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(blue) in mosquito gut
Credit: Antoine Nicot
and Jacques Denoyelle
Experiments in canaries have shown that Plasmodium parasites react when non-infected mosquitoes bite their hosts, and the parasite responses increase transmission to the mosquito.
Like many other parasites, Plasmodium goes through a phase of chronic infection during which most of the parasites are in a dormant stage, and parasite numbers in the blood are very low.
Every now and then, however, the parasites “relapse,” and numbers increase, but the cause of this is not well understood.
So researchers set out to determine whether bites from non-infected mosquitoes can trigger relapses in Plasmodium during chronic infections, and whether relapses are associated with higher rates of transmission to the vector, ie, infection of the mosquitoes.
Sylvain Gandon, PhD, of the Université de Montpellier in France, and his colleagues described this research in PLOS Pathogens.
Specifically, the researchers studied the interaction between Plasmodium relictum, the parasite responsible for most cases of bird malaria in European songbirds, and its natural vector, a mosquito called Culex pipiens.
The team infected domestic canaries with P relictum and tested whether bites from uninfected Culex mosquitoes could trigger malaria relapses during chronic infection.
Indeed, parasite numbers in the blood routinely increased after the canaries were bitten. Moreover, the higher parasite loads following mosquito bites translated into higher infection rates in the mosquitoes.
The researchers therefore concluded that P relictum has the ability to boost its own transmission during the chronic phase of the vertebrate infection after being exposed to mosquito bites.
Although it is unclear if this also occurs in humans, the team suggested that better understanding of this phenomenon could eventually improve malaria control.
They also pointed out that many other pathogens alternate between acute and dormant phases. So better understanding of the ecological determinants and evolutionary forces governing parasite relapses could have wide-ranging applications. 
(blue) in mosquito gut
Credit: Antoine Nicot
and Jacques Denoyelle
Experiments in canaries have shown that Plasmodium parasites react when non-infected mosquitoes bite their hosts, and the parasite responses increase transmission to the mosquito.
Like many other parasites, Plasmodium goes through a phase of chronic infection during which most of the parasites are in a dormant stage, and parasite numbers in the blood are very low.
Every now and then, however, the parasites “relapse,” and numbers increase, but the cause of this is not well understood.
So researchers set out to determine whether bites from non-infected mosquitoes can trigger relapses in Plasmodium during chronic infections, and whether relapses are associated with higher rates of transmission to the vector, ie, infection of the mosquitoes.
Sylvain Gandon, PhD, of the Université de Montpellier in France, and his colleagues described this research in PLOS Pathogens.
Specifically, the researchers studied the interaction between Plasmodium relictum, the parasite responsible for most cases of bird malaria in European songbirds, and its natural vector, a mosquito called Culex pipiens.
The team infected domestic canaries with P relictum and tested whether bites from uninfected Culex mosquitoes could trigger malaria relapses during chronic infection.
Indeed, parasite numbers in the blood routinely increased after the canaries were bitten. Moreover, the higher parasite loads following mosquito bites translated into higher infection rates in the mosquitoes.
The researchers therefore concluded that P relictum has the ability to boost its own transmission during the chronic phase of the vertebrate infection after being exposed to mosquito bites.
Although it is unclear if this also occurs in humans, the team suggested that better understanding of this phenomenon could eventually improve malaria control.
They also pointed out that many other pathogens alternate between acute and dormant phases. So better understanding of the ecological determinants and evolutionary forces governing parasite relapses could have wide-ranging applications.
(blue) in mosquito gut
Credit: Antoine Nicot
and Jacques Denoyelle
Experiments in canaries have shown that Plasmodium parasites react when non-infected mosquitoes bite their hosts, and the parasite responses increase transmission to the mosquito.
Like many other parasites, Plasmodium goes through a phase of chronic infection during which most of the parasites are in a dormant stage, and parasite numbers in the blood are very low.
Every now and then, however, the parasites “relapse,” and numbers increase, but the cause of this is not well understood.
So researchers set out to determine whether bites from non-infected mosquitoes can trigger relapses in Plasmodium during chronic infections, and whether relapses are associated with higher rates of transmission to the vector, ie, infection of the mosquitoes.
Sylvain Gandon, PhD, of the Université de Montpellier in France, and his colleagues described this research in PLOS Pathogens.
Specifically, the researchers studied the interaction between Plasmodium relictum, the parasite responsible for most cases of bird malaria in European songbirds, and its natural vector, a mosquito called Culex pipiens.
The team infected domestic canaries with P relictum and tested whether bites from uninfected Culex mosquitoes could trigger malaria relapses during chronic infection.
Indeed, parasite numbers in the blood routinely increased after the canaries were bitten. Moreover, the higher parasite loads following mosquito bites translated into higher infection rates in the mosquitoes.
The researchers therefore concluded that P relictum has the ability to boost its own transmission during the chronic phase of the vertebrate infection after being exposed to mosquito bites.
Although it is unclear if this also occurs in humans, the team suggested that better understanding of this phenomenon could eventually improve malaria control.
They also pointed out that many other pathogens alternate between acute and dormant phases. So better understanding of the ecological determinants and evolutionary forces governing parasite relapses could have wide-ranging applications.