Many public health experts to now wonder if the State has been a little too complacent in its ‘over dependence’ on doxycycline, to the exclusion of all other possible strategies, including better epidemiological research and improved risk communication to people
For a disease that has displayed a consistent pattern and mortality profile over decades, leptospirosis has been claiming an unusually high number of lives in Kerala in recent years.
In the past two years alone, leptospirosis emerged as the infectious disease that killed the maximum number of people, with the proportion of mortality going up every year. This has led many public health experts to now wonder if the State has been a little too complacent in its “over dependence” on the broad-spectrum antibiotic doxycycline as the one-shot strategy to prevent and manage leptospirosis to the exclusion of all other possible strategies, including better epidemiological research and improved risk communication to people.
The scale of the problem
Leptospirosis is a tropical zoonotic disease, highly integrated with an environment in which both humans and animals thrive. The Leptospira bacterium that causes leptospirosis spreads through the urine of infected livestock, pets, rodents and wild animals. The bacteria can persist for several weeks to months in contaminated soil and enter human bodies through minor cuts or abrasions on the skin or even through sodden skin.
The profile of those who are affected by the disease has remained more or less the same: most are farmers or manual/agricultural labourers or people whose work puts them at risk of regular contact with water/soil that may be contaminated. M. Abraham Ittyachen, professor of medicine, MOSC Medical College, Kolenchery, who has been treating leptospirosis for the past two decades, says that in Central Kerala, cases usually spike during the pineapple harvest season. “Plantation workers go into the pineapple fields early in the morning. They wear gum boots, but the skin on their hands, which are unprotected, sustain micro tears from the serrated leaf edges. The dew on the leaves, is often contaminated by rodents in the farm.”
However, this picture is changing in recent times, with even urban residents contracting the disease.
Leptospirosis cases are reported throughout the year in Kerala. Cases generally spike during the monsoon season and then start to dip as the dry season begins.
Yet this year, in just the first two months, the Integrated Disease Surveillance Programme has reported 567 cases and 37 deaths (including confirmed and probable cases) due to leptospirosis. In 2024, the State had the largest number of leptospirosis cases at 5,999 and 386 deaths. It was no different in 2023, when there were 5,186 cases and 282 deaths, meaning that leptospirosis mortality spiked by 36.8% just between 2023 and 2024.
What is going wrong?
“From the public health point of view,” says R. Aravind, Head of Infectious Diseases, Government Medical College, Thiruvananthapuram, “this rise in cases and deaths essentially means that we need to put our focus back on preventing leptospirosis because there are limits to how well we can treat the disease, the severity of which is often unpredictable.”
A senior clinician in the State Health Services adds: “We have to acknowledge first, that we need to do better to save lives. Is there something that we are missing ? Why are some people dying of sudden worsening of the disease, while some seem to do well on antibiotics? There is a marked difference in the outcome of serious patients in hospitals too,” he says.
The Leptospira bacterium that causes leptospirosis spreads through the urine of infected livestock, pets, rodents and wild animals. File photograph used for representational purposes only
The diversity of Leptospira species, serovars (variation within the bacteria species), and strains, influence disease severity and therefore, the treatment regime. Currently, the genus Leptospira, the causative agent of leptospirosis has over 300 serovars, as per medical literature.
This is compounded by a problem with diagnosis. Leptospirosis presents with a wide spectrum of symptoms, many of which may mimic clinical symptoms of other tropical diseases like dengue, H1N1 or scrub typhus, making the diagnosis of an acute undifferentiated febrile illness very difficult. Medical literature says that in up to 8% of the cases, there could be co-infections — for instance, leptospirosis-dengue together. Typical and atypical presentations of leptospirosis are seen in the same season. So while recognising and treating the disease early is important, this easier said than done, say doctors.
The laboratory diagnosis of leptospirosis also continues to be a challenge, because current serological tests for antibodies, like ELISA, do not give confirmatory results in the acute phase of the disease. In recent years, the health department has introduced RT PCR tests for leptospirosis screening at the State and district public health laboratories, which can give confirmatory results within the first week itself, in the early phase of the disease. But these are seriously under utilised by clinicians, who say they cannot wait for a week for results to come back as they have to start treatment early.
An over reliance on doxycycline?
The State health system’s strategy, till date, has been to persuade those people considered to be at high risk of contracting the disease, to take doxycycline as pre-exposure prophylaxis. But compliance has been poor. “In a special contingency like a flood, people might listen to the health department’s directive. But expecting a dairy/paddy farmer working who works every single day in the field to take doxycycline on a regular, long-term basis would be asking too much, given that the drug has its own side effects like nausea and gastric issues,” health officials say.
Also, experts ask if there is too much emphasis placed on doxycycline: the latest Cochrane Systematic Review (March 14, 2024), examined the question, ‘Is the use of antibiotics beneficial for treating leptospirosis?’ The review included nine trials with 1,019 participants from Barbados, Brazil, Malaysia, Panama, the Philippines, and Thailand. It suggested that antibiotics (penicillin, doxycycline, azithromycin, cefotaxime, and chloramphenicol) currently used to treat leptospirosis, may have no effect on mortality (death) and side effects associated with leptospirosis infection.
The 5% of cases that progress to severe disease
Leptospirosis is associated with a broad spectrum of severity, ranging from subclinical or mild illness (anicteric) in 90-95% cases, which manifests as fever, myalgia, headaches, conjunctival suffusion and mild gastrointestinal symptoms. Some of these may be self-resolving, but a small proposition can potentially develop into serious illness. These 5-10% of cases are severe and the prognosis, unpredictable, says Dr. Aravind. Patients present late, with pulmonary involvement and multi-organ failure having set in on the third or fourth day itself, requiring mechanical ventilation and dialysis.
The rate of self-treatment is also high in the initial days of the fever and myalgia, when people will dose themselves with painkillers, refusing to see the doctor,” says Prof. Ittyachen, and this leads to delays in treatment.
“Intensive supportive management is the key to manage patients whose disease worsens. There are ICU facilities at secondary care levels in district and general hospitals, but there are acute staff shortage issues in running these facilities round the clock. So we are forced to refer all these patients to the medical colleges, which are overcrowded and where delays are possible,” said a doctor in the government health service.
The profile of those who are affected by the disease has remained more or less the same: with most of the affected being most are farmers or manual/agricultural labourers or people whose work puts them at risk of regular contact with water/soil that may be contaminated. File photograph used for representational purposes only
The right kind of treatment
Despite the ‘over-dependence’ on doxycycline however, it still remains a key element in the treatment regimen. Prof. Ittyachen says one cannot go wrong in starting doxycycline early on, even when the patients’ symptoms might be hard to distinguish. However, intensive critical care is the key once the disease worsens.
“If one were to look at the larger picture, disease and deaths are mostly happening amongst the low socio-economic strata. We should continue to address the high-risk groups– farmers, dairy workers, manual labourers, veterinary department workers and anyone whose occupation puts them in contact with water and soil on a regular basis — and reiterate the message on leptospirosis prevention,” Dr. Aravind said.
That said, the Health Department needs to examine if it is addressing the risk communication properly. Are people being made aware of the potential consequences of contracting leptospirosis or that proper personal protection and doxycycline prophylaxis can save lives? People should be given clear and repeated communication that fever with body pain (muscle pain, localised to calf and lumbar region) could turn out to be leptospirosis and that they should see a doctor. Young doctors in Health Service will also need some hand-holding so that they learn to recognise the disease early, doctors say.
A differential diagnosis?
“One question that we need to ponder seriously would be whether a good proportion of these leptospirosis-suspected cases are, in fact, hantavirus infections. This is not a new premise. The clinical symptoms of leptospirosis and hantavirus infection are very similar. Hantavirus is considered to be the differential diagnosis of leptospirosis,” T.S. Anish, a public health expert, says.
In 2014 itself, the possibility that the increasing number of patients dying of suspected leptospirosis, could in fact be hantavirus cases, had been in focus, after three “suspected “ hantavirus cases had been identified in Thiruvananthapuram. However, despite serological evidence of the same, the National Institute of Virology had not acknowledged this.
Watch: What is the hantavirus?
Proper confirmatory tests for hanta were still evolving then but today, PCR tests as well as IGM Elisa test for hanta are available at the Institute of Advanced Virology, Thiruvananthapuram.
Director of IAV, E. Sreekumar, says that while the Institute had facilities to test for hanta, clinicians raising a query over hantavirus were rare. “We have, in recent times, tested over 50 samples of suspected leptospirosis cases for hanta but none yielded positive results. As leptospirosis is so closely linked to water bodies and the environment, it would be important to check the geographical distribution of suspected leptospirosis deaths to see of there is a pattern there,” Dr. Sreekumar says.
As a disease that fits perfectly into the ‘One Health’ framework, integrated leptospirosis prevention and control with multi-sectoral involvement –clinicians, microbiologists, public health experts, environmental science/ecology divisions, dairy farming, inland fisheries and veterinarians — would help in risk assessment, environmental surveillance, early detection and better clinical management of the disease.
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