Mosquitoes immune to chemical substances within the north


By Tobbias Jolly Owiny

Researchers have found that mosquitoes have become resistant to chemicals used by the Ministry of Health in northern Uganda during the indoor residual spray exercise.
The research was carried out by scientists from Gulu University with the support of Training Researchers for Professional Excellence in East Africa (THRIVE), a consortium operating across East Africa.

Scientists say mosquitoes in the northern region have developed a special adaptation over time to protect themselves from the effects of the chemicals that kill them.
The reveal came Monday while research was being disseminated on the Gulu University campus.

“We have found that the effectiveness of chemical vector control measures with pyrethroid in the north is currently being challenged by the development of insecticide resistance in all major malaria vector species. If this option is not activated, it can lead to a significant increase in malaria incidence and mortality, ”said Dr. Richard Echodu, one of the investigators.

Using samples from Gulu, Kitgum, Agago and Oyam districts and Moroto and Abim districts in the Karamoja sub-region with the highest malaria prevalence, the study aimed to identify Anopheles sibling species and their susceptibility to carbamate (bendiocarb), pirimiphos identify -Methyl and pyrethroid insecticides.
The results found that mosquito mortality was between 98 and 100 percent for bendiocarb and between 100 and 100 percent for pirimiphos methyl insecticides within 24 hours of exposure. However, mortality was lower in mosquito samples exposed to pyrethroid insecticides, which are widely used in the north.

During the study, adult Anopheles mosquitoes were identified morphologically and by polymerase chain reaction (PCR) techniques. Their vulnerability status was then assessed in September and October 2019 using the World Health Organization (WHO) standard tube test method.
In an interview, Prof. Elizabeth Opiyo, the lead researcher, said that a total of 500 (two to five day old) adult female anopheles raised from larval / pupa collections from various breeding grounds were subjected to tests to determine their susceptibility.

“In areas where we’ve seen resistance, we definitely need to rotate and use different classes of insecticides than those currently in use because the mosquitoes have developed resistance to pyrethroids. These can be bicarbonates or organophosphates,” said Prof. Opiyo.


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