The continuous hot and dry weather can increase a person's risk of suffering from dehydration and heat stroke, according to Director-General of Health Datuk Dr Noor Hisham Abdullah.

"The extreme hot weather can cause a person to sweat a lot and lose the necessary body fluids, hence causing the person to easily feel tired and become less energetic," he said in a statement here today.

He said the hot and dry season could also cause other problems, such as water crisis, forest fires and haze, as well as heat-related illness, such as upper respiratory tract infection, asthma and conjunctivitis.

"Children and elderly people are among those most at risk to get this diseases," he said.

As such, Dr Noor Hisham advised the public to take caution and preventive measures to reduce the impact of the hot and dry weather on their health as this weather condition was expected to last until March.

He said according to the Meteorological Department, the hot and dry weather condition was caused by the El Nino phenomenon, which is expected to cause a reduction in rainfall intensity by 20 to 60 per cent and a temperature rise of between 0.5 to 2.0 degrees Celsius from between 28.6 and 35 degrees Celsius on normal day or from between 35 and 37 degrees Celsius on hot day.

Dr Noor Hisham advised the public to drink boiled water and at the same time limiting their outdoor activities, or if unavoidable, wear a hat or umbrella to protect themselves from extreme exposure to hot weather.

The public should also wear light clothing and avoid heavy and tight clothing whenever possible, he said.

In another development, he said the El Nino phenomenon could also cause the number of dengue fever cases nationwide to rise by up to 50 percent.

He said this was because the hot and dry weather would cause the cycle of life of Aedes mosquitoes to be reduced to only seven days and lead to an increase in mosquito population.

"Besides, high temperature will cause the mosquitoes to be more active and increase their bite frequency, hence the spreading of dengue virus will be more rampant," he said.

Meanwhile, Dr Noor Hisham said that dengue fever had claimed four lives in the first week of this year, namely in Selangor, Negeri Sembilan, Johor and Federal Territories.

He said a total of 3,337 cases of dengue fever were reported nationwide in the same period, an increase of 33 per cent (826 cases) compared to the previous week (final week of 2015).

In addition, he said the number of dengue localities had also increased during the first week this year to 1,044 from 907 in the previous week, while the number of dengue hotspots had also increased to 161 from 145 previously, involving seven states, namely Selangor (122), Johor (22), Perak (eight), Penang (four), Sabah and Negeri Sembilan (two each), Kuala Lumpur and Putrajaya (one).

"Overall, a total of 120,836 dengue cases were reported last year, an increase of 11.2 per cent or 12,138 cases from 108,698 cases reported in 2014," he added.