Sterilizing Mosquitoes To Kill Off Infectious Diseases

An innovative technique that sterilizes male mosquitoes using radiation will soon be tested as part of global health efforts to control the spreading of serious diseases.

Diseases transmitted by mosquitoes such as malaria, dengue, Zika, chikungunya, and yellow fever account for about 17 percent of all infectious diseases globally, claiming more than 700,000 lives each year.

According to the World Health Organization (WHO) news release on November 14, 2019, the Sterile Insect Technique (SIT) is a form of 21st-century insect birth control.  

This process involves rearing large quantities of sterilized male mosquitoes in dedicated facilities and then releasing them to mate with females in the wild. 

As these male mosquitoes do not produce any offspring, the overall insect population declines over time.

The SIT was first developed by the U.S. Department of Agriculture and has been used successfully to target insect pests that attack crops and livestock, such as the Mediterranean fruit fly and the New World screwworm fly. 

SIT is currently in use globally in the agriculture sector on 6 continents.

The Special Programme for Research and Training in Tropical Diseases (TDR) and the International Atomic Energy Agency (IAEA), in partnership with the Food and Agriculture Organization of the United Nations (FAO), and the WHO have developed a guidance document for countries that have expressed interest in testing the Sterile Insect Technique (SIT) for Aedes mosquitoes.

“Half the world’s population is now at risk of dengue,” said Dr. Soumya Swaminathan, WHO Chief Scientist, in a press release. “And despite our best efforts, current efforts to control it are falling short.”

“We desperately need new approaches and this initiative is both promising and exciting.”

The guidance on using the SIT technique to control diseases in humans recommends adopting a phased approach that allows time to test the efficacy of the sterilized insects. Epidemiological indicators monitor the impact of the method on disease-transmission. 

It also provides recommendations on mass production of the sterile mosquitoes, government and community engagement, measuring the impact of the technique, and assessing cost-effectiveness.

“Countries seriously affected by dengue and Zika have shown real interest in testing this technology as it can help suppress mosquitoes that are developing resistance to insecticides, which are also negatively impacting the environment,” said Florence Fouque, a scientist at TDR.  

The collaborative effort includes plans to support three multi-country teams of research institutions, vector control agencies, and public health stakeholders to test the SIT against Aedes mosquitoes. 

“The use of the Sterile Insect Technique in the agriculture sector in the past 60 years has shown that it is a safe and effective method,” said Jérémy Bouyer, medical entomologist at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. 

“We are excited to collaborate with TDR and WHO to bring this technology to the health sector to fight human diseases.”

In recent decades, the incidence of dengue has increased dramatically due to environmental changes, unregulated urbanization, transport and travel, and insufficient sustainable vector control tools and their application. 

Dengue outbreaks are currently occurring in several countries, notably on the Indian sub-continent. 

Bangladesh is facing the worst outbreak of dengue since its first recorded epidemic in 2000. 

This South Asian nation has seen the number of cases rise to over 92,000 since January 2019, with daily admissions peaking at more than 1,500 new dengue patients in hospitals in recent weeks and is one of the countries to express interest in the SIT.

But, is any country prepared for a disease epidemic?

The new Global Health Security (GHS) Index suggests that not a single country in the world is fully prepared to handle an epidemic or pandemic.

The inaugural GHS Index released on October 24, 2019, finds severe weaknesses in all 195 countries’ abilities to prevent, detect, and respond to significant disease outbreaks. 

The average overall GHS Index score for 2019 is slightly over 40, out of a maximum score of 100. Among the 60 highest-income countries assessed, the DHS average score is 51.9.

Disease outbreak news

• November 14, 2019 – The Pan American Health Organization (PAHO) reported 2,733,635 confirmed Dengue Fever cases so far in 2019. This is the largest number of Dengue cases recorded in the history of Dengue in the Americas and has already exceeded by 13 percent the total number of cases reported in 2015, the previous record year.
• November 6, 2019 – ‘Malaria Day in the Americas’ is being observed for the 13th time. It is envisioned to be the platform upon which countries of the Region can engage in a year-round campaign to combat the disease.
• October 25, 2019 – To better detect, understand, and respond to emerging infectious disease threats such as dengue, the CDC is supporting research studies to better understand acute febrile illnesses in Belize, Guatemala, and the Dominican Republic.

However, not all scientists agree with this mosquito extinction method.

In a July 2019 article published in Nature, the authors said ‘building a gene to manipulate or eradicate a population is like picking a fight with natural selection, and that fight might not be easy to win.’

'The theory says that, in principle, if you release the modified mosquitoes once, they would spread continent-wide.' "The reality is that would happen very slowly,” says population biologist Charles Godfray at the University of Oxford, UK, a collaborator with Target Malaria and the study’s lead researcher.

Another concern is that a modified gene has the potential to alter entire populations and therefore entire ecosystems. They could also, in theory, negatively affect human health by causing a parasite to evolve to be more virulent or to be carried by another host, says molecular biologist and bioethicist Natalie Kofler.

The TDR, the Special Programme for Research and Training in Tropical Diseases, is a global program of scientific collaboration that helps facilitate, support and influence efforts to combat diseases of poverty. It is co-sponsored by the United Nations Children’s Fund, the United Nations Development Programme (UNDP), the World Bank and WHO.

Mosquito-borne disease news published by Precision Vaccinations