Encephalitis is a disease present across much of India, responsible for thousands of deaths within the country every year, though rarely attracts the same manner of media exposure as other conditions such as malaria or HIV. That is, until recently.
The recent spate of child deaths resulting from the condition in Bihar has cast a media spotlight on encephalitis. In just a short period of time the death toll stands significantly in excess of 100 – attributed to acute encephalitis syndrome (AES).
Prevalence of encephalitis
Encephalitis typically occurs in a sporadic fashion in India. Studies have noted that there is often little to no clustering of the disease, implying that it is not caused by an infectious component. Examples illustrated within these studies have shown that multiple people may be simultaneously afflicted with the disease on an individual basis, cases occurring across villages separated by a considerable distance.
The situation in Bihar is concerning. What is notable about the spate of child deaths is its consistency — it occurs every year and in the same timeframe. Since 1995, child deaths have occurred in the state around the time of the the lychee season. Linking the majority of these child deaths is malnutrition, alongside consumption of lychees — likely to excess.
There are more predictable patterns of encephalitis that occur. These are associated with infectious diseases that share the condition as a common symptom. Among them are the Japanese encephalitis virus (JEV), the leading diagnosed cause of acute encephalitis, as well as numerous enteroviruses, scrub typhus, and measles.
The diagnosis of AES is more often applied where no etiological (causative) agent is identified. These instances typically occur within individuals also diagnosed with hypoglycemia. Malnourished children appear to be — by a considerable margin — the most at-risk group. These factors combined with the sporadic occurrence implicate an ingested substance, such as the lychees.
Previous investigations into the lychees relation to the Bihar occurrences found that high levels of hypoglycin A and methylenecyclopropylglycine (MCPG) were present, particularly in the seeds and aril of unripened lychee fruit. Both of these molecules are capable and documented to have a degree of toxicity.
Symptoms
Encephalitis is described as the acute onset of fever and a change in mental status (including symptoms such as confusion, disorientation, coma or inability to talk), and/or new onset of seizures.
The condition is a result of inflammation and resultant swelling within the brain. The initial onset of flu-like symptoms may not occur at all — likely a result of the varying causes of the disease which are in some cases still poorly understood. More lethal symptoms such as the inducing of a coma, as well as the potential for fatality can occur within hours of onset, making the condition a major concern, reflected in its high mortality rate.
Prevention and treatment
Many of the viral infections that can cause encephalitis are vaccine preventable. The MMR vaccine, as well as the Japanese encephalitis vaccine, can allow for protection against some forms of the condition.
In the instances of AES where a specific cause is undetermined, it is worth noting that the primary group at risk is children. A well-balanced diet seems to play a role in alleviating the risk of the condition if the toxic components of the lychees in Bihar are indeed playing a role. Avoidance of excess consumption of unripened lychees in this case is also critical.
Treatment of the condition is dependent on the cause. A major hurdle to treatment of the condition is its rapid onset, often killing a person within a day of onset. It is therefore vital to seek hospital treatment if any of the symptoms such as changes in mental state are observed.
Antivirals are used in the case of virus-derived encephalitis. However, in many instances symptom management is the only means of treating the condition. Often this can include placing the individual on a ventilator — a treatment that may not be available in some rural areas.
