Climate change impact: ‘Harmless’ mosquito species now spreading malaria in Pakistan, say scientists

ISLAMABAD: Climate change has turned an inoffensive and harmless species of mosquito into a lethal vector of malaria in Pakistan by wiping out a major species of mosquitoes responsible for causing malaria in South Asia, a team of Pakistani and international scientists claimed on Wednesday

“Extremely high temperatures followed by devastating floods due to climate change have ‘wiped out’ a major species of mosquitoes the ‘Anopheles culicifacies’, which was known for causing Malaria in Pakistan. Alarmingly, a previously unknown and harmless species of mosquitoes called Anopheles pulcherrimus is now spreading Malaria at an alarming pace in the flood-affected areas of Sindh, Balochistan and South Punjab”, Muhammad Mukhtar, a leading Pakistani entomologist told The News.

More than five million suspected cases of malaria have so far been reported from the flood-affected areas of Sindh, Balochistan and South Punjab from January to November 2022, officials in the Ministry of National Health Services, Regulations and Coordination (NHS,R&C) said, adding that new revelations regarding the change in malaria-causing species in Pakistan have emerged as an ‘alarming development’ for the entire world. “During the current field investigation, surprisingly not a single specimen of ‘Anopheles culicifacies’ in four districts of Sindh and Balochistan including was found. This shows that this species has been wiped out from the flood-affected districts, most probably due to extraordinarily high temperatures followed by devastating floods this year. Now Malaria in these areas is most probably being spread by a non virulent and harmless species of mosquitoes called Anopheles pulcherrimus”, Muhammad Mukhtar, who is the Director of Malaria Control at NHS,R&C claimed.

Samples of ‘Anopheles Pulcherrimus’ captured from the districts Qambar Shahdadkot and Khairpur in Sindh and Sohbatpur and Jafferabad were immediately sent to Center for Disease Control and Prevention (CDC) Atlanta, United States for DNA testing. The testing would ascertain if the mosquito was feeding on human or animal blood in the flood-affected areas, Dr. Mukhtar informed. Accompanied by Dr. Samira Al Eryani, World Health Organization (WHO) Regional Advisor On Vector Control, Dr. Mukhtar collected thousands of mosquitoes from the flood-affected areas and was surprised to see that ‘unexpectedly high densities’ of Anopheles pulcherrimus were found in all four districts of Sindh and Balochistan, which was previously unknown for causing Malaria in Pakistan. “Previously there was no concrete evidence of the role of Anopheles pulcherrimus in Malaria transmission. There is no doubt a large population of Anopheles pulcherrimus have also been reported in Punjab and Sindh but was never incriminated as Malaria Vector”, Dr. Mukhtar further explained.

According to Dr. Mukhtar, the incidence of Malaria was ‘5 to 10 times’ higher in the flood-hit areas and added probably it could be due to the new-malaria-causing species, which has replaced the original malaria vector. “During our investigation, we collected a total of 433 mosquitoes, of which 393 (90.8%) were Anopheles pulcherrimus, 13 (3.0%) were Anopheles stephensi and 17 (3.9%) were Culex mosquitoes which have yet not identified”, he said adding that it indicates the serious effects on climate change on natural habitats and behaviours of vectors responsible for malaria and dengue in Pakistan.

To a query, he said DNA and other test results from CDC Atlanta, United States are due in the next few weeks and if it is confirmed that mosquito-causing species has been replaced with a previously unknown vector, a complete overhaul of strategy to deal with vector-borne diseases would be required in Pakistan.