Lyme disease is caused by a spirochaete Borrelia burgdorferi. Borrelia is transmitted to humans by the bite of infected ticks belonging to a species of the genus Ixodes(deer ticks). Clinical manifestations of Lyme disease are heterogenous and in the early phase mainly include erythema migrans (EM) and musculoskeletal symptoms. In the late stages, neurologic system, heart, joints and eyes become affected and chronic skin changes appear. Different clinical manifestations, overlapping symptoms and high antigenic variability of borrelia makes a reliable diagnosis of Lyme disease difficult. If detected early, symptoms are eliminated by antibiotics. Late, delayed or inadequate treatment may lead to serious complications. The standard diagnostic protocol for laboratory confirmation consists of a 2 step algorithm including enzyme linked immunosorbent assay (ELISA) and western blot (WB) test for confirmation.
In India, Lyme disease is not commonly considered in the differential diagnosis of uveitis. Recently we reported a case of neuroretinitis hailing from a forest region of Nagarhole, Kodagu district, Karnataka, South India who was diagnosed as a possible Lyme disease on the basis of a positive western blot test to borrelia burgdorferi antigen and improvement with doxycycline. However the tick isolated was not Ixodes but Haemophysalis. We have had 2 similar cases after this from the forest areas of Nagarhole in south India. In addition, there has been an outbreak of Lyme borreliosis in Wayanad district of kerala. There has also been sporadic reports of Lyme disease in Northern India from Shimla and Harayana. Praharaj et al found that 13% of population in north eastern states of India were positive for Borrelial antibodies. Ixodes ticks have been reported in the Himalayan regions of India and more recently in the Western ghats and thus there is a likelihood that Lyme disease may exist in our country. Currently we do not have any data on the seroprevalence of this disease in our patient population nor do we know if Lyme disease is underdiagnosed in India. The aim of this study is to determine the seroprevalence of Lyme disease in a patient population at risk, residing in and around the forests of Nagarhole and Bandipur in south India and describe any ocular or systemic manifestations of this disease. This study is the first of its kind in South India.
Materials and Methods: The study was undertaken in the forest areas of Nagarhole and Bandipur in South India between March 2017 – Feb 2019. The study population included forest department works and helpers deployed in these jungles and natives of the Nagarhole and Bandipur forest ranges.
Inclusion criteria: Subjects ≥ 18 years of age; working or living in the forest area of Nagarhole or Bandipur and those patients capable of giving informed consent will be included in the study.
Exclusion criteria: Subjects < 18 years of age and those patients not capable of giving informed consent.
This study had our Institutional ethics committee approval and all necessary clearances from the principal conservator of forests. The study on human subjects was conducted as per the declaration of Helsinki.
Forest workers and helpers were screened in different areas of Bandipur and Nagarhole ranges in South India. After an informed consent, all participants completed a questionnaire about area of residence, age, gender, profession, exposure to tick bites, symptoms involving skin, nervous system and joints. A systemic examination was done by an infectious disease specialist. Ocular evaluation was done by an ophthalmologist and included best corrected visual acuity, slitlamp, dilated fundus and intraocular pressure examinations. Extraocular motility and pupillary examinations were done by means of a torch light.
3.5ml of peripheral venous blood was collected from the antecubital vein of the subjects. The blood was allowed to clot and the serum was separated by centrifugation. The sera were then transported on dry ice to Vittala International Institute of Ophthalmology and stored in multiple aliquots and frozen at -70oC.
All sera samples were screened using an ELISA test for detection of specific IgM and IgG antibodies against Borrelia Burgdorferi (Novatech, Germany), according to manufacturer’s instructions. In order to avoid cross reactivity and false positive results, the positive serum samples were also tested for rheumatoid factor, antinuclear antibodies and Treponema pallidum haemagglutination tests.
If the tests were positive for ELISA, confirmation was done by western blot analysis for IgM and IgG antibodies(Viramed biotech Ag, Borrelia B31 Virablot, Germany) according to the manufacturer’s recommendations. Antibodies against individual antigenic fractions p100, VlsE, p58, p41, p39, OspA, OspC, p18. The interpretation of the results were done according to the scheme proposed by the producer.
Ticks were collected from the forests by the “tick drag” method. They were grouped, crushed and subjected to PCR to verify if they harbor the spirochete Borrelia Burgdorferi in them. Statistical analysis including descriptive statistics was done using SPSS package at <5% level of significance.
Results: 518 forest workers and helpers were screened. Out of this, there were 450 males(86.9%) and 68 females(13.1%). Only 463 blood samples were collected. ELISA was positive for IgM antibodies in 83 cases (17.6%) and IgG antibodies in 26 cases(5.5%). Indeterminate results were obtained in 61 cases (13%). Western blot positivity was seen in 15 cases (14.4%). There was a significant correlation between h/o exposure to tick bite and ELISA positivity (0.023). There was no correlation between arthritis, skin rashes, CNS symptoms, cardiovascular abnormalities with seropositivity. One patient in this study with seropositivity with western blot confirmation had unilateral retinal vasculitis.
Discussion: Current study shows a high seroprevalence of 14.4% for Lyme disease in forest areas of bandipur and nagarhole. Dermatological and arthritis are seen in this population. However there was no significant correlation between the seropositivity and other clinical presentations. In all probabilities, the high seroprevalence indicates an asymptomatic disease in this patient population and is important to find the vector in the ticks.
Conclusion: There is a high seroprevalence of Lyme disease in patient population of nagarhole and bandipur. Future studies including a Next-Generation Sequencing-Based Molecular Approach to characterize a tick vector in lyme disease.