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Malaria can thrive in cooler climes too: Know the risks and protect yourself

Infants and children under the age of 5 years are particularly susceptible to this disease as are pregnant women and HIV patients. © Shutterstock

Contrary to belief, malaria, a parasitic infection that results from mosquito bites, can also survive in cold regions. Know how to avoid and also deal with this condition.

Written by Jahnavi Sarma |Updated : October 2, 2019 3:31 PM IST

According to the World Health Organisation, malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes. It is preventable and curable. WHO says that in 2017 alone there were about 219 million cases of malaria in 87 countries around the world. The same year saw the deaths of 435,000 people from this disease. And, this is when malaria is a curable and preventable disease.

Young children are particularly vulnerable to it and the risk goes down as you get older. You get this disease if the female Anopheles mosquito bites you. Paradoxically, these mosquitoes can also get the parasite by biting an infected human. Then they go and bite other healthy people and spread the disease. Malaria parasites multiply rapidly in the red blood cells and cause symptoms like chills, fever and a low blood count. If left untreated and, in severe cases, it may lead to coma and even death.

This mosquito-borne disease is widely rampant in tropical and subtropical regions. But a study says that these parasites can also develop faster in mosquitoes at lower temperatures than previously thought. The findings of this study suggest that even slight climate warming can significantly increase the risk of malaria for hundreds of thousands, if not millions, of people in colder regions. This includes travellers to these areas too.

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Malaria may thrive in colder temperature too: Study

According to researchers at Penn State, the rate of transmission of this disease to humans is strongly determined by the time it takes for the parasites to develop in the mosquito. The quicker the parasites develop, the greater the chance that the mosquito will survive long enough for the parasites to complete their development and be transmitted to humans.

Researchers say that previous studies on the subject suggested that these parasites develop very slowly in cooler temperatures. Hence, mosquitoes are unable to transmit it to human during their lifespan. But this study challenges this long held belief.

Study debunks earlier theories that cooler regions are free of malaria risks

For the purpose of the study, researchers experimented on two malaria-hosting mosquito species, Anopheles stephensi and Anopheles gambiae. They kept these malaria-infected mosquitoes in the laboratory under a variety of temperatures ranging from 16 to 20 degrees Celsius. They also maintained a separate control set of mosquitoes at 27 degrees Celsius. This temperature is ideal for malaria transmission. Researchers also varied the daily temperatures by 10 degrees Celsius, 5 degrees above and below the daily mean.

It was believed that the parasites in the mosquito take 56 days to develop at 18 degrees Celsius. This is just above the minimum threshold for development. But this study proved that only 31 days are enough for this. They also saw that with variation in temperature, faster parasite growth happened at the cooler end, ie, 18 degrees Celsius. In fact, at this temperature, they grew in just 27 days.

They, therefore, concluded that even small increases in temperature can dramatically increase malaria infections in humans. This is because the parasites develop much faster at these lower temperatures than has been previously estimated, they say. Researchers are hopeful that these findings will save millions of people living in cooler geographical areas like mountainous regions. Biology Letters published this study.

Symptoms of malaria

Symptoms of malaria usually set in after about 10 to 15 days of mosquito bite. You may run high temperature, experience chills as temperature rises and also have a headache. It can also cause muscle ache, general weakness, nausea and vomiting, cough, diarrhoea and abdominal pain. Immediate treatment is necessary as it can lead to fatal complications. If left untreated, it can lead to multi-organ failure, pulmonary oedema, convulsions and circulatory collapse. But sometimes, malaria symptoms are too mild to spot. In such cases, it is not life-threatening. But be alert for more severe symptoms and, if you have any, consult a doctor immediately.

In children, symptoms may be slightly different and more severe. They may exhibit respiratory distress and suffer from severe anaemia. At times, it may also lead to cerebral malaria. But the good news is that, in areas where malaria is common, some people may enjoy partial immunity.

High risk groups

Malaria is rampant in sub-Saharan Africa. Other regions that are at risk are South-East Asia, Eastern Mediterranean, Western Pacific and the Americas.

It also strikes some population groups more than others. Infants and children under the age of 5 years are particularly susceptible to this disease as are pregnant women and HIV patients. Babies are sometimes born with the malaria parasite if their mother has the infection. Migrants and travellers to high risk areas are also at risk.

Preventive tips

Prevention is better than cure. So, if you take proper precautions to avoid mosquito bites, you will be able to avoid this disease.

Wear protective clothes like long trousers and full sleeve shirts. Less exposure of skin means there are less chances of a mosquito biting you. This is a must especially at dusk and dawn. You can also use a mosquito net while sleeping. An insecticide-treated net is the best option but if this is not available a normal net will also do. Use insecticides liberally, indoors as well as outdoors. This will reduce malaria transmission. Prevent collection of stagnant water in and around the house. This can become the breeding ground for mosquitoes. Other than this, there are anti-malarial drugs, which you can take as a precautionary measure. Ask your doctor about this.

Travellers must be aware of the risks and avoid mosquito bites. You must carry anti-malarial drugs to ensure that you are not caught unaware. This will help prevent acute malaria attacks. Wear protective clothing and use insect repellents. This will bring down your risk of being bitten by the carrier mosquito.

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