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Credit: James Gathany
Mosquitoes’ ability to transmit malaria may be affected by antibiotics in the blood of those they bite, according to research published in Nature Communications.
Feeding on blood that contained the antibiotics penicillin and streptomycin (PS) hindered bacterial growth in mosquitoes’ guts.
The mosquitoes also became more susceptible to malaria infection, exhibited improved fertility, and lived longer than mosquitoes whose blood meals did not contain PS.
Study investigators said these findings do not suggest people should avoid taking antibiotics. But the study does indicate that more research is needed to explore how different combinations of antibiotics affect mosquitoes’ ability to spread malaria.
“Antibiotics are a valuable weapon in the fight against malaria and other diseases,” said study author Mathilde Gendrin, PhD, of Imperial College London in the UK.
“Our study suggests that the presence of antibiotics in people’s blood may have hidden effects on the guts of mosquitoes when mosquitoes ingest that blood, and that these effects could alter the mosquitoes’ ability to transmit malaria.”
Dr Gendrin and her colleagues chose to evaluate the effects of PS because these antibiotics are not used to combat malaria and don’t directly affect malaria parasites.
The team began their research by supplementing blood with therapeutic concentrations of PS and feeding the blood to Anopheles gambiae mosquitoes.
The investigators monitored the bacterial load in the mosquito gut over 3 blood feeds offered every 3 days. And they found that the proliferation of bacteria typically seen at 24 hours after a blood meal was reduced by 70% when mosquitoes received blood containing PS.
Next, the researchers conducted 3 experiments to determine whether receiving blood containing PS would influence the mosquitoes’ susceptibility to malaria infection.
In the first experiment, the team fed mosquitoes blood from rodents infected with Plasmodium berghei before or after the animals received PS.
The investigators assessed infection by counting the proportion of mosquitoes carrying oocysts (prevalence) and the number of oocysts per mosquito (intensity). In the presence of PS, infection prevalence increased by 21% (P=5.10-7), and the median intensity doubled (P=0.041).
In the second experiment, the researchers assessed the effect of PS on infection with human parasites. They fed mosquitoes blood containing Plasmodium falciparum gametocytes (cultured in vitro) and supplemented the blood with PS or buffer.
Again, the team observed higher infection prevalence (P=0.0033) and intensity (P=0.00026) in the presence of PS.
In the third experiment, the investigators fed mosquitoes blood freshly drawn from children carrying P falciparum gametocytes. The blood was supplemented with PS or buffer.
Once more, the intensity of infection significantly increased in the presence of PS (P=0.02). The 6.3% increase in infection prevalence was not statistically significant (P=0.4), but the researchers said this was likely due to the reduced statistical power of the experiment.
The team’s final experiments assessed the effects of PS on mosquitoes’ fertility and survival.
Exposure to PS led to a 32% higher proportion of egg-laying females (P=0.0038) and a 53% higher average number of eggs per female (P=0.016), although the proportion of eggs hatching into larvae was not affected.
Mosquito survival increased significantly after the insects ingested PS-treated human blood. The P value was 0.017 for the first blood meal and 0.0016 for all 3 blood meals.
“We only looked at two antibiotics in our study, so this is early stage research, and we don’t know what it means for other antibiotics,” Dr Gendrin noted.
“It’s possible other antibiotics might have no effect, or that they might make it harder for mosquitoes to transmit malaria. We would like to see much more research carried out to further understand our findings and to explore how other antibiotics might affect bacteria in the guts of mosquitoes.”
“Ultimately, we hope that understanding any hidden effects of different antibiotics would mean we can combat the spread of malaria more effectively,” added study author George Christophides, PhD, also of Imperial College London.
“For example, if particular antibiotics make mosquitoes more able to transmit malaria, the use of these could be combined with supply of bed nets in order to reduce mosquito bites. Additionally, if a doctor prescribed such antibiotics to a malaria patient, they could combine this with a drug such as atovaquone that can both treat malaria and block its transmission.” 
Credit: James Gathany
Mosquitoes’ ability to transmit malaria may be affected by antibiotics in the blood of those they bite, according to research published in Nature Communications.
Feeding on blood that contained the antibiotics penicillin and streptomycin (PS) hindered bacterial growth in mosquitoes’ guts.
The mosquitoes also became more susceptible to malaria infection, exhibited improved fertility, and lived longer than mosquitoes whose blood meals did not contain PS.
Study investigators said these findings do not suggest people should avoid taking antibiotics. But the study does indicate that more research is needed to explore how different combinations of antibiotics affect mosquitoes’ ability to spread malaria.
“Antibiotics are a valuable weapon in the fight against malaria and other diseases,” said study author Mathilde Gendrin, PhD, of Imperial College London in the UK.
“Our study suggests that the presence of antibiotics in people’s blood may have hidden effects on the guts of mosquitoes when mosquitoes ingest that blood, and that these effects could alter the mosquitoes’ ability to transmit malaria.”
Dr Gendrin and her colleagues chose to evaluate the effects of PS because these antibiotics are not used to combat malaria and don’t directly affect malaria parasites.
The team began their research by supplementing blood with therapeutic concentrations of PS and feeding the blood to Anopheles gambiae mosquitoes.
The investigators monitored the bacterial load in the mosquito gut over 3 blood feeds offered every 3 days. And they found that the proliferation of bacteria typically seen at 24 hours after a blood meal was reduced by 70% when mosquitoes received blood containing PS.
Next, the researchers conducted 3 experiments to determine whether receiving blood containing PS would influence the mosquitoes’ susceptibility to malaria infection.
In the first experiment, the team fed mosquitoes blood from rodents infected with Plasmodium berghei before or after the animals received PS.
The investigators assessed infection by counting the proportion of mosquitoes carrying oocysts (prevalence) and the number of oocysts per mosquito (intensity). In the presence of PS, infection prevalence increased by 21% (P=5.10-7), and the median intensity doubled (P=0.041).
In the second experiment, the researchers assessed the effect of PS on infection with human parasites. They fed mosquitoes blood containing Plasmodium falciparum gametocytes (cultured in vitro) and supplemented the blood with PS or buffer.
Again, the team observed higher infection prevalence (P=0.0033) and intensity (P=0.00026) in the presence of PS.
In the third experiment, the investigators fed mosquitoes blood freshly drawn from children carrying P falciparum gametocytes. The blood was supplemented with PS or buffer.
Once more, the intensity of infection significantly increased in the presence of PS (P=0.02). The 6.3% increase in infection prevalence was not statistically significant (P=0.4), but the researchers said this was likely due to the reduced statistical power of the experiment.
The team’s final experiments assessed the effects of PS on mosquitoes’ fertility and survival.
Exposure to PS led to a 32% higher proportion of egg-laying females (P=0.0038) and a 53% higher average number of eggs per female (P=0.016), although the proportion of eggs hatching into larvae was not affected.
Mosquito survival increased significantly after the insects ingested PS-treated human blood. The P value was 0.017 for the first blood meal and 0.0016 for all 3 blood meals.
“We only looked at two antibiotics in our study, so this is early stage research, and we don’t know what it means for other antibiotics,” Dr Gendrin noted.
“It’s possible other antibiotics might have no effect, or that they might make it harder for mosquitoes to transmit malaria. We would like to see much more research carried out to further understand our findings and to explore how other antibiotics might affect bacteria in the guts of mosquitoes.”
“Ultimately, we hope that understanding any hidden effects of different antibiotics would mean we can combat the spread of malaria more effectively,” added study author George Christophides, PhD, also of Imperial College London.
“For example, if particular antibiotics make mosquitoes more able to transmit malaria, the use of these could be combined with supply of bed nets in order to reduce mosquito bites. Additionally, if a doctor prescribed such antibiotics to a malaria patient, they could combine this with a drug such as atovaquone that can both treat malaria and block its transmission.”
Credit: James Gathany
Mosquitoes’ ability to transmit malaria may be affected by antibiotics in the blood of those they bite, according to research published in Nature Communications.
Feeding on blood that contained the antibiotics penicillin and streptomycin (PS) hindered bacterial growth in mosquitoes’ guts.
The mosquitoes also became more susceptible to malaria infection, exhibited improved fertility, and lived longer than mosquitoes whose blood meals did not contain PS.
Study investigators said these findings do not suggest people should avoid taking antibiotics. But the study does indicate that more research is needed to explore how different combinations of antibiotics affect mosquitoes’ ability to spread malaria.
“Antibiotics are a valuable weapon in the fight against malaria and other diseases,” said study author Mathilde Gendrin, PhD, of Imperial College London in the UK.
“Our study suggests that the presence of antibiotics in people’s blood may have hidden effects on the guts of mosquitoes when mosquitoes ingest that blood, and that these effects could alter the mosquitoes’ ability to transmit malaria.”
Dr Gendrin and her colleagues chose to evaluate the effects of PS because these antibiotics are not used to combat malaria and don’t directly affect malaria parasites.
The team began their research by supplementing blood with therapeutic concentrations of PS and feeding the blood to Anopheles gambiae mosquitoes.
The investigators monitored the bacterial load in the mosquito gut over 3 blood feeds offered every 3 days. And they found that the proliferation of bacteria typically seen at 24 hours after a blood meal was reduced by 70% when mosquitoes received blood containing PS.
Next, the researchers conducted 3 experiments to determine whether receiving blood containing PS would influence the mosquitoes’ susceptibility to malaria infection.
In the first experiment, the team fed mosquitoes blood from rodents infected with Plasmodium berghei before or after the animals received PS.
The investigators assessed infection by counting the proportion of mosquitoes carrying oocysts (prevalence) and the number of oocysts per mosquito (intensity). In the presence of PS, infection prevalence increased by 21% (P=5.10-7), and the median intensity doubled (P=0.041).
In the second experiment, the researchers assessed the effect of PS on infection with human parasites. They fed mosquitoes blood containing Plasmodium falciparum gametocytes (cultured in vitro) and supplemented the blood with PS or buffer.
Again, the team observed higher infection prevalence (P=0.0033) and intensity (P=0.00026) in the presence of PS.
In the third experiment, the investigators fed mosquitoes blood freshly drawn from children carrying P falciparum gametocytes. The blood was supplemented with PS or buffer.
Once more, the intensity of infection significantly increased in the presence of PS (P=0.02). The 6.3% increase in infection prevalence was not statistically significant (P=0.4), but the researchers said this was likely due to the reduced statistical power of the experiment.
The team’s final experiments assessed the effects of PS on mosquitoes’ fertility and survival.
Exposure to PS led to a 32% higher proportion of egg-laying females (P=0.0038) and a 53% higher average number of eggs per female (P=0.016), although the proportion of eggs hatching into larvae was not affected.
Mosquito survival increased significantly after the insects ingested PS-treated human blood. The P value was 0.017 for the first blood meal and 0.0016 for all 3 blood meals.
“We only looked at two antibiotics in our study, so this is early stage research, and we don’t know what it means for other antibiotics,” Dr Gendrin noted.
“It’s possible other antibiotics might have no effect, or that they might make it harder for mosquitoes to transmit malaria. We would like to see much more research carried out to further understand our findings and to explore how other antibiotics might affect bacteria in the guts of mosquitoes.”
“Ultimately, we hope that understanding any hidden effects of different antibiotics would mean we can combat the spread of malaria more effectively,” added study author George Christophides, PhD, also of Imperial College London.
“For example, if particular antibiotics make mosquitoes more able to transmit malaria, the use of these could be combined with supply of bed nets in order to reduce mosquito bites. Additionally, if a doctor prescribed such antibiotics to a malaria patient, they could combine this with a drug such as atovaquone that can both treat malaria and block its transmission.”