Dengue, chikungunya may hit early this year
HEALTH WORRIES Scientists say quick onset of summer to precipitate vectorborne viruses
NEWDELHI: A warmer-than-usual winter, earlier-than-usual summer, and very early trends of the disease have prompted experts to call for immediate measures to prevent the spread of dengue in the national Capital.
Meanwhile, scientists warn that this year could see more chikungunya cases, courtesy the medical equivalent of t he so-called base effect, where the previous year’s data affects this year’s. While there is no cause for alarm yet, given the weather conditions, efforts to contain the breeding of the mosquitoes responsible for transmitting both diseases should have begun by now, if not earlier, the experts add.
Till March 3, Delhi hospitals tracked by the South Delhi Municipal Corporation reported 15 cases of dengue, five more than last year when the mosquitoborne disease infected 9,271 people and killed 10.
“The high numbers at this time of the year are most likely because it was a warm winter and the temperatures did not drop enough to end mosquito breeding and virus transmission,” said Dr BK Hazarika, municipal health officer, Delhi. “It is important for
The temperature must remain below at least 16 degrees for 10-15 days at a stretch for the mosquitoes and the virus to die
Day temperature 1-1.5 degrees Celsius above normal can increase the transmission window
Aedes aegypti can breed in a film of water and breeding continues indoors through the winter
Warm weather leads to people using coolers and water-storage pots before summer, which become breeding grounds for mosquitoes
Unlike dengue, chikungunya offers herd immunity, and the dip in cases in 2017 is likely to lead to more cases this year
the temperature to remain below at least 16 degrees for 10 to 15 days at a time for the mosquitoes and the virus to die,” he explained. That hasn’t happened this year.
The spike in day temperatures, already 1 to 1.5 degrees Celsius above normal, is also creating breeding grounds for the Aedes mosquitoes -- Aedes (Stegomyia) aegypti and the Aedes Alpopictus – that spread dengue and chikungunya. “Even small environmental changes of 1-2 degrees in temperature and in humidity matter,” said Dr Neena Valecha, director, National Institute of Malaria Research, New Delhi. According to her, mosquitoes can breed indoors, changing their behaviour. “High temperature increases the transmission win- dow,” Dr Valecha added.
Dengue causes flu-like illness, with symptoms of headache, pain behind the eyes, muscle and joint pains, nausea, vomiting, swollen glands or rashes lasting for two to seven days.
Dengue cases Chikungunya cases
Malaria cases
No. of deaths