LAHORE: Climate Investment Funds (CIF), Climate Support Facility (CSF), and the World Bank are jointly concerned about the role of climate change in the rise of vector-borne diseases in Pakistan, which already face numerous health issues.
In a recent review named Climate and Health Vulnerability Assessment of Pakistan, the impact of climate change, weather, and other vector-borne illnesses in Pakistan was described.
Repot reads that Pakistan is one of the most vulnerable countries in the world to climate change. Dengue is the fastest-emerging arboviral threat in Pakistan, with an 800-fold increase in cases between 1995–2004 and 2019.
Vector feeding and habitat preferences, coupled with other factors including climate and environmental changes, as well as human population dynamics, in Pakistan, have and will continue to influence the patterns of the dengue transmission risk.
More than 62 million people are vulnerable to dengue in Pakistan, with the populations of Punjab and Islamabad at the highest risk, the report said. It said suitability is largely concentrated in the north-central portion of the country and within the Indus Basin.
According to the report, nearly 54 percent of Punjab is suitable for the dengue vector species, approximately 16 percent of which is populated by more than 31 million people.In Islamabad, nearly 80 percent of the total area is suitable for dengue vectors; of this area, 16 percent is populated by more than 350,000 people. Overall, 36 percent of Pakistan is suitable for dengue vectors.
WB projects that in the 2030s and 2050s, the suitable area is expected to increase to 36 percent and decrease to 35 percent during the respective time periods, with around 61 million people being exposed. Notably, Khyber Pakhtunkwa will experience the greatest increase in population exposed to dengue vector.
It said that ongoing climate and infrastructural changes in Pakistan could promote the emergence of Zika, yellow fever, and Japanese encephalitis (JE). Vectors of dengue in Pakistan are the same mosquito species that transmit Zika and yellow fever—diseases that are endemic in neighboring China and India.
Suitable areas for dengue described above have the potential to become areas at risk for the transmission of Zika and yellow fever. Punjab and Sindh have sizable populations of the JE mosquito vectors (Culex tritaeniorhynchus and Culex pseudovishnui).
WB said that over 60 million people live in high-risk areas of malaria and nearly 50 million live in areas of low to medium risk. These figures were estimated in 2018 and show that malaria is an important cause of morbidity and mortality in Pakistan. Historically, Sindh has been among the regions with the highest number of malaria cases across the country.
The population living in Punjab is the most vulnerable to malaria, albeit with decreasing vulnerability through 2050. While only 56 percent of Punjab during the historic period was suitable for the malaria vector species, this area is populated by more than 70 million people—65 percent of Punjab’s total population.
More than half of all regions in Pakistan demonstrate a total suitable area of greater than 50 percent for malaria vector species. Model results across all time periods show that 100 percent of the Islamabad Capital Territory is suitable for malaria vectors, 51 percent of which is currently populated by more than 1.4 million people.
Shifting the suitability of malaria vectors in Pakistan will marginally change the subnational geography of malaria transmission risk through 2050 under high-emission scenarios. Around 37 percent of Pakistan will be suitable for malaria vectors during all the time periods assessed. However, subnational variations and the populations impacted could potentially result in fewer people being at risk.
Despite the strong correlation between VBD vectors and climate factors, climate is merely one determinant in the VBD transmission risk. The future risk of these diseases will depend not only on changing climate conditions that define vector suitability but also environmental, social, and economic conditions. For example, climate change is arguably less of an immediate threat to the emergence of Zika, yellow fever, and JE than the increasing connectivity between Pakistan and endemic countries that is facilitated by the CPEC.
The burden of waterborne diseases (WBDs) throughout Pakistan is significant, characterized by high rates of morbidity and mortality; WBDs are especially deadly in the case of children under five years of age. In 2019, diarrheal diseases were the fourth-leading cause of mortality in Pakistan.
Current drivers of WBDs throughout the country are attributable to many factors, including sources, quality, and quantity of drinking water; sanitation facilities; and hygiene practices—each of which may be affected by weather and climate change.
Understanding the historic burden and patterns of diarrheal diseases in Pakistan is challenging in the absence of a dedicated surveillance system. However, findings from the Demographic Health Surveys conducted in Pakistan (PDHS) show that overall, the country had seen a downward trend in the prevalence of diarrhea in children under 5 years of age in the two weeks prior to the survey, decreasing from 23 percent in the 2012–2013 PDHS to 19 percent in the 2017–2018 PDHS.
Prevalence rates were the same for children in urban and rural areas (19 percent) in 2018, though children from urban areas were more likely to receive advice or treatment. Notably, regions such as Punjab and Khyber Pakhtunkhwa have a prevalence of diarrhea above 20 percent.
Water quality is the most significant driver of waterborne diseases (WBDs) in Pakistan. Only 20 percent of the population has access to safe drinking water, and estimates suggest that 30 percent of all diseases and 40 percent of all mortalities can be attributed to polluted water. The decline in Pakistan’s surface water quality is attributable to contamination from sewage and industrial effluents, in addition to agricultural runoff to the water supply.
Climate change can impact water quality through temperature increases, which facilitate the proliferation of waterborne bacteria and algal toxins, and through flood events caused by the increasing intensity of precipitation and glacial melting in some regions of Pakistan.
Floods not only damage sanitation infrastructure but also carry pathogens, dissolved organic pollutants, industrial effluents, and agricultural runoff into surface water and groundwater sources. Drought conditions also affect water quality, and limited water quantity can force populations to use contaminated water sources for drinking, bathing, and agricultural irrigation.
Limited data make quantifying the direct risk of climate change on the historic prevalence of WBDs in Pakistan challenging. However, recent extreme weather events highlight the country’s vulnerability to WBD risks. In 2010, heavy monsoon rains led to one of the worst flood events in Pakistan’s history, with the reported laboratory confirmation of 99 cases of cholera from flood-affected regions. Likewise, floods in Karachi in August 2020 led to reports of cholera, typhoid, and hepatitis as water supply lines were compromised.
WBDs are likely to increase in Pakistan in the face of a changing climate, with potentially more than 5 million people at risk. Despite the potential for significant health impacts, the research on the relationship between climate change on water quality and WBDs in Pakistan is insufficient to provide precise estimations of future projections of the WBD risk.
However, it is recognized that extreme weather events increase WBD risk, such as through floods and droughts. Floods in Pakistan are projected to increase in frequency and intensity, with an additional population of approximately 5 million potentially exposed to extreme riverine floods by 2035–2044. Likewise, the rate of glacial melting in South Asia has increased, with consequent flood impacts for the population at risk. Districts along the Indus River system will be the most vulnerable to flood-related WBD risks.
Taking historic flood events in Pakistan as an indication, the increase in future flood events could result in the breakdown of sanitation infrastructure, thus leading to the contamination of the drinking water supply and in turn increasing the rates of diarrheal diseases including cholera, cryptosporidiosis, rotavirus, typhoid, and paratyphoid. Evidence from the rural areas in regions such as Punjab shows that where sewer drains do exist, they are commonly open, with no treatment of effluents, which can lead to soil and water contamination in normal conditions and present a significant risk to health under flood conditions.
Alongside floods, increased temperatures due to climate change may lead to Sindh and Balochistan experiencing more frequent and/or intense drought events, with the consequent increased rates of diarrheal diseases driven by insufficient water quality and inadequate quantity availability for hygiene practices. This would lead to outbreaks of E. coli and Salmonella from the combination of contaminated food sources and inadequate hygiene facilities. The impact of floods and droughts on WBD risks will be compounded by socioeconomic inequalities including poverty, level of education, access to healthcare, age, and gender.