnose Hepatitis A from other types of acute viral Hepatitis?

A. Specific diagnosis is made by the detection of HAV-specific IGM and IG antibodies in the blood. Additional tests include reverse transcriptase polymerase chain reaction (RT-PCR) to detect the Hepatitis A virus RNA, but this may require specialised laboratory facilities.

Q. What is the treatment?

A. There is no specific treatment for Hepatitis A.

Q. How long will it take for a patient to recover?

A. Recovery from symptoms following infection may be slow and may take several weeks or months. Therapy is aimed at maintaining comfort and adequate nutritional balance, including replacement of fluids that are lost from vomiting and diarrhoea.

Q. What guidelines can you give us on how we can prevent contracting the disease.

A. Hepatitis A is a preventable disease. Its spread can be reduced in the following ways:

* Having adequate supplies of safe drinking water. Drinking contaminated water in community tanks or in wells is one way of contracting the disease. If you have a well, its best to chlorinate the water before use. Consult a PHI if you need advice on how to do this.

* Proper disposal of sewage within communities
* Following good personal hygienic practices such as regular hand-washing with safe water.
* Avoid eating raw vegetables
* Avoid eating raw meat

Q. Are there drugs to prevent Hepatitis A? Are they safe? What are the side effects?

A. Several Hepatitis A vaccines are available internationally. All are similar in terms of how well they protect people from the virus and their side-effects. No vaccine is licensed for children younger than one year of age. Nearly 100 percent of people develop protective levels of antibodies to the virus within one month after a single dose of the vaccine. Even after exposure to the virus, a single dose of the vaccine within two weeks of contact with the virus has protective effects. Still, manufacturers recommend two vaccine doses to ensure a longer-term protection of about five to eight years after vaccination. Millions of people have been immunised worldwide with no serious adverse effects.

Q. When is the vaccine given usually?

A. The vaccine can be given as part of regular childhood immunisations programs and also with other vaccines and also with other vaccines given for travellers.

Q. Can patients with viral Hepatitis be treated at home?

A. Only if they are mild cases. If treated at home, it is very important that the patient is isolated so that he does not infect others inside the same house.

Those with severe symptoms of the disease however, must be treated in a hospital facility, where the environment is clean and there is trained staff in attendance.

Q. Your message to the public?

A. Hepatitis is a preventable disease. It can be prevented with universal vaccination.

If treated in time, you can avoid long term complications that can lead to liver disease and liver cancer.

Calcium has surprising role in sensing pain

When you accidentally touch a hot oven, you rapidly pull your hand away. Although scientists know the basic neural circuits involved in sensing and responding to such painful stimuli, they are still sorting out the molecular players.

Researchers have made a surprising discovery about the role of a key molecule involved in pain in worms, and have built a structural model of the molecule. These discoveries may help direct new strategies to treat pain in people.

In humans and other mammals, a family of molecules called TRP ion channels plays a crucial role in nerve cells that directly sense painful stimuli.

Researchers are now blocking these channels in clinical trials to evaluate this as a possible treatment for various types of pain.

The roundworm Caenorhabditis elegans also expresses TRP channels - one of which is called OSM-9 - in its single head pain-sensing neuron (which is similar to the pain-sensing nerve cells for the human face). OSM-9 is not only vital for detecting danger signals in the tiny worms, but is also a functional match to TRPV4, a mammalian TRP channel involved in sensing pain.

In the new study, researchers created a series of genetic mutant worms in which parts of the OSM-9 channel were disabled or replaced and then tested the engineered worms’ reactions to overly salty solution, which is normally aversive and painful.

Specifically, the mutant worms had alterations in the pore of the OSM-9 channels in their pain-sensing neuron, which gets fired up upon channel activation to allow calcium and sodium to flow into the neuron. That, in turn, was thought to switch on the neural circuit that encodes rapid withdrawal behaviour - like pulling the finger from the stove.

“People strongly believed that calcium entering the cell through the TRP channel is everything in terms of cellular activation,” said lead author Wolfgang Liedtke, an associate professor of neurology at Duke University School of Medicine. With then-graduate student Amanda Lindy, “we wanted to systemically mutagenise the OSM-9 pore and see what we could find in the live animal, in its pain behaviour,” Liedtke said.

To the group's surprise, changing various bits of OSM-9's pore did not change most of the mutant worms’ reactions to the salty solution. However, these mutations did affect the flow of calcium into the cell. The disconnect they saw suggested the calcium was not playing a direct role in the worms’ avoidance of danger signals.

Calcium has been thought to be indispensable for pain behaviour - not only in worms’ channels but in pain-related TRP channels in mammals. So results from the engineered OSM-9 mutant worms will change a central concept for the understanding of pain, Liedtke said.

To see whether calcium might instead play a role in the worms’ ability to adapt to repeated painful stimuli, the group then repeatedly exposed pore-mutant worms to the aversive and pain stimuli. After the tenth trial, a normal worm becomes less sensitive to high salt. But one mutant worm with a minimal change to one specific part of its OSM-9 pore - altered so that calcium no longer entered but sodium did - was just as sensitive on the tenth trial as on the first.

The results confirmed that calcium flow through the channel makes the worms more adaptable to painful stimuli; it helps them cope with the onslaught by desensitising them. This could well represent a survival advantage, Liedtke said.

To put the findings into a structural context, Liedtke collaborated with computational protein scientists Damian van Rossum and Andriy Anishkin from Penn State University, who built a structural model of OSM-9 that was based the recently resolved structure of TRPV1, the molecule that senses pain caused by heat and hot chilli peppers.

The team was then able to visualise the key parts of the OSM-9 pore in the context of the entire channel. They understood better how the pore holds its shape and allows sodium and calcium to pass. Liedtke said that understanding this structure could be a great help in designing compounds that will not completely block the channel but will just prevent calcium from entering the cell. Although calcium helps desensitize worms to painful stimuli in the near term, it might set up chronic, pathological pain circuits in the long term, Liedtke said.

So, as a next step, the group plans to assess the longer-term effects calcium flow has in pain neurons. For example, calcium could change the expression of particular genes in the sensory neuron.

And such gene expression changes could underlie chronic, pathological pain.

“We assume, and so far the evidence is quite good, that chronic, pathological pain has to do with people's genetic switches in their sensory system set in the wrong way, long term. That's something our new worm model will now allow us to approach rationally by experimentation,” Liedtke said.

- MNT

Bacteria, an alternative to antibiotics

Bacteria found in honeybees could be used as an alternative to antibiotics and in the fight against antibiotic-resistant strains of MRSA.

For millennia, raw unmanufactured honey has been used to treat infections. Scientists believe its effectiveness could lie in a unique formula comprised of 13 types of lactic acid bacteria found in the stomachs of bees.

The bacteria, which are no longer active in shop-bought honey, produce a myriad of active anti-microbial compounds.

The findings could be vital both in developing countries, where fresh honey is easily available, as well as for Western countries where antibiotic resistance is an increasingly concerning issue. By applying the bacteria to pathogens found in severe human wounds - including MRSA - scientists from Lund University, Sweden, found that the formula from a bee’s stomach successfully counteracted the infections.

Researchers believe that the formula works so potently because it contains a broad spectrum of active substances, unlike conventional man-made antibiotics.

“Antibiotics are mostly one active substance, effective against only a narrow spectrum of bacteria. When used alive, these 13 lactic acid bacteria produce the right kind of antimicrobial compounds as needed, depending on the threat,” Dr Tobias Olofsson of the Medical Microbiology department at Lund University said.

“It seems to have worked well for millions of years of protecting bees’ health and honey against other harmful microorganisms. “However, since store-bought honey doesn't contain the living lactic acid bacteria, many of its unique properties have been lost in recent times,” he said.

To take the study forward, scientists will investigate wider clinical use against topical infections, on both humans and animals.

The findings are likely to give further ammunition to bee protection groups, after a separate study found that the use of neonicotinoids - the world’s most commonly used pesticides - damage vital bee populations.

It warned that the pesticides, which are linked to the decline of honeybees and other beneficial organisms including earthworms and butterflies, are having a dramatic impact on ecosystems that support food production and wildlife.

- The Independent