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SERO-POSITIVITY FOR LEPTOSPIROSIS A PILOT STUDY
S BORWANKAR*, RV POPERE**, RB GURAV#, S KARTIKEYAN##
*Assistant Lecturer; **Professor and Head, Department of Microbiology; #Lecturer; ##Associate Professor, Department of Preventive and Social Medicine, Rajiv Gandhi Medical College, Kalwa, Thane - 400 605, Maharashtra.
A pilot study conducted on 77 in-patients during an outbreak of leptospirosis in Thane (Maharashtra), revealed a sero-positivity rate of 19.48%. There was a preponderance of males. Since the symptoms of leptospirosis may be non-specific, the health care providers should have a high index of clinical suspicion so that the disease is diagnosed at an early stage.
INTRODUCTION
The last decades of the previous millennium saw the emergence and reemergence of many infectious diseases. [1] This has shaken mankind out of its complacency and has made it realize that the fight against infectious diseases has to be an ongoing battle. [2] Leptospirosis is one of the emerging infections, which has the dubious distinction of being an occupational as well as a zoonotic disease. [1,2] Increased awareness of the disease has led to increased recognition.[4] In 1995, after widespread flooding in Nicaragua (Central America), an epidemic of leptospirosis affected about 2,000 persons and killed at least 13 individuals. [4] In 1997, 9 sportsmen involved in white-water rafting (a water sport), were infected in Costa Rica (in Central America). [4]
Till the 1980’s, very few reports on leptospirosis originated from India. [2] This is in spite of the fact that the isolation of the causative organism was first reported, in the year 1931, by Taylor and Goyle, from the Andaman and Nicobar islands. [8] During the late 1980’s, outbreaks of the disease were reported from Tamil Nadu, Mysore (Karnataka) and Nagpur (Maharashtra). In 1997, thousands of people were affected in Surat (Gujarat). After the super-cyclone in Orissa in October 1999, outbreaks of fever with pulmonary haemorrhage occurred in the flooded villages. In July-August 2000, cases of leptospirosis were reported from Gujarat, Maharashtra, Kerala and Andaman and Nicobar islands. [1] Sero-prevalence rate of more than 55% has been observed in the general population of North Andamans. [9]
Occupational as well as recreational contact with fresh water, damp soil or vegetation contaminated by urine of infected animals (especially rodents, dogs and pigs which are the animal reservoirs) is responsible for the transmission of this disease. Asymptomatic animals excrete the causative organism - Leptospira interrogans (a spirochaete) - in their urine. All animals are potential reservoirs for the disease, although cases of leptospirosis among cats are rare. Hence, veterinarians, animal handlers and pet owners form a high-risk group. [4]
Human infection occurs by direct contact with urine or blood of an infected animal or from contaminated water, soil or vegetables. Though the usual portal of entry is the abraded or broken skin or mucous membranes, leptospira can also enter the human body through unabraded skin. [3] Thus, behavioural factors like walking barefoot and open air defaecation are associated with a high risk of leptospiral infection. [1 , 3 , 10 , 11] There is a strong occupational predisposition and the disease is more common among those who work in sewers, slaughterhouses, mines, sugarcane fields and rice fields. [1 , 3] Ingestion of water during watersports is also a mode of transmission. [4]
Like leptospirosis in animals, the infection in humans may often be subclinical. Human disease may manifest as non-specific symptoms. [3] Patients are usually subjects to various laboratory investigations, which generally do not include serology for the detection of leptospirosis. This may be attributed to a low index of suspicion for the disease.
The aim of this pilot study was to determine the profile of patients who tested sero-positive for leptospirosis, during an outbreak of the disease in August, 2000.
METHODOLOGY
The present study was conducted during an outbreak of Leptospirosis in August, 2000. The study population comprised 77 in-patients (61 males and 16 females) who were admitted in a referral hospital in Thane (Maharashtra), during the month of August 2000. The personal particulars and clinical history of the patients was recorded on a proforma.
A dipstick assay was used for the diagnosis of leptospira-specific Immunoglobulin M (IgM) antibodies in serum samples of patients who had acute febrile illness with symptoms suggestive of leptospirosis (Table 1). The dipstick assay was preferred because it was easy to perform quickly and it did not require electricity or special equipment. Moreover, the dipstick and the staining reagent could be stored for prolonged periods at tropical temperatures. [14]
INDX DIP-S-STICKSÂ (Lot 052699) manufactured by Integrated Diagnostics Inc., Baltimore, USA, were used for the dipstick assay, which was done as per the instructions given in the manufacturer’s catalogue. [5] Samples with 3 or 4 reactive dots were taken as diagnostic (i.e. "sero-positive") for leptospirosis. [5] The data were collected, tabulated, analyzed and discussed.
Clinical criteria suggestive of leptospiral infectionAcute febrile illness with headache, myalgia and prostration, associated with any of the following symptoms:
* Sub-conjunctival haemorrhage
* Meningeal irritation.
* Anuria / Oliguria and/or proteinuria.
* Jaundice.
* Haemorrhages from intestines (haematemesis / melaena),lungs (haemoptysis), skin (petechiae), sub-conjunctival haemorrhages.
* Cardiac arrhythmia or failure.
* Skin rash.
* History of exposure to infected animals or an environment contaminated with animal urine.Source : Reference Nos. 6 and 7.
RESULTS AND DISCUSSION
Outbreak of a total of 77 in-patients with symptoms suggestive of leptospirosis, 15 (19.48%) tested sero-positive by the Dip stick assay. Among these 15 seropositive patients, males outnumbered females by a ratio of 4:1 (Table 2). The higher prevalence among males is universal and is usually attributed to their outdoor activities. [10] In the present study, 40% of the sero-positive patients were in the age group of 25-34 years. However, another study by Sehgal et al [12], most of the patients of leptospirosis were aged between 5-14 years. The disease was not found to be significantly associated with occupation. Only two patients were hawkers (vegetable vendors), who gave a history of occupational exposure to vegetables, soil and water, which were probably contaminated by Leptospira. Dasgupta, [13] has reported in a study, that leptospirosis was not found to be confined to any particular occupational group. In such cases, leptospiral infection may be attributed to several behavioural and environmental factors.[10]
Murhekar et al [10] have found that the following factors were associated with increased risk of leptospiral infection - location of residence in low lying areas, contact with animals, walking barefoot, open-air defaecation, rat infestation, use of drinking water from wells or streams, habit of bathing in ponds, exposure to stagnant water while walking. In the present study, except in the case of the two vegetable vendors, these behavioural or environmental factors were not found to be significantly associated with leptospiral infection. The lack of statistical significance may be due to the small size of the sample. Factors like religion, education and socio-economic status were not statistically significant.
The major clinical manifestations were - nausea and vomiting (53.33%); haemorrhages (26.67%); headache and body ache (20%); fever with chills and/or rigors (16.67%). Many patients had multiple clinical manifestations. None of the patients had jaundice or skin rashes. Due to the varied clinical manifestations of the disease, rapid and cost-effective laboratory techniques would be required for early diagnosis. This is essential because delayed diagnosis can cause progressive involvement of the liver, kidney and the heart, leading to death. [3]
Since the disease can also occur sporadically, health care providers should have a high index of clinical suspicion so that the investigations are done at an early stage. It should be realized that changes in behavioural and environmental factors are the only weapons for long-term control of this disease.
Features of sero-positive casesFeature Males
n=12Females
n=3Total
n=15Age group
< 14 yrs.
15-24 yrs.
25-34 yrs.
35 yrs.+
01 (08.33)
04 (03.33)
05 (41.84)
02 (16.67)
02 (66.67)
-
01 (03.33)
-
03 (20.00)
01 (26.67)
08 (40.00)
02 (13.33)Occupation
Student
Housewife
Unskilled worker
Hawker
01 (08.33)
-
09 (75.00)
02 (16.67)
02 (66.67)
01 (33.33)
-
-03 (20.00)
01 (06.67)
04 (60.00)
02 (13.33)Clinical manifestations
Headache and body ache
Fever, chills, rigors
Nausea, vomiting
Haemorrhages
Oliguria
Meningitis, convulsions
02 (16.67)
08 (66.67)
06 (50.00)
03 (25.00)
01 (08.33)
01 (06.67)
01 (33.33)
02 (66.67)
02 (66.67)
01 (33.33)
-
-
03 (20.00)
10 (16.67)
08 (53.33)
04 (26.67)
01 (06.67)
01 (06.67)Figures in parenthesis indicate percentages. Many patients had multiple clinical manifestations.
REFERENCES
1.Park K. Park’s Text Book of preventive and social medicine. 16th edition 2000. Banarsidas Bhanot, Jabalpur. Page 219.
2.Sehgal SC. Emergence of leptospirosis as a public health problem. Proceedings of the round table conference on leptospirosis; Pune 1998; 3 : 7-17.
3.Mitra DK. Leptospirosis. Chapter in : Sainani GS (Edited), API Text book of Medicine, 6th edition, 1999. Association of Physicians of India, Mumbai. Page 62.
4.Website:http://www.cdc.gov/ncidod/dbmd/diseaseinfo/leptospirosisg.htm
5.Integrated diagnostics incorporated : Catalogue number 5065M-02-10 and 5065M-01-50. Integrated Diagnostics Inc., Baltimore, USA. 1999; 2-9.
6.Sehgal SC. Recommendations of National symposium on leptospirosis. Indian Journal of Medical Microbiology 1977; 15 (4) : 211-2.
7.Kuriakose M, Eapen CK, Punoose E, Koshi G. Leptospirosis - Clinical spectrum and correlation with seven simple laboratory tests for early diagnosis in the Third World. Transactions of the Royal Society of Tropical Medicine and Hygiene 1990; 84 (3) : 419-21.
8.Taylor J, Goyle AN. Leptospirosis in the Andamans. Indian Journal of Medical Research Memoirs. Supplementary series to the Indian Journal of Medical Research. Memoir No. 20. 1931; 55-6.
9.Sehgal SC, Murhekar MV, Sugunan AP. A sero-survey for leptospirosis in North Andamans. Indian Journal of Medical Microbiology 1994; 12 : 289-91.
10.Murhekar MV, Sugunan AP, Vidyachari P, Sharma S, Sehgal SC. Risk factors in the transmission of leptospiral infection. Indian Journal of Medical Research 1998; 107 : 218-23.
11.Faine S. Guidelines for the control of leptospirosis. WHO offset publication no. 62. World Health Organization, Geneva. 1982; 21-22,79.
12.Sehgal SC, Murhekar MV, Sugunan AP. Outbreak of leptospirosis with pulmonary involvement in North Andaman.Indian Journal of Medical Research 1995; 102 : 9-12.
13.Dasgupta BM. Leptospirosis in India. The Indian Medical Gazette. 1938; 73 : 449-53.
14.Gussenhoven GC, Menno AWG, van der Hoorn, Goris MGA, Terpstra WJ, Hartskeerl RA, Mol BW, van Ingen CW, Smits HL. LEPTO Dipstick, a Dipstick assay for detection of leptospira-specific immunoglobin M antibodies in human sera. Journal of Clinical Microbiology 1997; 35 (1) : 92-7.
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