The Telegraph
Saturday , May 24 , 2014
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Bartered: bacteria for Celsius Microbes feel the heat in season of surge

- Heatwave spares city several diseases of the season

Here’s the summer deal to beat all cool deals. For each abnormally hot day that you have had to endure this season, there are apparently a few pesky microbes less for your body to contend with.

Many Calcuttans might have preferred a lesser premium for health insurance than being scorched by a 10-day heatwave, but experts say the Celsius surge did shield the city from many diseases common at this time of the year.

“Microbes affecting humans thrive in temperature up to a maximum of 37 degrees Celsius. Anything beyond that and they perish rapidly. Microbes proliferate in moist and humid conditions but if the temperature is high, they can’t survive even if the other conditions are met,” Pallab Ray, professor of medical microbiology at the Chandigarh-based Post Graduate Institute of Medical Education and Research, said on Friday.

So, if there have been fewer people visiting hospitals and clinics with respiratory tract diseases, conjunctivitis and the flu this summer, thank the Celsius for making the city too hot for viruses and bacteria to live!

Doctors say it is much easier to stay healthy in dry, warm weather with some basic precautions than in a less hot but humid environment that Calcutta gets around this time of the year. There are a few basic precautions to take, of course, such as avoiding frequent temperature change and not drinking chilled water or eating cut fruits sold on the streets.

Viruses and bacteria aren’t the only irritants struggling to survive in the extreme heat. Lack of rain has prevented accumulation of water for mosquitoes to breed and trigger an outbreak of dengue and malaria.

“Clean surface water is the ideal breeding ground for mosquitoes. Uninterrupted sunshine means surface water drying up, which is why you will find that the mosquito population has declined,” said a scientist with the Indian Council of Medical Research.

When the weather is hot and dry, most cases of throat and lung infection are caused by dormant viruses that become active because of factors like drinking chilled water or frequently going in and out of an air-conditioned environment.

“In heatwave conditions, people also tend to drink water without checking if it’s potable. This is a common trigger for gastrointestinal diseases and temperature has nothing to do with it,” a doctor said.

Over the past two weeks, most hospitals and clinics have had more people reporting symptoms of heatstroke than viral diseases.

“We have been getting patients mainly with fever caused by other medical conditions such as heatstroke, jaundice and gastro-enteric diseases caused by carelessness. There are also instances of fever caused by frequent change of temperature,” critical care expert Subrata Maitra said.

According to microbiologist Ray, microbes are mainly transmitted through the environment with heat and sunshine as key factors. Microbes can be transmitted to a doorknob or a telephone receiver by a carrier. When another person touches the object, transmission is likely. Since extreme heat significantly reduces the lifespan of a microbe, there is a lesser chance of it surviving long enough for transmission to be possible.

“Transmission of viruses is sporadic now. But once rain brings down the temperature and humidity rises, microbes will become active again,” said Mandeet Chadha, deputy director of the National Institute of Virology in Pune.

City-based microbiologist Bhaskar Narayan Chaudhuri said the rainy season that everyone was looking forward to would bring multiple health threats. “Adeno and rhinoviruses that cause respiratory tract infections in adults and respiratory syncytial virus and Paramyxovirus that mainly attack children thrive when there isn’t enough sunshine.”

Calcutta faced its longest heatwave in memory from May 12 to 21 with the maximum temperature peaking at 41.5 degrees Celsius.