A study aimed at exploring ways to prevent the recurrence of kala-azar infections has developed a monitoring strategy that could reduce the potential for or occurrence of the disease’s resurgence.
According to doctors, kala-azar or visceral leishmaniasis has a natural cyclical phenomenon, with intervals of ten to fifteen years of dormancy followed by a resurgence in high quantities.
A state health department doctor said that preventive measures implemented during the inter-epidemic years can aid in controlling or postponing the reappearance of the disease.
Kala-azar “is fatal if left untreated in over 95% of cases”, says the website of the World Health Organisation (WHO). Irregular bouts of fever, weight loss, enlargement of the spleen and liver, and anaemia are the symptoms of the disease. WHO states that most cases occur in Brazil, east Africa and India.
Doctors and former students of the School of Tropical Medicine, along with state health department officials, took an active role in the study conducted across five districts of Bengal — Uttar and Dakshin Dinajpur, Malda, Mushidabad and Darjeeling — where kala-azar outbreaks were reported between 2010 and 2014. Several other doctors and health department officials lent their support.
“The study team collected data over the last 15 years from these places,” said a health department official.
A member of the study team stated that persons infected with kala-azar, as well as those residing within 500m of them, were screened. Blood tests were conducted to find out whether the parasite that transmits the disease was present in the samples.
The investigators found many new cases of post-kala-azar dermal leishmaniasis (PKDL), a dermal manifestation that arises in individuals previously treated for kala-azar. It typically develops months or even years after the treatment.
There were some relapse cases of PKDL also.
Persons with a documented history of kala-azar infection who are presenting with PKDL for the first time are regarded as new cases. In contrast, individuals who have been infected with kala-azar, experienced one previous episode of PKDL, and are now
showing signs of PKDL are categorised as relapses.
Doctors said small nodules and hypopigmented patches appear on the skin during PKDL, but the patient does not feel any pain or fever.
“There is no need or desire in many such people to seek treatment, and that is the
worrying part. PKDL means the parasite that causes kala-azar is still present in their skin. A sandfly can bite the person, pick up the parasite and transmit it to another person,” said a health department official.
A member of the study team stated that even if people sought treatment, they turned up quite late. The delay keeps the possibility of transmission alive.
There is a treatment to cure PKDL and destroy the parasite. “It is an 84-day treatment. There is a risk that people may drop out of treatment before the course of drugs is complete. We sent surveyors to their homes every 7 days. They saw the medicine strips to ensure that doses were not missed,” said a study team member.
“In our study, we have concluded that we need to shift from waiting for a patient to come for treatment to a health centre, to actively searching for signs and symptoms in people. We believe this strategy can reduce the possibility of resurgence or at least delay it. If we can keep delaying it, we may finally be able to stop the resurgence,” said a study team member.
The study conducted over four years has been published in the journal Tropical Medicine and International Health. The Federation of European Societies for Tropical Medicine and International Health publishes the journal.
Many people screened as part of the study were also categorised as asymptomatic leishmanial infection (ALI) cases. The screening showed the presence of the parasite in them, but there were no external manifestations. “They have to be monitored and treated if symptoms appear. In most such people, symptoms never manifest,” said a study team member.
Doctors said kala-azar typically spreads among the poor people. It needs an environment where sandflies can live. “Sandflies reproduce in large numbers in cowsheds,” said a study team member.
The study was designed by Subhasish Kamal Guha, former director of the School of Tropical Medicine (STM); Ardhendu Kumar Majhi, a former reader at STM; Dipankar Maji, a state health department official; and Pabitra Saha, who teaches zoology at PR Thakur Government College in Thakurnagar.
Anwesha Samanta and Ashif Ali Sardar, both of whom completed their PhDs from STM, and Amartya Kumar Misra, an assistant professor at STM worked extensively in the field.