[LAHORE] Dengue fever outbreaks in Pakistan are turning more severe, an analysis of recent outbreaks shows.
An estimated 100 million persons worldwide get infected with dengue, a resurging viral infection spread by the mosquito Aedes aegyptii.
Several hundred thousands of them develop dengue haemorrhagic fever (DHF) — a more severe, usually fatal form in which bleeding and shock occurs.
A study of two outbreaks in Lahore in 2008, conducted on 110 patients from two hospitals, showed more than half of them developed the more severe form.
Malik Asaf Humayoun, head of the department of medicine at Allama Iqbal Medical College and the Jinnah Hospital, and colleagues describe this increase in the more severe form compared to previous years as alarming.
Four strains of the dengue virus circulate worldwide, including South Asia, and the fatal DHF form occurs when a previously infected and cured dengue patient gets re-infected again, usually with a different strain of the virus.
Two of these were reported in previous outbreaks in Karachi city, while a third has now been newly reported in the Lahore outbreak.
"There is urgent need to have a countrywide epidemiological survey for multiple dengue serotypes (strains)," Humayoun told SciDev.Net.
There is also a need for larger clinical studies in Pakistan and other South Asian countries to better understand the range of infections, endemic patterns and genetic susceptibility of different populations to the dengue virus, the researchers concluded.
Health authorities should consider strengthening surveillance for dengue infection, given the potential for future outbreaks with increased severity, they said.
The Pakistan study adds to growing concern over dengue control in Asia. The World Health Organization South East Asia Regional Office (SEARO) in March recommended a shift from 'top-down' dengue control approaches entirely based on insecticide fogging to community-based approaches involving political and religious leaders (see Dengue programmes 'too paternalistic').
The Pakistan study was published in the International Journal of Infectious Diseases earlier this year.
Int J Infect Dis doi:10.1016/j.ijid.2009.10.008 (2010)