New Drug Could Turn Humans Into Mosquito Repellent

The fight against mosquito-borne diseases may have a new weapon: a drug that makes human blood toxic to mosquitoes. Scientists have discovered that nitisinone, typically used to treat rare genetic disorders, exhibits a "hidden superpower" by killing mosquitoes that ingest the blood of those taking the medication. This breakthrough could offer a promising complementary strategy for controlling mosquito populations and reducing the spread of diseases like malaria.

Nitisinone: A Dual-Purpose Drug

Nitisinone is primarily prescribed to individuals with rare inherited conditions, such as alkaptonuria and tyrosinemia type 1, who struggle to break down the amino acid tyrosine. The drug functions by blocking an enzyme called 4-hydroxyphenylpyruvate dioxygenase (HPPD), preventing the buildup of harmful byproducts in the human body. However, researchers at the Liverpool School of Tropical Medicine and the University of Notre Dame have found that nitisinone has an additional effect on mosquitoes. When mosquitoes consume blood containing nitisinone, the drug also inhibits the HPPD enzyme in their bodies, disrupting their ability to digest blood properly and ultimately leading to their death.

How the Discovery Was Made

The discovery of nitisinone's mosquitocidal properties came about through collaboration with the Robert Gregory National Alkaptonuria Centre at the Royal Liverpool University Hospital. The center was conducting nitisinone trials with patients diagnosed with alkaptonuria, who then volunteered to donate their blood for research purposes. Scientists found that mosquitoes that fed on the blood of these patients died within 12 hours, revealing the drug's unexpected "superpower."

Nitisinone vs. Ivermectin

The researchers compared nitisinone's effectiveness against ivermectin, an antiparasitic medication already recognized for its ability to shorten mosquito lifespans and decrease malaria transmission. While ivermectin has shown promise, its widespread use raises concerns about environmental toxicity and the development of ivermectin resistance. Nitisinone, on the other hand, appears to have a longer half-life in human blood, meaning its mosquitocidal activity persists for a more extended period. Furthermore, nitisinone demonstrated effectiveness against mosquitoes of all ages, including older ones more likely to transmit malaria, and even against insecticide-resistant mosquitoes.

Potential Benefits and Concerns

The potential benefits of using nitisinone as a mosquito control strategy are significant. Malaria continues to be a major global health challenge, responsible for over half a million deaths annually. Existing methods to combat malaria, such as insecticide-treated bed nets and antimalarial drugs, face challenges due to growing mosquito populations, behavioral changes in mosquitoes (like increased outdoor feeding), and the development of resistance to insecticides and drugs. Nitisinone could provide a valuable complementary tool to combat these challenges.

However, researchers also emphasize the need for caution and further investigation. While nitisinone appears to be relatively safe for humans and may not harm other beneficial insects, its broader ecological impacts require careful assessment. There is also a risk that mosquitoes could develop resistance to nitisinone if it is used extensively.

The Future of Nitisinone in Mosquito Control

The research team suggests that alternating between nitisinone and ivermectin could be a beneficial strategy to mitigate the risk of resistance. They also plan to conduct semi-field trials to determine the most effective dosages of nitisinone in real-world scenarios. If these trials prove successful, nitisinone could become a valuable addition to the arsenal of tools used to combat mosquito-borne diseases, particularly in regions where malaria is prevalent.

Current Mosquito Bite Prevention Methods

While the development of nitisinone as a mosquito control strategy is promising, it is still in the early stages. In the meantime, individuals can take several steps to protect themselves from mosquito bites and the diseases they carry. These include:

• Using insect repellents: Repellents containing DEET, picaridin, oil of lemon eucalyptus, or IR3535 are effective in deterring mosquitoes. Always follow the label instructions when applying repellent, and take precautions when using it on children.
• Wearing protective clothing: When possible, wear long-sleeved shirts, long pants, and socks to minimize exposed skin. Light-colored, loose-fitting clothing is preferable, as mosquitoes can bite through tight clothing.
• Avoiding peak mosquito activity: Mosquitoes are most active during dusk and dawn. Limit outdoor activities during these times, or take extra precautions to protect yourself from bites.
• Removing standing water: Mosquitoes breed in standing water. Eliminate sources of standing water around your home, such as old tires, buckets, and clogged gutters. Empty and clean birdbaths and pet water bowls regularly.
• Using mosquito netting: Ensure that your home has screens on windows and doors to keep mosquitoes out. When traveling, use mosquito netting over beds, especially in areas where mosquito-borne diseases are common.

Conclusion

The discovery of nitisinone's mosquitocidal properties represents a significant step forward in the fight against mosquito-borne diseases. While further research is needed to fully understand its potential and address any potential risks, nitisinone offers a promising new avenue for controlling mosquito populations and protecting public health. In the meantime, individuals should continue to take personal precautions to avoid mosquito bites and reduce their risk of contracting diseases like malaria, Zika virus, and West Nile virus.