Improved dengue control not just an MOH issue
Efforts to reduce rates of dengue fever in the country require the cooperation of multiple stakeholders to truly become effective, says a Ministry of Health (MOH) official.
According to Dr Rose Nani Mudin, head of the Vector-Borne Disease Section (PPKA) of the MOH, the government has recognized that traditional government-driven vector control efforts—eg, insecticide and larvicide spraying to reduce mosquito proliferation, and Aedes surveys in affected areas—have failed to significantly reduce incidence of dengue in the population, raising questions among the public and from the government itself regarding their long-term efficacy.
“A new approach of integrated management of dengue with multiple ministries and agencies started in 2014, with a consensus to form the National Dengue Task Force,” said Rose. “The plan of action focuses on improvements in case management, environmental management and cleanliness, vector control, as well as health promotion and advocacy.”
Rose noted that in 2014, the total number of new dengue cases in the country surged to a high of 108,698—an unprecedented high compared to the previous 20 years, which ranged from 6,000 to 49,000 cases per year. However, this was in part due to a new Ministry requirement that year that required blood samples from all suspected cases of dengue nationwide to be tested either by NS1 antigen, RT-PCR (reverse transcription polymerase chain reaction), or IgM/IgG antibody assays.
Meanwhile, although incidence rates have climbed over the years—from 31.6 per 100,000 population in 2000, to 396.4 in 2015—mortality rates from dengue have declined from 0.62 percent to 0.3 percent in the same span of years.
“Our case fatality rate is reducing,” said Rose. “And that is the outcome of the effort of all the clinicians and paediatricians all over Malaysia, as well as our [PPKA] teams, who try every year to correct shortfalls and improve management of the disease in clinics and hospitals.”
One issue faced in combating dengue’s spread is that epidemics are increasingly regional phenomena, impacted by climate fluctuations and increasing frequency of air travel; a comparison of weekly dengue cases recorded in Malaysia, Singapore, Phillippines and Laos in 2016 showed that all four countries experienced a concurrent escalation of cases between weeks 19 to 27.
In addition to this, while the proportion of the four known DENV serotypes in the country are known to fluctuate from year to year among the population—a phenomenon known as serotype shift—Rose noted that their distribution also varied between states in any given year. In 2013, the PPKA found that while the DENV-2 serotype was predominant overall (accounting for 40 to 60 percent of dengue cases through the year), individual states like Kelantan and Sabah had a much higher proportion of DENV-4 cases compared to DENV-2 (61 vs. 16.5 percent, and 57.1 vs. 12.7 percent, respectively).
“A majority of dengue patients are of a productive age group (15 to 54 years of age) who usually go out to schools or work at dawn or in the morning, and are at higher risk of infection,” said Rose, who added that this demographic was targeted for education programmes regarding preventative measures such as long-sleeved attire and the use of mosquito repellents.
Rose expressed hopes that wider accessibility of live outbreak information to the public through sites such as iDengue (idengue.remotesensing.gov.my), social mobilization projects in schools and workplaces to reduce breeding sites, as well as new innovations such as the Wolbachia mosquito breeding project and dengue vaccination would help reduce overall rates of dengue incidence.
“Dengue prevention requires a shared responsibility between individuals, communities and agencies, with the view to reduce dengue incidence and [mortality],” said Rose, who was speaking at the National Dengue & Arbovirus Infection Conference 2017, held in Kuala Lumpur recently.