Cholera | 06 Oct 2023

Source: TH

Why in News?

According to the World Health Organization (WHO)’s weekly Epidemiological Record, the World reported more than twice as many cholera cases in 2022 as it did in 2021.

• This escalation presents a substantial challenge to the WHO ambitious goal set in 2017 to reduce global cholera deaths by 90% by 2030.

What is Cholera?

• About:
  • Cholera, a water-borne disease primarily caused by the bacteria Vibrio cholerae strains O1 and O139, poses a significant public health challenge worldwide.
    • Strain O1 is the predominant cause of outbreaks, with O139 occurrences being rare and mostly confined to Asia.
  • It is an acute diarrheal illness caused by infection of the intestine.
  • The infection is often mild or without symptoms, but sometimes can be severe.
• Symptoms:
  • Profuse watery diarrhoea, Vomiting, Leg cramps
• Transmission:
  • A person may get cholera by drinking water or eating food contaminated with the cholera bacterium.
  • The disease can spread rapidly in areas with inadequate treatment of sewage and drinking water.
• Vaccine:
  • Currently there are three WHO pre-qualified Oral Cholera Vaccines (OCV), Dukoral, Shanchol, and Euvichol-Plus. All three vaccines require two doses for full protection.

What are Factors Driving the Escalation of Cholera Cases?

• Decline in Covid Pandemic Restrictions:
  • The decline in Covid-19 pandemic restrictions played a crucial role in allowing the spread of cholera. Limited investments in providing adequate care to vulnerable populations, effects of climate change, and escalating conflicts further exacerbated the situation.
• Insufficient Access to Sanitation:
  • The symbiotic relationship between cholera transmission and insufficient access to clean water and sanitation facilities is a critical factor.
  • Notably, Vibrio cholerae bacteria tend to thrive in warmer waters with lower salinity, conditions intensified by climate change-induced floods, heatwaves, intense monsoonal rains, storms, and prolonged warm periods.
• Vibrio Pathogens and Microplastics:
  • According to research from the University of Florida in June 2023, Vibrio pathogens possess a unique capability to adhere to microplastics, potentially adapting to this environment, even in the open ocean.
  • This interaction between Vibrio bacteria and microplastics signifies an additional dimension to cholera transmission dynamics, necessitating further investigation and policy considerations.
• Climate Change and Cholera Transmission:
  • A study published in 2021 in The Lancet Planetary Health emphasizes how climate change intensifies cholera concerns.
  • It predicted a potential increase of 38,000 km in coastline conducive to Vibrio bacteria development by 2100, compared to the 1850-2014 average.

What are the Geographical Distribution and Cholera Trends?

• The majority of cholera cases persistently emanate from Africa and Asia, with Europe sporadically reporting "imported cases."
• In Africa, the 2022 cholera cases were more dispersed compared to 2021, with no single country reporting more than 25% of all cases and 30% of all deaths.
  • However, this apparent improvement is overshadowed by the doubling of case and death numbers in countries apart from Nigeria, which experienced a massive cholera outbreak in 2021.
• A similar pattern of increased cases was observed in Asia, notably in countries like Lebanon, Syria, and Afghanistan.

What can be the Response Measures to Tackle Cholera?

• To address the growing cholera burden globally, adaptations in the recommended oral cholera vaccine regimen have been made.
• While awaiting the fruition of larger-scale manufacturing investments, the management of the emergency stockpile for the oral cholera vaccine has modified the vaccination regime, reducing it from two doses to a single dose.
  • This strategic adjustment aims to enhance the efficiency and reach of cholera vaccinations.