Global warming to create ideal grounds for deadly diseases | Greenwatch Dhaka | The leading online daily of Bangladesh

Global warming to create ideal grounds for deadly diseases


Britain may be chilly, but at least a trip to the seaside here is unlikely to leave one with anything more serious than an ear infection.
But could that change? Last week it was reported that some experts fear Britain is on course to be warmer and wetter as global temperatures rise.
According to a report from the Department of Health, Health Effects Of Climate Change In The UK, British winters will become less cold but wetter, whereas summers will become warmer and probably drier in some places.
Some warn that these changes could create ideal conditions for some of the world’s most unpleasant and deadlier diseases to get a hold in the Mediterranean and even the UK,, says a report published in the Daily Mail, London. But the situation could be more dangerous in trophical counbtries including Bangladesh where bacteria of diseases already have faourable breeding conditions.



These include cholera and zika, which is linked to microcephaly (a devastating brain defect) in babies.
And a study, Explaining Ocean Warming, published this month by the International Union for Conservation of Nature suggested that a form of tropical food poisoning known as ciguatera — caused by eating fish that have consumed toxins released in seawater by algae — could soon be common around the UK’s coastline.
Water temperatures on the South Coast in July and August are already edging up to the 15c needed to support a bloom of the algae.
Warmer temperatures ‘will have far reaching effects on a whole range of public health in the UK’, says Dr Nick Watts, director of the UK Health Alliance on Climate Change.
‘This includes increased risk of water-borne diseases across Europe such as cholera, as well as those that are carried by insects that thrive in warmer temperatures.’
So what can we expect?
CURRENTLY FOUND: Cholera is endemic in many parts of south-eastern and central Asia including Bangladesh and Pakistan.
It also affects countries in Africa and South America.
WHAT IS IT? A water-borne illness, it is spread by a bacterium called Vibrio cholerae which is linked to plankton found in marine environments.
It causes acute diarrhoea, vomiting and cramps and can lead to severe dehydration which can kill within hours.
Once ingested, it passes out via an infected person’s faeces, which leads to rapid spread in areas where sewage or drinking water are inadequately treated.
Oral rehydration salts, or rapid intravenous administration of fluids nearly always cure it.
Cholera affects up to 4.3 million people every year. There were pandemics here in the 1840s, 1850s and 1860s but improved sewage systems and clean water supplies meant it never reached epidemic proportions again.
However it could make a comeback in the UK and the rest of Europe, according to Professor Parmesan, who is co-author of the Explaining Ocean Warming report’s chapter on water-borne diseases.
‘In warmer seas, you get a bigger build of plankton which co-exist with Vibrio cholerae, allowing the pathogen to build up in the marine environment where it is eaten by fish which end up being eaten by humans.’
She says Vibrio cholerae can also survive in relatively fresh water for long periods, meaning it can get into the water systems via estuaries and rivers.
So cholera could infect Britons who drink infected water or eat fish which are contaminated, but it is unlikely that it will spread more widely because of our water treatment plants and sanitation systems, says Professor Parmesan.
A vaccination, given as a drink, is available to protect travellers against cholera.
CURRENTLY FOUND: Zika is now found in many countries throughout South America and the Caribbean as well as the Pacific Islands. There have also been locally acquired cases in Florida.
WHAT IS IT? Zika is a mosquito-borne disease that causes a mild rash, but may have no symptoms at all; it is linked to brain defects in babies. There is currently no vaccine.
The World Health Organisation has identified certain parts of Southern France and Spain, areas around the Black Sea and Madeira as probable sites where zika could soon emerge.
Jimmy Whitworth, a professor of international public health at the London School of Hygiene and Tropical Medicine, says that the threat of zika spreading to Europe is ‘real’.
‘Countries in southern Europe, including France and Italy need to be especially vigilant.’
The virus is carried by a variety of mosquitos; the main type is the aedes aegypti mosquito, which has spread from East Africa to many parts of the world and thrives in warm, wet conditions.
But potentially more problematic is the Aedes albopictus mosquito, which can survive cooler climates.
Also known as the Tiger mosquito, the albopictus is now found in the U.S. and Europe as well as most tropical and subtropical areas.
‘Its range has been expanding as it successfully adapts to cooler regions, hibernating over the winter,’ explains Professor Whitworth.
Globalisation and the mass movement of people has accelerated this process as well as a trick unique to its species — its eggs can dry out and reactivate when rehydrated later.
‘The international trade in used tyres may be one of the main contributing factors to its spread because tyres collect water and are ideal mosquito breeding grounds,’ says Dr Jo Lines, a professor of malaria control and vector biology at the London School of Hygiene and Tropical Medicine.
He says the best protection is ‘destroying the water traps where they lay their eggs, near to human habitation and wearing insect repellent and protection during the day [when the albopictus bites].
CURRENTLY FOUND: India, Brazil, Iran, Bangladesh and Sudan.
WHAT IS IT? This disease, which affects around 350 million people living in 88 tropical and subtropical countries, is spread by the bite of female phlebotamine sand flies, which pass on tiny parasites to human hosts.
The parasites can cause nasty lesions on the skin as well as mouth ulcers and damage to the spleen and liver.
According to Dr Nick Watts: ‘There is evidence in several scientific reviews that the sand flies that carry leishmaniasis are spreading North, up from the Mediterranean region and across Europe.
‘There have only been a small number of cases in the developed world, but the parasite itself is now endemic in Spain, Portugal and Italy and is spreading further across Europe, helped by hotter longer summers and warmer winters.’
Topical creams can help skin lesions and oral medication can usually eradicate the parasite.
Prevention is by using insecticides and nets while sleeping since the sand flies tend to bite around sunset and at night.
CURRENTLY FOUND: Dengue fever is a leading cause of death among children in many Asian and Latin American countries.
Chikungunya is found in Africa, Asia and the Indian subcontinent.
What is it? Dengue fever is a viral disease which causes fever and painful joints and rash and can lead to bleeding in the gastrointestinal tract and death.
It can be transmitted by the Aedes aegypti and the Aedes albopictus mosquitos.
Before 1970 only nine countries had experienced severe dengue epidemics, but the disease is now endemic in more than 100, including Florida, Japan and Brazil.
Dengue picked up from infected local mosquitos (as opposed to being acquired while abroad) was reported for the first time in Europe in Croatia in 2010 and France in the same year.
The aedes albopictus mosquito can also spread the viral disease chikungunya which causes fever and severe joint pain. There is no treatment except trying to relieve symptoms.
Aedes albopictus was responsible for an outbreak of chikungunya in Ravenna in Italy in 2007 when more than 200 people fell ill (one died).
Basic precautions against both diseases include using insect repellants, wearing long sleeves and ensuring windows are fitted with screens.
CURRENTLY FOUND: Subtropical and tropical areas including the Caribbean and the Bahamas
WHAT IS IT? A form of tropical food poisoning from eating fish that have consumed toxin released by algae.
It causes nausea, pain, neurological symptoms (such as tingling) — it can, rarely, be fatal.
The toxin, cigautoxin, is odourless and tasteless and cannot be removed by conventional cooking.
There been outbreaks in the Canary Islands and Madeira caused by locally caught fish; it’s also been reported around Florida, the Pacific islands, Hong Kong and Japan.
Ciguatera could be a health risk in British waters ‘within a few decades’ as sea temperatures continue to rise.
According to Professor Camille Parmesan, who is also national marine aquarium chair in the public understanding of Oceans and Human Health at Plymouth University, it’s not the only marine-borne infection that could increase because of warmer sea temperatures.
‘There are around 100 types of algae that release toxins that can end up in fish that we like to eat,’ she explains.
Harmful algal blooms are becoming more common around the Mediterranean — red tides, algal blooms that release toxins and stain the water red, have been found around the Greek coastline since the late Seventies.
People who eat oysters and other shellfish contamined with ‘red tide toxin’ can become seriously ill.
The Department of Health in Australia advises people to protect themselves from ciguatera by not eating reef fish larger than six pounds (the toxin accumulates in bigger fish).
Barrucada is considered most risky for ciguatera poisoning. There is no effective treatment.
CURRENTLY FOUND: Malaria is a major problem in parts of Africa, including Angola as well as parts of South America, India and Indonesia.
It is also widespread in tropical and subtropical regions such as Brazil, Tanzania and Nigeria. In 2015, there were 214 million cases of malaria worldwide resulting in an estimated 438,000 deaths.
WHAT IS IT? Malaria is a mosquito-borne disease caused by a single-celled parasite that passes from an infected female Anopheles mosquito (which thrives in warm, humid conditions) into a person’s blood via a bite.
It causes flu-like symptoms, fever and sweating followed by shivering. Severe complications include pneumonia, respiratory distress and kidney failure.
Some suggest it could be endemic in some parts of England by 2050 due to an influx of anopheles mosquitos which have already spread to parts of Southern Europe.
In 2012, home-grown malaria was reported in Greece — the first time in Western Europe since 1974.
The disease was caught within the country, suggesting that anopheles mosquitos living there had bitten an infected person in Greece (who was infected elsewhere) and then passed it to a local.
However some experts aren’t convinced. Dr Jo Lines agrees that warmer temperatures will make it easier for malaria to spread, however this isn’t the whole story.
‘Malaria used to be present in cooler countries, too, including Siberia. There were malaria outbreaks in the North Kent marshes during World War I. T
‘he anopheles mosquitos, which transmitted the infection, are still present there.’
He says the main reason that malaria vanished from Britain and other parts of Europe in the Seventies was because of improvement in housing and healthcare, drainage of the marshes and deforestation.
‘It is very unlikely that we will have malaria back in the UK, even if it gets warmer, as long as we take precautions against the risk,’ says Dr Lines.
These would include rapid diagnosis and treatment of disease in infected people.
Antimalarial medication is used to prevent and treat malaria, and pilot studies are ongoing on a new vaccine. – Daily Mail – World News Report via EIN News


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