News Excerpt:

Deaths caused by ingestion of rat poison containing yellow phosphorus is a major problem in a few States.

Key Points:

• A six-month survey carried out in six districts in Tamil Nadu in 2019 by the Tamil Nadu chapter of Indian Society of Gastroenterology (TN-ISG) found 450 people suffered from liver toxicity caused by ingestion of rat poison. 
• Of them, 131 patients died while 28 were discharged in a moribund state. Extrapolating it for the entire State, researchers estimated 1,584 such cases in 2019 in just six months with about 554 deaths. 
• Tamil Nadu has introduced a legislation to curb unrestricted access to rodenticide containing yellow phosphorus.

Development in this field:

• Until a few years ago, urgent liver transplantation was the only life saving option for such patients who developed acute liver failure. 
• Beginning December 2017, a team of researchers from CMC Vellore has been using plasma exchange through a centrifugal method ­— a simple and less expensive treatment — to save the lives of such people.
• Impressed by the success of the plasma exchange treatment by CMC Vellore and following the identification of rat poison (rodenticide) ingestion as the cause of liver failure and deaths. 
• The Tamil Nadu government through the Tamil Nadu Accident and Emergency Care Initiative of the National Health Mission (TAEI-NHM) programme started using plasma exchange in six apex government hospitals to treat these patients in March 2022. 
• Currently, 17 government hospitals across 15 districts in the State undertake plasma exchange to treat rodenticide-induced acute liver injury and acute liver failure cases.
• In 2022-2023, 1,237 acute liver toxicity patients due to rat poisoning in Tamil Nadu were treated with plasma exchange. 
• Of them, 825 survived and were discharged. 
• The survival rate was 63.9%.

Causes of rodenticide poisoning:

• Liver failure due to rat poison ingestion may be due to overactive immune responses. 
  • Researchers have found markers for innate immune responses turned on in patients with acute liver failure following ingestion of rat poison containing yellow phosphorus. 
  • Plasma exchange dampens these overactive immune responses, which helps save lives.
• In a retrospective analysis of 32 children ­at CMC Vellore with acute liver injury or acute liver failure due to rodenticidal ingestion, eight children were extremely sick and were eligible for plasma exchange. 

• • Of the eight, six children survived (75%). 

• In another study at CMC Vellore which included adults, of the 81 patients who were eligible for and underwent plasma exchange, 65 patients survived (80.2%). 
• Of the 81 patients who underwent plasma exchange, 32 had acute liver failure and 22 of the 32 such patients were saved through plasma exchange. 

Treatment:

• Initially only those who were severely sick — acute liver failure — were treated with plasma exchange. 
• The focus was on establishing the safety of the treatment rather than measuring the efficacy. 
• Now plasma exchange is used even in patients with acute liver injury, which is one stage earlier than acute liver failure.
• Earlier initiation of plasma exchange treatment has saved more patients. 
• Patients with acute liver injury can progress to acute liver failure very quickly, even within a few hours.  

Constraints:

• According to the TN-ISG study, currently over 99% of hepatotoxicity patients due to rodenticide ingestion in the State cannot access urgent liver transplantation. 
• The major constraint is the lack of a matched deceased donor or a live-related donor. 
• If liver transplantation is very expensive, patients are then required to remain on lifelong immuno-suppressants medications, which further increases the cost. 
• In comparison, the plasma exchange treatment, which involves removal (pheresis) of patient plasma and replacement of healthy plasma from voluntary blood donors, costs only one-tenth to one- twentieth of liver transplantation. 
• Normally, patients would require three plasma exchange sessions spread over three days; a decision to continue plasma exchange is taken on a daily basis.
• Worldwide, regular dialysis has not been shown to improve survival in patients with acute liver failure.
• This may be because standard dialysis technique removes only small- and medium-sized molecules, while plasma exchange helps remove macro molecules too.
• The removal of specific macromolecules may be an important reason why we are seeing increased success in treating patients with rodenticide ingestion-induced liver toxicity.

Way Forward:

• Government should regulate rodenticide poison properly so that the negative impact of such poisons can be reduced.
• Market availability of poison in the market will also be regularized.
• Futuristic approach in the health sector is the need of the hour. Hence, the government should work in the field of health and also try to stop such activity like ingestion of poison with metal therapy and awareness.