Kenya has restarted Indoor Residual Spraying campaign for the first time since 2012 in a move to keep off mosquitoes from residential houses.
Between February and March 2017, a total of 212,000 homes, which is estimated to be 98 percent of the targeted area in Migori County were sprayed, covering a population of more than 900,000 people, including some 15,000 pregnant women and 120,000 children under age five who are the most vulnerable to malaria.
The indoor residual spraying (IRS), which is vector control intervention, has not been implemented in Kenya for the past five years in an effort to practice insecticide resistance management.
According to the Global Plan for Insecticide Resistance Management in malaria vectors (GPIRM) insecticide resistance is widespread, and is now reported in nearly two thirds of countries with malaria transmission, and it affects all major vector species and all classes of insecticides, hence the need to take control measures.
However, a 2016 study headed by John E. Gimnig of Division of Parasitic Diseases and Malaria at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, United States of America, and published in Plos One health journal found out that both IRS and insecticide treated mosquito nets are effective tools for reducing malaria burden and when implemented in an area of moderate to high transmission with moderate ITN coverage, there may be an added benefit of IRS.
Before the spraying began in Migori in February, the Presidents Malaria Initiative (PMI) through the Africa Indoor Residual Spraying Project (AIRS) in Kenya collected more than a year’s worth of monthly entomological surveillance data, according to Bradley Longman, the Chief of Party at the AIRS Kenya.
“Teams of trained entomologists studied mosquitoes in Migori for species composition, resting behavior, biting rates and insecticide susceptibility. These studies placed particular emphasis on how mosquitoes behaved in Western Kenya to identify the best strategy to kill them,” writes Longman.
In collaboration with the Kenya National Malaria Control Program, the Ministry of Health and local authorities, the PMI AIRS Project developed an implementation plan to spray all sleeping structures in six sub-counties in Migori County, which include Rongo, Awendo, Uriri, Suna East, Suna West and Nyatike.
After Migori, the IRS campaign will be extended to other epidemic areas within the Western Kenya region including Homabay, Kisumu, Siaya, Kakamega, Vihiga, and Busia.
The chemicals are sprayed on the wall because according to Longman, mosquito will always rest on a nearby wall until it has digested the blood.
If the person bitten carries the malaria parasite, that mosquito will then pass on the parasite to the next person it bites – often a neighbor, child or someone else living nearby.
By spraying walls with a long-lasting insecticide that is safe for humans, mosquitoes get a deadly dose and won’t survive to bite – and infect – another person. In this way, says Longman, indoor residual spraying disrupts malaria transmission and reduces the mosquito population.
The main objective of the government is to have at least 80 percent of people living in malaria risk areas use appropriate malaria preventive interventions by 2018.