World Mosquito Day 2021

About half of the world’s population is at risk of malaria. In 2019, there were an estimated 229 million cases of malaria worldwide that claimed the lives of approximately 409,000 people—67 percent of whom were young children. Despite gains that have been made over the past two decades in expanding access to malaria prevention tools and treatments, challenges such as drug and insecticide resistance continue to hamper control efforts. To eradicate malaria, we need new treatments, vaccines, diagnostics, and vector control technologies.

Which of the following is not a nickname for dengue fever?

Cruciamen is not another name for dengue fever, but breakbone and dandy are! The nickname breakbone fever characterizes the severe muscle, joint, and bone pain caused by the disease, while dandy fever comes from a description of the gait and posture of enslaved people in the West Indies who suffered from dengue.

 

As many as 400 million dengue infections occur annually, yet unfortunately, to date there is no specific treatment or cure for this disease. While there is a vaccine, it is only appropriate for use in certain circumstances.

Nootkatone is an oil found in grapefruits and cedar trees. It repels mosquitoes, as well as ticks, bedbugs, and fleas. Naturally derived, inexpensive, and long-lasting, it could provide an additional alternative option to synthetically produced repellents. It works differently than previous classes of insecticides, so can kill bugs that have developed resistance to DDT, pyrethroids, and other commonly used insecticides. Its properties were first discovered by the US Centers for Disease Control and Prevention (CDC).

Tafenoquine is a single-dose medicine to prevent the relapse of Plasmodium vivax malaria, which was developed by GHTC member Medicines for Malaria Venture and GSK with support from the US Agency for International Development (USAID) and the Department of Defense (DoD). It is the first new treatment for this indication in more than 60 years.

This disease, for which there is no specific treatment or licensed vaccine, is one of two mosquito-transmitted diseases on the World Health Organization’s (WHO) list of priority pathogens with the greatest epidemic potential.

The correct answer is Zika. Rift Valley fever is the other disease on WHO’s list which can be transmitted by mosquitoes.

 

While no licensed vaccine for Zika is available, more than 40 vaccine candidates are in preclinical or clinical development, including candidates developed with support from the National Institutes of Health (NIH), DoD, and the Biomedical Advanced Research and Development Authority (BARDA). Several therapies are also in development.

In July, in a close-to-real-world study, scientists reported they were able to wipe out populations of malaria-transmitting mosquitoes within 245 to 311 days by using gene-drive technology, a type of genetic engineering, to render the females infertile. The gene-drive technology, meant to work alongside existing tools such as bednets, insecticides, and vaccines, introduces a set of genetic instructions that rapidly spread through a mosquito population as they mate and pass on this infertility trait, eventually leading the entire population to crash.

Which compound, first derived from a Chinese herb, is the basis of combination therapies which have become the gold standard for treating P. falciparum malaria worldwide?

Artemisinin was first isolated from the sweet wormwood plant employed in Chinese traditional medicine. Artemisinin-based combination therapies (ACTs), first developed in the 1990s, use artemisinin and its semisynthetic derivatives and have become the standard treatment for P. falciparum malaria worldwide. ACTs have helped contribute to a 60 percent decline in global malaria mortality between 2000 and 2019.

Mosquitoes infected with Wolbachia, a bacterium that impacts their reproduction and reduces population size, have been released to fight dengue and other mosquito-borne diseases in locations ranging from Indonesia to the Florida Keys, with early results showing promise. NIH and USAID have funded research into this approach.

In what year did pilot implementation begin for the world’s first malaria vaccine?

The world’s first—and to date, only—malaria vaccine, RTS,S, which provides partial protection in young children, began pilot implementation in parts of three sub-Saharan African countries—Ghana, Kenya, and Malawi—in 2019. The vaccine was developed through a unique, multisector partnership, led by GSK and GHTC member PATH—and now in collaboration with WHO—with critical contributions from the DoD Walter Reed Army Institute of Research and other US agencies. Two new malaria vaccine candidates, including one that pairs a shot of the live parasite that causes the disease with a dose of infection-fighting drugs, showed promise in small trials this year, expanding potential for an additional vaccine against the disease in the coming years.

There is no approved vaccine for which of the following mosquito-borne diseases? (Hint: Its name is derived from a word in the Kimakonde language meaning “to become contorted.”)

There is no approved vaccine for chikungunya, but several candidates are in late-stage development. Earlier this month, Valneva reported top-line data from a phase 3 trial of VLA1553, its live-attenuated, single-dose chikungunya vaccine candidate—the first ever phase 3 trial results for a chikungunya vaccine—bringing new hope that in the coming years, we will have a vaccine against this disease that causes debilitating joint pain and fever.

Vector control tools, including insecticide-treated bednets and indoor residual spraying, have driven dramatic declines in malaria. These two tools are responsible for an estimated 78 percent of malaria cases averted between 2000 and 2015.