The outbreak of dengue epidemic in Peshawar infecting around 13000 people and claiming 54 lives in a span of two and a half months, has rang alarms about risks of increase in vector borne diseases due to climate change.
According to Dengue Response Unit (DRU), the total number of suspected dengue cases in Peshawar till October 5, 2017 are 60,807. The health department conducted 60,665 dengue serology screening out of which 12632 proved positive. About 147 confirmed cases of Chiken Gunya are also reported in Swabi district during that period out of which 51 have recovered from the disease.
“Prolong summer and irregular precipitation pattern due of climate change are factors attributing to increase in vector borne diseases including Malaria, dengue, zika, yellow fever and chikun gunya,” warns environmentalists, Public Health experts and entomologists.
“Vector borne diseases (VBDs) are transmitted to humans through the bites of insects including mosquitoes, ticks and flies,” appraises Dr. Farrah Zaidi, Assistant Professor and Teacher of Entomology at Zoology Department of Peshawar University.
“Research studies by international institutions including World Health Organization (WHO) have found nexus between climate change and vector borne diseases,” Dr. Farrah told APP.
The timing of the outbreak of dengue in Peshawar starting from mid June and its prevalence even in the month of October supports the research findings that dengue and malaria would likely to spread and increase in countries which are in grip of global warming, warns Dr. Farrah.
To substantiate her viewpoint, she gave reference of a study of Highland Malaria Project, part of an umbrella international collaboration `Mapping Malaria Risk in Africa” which says, World Health Organization estimates that approximately 300–500 million cases of malaria occur worldwide each year.
“A global increase in malaria may be associated with deforestation, water development projects and agricultural practices in poor countries,” the report proposes.
High altitude regions have been protected from malaria endemicity because parasite sporogony and vector development are inefficient in low temperatures. According to another report of World Health Organization (WHO) which says dengue is fast emerging as pandemic-prone in many parts of the world.
“The incidence of dengue has increased 30 fold over the last 50 years. Up to 50-100 million infections are now estimated to occur annually in over 100 endemic countries, putting almost half of the world’s population at risk,” report adds.
Explaining reasons behind increase in vector borne diseases due to climate change, Dr. Farrah said the biological life cycle of insects in summer and winter are separate.
In winter the Aedes aegypti mosquito which spreads dengue takes around 25 to 30 days to grow and matures. While the same process, starting from eggs laying to conversion into larva, pupa and full grown mosquito, takes a short period of around two weeks in tropical season.
Optimal climatic conditions when temperature is between 25 to 30 degree Celsius, vector development and transmission improves besides increase in its reproduction and biting rate. Even the pathogen incubation period reduces in summer to seven days from average of 20 to 25 days.
“Warm and humid weather also improves digestion of dengue mosquito whose blood meal requirement enhances and excessive biting ensues in increased transmission of virus among humans.”
“Poor sanitation, improper waste disposal, water shortage, ill planned irrigation and deforestation are the factors contributing to vector borne diseases,” observed Dr. Shehzad Faisal, Team Leader Dengue Response Unit (DRU) Health Department of Khyber Pakhtunkhwa.
“Apart from other reasons including semi-urbanization and its related problems, hot weather and excessive rainfall are also risk factors behind outbreak of dengue epidemic in Peshawar,” claimed Dr. Shehzad. “The main problem in containing dengue spread is lack of awareness among masses and delay of warm weather,” comments Muhammad Abid Majeed, Secretary Health Khyber Pakhtunkhwa.
In the prevailing weather, when temperature is around 25 to 35 degree Celsius, the mosquito is active and the only way to contain dengue is to destroy breeding sites and eggs, he told APP.
Abid Majeed said illiteracy is also a factor that is hampering dengue prevention because people are not accepting official advices of containing the contagion, but insist on arranging fogging.
“Excessive use of larvacide has many side effects on human health and it will also result in contamination of ground water,” he opined.
“Climate Change is a global issue and has multi dimensional effects on environment, agriculture and human health,” comments Sadiq Khattak, Chief Conservator Forest Department Khyber Pakhtunkhwa.
Talking to APP, Sadiq Khattak agreed that vector borne diseases are increasing due to delay in duration of summer season. He said in Pakistan ratio of forests depletion is much high due to over reliance of people on timber for fuel requirements. “The best way to tackle problem of global warming is carbon sequestration through growing trees and Khyber Pakhtunkhwa enjoys the distinction of planting one billion trees in record time of three years under its Billion Tree Tsunami Project (BTTP) which on maturity in 2018 will help in reducing the average temperature of the province by around two degree Celsius,” Khattak observed.
“The current outbreak of dengue has diverted attention of health department on vector controlling measures to prevent future occurrence of the disease,” said Dr. Shaheen Afiridi, Director Public Health KP. Talking to APP, Dr. Shaheen said after emergence of the disease, it was felt that the Health department should have a team of entomologists for surveillance of vectors at larval, pupal and adult stages.
She informed that KP government has chalked out a comprehensive six months dengue prevention and control plan in line with the guidelines of WHO.
The plan included revision of Provincial IVM (Integrated Vector Management) programme with the agreed and approved structure to meet all technical and managerial needs.
The government has also decided to appoint 41 entomologists for working on destroying vectors’ eggs and breeding sites to prevent future outbreak of the disease.
“Preventing vector borne diseases is an emerging concept and Public Health department needs in-depth research, resources, technical assistance and public cooperation in achievement of this goal,” Dr. Shaheen observed.
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