Abstract- beer consumption increases human atractiveness to malaria mosquitoes

Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers' odours).

Abstract Top
Background
Malaria and alcohol consumption both represent major public health problems.

Abstract Top
Background
Malaria and alcohol consumption both represent major public health problems.

Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers' odours).

Thus, the positive relationship between mosquito activation and time simply reflects the natural circadian flight activity, the process by which hungry females of An. gambiae engage in non-oriented flight to optimise their chance of encountering host stimuli [44].

We found that beer consumption not only enhanced the number of mosquitoes that engage in odour-mediated upwind flight (mosquito activation) but also enhanced the strength of their odour-mediated anemotactic response (mosquito orientation).

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

Abstract Top
Background
Malaria and alcohol consumption both represent major public health problems.

We found that beer consumption not only enhanced the number of mosquitoes that engage in odour-mediated upwind flight (mosquito activation) but also enhanced the strength of their odour-mediated anemotactic response (mosquito orientation).

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

Water consumption had no effect on human attractiveness to An. gambiae mosquitoes, but beer consumption increased volunteer attractiveness.

Beyond this coincidental side effect of beer consumption, mosquitoes may have evolved preferences for people who recently consumed beer - possibly due to reduced host defensive behaviours or highly nutritious blood-meals.

Mosquito activation and orientation are important parts of the natural host-seeking process of An. gambiae and any increases in these behaviours will facilitate vector-human contacts [23], [24].

The outlook may be even worse if we consider that alcohol contributes substantially to the global burden of diseases [48], especially by compromising the host immune defence against parasites.

The level of exhaled carbon dioxide and body temperature had no effect on human attractiveness to mosquitoes.

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

We postulate that the metabolism of alcohol following beer consumption induces changes in breath and odour markers (i.e. increases the production of kairomones such as 1-octen-3-ol) that increases attractiveness to An. gambiae.

Alcohol consumption is rising in developing countries and, as efforts to manage malaria are expanded, understanding the links between malaria and alcohol consumption becomes crucial.

We found that beer consumption not only enhanced the number of mosquitoes that engage in odour-mediated upwind flight (mosquito activation) but also enhanced the strength of their odour-mediated anemotactic response (mosquito orientation).

We found that beer consumption not only enhanced the number of mosquitoes that engage in odour-mediated upwind flight (mosquito activation) but also enhanced the strength of their odour-mediated anemotactic response (mosquito orientation).

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

The alcoholic beverage used in this experiment is a very popular drink in West Africa [36].

We postulate that the metabolism of alcohol following beer consumption induces changes in breath and odour markers (i.e. increases the production of kairomones such as 1-octen-3-ol) that increases attractiveness to An. gambiae.

In field situations, odour-mediated anemotaxis is an effective strategy to locate a vertebrate.

Second, compounds which are termed attractants can also act as repellents at high concentrations [45].

In natural conditions, human exhalations are dispersed and strongly diluted before contacting host-seeking mosquitoes [42].

The level of exhaled carbon dioxide and body temperature had no effect on human attractiveness to mosquitoes.

Although beer consumption significantly increased the volunteer attractiveness relative to the outdoor air control (mosquito orientation), the absence of orientational bias toward volunteer odours in the three other treatments (BB, BW and AW) is intriguing.

By ascertaining beer consumption as a risk factor, our study has identified a potential underlying cause of heterogeneous biting, and hence provides insights into the feasibility of targeted interventions.

Despite thorough investigations, the role of CO2 in host-finding by An. gambiae mosquitoes remains equivocal [24].

Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers' odours).

Beyond this coincidental side effect of beer consumption, mosquitoes may have evolved preferences for people who recently consumed beer - possibly due to reduced host defensive behaviours or highly nutritious blood-meals.

Upon arrival in the vicinity of the host, additional cues such as warm, moist convective currents and host movement are exploited by the insect to orientate toward the host.

Our aim was to ascertain the effect of beer consumption on human attractiveness to malaria mosquitoes in semi field conditions in Burkina Faso.

Water consumption did not affect these mosquito behavioural responses, demonstrating that beer was solely responsible for increased human attractiveness.

Second, compounds which are termed attractants can also act as repellents at high concentrations [45].

Thus, the positive relationship between mosquito activation and time simply reflects the natural circadian flight activity, the process by which hungry females of An. gambiae engage in non-oriented flight to optimise their chance of encountering host stimuli [44].

Recent models have stressed that local malaria control can only be reached if people who are bitten the most can be identified [20].

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

This result is in apparent contradiction with the general acceptance that blood-feeding insects are attracted to carbon dioxide.

Our aim was to ascertain the effect of beer consumption on human attractiveness to malaria mosquitoes in semi field conditions in Burkina Faso.

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

First, it is increasingly recognized that while CO2, a compound exhaled by all mammals, induces mosquito activation, it does not provide accurate orientational cues to the anthropophilic An. gambiae [24], [42].

Alcohol consumption is a widespread phenomenon throughout the world and represents one of the most pressing global health priorities [47].

Here, higher body temperatures were not associated with higher attractiveness and beer consumption actually resulted in decreased body temperatures.

Thus, the positive relationship between mosquito activation and time simply reflects the natural circadian flight activity, the process by which hungry females of An. gambiae engage in non-oriented flight to optimise their chance of encountering host stimuli [44].

We found that beer consumption not only enhanced the number of mosquitoes that engage in odour-mediated upwind flight (mosquito activation) but also enhanced the strength of their odour-mediated anemotactic response (mosquito orientation).

The outlook may be even worse if we consider that alcohol contributes substantially to the global burden of diseases [48], especially by compromising the host immune defence against parasites.

In natural conditions, human exhalations are dispersed and strongly diluted before contacting host-seeking mosquitoes [42].

Higher levels of exhaled breath (as measured with a CO2 analyser) were not associated with higher attractiveness and beer consumption did not affect CO2 expiration rate.

Finally, the fine-scale structure of the CO2 plume (continuous vs. pulsed stream) is known to affect the orientation, with a continuous plume reducing the behavioural responses of mosquitoes [24], [46].

Mosquito activation and orientation are important parts of the natural host-seeking process of An. gambiae and any increases in these behaviours will facilitate vector-human contacts [23], [24].

Mosquito activation and orientation are important parts of the natural host-seeking process of An. gambiae and any increases in these behaviours will facilitate vector-human contacts [23], [24].

We found that higher levels of expired CO2 were associated with lower mosquito orientation.

In field situations, odour-mediated anemotaxis is an effective strategy to locate a vertebrate.

We postulate that the metabolism of alcohol following beer consumption induces changes in breath and odour markers (i.e. increases the production of kairomones such as 1-octen-3-ol) that increases attractiveness to An. gambiae.

Upon arrival in the vicinity of the host, additional cues such as warm, moist convective currents and host movement are exploited by the insect to orientate toward the host.

Expanding experiments and observations on the attractiveness of people consuming alcohol to malaria mosquitoes and Plasmodium sp. development in these hosts should allow us to gauge the role of alcohol consumption on the transmission dynamic of malaria.

Expanding experiments and observations on the attractiveness of people consuming alcohol to malaria mosquitoes and Plasmodium sp. development in these hosts should allow us to gauge the role of alcohol consumption on the transmission dynamic of malaria.

First, it is increasingly recognized that while CO2, a compound exhaled by all mammals, induces mosquito activation, it does not provide accurate orientational cues to the anthropophilic An. gambiae [24], [42].

Recent models have stressed that local malaria control can only be reached if people who are bitten the most can be identified [20].

By ascertaining beer consumption as a risk factor, our study has identified a potential underlying cause of heterogeneous biting, and hence provides insights into the feasibility of targeted interventions.

Expanding experiments and observations on the attractiveness of people consuming alcohol to malaria mosquitoes and Plasmodium sp. development in these hosts should allow us to gauge the role of alcohol consumption on the transmission dynamic of malaria.

Here, higher body temperatures were not associated with higher attractiveness and beer consumption actually resulted in decreased body temperatures.

Beyond this coincidental side effect of beer consumption, mosquitoes may have evolved preferences for people who recently consumed beer - possibly due to reduced host defensive behaviours or highly nutritious blood-meals.

Therefore, people who drink beer are not only at higher risk of exposure to malaria mosquitoes but could also be more vulnerable to the Plasmodium parasites.

To eliminate the possibility that other active ingredients in beer apart from alcohol could be driving the observed effects, future studies are needed to test whether consumption of other alcoholic beverages also increases the risk of being bitten by An. gambiae, and hence being infected with malaria parasites in natural situations.

To the best of our knowledge, this study provides the first evidence that beer consumption increases human attractiveness to An. gambiae, which is the principal vector of malaria in Africa.

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

Discussion Top
We explored the effect of beer consumption on human attractiveness to a natural population of An. gambiae using a Y-olfactometer designed to accommodate total body emanations as a source of odour stimuli.

Despite individual volunteer variation, beer consumption consistently increased attractiveness to mosquitoes.

Alcohol consumption is rising in developing countries and, as efforts to manage malaria are expanded, understanding the links between malaria and alcohol consumption becomes crucial.

Our aim was to ascertain the effect of beer consumption on human attractiveness to malaria mosquitoes in semi field conditions in Burkina Faso.

Numerous studies have demonstrated that moderate and chronic alcohol consumptions can have strong immunosuppressive effects [49].

Alcohol consumption is a widespread phenomenon throughout the world and represents one of the most pressing global health priorities [47].

By ascertaining beer consumption as a risk factor, our study has identified a potential underlying cause of heterogeneous biting, and hence provides insights into the feasibility of targeted interventions.

Discussion Top
We explored the effect of beer consumption on human attractiveness to a natural population of An. gambiae using a Y-olfactometer designed to accommodate total body emanations as a source of odour stimuli.

Water consumption did not affect these mosquito behavioural responses, demonstrating that beer was solely responsible for increased human attractiveness.

Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers' odours).

To eliminate the possibility that other active ingredients in beer apart from alcohol could be driving the observed effects, future studies are needed to test whether consumption of other alcoholic beverages also increases the risk of being bitten by An. gambiae, and hence being infected with malaria parasites in natural situations.

This hypothesis is appealing but requires further investigations.

Alcohol consumption is a widespread phenomenon throughout the world and represents one of the most pressing global health priorities [47].

This hypothesis is appealing but requires further investigations.

Finally, the fine-scale structure of the CO2 plume (continuous vs. pulsed stream) is known to affect the orientation, with a continuous plume reducing the behavioural responses of mosquitoes [24], [46].

Finally, it is crucial to investigate the effect of alcohol consumption on the success of gametocyte (the Plasmodium infective stage for mosquitoes) production.

Alcohol consumption is rising in developing countries and, as efforts to manage malaria are expanded, understanding the links between malaria and alcohol consumption becomes crucial.

This result is in apparent contradiction with the general acceptance that blood-feeding insects are attracted to carbon dioxide.

The level of exhaled carbon dioxide and body temperature had no effect on human attractiveness to mosquitoes.

To eliminate the possibility that other active ingredients in beer apart from alcohol could be driving the observed effects, future studies are needed to test whether consumption of other alcoholic beverages also increases the risk of being bitten by An. gambiae, and hence being infected with malaria parasites in natural situations.

Despite thorough investigations, the role of CO2 in host-finding by An. gambiae mosquitoes remains equivocal [24].

By ascertaining beer consumption as a risk factor, our study has identified a potential underlying cause of heterogeneous biting, and hence provides insights into the feasibility of targeted interventions.

The alcoholic beverage used in this experiment is a very popular drink in West Africa [36].

In this species, the biting cycle starts at sunset and rises to peak between 24:00 and 1:00 [24].

Therefore, the increased attractiveness following beer consumption found here raises crucial issues regarding strategic planning for malaria control.

By ascertaining beer consumption as a risk factor, our study has identified a potential underlying cause of heterogeneous biting, and hence provides insights into the feasibility of targeted interventions.

Therefore, the absence of orientational bias for the volunteer odour-baited trap may have stemmed from the fact that our bioassay removes some of these host-related short-range stimuli.

Abstract Top
Background
Malaria and alcohol consumption both represent major public health problems.

Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers' odours).

Our results also indicate that increased exhaled breath cannot account for the observed increase in human attractiveness following beer consumption.

Therefore, people who drink beer are not only at higher risk of exposure to malaria mosquitoes but could also be more vulnerable to the Plasmodium parasites.

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

Like most anopheline species, An. gambiae is a night biter.

Water consumption did not affect these mosquito behavioural responses, demonstrating that beer was solely responsible for increased human attractiveness.

Upon arrival in the vicinity of the host, additional cues such as warm, moist convective currents and host movement are exploited by the insect to orientate toward the host.

Upon contact with odour stimuli, An. gambiae then switches from this appetitive search to the actual host location behaviours.

The outlook may be even worse if we consider that alcohol contributes substantially to the global burden of diseases [48], especially by compromising the host immune defence against parasites.

Although beer consumption significantly increased the volunteer attractiveness relative to the outdoor air control (mosquito orientation), the absence of orientational bias toward volunteer odours in the three other treatments (BB, BW and AW) is intriguing.

By ascertaining beer consumption as a risk factor, our study has identified a potential underlying cause of heterogeneous biting, and hence provides insights into the feasibility of targeted interventions.

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

First, it is increasingly recognized that while CO2, a compound exhaled by all mammals, induces mosquito activation, it does not provide accurate orientational cues to the anthropophilic An. gambiae [24], [42].

Upon arrival in the vicinity of the host, additional cues such as warm, moist convective currents and host movement are exploited by the insect to orientate toward the host.

Accordingly, the CO2 concentration released in the volunteer trap (575 ppm on average) may have been too strong, resulting in a negative effect on mosquito orientation [15].

Upon contact with odour stimuli, An. gambiae then switches from this appetitive search to the actual host location behaviours.

This hypothesis is appealing but requires further investigations.

In field situations, odour-mediated anemotaxis is an effective strategy to locate a vertebrate.

At least three lines of arguments can be advanced to resolve this apparent contradiction.

By ascertaining beer consumption as a risk factor, our study has identified a potential underlying cause of heterogeneous biting, and hence provides insights into the feasibility of targeted interventions.

Abstract Top
Background
Malaria and alcohol consumption both represent major public health problems.

Despite individual volunteer variation, beer consumption consistently increased attractiveness to mosquitoes.

The increased attractiveness of pregnant women has been attributed to increased body temperatures and exhaled breath [30].

Recent models have stressed that local malaria control can only be reached if people who are bitten the most can be identified [20].

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

Mosquito activation and orientation are important parts of the natural host-seeking process of An. gambiae and any increases in these behaviours will facilitate vector-human contacts [23], [24].

The outlook may be even worse if we consider that alcohol contributes substantially to the global burden of diseases [48], especially by compromising the host immune defence against parasites.

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

Thus, the positive relationship between mosquito activation and time simply reflects the natural circadian flight activity, the process by which hungry females of An. gambiae engage in non-oriented flight to optimise their chance of encountering host stimuli [44].

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

Therefore, the absence of orientational bias for the volunteer odour-baited trap may have stemmed from the fact that our bioassay removes some of these host-related short-range stimuli.

By ascertaining beer consumption as a risk factor, our study has identified a potential underlying cause of heterogeneous biting, and hence provides insights into the feasibility of targeted interventions.

Accordingly, the CO2 concentration released in the volunteer trap (575 ppm on average) may have been too strong, resulting in a negative effect on mosquito orientation [15].

In this species, the biting cycle starts at sunset and rises to peak between 24:00 and 1:00 [24].

Our results also indicate that increased exhaled breath cannot account for the observed increase in human attractiveness following beer consumption.

Thus, the positive relationship between mosquito activation and time simply reflects the natural circadian flight activity, the process by which hungry females of An. gambiae engage in non-oriented flight to optimise their chance of encountering host stimuli [44].

Alcohol consumption is a widespread phenomenon throughout the world and represents one of the most pressing global health priorities [47].

Upon arrival in the vicinity of the host, additional cues such as warm, moist convective currents and host movement are exploited by the insect to orientate toward the host.

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

First, it is increasingly recognized that while CO2, a compound exhaled by all mammals, induces mosquito activation, it does not provide accurate orientational cues to the anthropophilic An. gambiae [24], [42].

Therefore, the absence of orientational bias for the volunteer odour-baited trap may have stemmed from the fact that our bioassay removes some of these host-related short-range stimuli.

Alcohol consumption is rising in developing countries and, as efforts to manage malaria are expanded, understanding the links between malaria and alcohol consumption becomes crucial.

Water consumption did not affect these mosquito behavioural responses, demonstrating that beer was solely responsible for increased human attractiveness.

The outlook may be even worse if we consider that alcohol contributes substantially to the global burden of diseases [48], especially by compromising the host immune defence against parasites.

Mosquito activation and orientation are important parts of the natural host-seeking process of An. gambiae and any increases in these behaviours will facilitate vector-human contacts [23], [24].

Finally, the fine-scale structure of the CO2 plume (continuous vs. pulsed stream) is known to affect the orientation, with a continuous plume reducing the behavioural responses of mosquitoes [24], [46].

This result is in apparent contradiction with the general acceptance that blood-feeding insects are attracted to carbon dioxide.

To eliminate the possibility that other active ingredients in beer apart from alcohol could be driving the observed effects, future studies are needed to test whether consumption of other alcoholic beverages also increases the risk of being bitten by An. gambiae, and hence being infected with malaria parasites in natural situations.

Numerous studies have demonstrated that moderate and chronic alcohol consumptions can have strong immunosuppressive effects [49].

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

Accordingly, the CO2 concentration released in the volunteer trap (575 ppm on average) may have been too strong, resulting in a negative effect on mosquito orientation [15].

Thus, the positive relationship between mosquito activation and time simply reflects the natural circadian flight activity, the process by which hungry females of An. gambiae engage in non-oriented flight to optimise their chance of encountering host stimuli [44].

Therefore, the increased attractiveness following beer consumption found here raises crucial issues regarding strategic planning for malaria control.

Therefore, the absence of orientational bias for the volunteer odour-baited trap may have stemmed from the fact that our bioassay removes some of these host-related short-range stimuli.

The outlook may be even worse if we consider that alcohol contributes substantially to the global burden of diseases [48], especially by compromising the host immune defence against parasites.

Discussion Top
We explored the effect of beer consumption on human attractiveness to a natural population of An. gambiae using a Y-olfactometer designed to accommodate total body emanations as a source of odour stimuli.

Abstract Top
Background
Malaria and alcohol consumption both represent major public health problems.

We found that beer consumption not only enhanced the number of mosquitoes that engage in odour-mediated upwind flight (mosquito activation) but also enhanced the strength of their odour-mediated anemotactic response (mosquito orientation).

Upon arrival in the vicinity of the host, additional cues such as warm, moist convective currents and host movement are exploited by the insect to orientate toward the host.

This hypothesis is appealing but requires further investigations.

Similar results have been recently obtained using the same methodology and mosquito population [39].

Recent models have stressed that local malaria control can only be reached if people who are bitten the most can be identified [20].

Alcohol consumption is rising in developing countries and, as efforts to manage malaria are expanded, understanding the links between malaria and alcohol consumption becomes crucial.

The outlook may be even worse if we consider that alcohol contributes substantially to the global burden of diseases [48], especially by compromising the host immune defence against parasites.

To the best of our knowledge, this study provides the first evidence that beer consumption increases human attractiveness to An. gambiae, which is the principal vector of malaria in Africa.

Upon contact with odour stimuli, An. gambiae then switches from this appetitive search to the actual host location behaviours.

Methodology/Principal Findings
We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes).

Therefore, the increased attractiveness following beer consumption found here raises crucial issues regarding strategic planning for malaria control.

Finally, the fine-scale structure of the CO2 plume (continuous vs. pulsed stream) is known to affect the orientation, with a continuous plume reducing the behavioural responses of mosquitoes [24], [46].

Despite individual volunteer variation, beer consumption consistently increased attractiveness to mosquitoes.

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

Conclusions/Significance
These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

Similar results have been recently obtained using the same methodology and mosquito population [39].

Higher levels of exhaled breath (as measured with a CO2 analyser) were not associated with higher attractiveness and beer consumption did not affect CO2 expiration rate.

To eliminate the possibility that other active ingredients in beer apart from alcohol could be driving the observed effects, future studies are needed to test whether consumption of other alcoholic beverages also increases the risk of being bitten by An. gambiae, and hence being infected with malaria parasites in natural situations.