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The goal of eliminating malaria in countries like India could be more achievable if mosquito-control efforts take into account the relationship between mosquitoes and cattle, according to an international team of researchers.
The group analyzed 2 mosquito
species found in Odisha, the state with the highest number of malaria cases in
India, and found that both species fed on cattle as well as humans.
“In many parts of the world, the mosquitoes responsible for transmitting malaria are specialist feeders on humans and often rest within human houses,” said Matthew Thomas, PhD, of Pennsylvania State University in University Park, Pennsylvania.
“We found that, in an area of India that has a high burden of malaria, most of the mosquitoes that are known to transmit malaria rest in cattle sheds and feed on both cows and humans.”
Dr Thomas and his colleagues reported these findings in Scientific Reports.
According to the researchers, cattle sheds in India are often next to, and sometimes even share a wall with, human houses. However, current malaria control efforts are restricted to domestic dwellings only.
“Given this cattle-shed ‘refuge’ for mosquitoes, focusing only on humans with regard to malaria control is a bit like treating the tip of an iceberg,” said study author Jessica Waite, PhD, also of Pennsylvania State University.
She, Dr Thomas, and their colleagues determined the importance of cows in the malaria-control problem by capturing adult mosquitoes in different habitats within 6 villages in Odisha state—which has the highest number of malaria cases in the country—and noting where the mosquitoes had been resting.
The team then used molecular techniques to determine which species of mosquitoes had been captured and which hosts they had been feeding on.
The researchers collected 1774 Anopheles culicifacies mosquitoes and 169 Anopheles fluviatilis mosquitoes across all study sites.
Both species were denser in cattle sheds than in human dwellings, and both were feeding on humans as well as cattle.
Next, the researchers used their field-collected data to help build a computer model that simulated the life of an adult mosquito. The team used the model to explore how best to control the mosquitoes to have maximum impact on malaria transmission in these villages.
“Our model analysis suggests that conventional control tools—such as insecticide-treated bed nets and indoor insecticide sprays—are less effective when mosquitoes exhibit ‘zoophilic’ behaviors (having an attraction to nonhuman animals),” Dr Thomas said.
“However, extending controls to better target the zoophilic mosquitoes—for example, by broadening coverage of non-repellant insecticide sprays to include cattle sheds—could help reduce transmission dramatically.”
Dr Waite added that the model suggests very little cattle-based vector control effort would be required to drive malaria transmission in the region to elimination.
“We show that directing even modest amounts of effort to specifically increase mosquito mortality associated with zoophilic behavior can shift the balance towards elimination,” she said.
“Understanding the dynamic between humans, cattle, and mosquitoes could have major implications for malaria control policy and practice, not only in India, but in other areas where transmission is sustained by zoophilic vectors,” Dr Thomas said.
“Specifically, optimizing use of existing tools will be essential to achieving the ambitious 2030 elimination target set by the World Health Organization, which aims to decrease malaria cases globally by 90% compared to 2015 levels and eliminate malaria in at least 35 additional countries by 2030.” 
Photo by Ilya Mauter
The goal of eliminating malaria in countries like India could be more achievable if mosquito-control efforts take into account the relationship between mosquitoes and cattle, according to an international team of researchers.
The group analyzed 2 mosquito
species found in Odisha, the state with the highest number of malaria cases in
India, and found that both species fed on cattle as well as humans.
“In many parts of the world, the mosquitoes responsible for transmitting malaria are specialist feeders on humans and often rest within human houses,” said Matthew Thomas, PhD, of Pennsylvania State University in University Park, Pennsylvania.
“We found that, in an area of India that has a high burden of malaria, most of the mosquitoes that are known to transmit malaria rest in cattle sheds and feed on both cows and humans.”
Dr Thomas and his colleagues reported these findings in Scientific Reports.
According to the researchers, cattle sheds in India are often next to, and sometimes even share a wall with, human houses. However, current malaria control efforts are restricted to domestic dwellings only.
“Given this cattle-shed ‘refuge’ for mosquitoes, focusing only on humans with regard to malaria control is a bit like treating the tip of an iceberg,” said study author Jessica Waite, PhD, also of Pennsylvania State University.
She, Dr Thomas, and their colleagues determined the importance of cows in the malaria-control problem by capturing adult mosquitoes in different habitats within 6 villages in Odisha state—which has the highest number of malaria cases in the country—and noting where the mosquitoes had been resting.
The team then used molecular techniques to determine which species of mosquitoes had been captured and which hosts they had been feeding on.
The researchers collected 1774 Anopheles culicifacies mosquitoes and 169 Anopheles fluviatilis mosquitoes across all study sites.
Both species were denser in cattle sheds than in human dwellings, and both were feeding on humans as well as cattle.
Next, the researchers used their field-collected data to help build a computer model that simulated the life of an adult mosquito. The team used the model to explore how best to control the mosquitoes to have maximum impact on malaria transmission in these villages.
“Our model analysis suggests that conventional control tools—such as insecticide-treated bed nets and indoor insecticide sprays—are less effective when mosquitoes exhibit ‘zoophilic’ behaviors (having an attraction to nonhuman animals),” Dr Thomas said.
“However, extending controls to better target the zoophilic mosquitoes—for example, by broadening coverage of non-repellant insecticide sprays to include cattle sheds—could help reduce transmission dramatically.”
Dr Waite added that the model suggests very little cattle-based vector control effort would be required to drive malaria transmission in the region to elimination.
“We show that directing even modest amounts of effort to specifically increase mosquito mortality associated with zoophilic behavior can shift the balance towards elimination,” she said.
“Understanding the dynamic between humans, cattle, and mosquitoes could have major implications for malaria control policy and practice, not only in India, but in other areas where transmission is sustained by zoophilic vectors,” Dr Thomas said.
“Specifically, optimizing use of existing tools will be essential to achieving the ambitious 2030 elimination target set by the World Health Organization, which aims to decrease malaria cases globally by 90% compared to 2015 levels and eliminate malaria in at least 35 additional countries by 2030.”
Photo by Ilya Mauter
The goal of eliminating malaria in countries like India could be more achievable if mosquito-control efforts take into account the relationship between mosquitoes and cattle, according to an international team of researchers.
The group analyzed 2 mosquito
species found in Odisha, the state with the highest number of malaria cases in
India, and found that both species fed on cattle as well as humans.
“In many parts of the world, the mosquitoes responsible for transmitting malaria are specialist feeders on humans and often rest within human houses,” said Matthew Thomas, PhD, of Pennsylvania State University in University Park, Pennsylvania.
“We found that, in an area of India that has a high burden of malaria, most of the mosquitoes that are known to transmit malaria rest in cattle sheds and feed on both cows and humans.”
Dr Thomas and his colleagues reported these findings in Scientific Reports.
According to the researchers, cattle sheds in India are often next to, and sometimes even share a wall with, human houses. However, current malaria control efforts are restricted to domestic dwellings only.
“Given this cattle-shed ‘refuge’ for mosquitoes, focusing only on humans with regard to malaria control is a bit like treating the tip of an iceberg,” said study author Jessica Waite, PhD, also of Pennsylvania State University.
She, Dr Thomas, and their colleagues determined the importance of cows in the malaria-control problem by capturing adult mosquitoes in different habitats within 6 villages in Odisha state—which has the highest number of malaria cases in the country—and noting where the mosquitoes had been resting.
The team then used molecular techniques to determine which species of mosquitoes had been captured and which hosts they had been feeding on.
The researchers collected 1774 Anopheles culicifacies mosquitoes and 169 Anopheles fluviatilis mosquitoes across all study sites.
Both species were denser in cattle sheds than in human dwellings, and both were feeding on humans as well as cattle.
Next, the researchers used their field-collected data to help build a computer model that simulated the life of an adult mosquito. The team used the model to explore how best to control the mosquitoes to have maximum impact on malaria transmission in these villages.
“Our model analysis suggests that conventional control tools—such as insecticide-treated bed nets and indoor insecticide sprays—are less effective when mosquitoes exhibit ‘zoophilic’ behaviors (having an attraction to nonhuman animals),” Dr Thomas said.
“However, extending controls to better target the zoophilic mosquitoes—for example, by broadening coverage of non-repellant insecticide sprays to include cattle sheds—could help reduce transmission dramatically.”
Dr Waite added that the model suggests very little cattle-based vector control effort would be required to drive malaria transmission in the region to elimination.
“We show that directing even modest amounts of effort to specifically increase mosquito mortality associated with zoophilic behavior can shift the balance towards elimination,” she said.
“Understanding the dynamic between humans, cattle, and mosquitoes could have major implications for malaria control policy and practice, not only in India, but in other areas where transmission is sustained by zoophilic vectors,” Dr Thomas said.
“Specifically, optimizing use of existing tools will be essential to achieving the ambitious 2030 elimination target set by the World Health Organization, which aims to decrease malaria cases globally by 90% compared to 2015 levels and eliminate malaria in at least 35 additional countries by 2030.”