KARACHI - Experts have directed the citizens to adopt preventive measures against Dengue Fever (DF) and Dengue Hemorrhagic Fever (DHF) and warned that recent torrential rains might stimulate the fatal diseases in the city. The city has witnessed two deaths from dengue fever during the current year while a total of 160 cases, suspected with diseases, have so far been reported in different hospitals of the metropolis, said Dr Shakil Malik, focal person of the Dengue Surveillance Cell, while talking to The Nation on Friday. He maintained that the dengue-suspected cases detected in the city were less in number as compared to last year. He cautioned the citizens to be careful of the disease in rainy season because it could prove specific for rapid breeding of mosquitoes causing dengue fever. "As many as 19 cases have been declared positive with dengue fever in the city in the ongoing year while 13 others reported at Ziaudin Hospital, 3 at Abbasi Shaheed Hospital, 2 at Bismillah Taqui and one case was reported at the NICH. Giving basic information about the disease, Prof Dr Syed Jamil Hassan Kazmi, an expert in mosquito species and the Chairman Geography Department, Karachi University, said that dengue was transmitted by the bite of an Aedes mosquito infected with anyone of the four dengue viruses. "It occurs in tropical and sub-tropical areas of the world. Symptoms appear in 3-14 days after the bite. Dengue fever is a febrile illness that affects infants, young children and adults. It is a mosquito-borne infection that causes a severe flu-like illness, and sometimes a potentially lethal complication called dengue haemorrhagic fever," he added. The current rainy season may create new breeding pools if not drained properly. While the temperature between 22 to 30 degree centigrade helps in the breeding of mosquitoes. City District Government Karachi should realise the issue early and start spraying kerosene oil over the water pools to halt the breeding of mosquitoes," he said. Dr Kazmi said, "As per World Health Organisation, the incidence of dengue has grown dramatically around the world in recent decades. Some 2.5 billion people - two fifths of the world's population - are now at risk from dengue. The WHO currently estimates there may be 50 million dengue infections worldwide every year. In 2007 alone, there were more than 8,90,000 dengue cases reported in the Americas, of which 26,000 were DHF. The disease is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, Southeast Asia and the Western Pacific. Southeast Asia and the Western Pacific are the most seriously affected areas. Before 1970, only nine countries had experienced DHF epidemics, a number that had increased more than four-fold by 1995". He said that not only is the number of cases increasing as the disease is spreading to new areas, but explosive outbreaks are occurring. In 2007, Venezuela reported over 80 000 cases, including more than 6 000 cases of DHF. Dengue fever is a severe, flu-like illness that affects infants, young children and adults, but seldom causes death. The clinical features of dengue fever vary according to the age of the patient. Infants and young children may have a fever with rash. Older children and adults may have either a mild fever or the classical incapacitating disease with abrupt onset and high fever, severe headache, pain behind the eyes, muscle and joint pains, and rash. Dengue haemorrhagic fever (DHF) is a potentially deadly complication that is characterised by high fever, often with enlargement of the liver, and in severe cases circulatory failure. The illness often begins with a sudden rise in temperature accompanied by facial flush and other flu-like symptoms. The fever usually continues for two to seven days and can be as high as 41_C, possibly with convulsions and other complications." Kazmi maintained, "There was no specific treatment for the disease whose viruses are transmitted to humans through the bites of infective female Aedes mosquitoes. The Aedes aegypti mosquito bites during the day, lives indoors in domestic settings and breeds in both clean and polluted water, while adult mosquito was destroyed in temperature beyond 38 C, the eggs can withstand desiccation and can hatch next year as well whenever conditions are conducive. The citizens are strongly cautioned to prevent themselves from mosquito bites by wearing appropriate dresses, using repellents and insecticides and watching against any collection of water even small puddles. The water collected under air conditioner vents, and even unused WCs in the house can serve as breeding grounds for Aedes aegypti mosquito." According to Centres for Disease Control and Prevention (CDC), "Dengue (DF) and dengue hemorrhagic fever (DHF) are caused by one of four closely related, but antigenically distinct, virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4), of the genus Flavivirus. Infection with one of these serotypes provides immunity to only that serotype for life, so persons living in a dengue-endemic area can have more than one dengue infection during their lifetime.