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Climate change behind infectious disease outbreaks

By M. Waqar Bhatti
April 28, 2022

KARACHI: Early summer and rising temperature in the relatively moderate months of the year due to climate change could be the leading reason behind ongoing outbreaks of water-borne diseases like diarrhoea, especially cholera as well as vaccine preventable diseases like measles in Karachi and other cities of Sindh as March 2022 was the ‘driest and warmest ever month’ month since 1961, health experts and meteorological officials said Wednesday.

Same is the situation in the month of April as most of the plains in vast areas of the country including Sindh, Punjab and Balochistan are in the grip of severe heat, health experts and officials said and added that climatic conditions were becoming increasingly favourable for the transmission of multiple infectious diseases by directly affecting biological features of pathogens including their growth survival and virulence.

“Diarrhoea and cholera outbreaks are also being reported from Bangladesh and some African countries besides Karachi and some other cities of Sindh, and I believe that early summers in these regions due to climate change are to blame for outbreaks of water-borne diseases as well as some other infectious diseases,” eminent Pakistan health expert and researcher Prof Dr Zulfiqar Bhutta told The News Wednesday.

An unprecedented increase in the cases of diarrhoea has been observed in Karachi and other cities of Sindh including Hyderabad, Nawabshah, Mirpurkhas and Sukkur and provincial health department confirmed that dozens of lab-confirmed cases of cholera were detected from district Central, South and East of Karachi as well as some other cities of the province including Badin.

Prof Zulfiqar Bhutta said there is a direct correlation between rising temperature and oubreaks of some infectious diseases like diarrhoea and measles, adding, post-pandemic challenges in addition to absolutely ‘zero investment’ in the area of Water, Sanitation and Hygiene (WASH) were also to be blamed for the outbreaks of diarrhoea, cholera and measles.

Former Special Assistant to Prime Minister (SAPM) on health Dr Faisal Sultan was a bit hesitant in linking the recent outbreaks of infectious diseases with rising temperature, saying it is a bit risky to automatically assign causality to higher temperatures.

“There may be linkages but diseases often are dependent upon more than one factor. But it is true that spread of gastrointestinal infections may be helped by higher temperatures which impact upon the length of time, certain foods can be safely stored before being consumed,” he added.

Some other experts including Dr Asif Saeed from the Sindh health department said high temperature increases the replication of pathogens, especially contamination in organic material and added that warm and dry weather creates ideal conditions for certain pathogens to infect humans, especially children with weak immunity.

Another senior physician and expert Dr Somia Iqtidar from Lahore said temperature has very variable affect on infections as some growth of some viruses, bacteria and other microorganism increases in the warm temperatures while some viruses and bacteria multiply rapidly within the bodies of their host in suitable temperatures.

“Day temperature of 22-24 degrees Celsius is very ideal for the bacterial infections, especially gastrointestinal infections like cholera and if the temperature increases further, an increase in water-borne diseases especially cholera is observed in our region. We have also seen cases of cholera like illness in Lahore after increase in daytime temperatures,” she added.

March 2022 the driest and warmest since 1961: PMD

On the other hand, Pakistan Meteorological Department said month of March 2022 was dry and warm month ever in the history of Pakistan since 1961 as the national mean monthly temperature of March 2022 for Pakistan as a whole was 22.92 °C, being 4.26 °C warmer than monthly average.

“March 2022 is now the ever warmest month since 1961. The last record was 31.09°C in 2004,” said Dr Sardar Sarfraz, Chief Meteorological Officer (CMO) Sindh while quoting Pakistan’s Monthly Climate Summary March 2022. Dr Sardar Sarfraz said the mean maximum (day) temperature at country-level was 30.89 C, being 5.01 C warmer than average of 25.88 C, and as such it was the 2nd warmest month during past 62 years.

“The night (minimum) temperature was 14.95 C, being 3.52 C warmer than country-average of 11.43 C and it is now the ever warmest night temperature since 1961. The last warmest night temperature was 14.57 C in 2010,” he added. As far as precipitation is concerned, national rainfall for the month of March 2022 was 62% below normal and ranked 9th driest month since 1961, the CMO Sindh said, adding that March 2022 rainfall was largely below normal over all the country with Balochistan (-66%), Sindh (-65%), Punjab (-65%), KP (-66%) & AJK (-48%) as all experienced extreme deficient rainfall.