Malaria can be carried by a number of mosquito species, the most common of which is aedes aegypti. However, more species exist that can adapt to differing conditions, allowing the reach of the disease to expand. Worryingly, the National Institute of Malaria Research (NIMR) has detected the presence of two mosquito species in and around Delhi that have been absent for 10 years.
Both species are Anopheles mosquitoes. Each variant however is adapted to different environments. Anopheles stephensi is an urban dwelling mosquito, as such is a threat within Delhi itself. It is a notable carrier of malaria and is a primary vector in states such as Chennai. Anopheles culicifacies is typically found in rural environments. Both species are a vector for malaria and so may present further issues in future years.
Malaria appears to be on the rise in Delhi despite it not being a high endemic region. As of June 28th, 113 cases have been recorded this year. Over the same period in 2016, only 39 people had contracted malaria. There were 19 in 2015 and 29 in 2014. This sudden rise cannot be solely attributed to the sudden reemergence of the two species of mosquito, but may be an indication that species more typical to the area are breeding in higher numbers.
However, according to Neena Valecha, director of NIMR, “It would not be correct to conclude that malaria cases are on the rise in Delhi…We need to do a year-on-year comparative study and not month-on-month analysis as vector breeding is influenced by seasonal variations like early rainfall and late monsoon”
Surveillance techniques have also improved which has led to far better reporting of malaria statistics, according to Dr Valecha. This better capacity for recording may at first glance make the data appear as though there is a disproportionate rise.
There is not an alarmingly high number of cases so far this year. However, with the establishment of breeding populations of more species capable of transmitting malaria with Delhi, the number of cases in the next few years could surge.
The All India Institute of Medical Sciences has blamed the unresponsive civic bodies for not taking care of the poor drainage system of the city. Poor drainage can lead to stagnant water which is an ideal breeding ground for mosquitos. Some have even accused civic bodies of deliberately understating dengue figures, in an attempt to evade responsibility. These are much the same criticisms levied at the state government of Kerala regarding inadequate cleaning of the city.
This is an issue that should be addressed before it escalates into an epidemic in the city. Issues such as altering climate conditions — which has also been implicated in the reemergence of the mosquito species — are far more difficult to address, but drains can be cleared to attempt to at least limit any potential for large scale breeding populations.