Repeat infection with malaria parasites might make mosquitoes more dangerous

In malaria-endemic regions, humans are often infected repeatedly with the Plasmodium parasite, and the consequences of such multiple infections are under intense study. In contrast, little is known about possible co-infection and its consequences in the Anopheles mosquitoes that transmit the disease. A study published on July 16th in PLOS Pathogens reports that not only can individual mosquitoes accumulate infections from multiple blood feeds, but also that an existing malaria infection makes mosquitoes more susceptible to a second infection, and that infections reach higher densities when another strain is already present.

Interested in interactions between malaria parasites and their insect hosts, Laura Pollitt, from the University of Edinburgh, UK, and colleagues in the US, asked whether and how mosquitoes can be infected with different Plasmodium strains, how such heterogeneous parasites interact in the insects, and whether such interactions affect transmission of malaria to vertebrate hosts.

The researchers set up cages of female Anopheles mosquitoes and allowed them at defined times to feed on mice infected with two different Plasmodium strains. This study design allowed them to examine how the presence of a co-infecting strain affects parasites that enter the vector first and second, and to test whether co-infection impacts mosquito survival.

The mosquito smells, before it sees, a bloody feast

The itchy marks left by the punctured bite of a mosquito are more than pesky, unwelcomed mementos of a day at the lake.

These aggravating bites can also be conduits for hitchhiking pathogens to worm their way into our bodies. Mosquitoes spread malaria, dengue, yellow fever and West Nile virus, among others. As the bloodsucking insects evolve to resist our best pesticides, mosquito control may shift more to understanding how the mosquitoes find a tasty -- and unsuspecting -- human host.

A team of biologists from the University of Washington and the California Institute of Technology has cracked the cues mosquitoes use to find us. As they report in a paper published July 16 in Current Biology, the minute insects employ a razor-sharp sense of smell to tip them off that a warm-blooded meal is nearby, and then use vision and other senses to home in on the feast.

"Very little was known about what a host looks like to the mosquito and how a mosquito decides where to land and begin to feed," said UW biologist Jeff Riffell, co-author on the paper and one of three professors collaborating on these efforts.

Virus-carrying mosquitoes are more widespread than ever, and spreading

Scientists behind the first global distribution maps of two species of dengue and chikungunya-carrying mosquitoes warn they are spreading to new areas where they could cause disease.

The population of the tiger mosquito, which is known to carry dengue and chikungunya, has rapidly expanded in parts of the US, Southern Europe and China over the past 10-15 years. A new study by scientists at Oxford University reports the growth and identifies areas not yet populated by the insects that are suitable for their survival, for example in Europe. The findings are published in the journal eLife.

"Given the lack of a vaccine or any antiviral treatment for either virus and the debilitating pain they both cause, knowing where the mosquitoes are spreading to and where they might turn up next is crucial for helping to protect communities," says first author Moritz Kraemer. This is especially true in Africa, where records are sparse.

Vaccine to protect global communities from malaria under development

A University of Oklahoma professor studying malaria mosquito interaction has discovered a new mosquito protein for the development of a new vaccine that is expected to stop the spread of the disease in areas where it is considered endemic. Malaria is transmitted by mosquitoes, and it infects millions of people in Africa, Asia and South America every year, causing a global health crisis. In addition to the local populations, U.S. military personnel stationed in these areas and travelers to these malaria-prone areas are at risk of becoming infected.

Jun Li, assistant professor in the Department of Chemistry and Biochemistry, OU College of Arts of Sciences, will travel to Kenya this July to test the newly-developed vaccine in the field. Since mosquitoes are essential for malaria transmission, Li and his colleagues from the OU Norman campus, the OU Health Sciences Center and John Hopkins University have found that an antibody used against a key mosquito protein inhibited malaria parasite invasion in mosquitoes. The antibody blocks the malaria parasite from the protein, which is needed for the parasite to invade mosquitoes.

Artificial blood to assist in mosquito control research

A "nuisance" is probably one of the nicest things people call mosquitoes.

Mosquitoes have been called the deadliest animal on the planet, because of the diseases they spread. So why would researchers want to develop an artificial buffet for them? The answer is simple. That "buffet" may lead to fewer mosquitoes. Stephen Dobson, a University of Kentucky professor of medical and veterinary entomology, believes his mosquito food can do just that. Others believe there's promise too.

Dobson's research on developing artificial blood for mosquitoes has made him a Grand Challenges Explorations winner, in an initiative funded by the Bill & Melinda Gates Foundation.

The artificial blood he developed will allow people in remote areas around the world to sustain colonies of mosquitoes, even in those areas with limited resources and difficult logistics.

Tracking genetic arms race between humans, mosquitoes

Every time you put on bug spray this summer, you're launching a strike in the ongoing war between humans and mosquitoes -- one that is rapidly driving the evolution of the pests.

Scientists studying mosquitoes in various types of environments in the United States and in Russia found that between 5 and 20 percent of a mosquito population's genome is subject to evolutionary pressures at any given time -- creating a strong signature of local adaptation to environment and humans.
This means that individual populations are likely to have evolved resistance to whatever local selection pressures are typical in their area -- and that understanding the genomes of those populations could one day help inform agencies about which pesticides are likely to be most effective against them.
"Mosquitoes adapt to heat, lifestyle, pesticides and so on -- and we see traces of that in their genome," said Sergey Nuzhdin, USC Dornsife College of Letters, arts and sciences professor and corresponding author of the study, which was published by Proceedings of the Royal Society B on June 17.

Protein discovery fuels redesign of mosquito-based malaria vaccine

A promising type of vaccine designed to eradicate malaria by blocking parasite transmission could be a step closer, as a result of experts uncovering new information about the targeted protein.

The international team of researchers co-led by Dr Natalie Borg from the Department of Biochemistry and Molecular Biology at Monash University, and Dr Rhoel Dinglasan from the Malaria Research Institute at the Johns Hopkins Bloomberg School of Public Health in Baltimore, USA, focused on a protein in the Anopheles mosquito midgut called AnAPN1.
The research, published in the journal Nature Structural & Molecular Biology, provides for the first time, detailed information on the shape of AnAPN1 and where antibodies against AnAPN1 that can and can't block parasite development, bind to the protein.