Integrated mosquito management to contain MBDs

Lt Col Nazmul Huda Khan, MBBS, MPhil, MPH :

Tomorrow, 20th August is the World Mosquito Day, when Bangladesh is grappling with an unprecedented outbreak of mosquito borne disease (MBD) dengue.

It is likely to register record numbers of dengue cases this year, along with record-breaking death tolls.

The year 2019 witnessed the most cases on record with 101,350 cases.

The death toll from the mosquito-borne disease has risen close to 400;where the previous record of 281 deaths reported in 2022.

World Mosquito Day is actually a stark reminder of mosquitoes’ devastating impact on global health.

This day is significant as it commemorates Sir Ronald Ross’s groundbreaking discovery in 1897 that linked mosquitoes to malaria transmission.

During the 19th century, death from malaria was a significant risk to the population with a mortality rate of about 10 per cent among the infected.

Major (Dr) Ross Ronald, a doctor of Royal British Army Medical Corps posted in India, started conducting experiments and confirmed that mosquitoes are the vector which carries this devastating parasite from human to human.

He was awarded with the Nobel Prize for Physiology or Medicine in 1902 for his work.

To make the world aware of this discovery and the devastating disease, Dr. Ross declared the observation of first World Mosquito Day right then and there.

Since then, every year 20 August began to be celebrated as World Mosquito Day.

Celebration of World Mosquito Day is carried out every year by the London School of Hygiene & Tropical Medicine since 1930.

Today, as we face a significant increase in mosquito-borne diseases worldwide, raising awareness and taking collective action is essential to combat this pressing health challenge.

As on today, around 3,500 species of mosquitoes have been identified in the earth, out of which more than 100 are responsible for causing deadly diseases e.g. Malaria, Dengue, Yellow fever, Japanese encephalitis, West Nile fever, Chickungunya, Kunjin Jamestown canyon virus, Zika, Venezuelan equine encephalitis, St Loius encephalitis, Pogostra disease, Ross Rivervirus, Lymphatic filariasis, Eastern equine encephalitis, Murray Valley encephalitis, Rift Valley fever, Lacrosse encephalitisetc. worldwide.

In Bangladesh, 123 species of mosquitoes have been identified; out of which, 14 have been detected in capital city.

Among MBDs; Dengue, malaria, filaria, chikungunya, zika and Japanese encephalitis are prevalent in Bangladesh.

In Bangladesh, other than dengue; about 35 per cent of the population of Bangladesh is at risk of contracting malaria, while it is estimated that around 70 million people are at risk of developing lymphatic filariasis.

Bangladesh also had an outbreak of chikungunya fever in 2017, where more than 13,000 were infected.

To contain and eliminate the public health threats of mosquitoes; World Health Organization (WHO) and Centre for Disease Control (CDC) put emphasis on Integrated Mosquito Management (IMM), that incorporates a comprehensive program in which mosquito populations are efficiently managed to minimize economic damage, public health risk and non-target impacts.

IMM uses methods to control mosquitoes based on an understanding of mosquito biology, the mosquito life cycle and the way mosquitoes spread infective agents.

The basic components of IMM include surveillance, source reduction, and control of all mosquito life stages, public education, community involvement and evaluation of actions taken.

Mosquito surveillance is the backbone of an integrated approach to mosquito management that provides the data on which all actions are taken.

Specification is critical in order to determine where the mosquitoes are breeding and whether or not there is a disease risk.

In addition, choices of control methods will be influenced by the species of mosquito that is present. Mosquito populations can be tracked over time to compare current data to historical numbers.

Source reduction is one of the most effective approaches to eliminate breeding habitat.

Key mosquito breeding areas must be destroyed by removing all indoor and outdoor containers where water can be collected and mosquitoes can lay their eggs and suspected areas should be sprayed with insecticides.

Measures to address waterlogging and cleaning of canals, water tanks, rainwater collection tanks, sump pits, downpipes and gutters should be put in place.

Though an important component, source reduction is not always feasible, particularly for certain habitats and if community participation is not strengthened.

With all sort of proactive measures, sometimes it is impossible to eliminate all breeding habitat or to control all mosquitoes before they become adults.

Therefore, adulticiding, or the control of adult mosquitoes through the application of adulticides is another important component of IMM.

Different species are active at different times and are susceptible to different adulticides. It is important to keep in mind that,mosquitoes are extremely adaptable and have several generations in only one season, so they can develop resistance to pesticides.

As a result, a critical component is the monitoring of such resistance.

Educating people to be aware of mosquito breeding habitat in their area and showing them how to reduce or eliminate such habitat can help reduce mosquito breeding.

People should also know on how to execute personal protection measures, whereby a person can be protected from mosquito bites using repellent, mosquito coil, mat, clothing and mosquito net.

The risk of mosquitoes entering their homes may be reduced by using window and door screens where feasible.

Wearing long pants and long-sleeved shirts can reduce mosquito bites when spending time at outdoors; special focus should be given to school children regarding their school uniform.

Maintaining data and information is a critical component of an Integrated Mosquito Management program.

GPS locations are important so that technician team can access potential breeding sites.

Maintaining data from year to year allows the concerned to understand the trends of life cycle and breeding.

Data collection and maintenance is also needed for regulatory and legislative compliance.

Research on the trend and evolution of the infective agents over the geographical time period and the implementation of inexpensive and accessible bioassay systems for early detection of outbreaks countrywide is also essential for sustainable progress to contain MBDs.

IMM is not belonged to a certain authority; everyone has a responsibility to help manage the risks posed by mosquitoes.

The key players include the community, landowners and managers, research and concerned educational institutions, local government along with its all machineries, the concerned ministries and their responsible organizationsand the state with its legislative and regulatory bodies.

It’s indeed a multisectoral approach. These initiatives can encourage people to take an active role in participating in IMM programme.

Mass media can impart more active and effective role by disseminating information to the people to perceive the holistic MBDs control programme and to contain the burden of mosquito borne ailments.

(The writer is a public health specialist, now deputed to Kuwait).