The common deadly disease that you haven't heard about

Vidyavati Bagh, the local auxiliary nurse midwife, or ANM, in charge of 22 villages in Odisha’s Bissamcuttack block, patiently listened to a description of scrub typhus. “No no, we don’t have this disease here,” she said confidently. Sitting in her home, in the village of Dukum in southwest Odisha, the 30-year-old government health worker rattled off with ease, all the known reasons for fever in the area – malaria, dengue, typhoid, and “viral fever”, an umbrella term health workers here often use for fevers they can’t identify.

Bagh, who has been an ANM since March 2019, and whose father was a health worker for most of his life, had never heard of scrub typhus. Yet, 11 km away, in the Christian Hospital Bissamcuttack, at least four patients were receiving intensive care after falling ill with the dangerous bacterial disease.

One, a 36-year-old construction worker, had just had a narrow escape from death. She had been admitted to Christian Hospital on October 4, in shock, with plummeting blood pressure and oxygen levels, and signs of damage to her kidneys. A single mother of a young girl, she spent two days hooked to a BiPAP machine before she could breathe on her own. When I saw her on October 6, her skin was sallow, she had trouble breathing and her feet were swollen. On one of her ankles, peeking out of the hem of her salwar, was the telltale mark of scrub typhus, a small, blackish lump of deadened tissue called an eschar. This is where she had been bitten by the chigger mite, which carries and spreads the bacteria that causes the disease.

After a series of failed diagnoses at her local Primary Health Centre and a private clinic, the woman reached Christian Hospital just in time for the doctors to recognise her symptoms, test her correctly and start treating her with the broad-spectrum antibiotic doxycycline.

The attending doctors asked her if she understood why she had got this fever, “joru” in the local language, or if she had noticed any “tickku”, or mite, that bit her. She shook her head. “It lives in grass and bushes,” they explained. She confirmed that she had been in patches of wild grass at her construction site, just outside Bissamcuttack town.

Scrub typhus is a zoonotic bacterial disease, that is, it is transmitted from animals to humans. According to the central government’s National Centre for Disease Control’s annual report of 2016-’17, there were 40 outbreaks of scrub typhus between 2008 and 2017.

Yet, scrub typhus receives scant attention in the media, that too only every few years. This monsoon season, it popped up as a “mystery fever” that attacked people, mostly children, in parts of Uttar Pradesh. A team from the National Centre for Disease Control and National Vector Borne Disease Control Programme confirmed the coexistence of scrub typhus and dengue in Firozabad district, according to a letter written by Union Health Secretary Rajesh Bhushan to Uttar Pradesh’s chief secretary on September 6.

Easy to misdiagnose, or miss entirely, simple to cure yet potentially lethal in its complications, the disease, caused by the Orientia tsutsugamushi bacterium, is found historically in the Asia Pacific region, where a billion people are at risk, according to some research. A systematic review of scrub typhus in the science journal PLOS, which tried to estimate its disease burden across the world, noted, “Scrub typhus is a serious disease: approximately 6% of cases die if untreated, and 1.5% if treated, but mortality can reach 13% in areas where the usual treatment does not always work well.”

Death rates were higher in cases with complications, the report noted, “reaching 14% in brain infections, 24% with multiple organ failure, and pregnancies with scrub typhus can have poor outcomes, with high miscarriage rates.”

First observed in Japan in 1899, scrub typhus erupted as an epidemic in India during World War II, in Assam and Bengal, and spread across states in the subsequent years. For the latter half of the 20th century, however, its numbers stayed low enough to escape notice.

Now, in the 21st century, diagnosed cases are on the rise in India, which some health experts attribute to environmental changes like deforestation. The disease is also being reported from Africa and South America, where it had never been seen before. Researchers have labelled it a “neglected” threat to India and Asia at large. As evidence of its prevalence mounts, there is a flurry of activity among the medical community to not only document the disease better, but to train doctors to diagnose and treat it.

Odisha is one of the states where intensive research is being carried out on the disease. The state faces frequent outbreaks of diseases – malaria, typhoid, acute encephalitis syndrome, or AES, and more recently, dengue. These outbreaks have taught Odisha to develop a disease surveillance system which, the state’s Additional Director Public Health Dr Prameela Baral explained, is being slowly redirected to track scrub typhus.

Christian Hospital Bissamcuttack, a 200-bed multi-speciality hospital in the middle of Odisha’s Adivasi belt, has patients flocking to it from Rayagada district, where it is located, as well as the neighbouring Malkangiri, Kandhamal and Koraput districts. Throughout September and much of October 2021, at least three or four scrub typhus patients were admitted to the hospital each day, out of the average 30 daily admissions, making up between 10% and 13% of the total admissions. The patients came in with symptoms such as collapsing lungs, damaged kidneys and high fever. Since the doctors are now quick to test for scrub typhus, many were diagnosed with the disease and placed in the hospital’s intensive care wards. And yet, apart from the doctors in the hospital, and those in regional government offices, none of the residents or local health workers or veterinarians that I met in the Rayagada and Koraput districts seemed to know why people were falling ill.

Chigger mites nest in shrubby vegetation, and feed on forest and rural rodents, such as rats, voles and field mice. They bite humans only in their larval stage. As with many zoonotic diseases, the number of cases rises in the monsoon season, from July to October, as the mite thrives in wet vegetation, and either bites people on exposed feet and legs, or climbs into their clothing to bite them in warmer parts of the body with thin, folded skin – for instance, the groin or armpits.

Infected individuals fall ill after an incubation period of between six and 21 days, making it difficult to trace when or where they got bit. Scrub typhus can cause a high grade fever, chills and headaches, often accompanied by a rash. It sometimes results in lymphadenopathy, or a swelling of the lymph nodes, and an eschar at the bite site. When they see patients with these symptoms, doctors and health workers in rural areas, where large-scale testing facilities are too far to access easily, typically prescribe doxycycline, which cures many bacterial illnesses.

“We only started thinking of and testing for scrub typhus three years ago,” said Dr John Oomen, a community health specialist and current Medical Superintendent at Christian Hospital. “There’s no data to show how prevalent it is.”

Two factors were crucial to determining prevalence, he said: “Knowledge that the disease exists, and then the ability to test for it.” With the Odisha government only beginning to train its doctors this year to test for scrub typhus, data remains scarce for now.

In the ward adjacent to the 36-year-old construction worker’s were three other scrub typhus patients – two with similar and one with worse symptoms. One, a 30-year-old Adivasi man, had high creatinine levels in his blood due to the extent of damage to his kidneys. Listening to his case details, Oomen seemed doubtful that he would survive. The two other men, to the doctor’s relief, had responded well to doxycycline.

These cases are only the tip of the iceberg – many don’t even make it to a facility of Christian Hospital’s scale. “We’ll only get these complicated cases,” said Oomen. In these cases, the bacteria attacks other body systems – such as the respiratory system, which causes hypoxia, or the brain, which causes patients to present symptoms of meningitis.

Simple cases of scrub typhus often don’t get correctly identified because its symptoms, like body ache and chills, resemble those of other febrile illnesses, or those characterised by high fever. Most patients don’t develop an eschar when bitten.

This perhaps explains why Vidyavati Bagh, the ANM in Dukum village, was familiar with the symptoms of scrub typhus but hadn’t heard of the disease. Even Lakshman Bagh, a health worker at the Bissamcuttack Community Health Centre, who lives in the village of Chatikona, where the Niyamgiri range begins, did not know about it. “I have seen 39 or 40 patients already today,” Bagh said when we met on the evening of October 6. “Two of them had a fever above 100.” Often, he added, the people who come to him “are almost unconscious and trembling”.

Lakshman Bagh, like Vidyavati, prescribes tests for malaria, typhoid and dengue, and also dispenses broad-spectrum antibiotics such as doxycycline and azithromycin for what they call “viral fever”, and suggests cold compresses to bring down body temperatures.

Oomen suggested that these antibiotics were curing simpler cases of scrub typhus, leaving patients none the wiser about the disease’s prevalence. “If practitioners see a fever that doesn’t test positive for anything, they give doxycycline, which takes care of a whole host of things,” he said.

Almost an hour away from the Christian Hospital, nestled in the Niyamgiri hills, are villages inhabited by the Dongria Kondh Adivasi community. In Kurli, one such village, Dinja Jakesika, a rare woman Adivasi sarpanch, had been keeping track of fever cases and deaths among her people. In mid-October, the 35-year-old said that there were six or seven cases of fever that did not match the symptoms of malaria, dengue, or other diseases she knew of. By her count there had been five deaths from unidentified fevers in the last three or four months in her village of 400 people. She had been encouraging villagers to seek medical help instead of relying on the local priest, as many were inclined to do.

“No, I don’t know scrub typhus,” she told me. “I haven’t seen these tickku.”

But when I described the symptoms to her, she realised that they matched the symptoms she had seen in those who had fallen sick in Kurli. “It gets bad in the rains,” she said.

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Despite the low levels of awareness of scrub typhus at the moment, some change is underway. On September 7, 2021, the National Centre for Disease Control wrote to all states, warning them of monsoon-related illness due to “prolonged and intermittent heavy rainfall”. The letter stated, “Zoonotic diseases such as Scrub Typhus and Leptospirosis have shown a rising trend in some of the states.”

On September 14, Odisha’s health department wrote to all Chief District Medical Officers and Public Health Officers to take “necessary preventive measures to strengthen daily fever surveillance”, and “start procurement of IgM ELISA kit for diagnosis of Scrub Typhus and Leptospirosis.”

In Odisha, the disease began to receive attention after an outbreak of suspected Japanese encephalitis in the Malkangiri district in November 2016, in which 100 children died. Though no cases of scrub typhus were found among the children, the incident led to greater testing for the disease, according to Baral, the state’s Additional Director Public Health.

“Some of the samples were inconclusive for JE,” said Baral. “But since their presentation was so similar to scrub typhus, we started testing for it.”

Stronger evidence of scrub typhus’s presence came from an ambitious study to map all fevers in India, especially those of unknown origins, which was launched in 2014 by the Manipal Centre for Virus Research. The Acute Febrile Illness project, or AFI, was supported by the United States’ Centre for Disease Control and was headquartered at the Manipal Institute of Virology. It had 32 sites across 10 states in the country, including two important ones in Koraput and Malkangiri districts of Odisha, which have historically borne a high burden of malaria cases.

The study was led by Dr G Arunkumar, who shot to the limelight when he, to quote Oomen, “cracked Nipah,” the virus that plagued the state of Kerala in 2018. Arunkumar and his team at the Manipal lab identified Nipah in the samples sent from the second patient in Kerala, successfully warning the state authorities of the disease in time.

His involvement with scrub typhus goes back further. In August 2017, 63 children died in Gorakhpur’s BRD Medical College, in eastern Uttar Pradesh, after their oxygen supply ran out overnight. In the ensuing tumult, the hospital authorities claimed, and most media reported, that the children had been admitted for Japanese encephalitis. Even before official investigations concluded, Arunkumar had told this reporter that he suspected they had scrub typhus. Just one month before the deaths, his team had tested blood samples of ailing children in the same district over 20 days, and determined that the cause of their illness was an acute bacterial infection and not, as with Japanese encephalitis, a viral infection. He believed that the Gorakhpur cases, too, had the same cause.

His suspicions were supported by a study that showed that scrub typhus has had a larger presence in the region than previously thought, and Japanese encephalitis a lesser one.

The AFI study ended on an abrupt, messy note. Reportedly irked by the US-based Centre for Disease Control’s support to the Manipal Institute of Virology, the Indian government shut the study down in 2019, and in February 2020, removed the Manipal institute from the Indian Council of Medical Research’s list of “Viral Research and Diagnostic Laboratories”, claiming it had stored Nipah virus strains without adequate security clearance. The government also canceled Manipal University’s license to accept foreign donations – a lifeline for most private research institutes in India.

Despite its premature end, the AFI project left behind indelible evidence of scrub typhus’s prevalence. An interim report submitted to Odisha’s health department noted that out of 847 cases that were identified as having some disease, “Scrub typhus accounted for 131 (15.5%) and Malaria accounted for 121 (14.3%) of cases.” In Malkangiri, according to the report, out of a total of 373 such cases, “Malaria accounted for 106 (28.4%) and Scrub typhus accounted for 72 (19.3%) cases.”

Malaria is the most common illness in the hilly interior regions of Odisha. Its high prevalence was a foregone conclusion. But the team was startled to find that scrub typhus was vying with it for the disease responsible for the most number of fever cases, said Oomen, the medical superintendent of Christian Hospital, who was in touch with the team members. (Arunkumar declined comment for this story.) The two diseases were also the highest co-infections that the AFI team found – that is, more patients came in with both illnesses than any other combination of two diseases.

Dr Arun Padhi, the District Public Health Officer, Koraput, remembers playing with chigger mites as a child. “I remember them gliding around on the smooth grass in our garden,” he said. “My friends and I would pick them up with sticks.” He added that the mites he played with were in their harmless adult stage, and were not the larvae that spread the disease.

The 62-year-old grew up in Ganjam, in Odisha’s Gajapati district, where these mites were common and known on sight. However, in his 30 years in Koraput, he has not seen them. “Perhaps because I live in the urban area,” he said.

He added, “There’s an Oriya word for them, ‘sadhaba bohu’, but it’s only used in the coastal districts. I haven’t met anyone in these regions who knows these words.”

Scientists are investigating why scrub typhus faded from their notice for decades and why it has returned. Dr Sanghamitra Pati, the director of the Regional Medical Research Centre, Bhubaneshwar, and her team are among those grappling with this puzzle. Among the questions they are attempting to answer is whether cases of the disease are actually on the rise, or more cases are being diagnosed because a greater number of tests are being conducted for it. ELISA tests, considered by the medical fraternity as the gold standard for testing for scrub typhus, have been deployed to district public health laboratories only in the past few years. Where the ELISA kits have not been sent, Pati hopes RT-PCR test equipment that the Centre sent to each Odisha district to monitor Covid-19 can now be used to test samples for scrub typhus, and thus help researchers obtain more accurate numbers of its prevalence.

“Perhaps it was never really gone,” said Oomen. “So, what is the history of scrub typhus, we don’t know. Does it exist, yes. What are the numbers, we don’t know.”

It has only been three years since his own hospital, Christian Hospital, added scrub typhus to a standard list of likely diseases that might be causing symptoms such as fevers, chills and rashes. The change was made after a doctor transferred from Christian Medical College, Vellore, a sister establishment and a major centre for research on scrub typhus, recognised the symptoms and urged his colleagues to start testing.

CMC Vellore was, in fact, instrumental in India waking up in the 1990s and 2000s to the suspected re-emergence of scrub typhus. “For almost 50 years before that, the disease disappeared from the visibility of the country’s medical professionals,” said virologist Dr Jacob John, who retired from the hospital nearly three decades ago. “I think because the numbers of the ticks and the rodents were low.” In the late 1990s, his then colleague at CMC, Dr Elizabeth Mathai started questioning why a number of fevers among their patients were not being identified. She tested the serum from their blood samples, looking specifically for rickettsial infections. This is a family of infections that scrub typhus belongs to, and Mathai soon identified the disease. “I think the numbers are now rampant and it’s all over the country,” said John.

“My guess is it came back because we have encroached into nature, we have killed snakes that kept the rodent numbers low, and because of increased warming.”

Oomen offered two more theories for the re-emergence of scrub typhus. One possibility, he said, was that insecticide spraying in the past killed the mites that carried the bacteria; now, as mass spraying has decreased in quantity due to environmental concerns, the mites have simply come back. The other theory, he said, is that as forests get cleared, rural rodents, like rats and field mice, mites, and humans start occupying the same land that was once dense vegetation. This puts humans in closer contact with all zoonotic diseases.

Dr Ira Praharaj, part of the Regional Medical Research Centre team, leaned towards this theory. “Scrub typhus and deforestation have a strong correlation,” she said, speaking from her office in Bhubaneswar.

Globally too, scrub typhus has expanded beyond what is commonly called the tsutsugamushi triangle, comprising Asia, Australia and islands in the Indian and Pacific Oceans where the disease was endemic. New cases have been reported from across the African continent and from South America.

As human and animal habitats increasingly collide, and diseases threaten to spillover from the latter to the former, it has become urgent to check zoonotic diseases. Key to the solution might be a ten-year-old concept that is slowly gaining ground in India, called One Health.

The World Health Organisation defines One Health as “an approach to designing and implementing programmes, policies, legislation and research in which multiple sectors communicate and work together to achieve better public health outcomes.”

The phrase was coined in a global symposium in 2004, at Rockefeller University, New York City, where health experts aimed to establish a “more holistic approach to preventing epidemic/epizootic disease and for maintaining ecosystem integrity for the benefit of humans, their domesticated animals, and the foundational biodiversity that supports us all”.

Instead of only relying on public health and medicine to combat infectious diseases, the One Health approach comprises methods that focus simultaneously on human health, agriculture, animal health, environmental health and antimicrobial resistance.

The concept has entered the realm of Indian policy, with the Centre adopting it to keep zoonotic diseases in check. While there have been focused programmes to tackle some diseases – for instance, anthrax, caused by a bacteria – the government has extended it broadly to other zoonotic diseases as well. In 2019, the National Centre for Disease Control organised a two-day workshop “for strengthening inter-sectoral coordination for prevention and control of zoonotic diseases”, including rabies, anthrax, scrub typhus and leptospirosis.

Dr Arun Padhi, the District Public Health Officer at Koraput, is encouraged by the increasing attention scrub typhus is getting. He was part of the AFI study led by Dr G Arunkumar, and understood, better than most, the need to spread awareness. “If doctors don’t know about the disease, how will people?” he said, speaking from his office in Koraput town. He added, “Forty years ago, scrub typhus was just a footnote in our medical texts. Now at least, there are chapters on it.”

Through September and October, he led training sessions of government-employed doctors to familiarise them with scrub typhus and strategies to contain it. The government’s hope is that educating these doctors will allow knowledge to trickle down to field-level health workers.

Meanwhile, in October 2021, the Regional Medical Research Centre team began a new surveillance project in Keonjhar district, north of Bhubaneswar. It will collect data on unknown fevers – technically called pyrexia of unknown origin – to determine how many of these test positive for scrub typhus, in an effort to determine the prevalence of the disease.

Based on the data, the team will choose a study site in the region, and over a period of three years, will provide technicians with test kits and train them to diagnose the disease. The project, headed by Dr Madhusmita Bal, is based on a previous study by Bal, conducted between June and November 2017 across Odisha. That study found that out of 413 patients examined, all under 15 years of age and with acute fever, 48.7% were positive for scrub typhus and 5.5% of them had developed systemic complications. “We did that study because of the rising numbers of encephalitis-like cases in the area and in India,” Bal said.

For now, data remains scarce. But Pati, the director of the Regional Medical Research Centre, said, “If you ask me three years from now, I’ll have proper scrub typhus data for you.”

Reporting for this story was supported by Internews’ Earth Journalism Network.