Africa, which is already battling the highest incidence of malaria with more than 90% of the world’s cases, should be wary of an Asian mosquito species that has the potential to spread the disease to urban areas of the continent – and more Exposing 126 million people at risk, new analysis suggests.
Unlike endemic mosquito species in Africa, which have settled in warm and humid areas in largely rural areas, this particular mosquito – An. stephensi – has performed in African cities in recent years.
“This mosquito is unlike any other primary malaria vector found in Africa – it can live in urban areas that other species just don’t like,” said lead author, Dr. Marianne Sinka from Oxford University.
“With around 40% of the African population living in urban areas, this means that many people who are currently protected by their environment could be exposed – if the mosquito spreads.”
Unlike its predecessors of this species, which usually cannot survive in polluted water, An. stephensi is very suitable for finding artificial water tanks or containers for laying eggs. The larval habits are similar to those of Aedes aegypti, the species responsible for yellow fever and Zika outbreaks.
That similarity could be exploited to introduce control measures that were previously effective for Aedes aegypti, although mosquitoes are known to be difficult to control in urban areas where adequate water sources are plentiful, she added.
Malaria outbreaks by An. stephensi has been reported in Djibouti and more recently in Ethiopia and Sudan. To predict the distribution of the species in Africa, the researchers combined location data for An. stephensi geographically with spatial models that identified the environmental conditions that are most suitable for him.
The results were sobering: 44 out of 68 African cities were predicted to be “highly suitable” locations, putting an additional 126 million people at increased risk of malaria if the species were to reproduce uncontrollably.
The causes of malaria transmission are obvious – data show that land use patterns, climate change as well as migration and urbanization all contribute. But in the case of An. stephensi, migration to urban areas, particularly along transport routes, appears to be implicated, the researchers said.
“We know that migration can bring the parasite to places where there is little or no transmission. Worldwide transport has taken many species to new locations in the past and has caused significant environmental damage over the years. Regarding mosquitoes, specifically Aedes albopictus, the primary dengue vector … and now on. stephensi “, remarked Sinka.
“The paper suggests that large urban areas … could be at great risk, but there is still no evidence that this mosquito is present,” said Prof. Chris Drakeley of the London School of Hygiene & Tropical Medicine, who was not involved in the study.
“It highlights a potential problem rather than an actual problem. But what do we have to do to prevent such a scenario? I think that would be really useful. “