Macroscopic Slide Agglutination Test Research Articles

Changing Trends in the Seroprevalence of Leptospirosis in Kelambakkam: A Ten-Year Retrospective Study

Introduction: Leptospirosis is a zoonotic infection affecting humans. The main sources of infection are animal reservoir hosts and man is the accidental host in the disease transmission process. The diagnosis is usually made by microscopy, culture, molecular techniques, and serological tests like ELISA, MAT (Microscopic Agglutination Test) and MSAT (Macroscopic Slide Agglutination Test). The ELISA method to detect IgM antibodies is used as a good cost-effective testing method. An increasing titre of IgM antibody is a sign of active leptospirosis. Aims and Objectives: The study aimed to evaluate the seroprevalence of Leptospirainfection over a 10-year period in a tertiary care hospital located in Kelambakkam village in Chengalpattu district. Material and Method: The samples were tested for the presence of specific Leptospira IgM antibodies in the patient’s serum using the Panbio Leptospira IgM ELISA kit. The samples were reported as positive/ negative/ equivocal accordingly. Results: This retrospective study included a total of 2035 patients, clinically suspected of leptospirosis, over a 10-year period from 2011 to 2021. 186 patients tested positive for specific IgM antibodies by ELISA method,giving an overall prevalence rate of 9.14%. Conclusion: The seroprevalence of leptospirosis over a time period of more than 10 years is highlighted in our study. Clinical suspicion of leptospirosis should be kept in mind at all times, especially now during the COVID-19 pandemic. The Panbio Leptospira IgM ELISA test kit used in our study proves to be a very useful method for diagnostic purposes, especially in limited-resource settings.

Development of a pooled antigen for use in the macroscopic slide agglutination test (MSAT) to detect Sejroe serogroup exposure in cattle

This study aimed to develop and evaluate a pooled antigen for use in the macroscopic slide agglutination test (MSAT) to detect cattle positive for the Sejroe serogroup. To this end, 193 bovine serum samples from different Pará State regions (Amazonia) were subjected to a reference microscopic agglutination test (MAT) for the serological diagnosis of leptospirosis using 11 serovars representing the Sejroe serogroup: Hardjo-prajitno; Hardjo-bovis; Sejroe; Wolffi; Guaricura (Bov.G.); Guaricura (M4/98); Ricardi; Gorgas; Recreo; Polonica and Medanensis. The three most prevalent serovars in the MAT were selected for the development of a pooled antigen for use in MSAT; subsequently, the 193 serum were assessed with the macroscopic slide agglutination test (MSAT) containing the developed antigen. The Kappa test was used to determine the general agreement between the MAT and MSAT results. As a result, of the 193 serum samples, 155 (80.3%) were reactive, and 38 (19.7%) were non-reactive in the MAT; Hardjo-prajitno, Wolffi and Medanensis were the three most prevalent serovars. Of the 193 serum samples tested in the MSAT using the developed pooled antigen, 114 were reactive (59.0%), and 79 (41.0%) were non-reactive; the Kappa coefficient was 0.52 (CI 95%, 0.40–0.63), indicating moderate agreement between the two tests. The MSAT with the pooled antigen including the most prevalent serovars detected bovines with the Sejroe serogroup exposure, mainly in animals with high titters in the MAT, and could be used to screen herds suspected of acute infection by this serogroup in Pará State.

Seroprevalence of leptospirosis in Chennai city, India.

Leptospirosis is a zoonotic disease, it occurs worldwide but is most common in tropical and subtropical countries. The magnitude of the problem varies from community to community. The serovars which cause the disease in a community change with adaptation to a new maintenance host and is epidemiologically important. Aims and Objectives: To determine the seroprevalence of leptospirosis in Chennai city. To identify the prevalent serovar in Chennai causing leptospirosis by using gold standard test Microscopic Agglutination Test (MAT). Methods: 1209 patients from Chennai, with fever of one-week duration and with signs and symptoms of Leptospirosis were the study population and were screened for Leptospirosis by Macroscopic Slide Agglutination Test (MSAT). The positive samples by MSAT were tested for the prevalent serovar and for confirmation by MAT and the results were analyzed statistically. Result: The seroprevalence of Leptospirosis is 17.8%. The prevalent serovar circulating in Chennai is L. grippotyphosa. Conclusion: Laboratory diagnosis is essential to confirm the current illness, and for epidemiological and public health reasons, namely to determine which serovar caused the infection, the likely source of infection and the potential reservoir and its location. This helps in control strategies.

An evaluation of dark field microscopy, culture and commercial serological kits in the diagnosis of leptospirosis

Context: This study was conducted to analyze the clinical utility of various leptospira diagnostic modalities. Aims: To evaluate the role of dark field microscopy (DFM), culture, immunochromatography (IgM Leptocheck), IgM enzyme-linked immunosorbent assay (IgM ELISA), macroscopic slide agglutination test (MSAT) and microscopic agglutination test (MAT) in diagnosing leptospirosis in febrile patients. Settings and Design: Descriptive study conducted in a tertiary care hospital from January 2011 to April 2012. Subjects and Methods: Blood, urine and paired sera from 100 patients with clinical suspicion of leptospirosis (study group) were collected and subjected to DFM, culture, IgM Leptocheck, IgM ELISA and MSAT. Fifty randomly selected sera from febrile patients tested positive for infections other than leptospirosis (control sera) were also subjected to the aforementioned serological assays. All the leptospira seropositive samples were subjected to MAT. Statistical Analysis Used: Positive predictive values (PPV) and coefficient of agreement (kappa). Results: None of the clinical samples showed positivity by DFM. Leptospira inadai was isolated from a urine sample. The seropositivity of IgM Leptocheck, IgM ELISA and MSAT was 16%, 46% and 47%, respectively. The PPV of these assays was 14.3%, 8.7% and 6.5%, respectively. Poor agreement was obtained among these assays. Only four study group leptospira seropositive samples were confirmed by MAT with Australis being the predominant serovar. None of the leptospira-positive control sera were confirmed by MAT. Conclusions: DFM and culture have limited utility in diagnosing leptospirosis with serology being the mainstay. The present study shows discordant results with the commercially available serological kits. Further studies should be done to evaluate the various diagnostic modalities.

Deciphering leptospirosis-a diagnostic mystery: an insight

Leptospirosis is an emerging infectious disease which has been recognized as the most common zoonotic infection in the world. It affects human beings and many other species of vertebrates .Most commonly, the infection is acquired by direct or indirect exposure to urine of reservoir animals through contaminated soil, mud & water entering via small abrasions or breaches in the skin & mucous membranes during occupational, recreational or vocational activities. The signs & symptoms resemble a wide range of bacterial & viral diseases & sometimes can present as food poisoning, chemical poisoning & snake bite also due to which the diagnosis is often missed. This review article aims to focus on the role of Dark Field Microscopy (DFM), culture, Enzyme Linked Immuno Sorbent Assay (ELISA), Macroscopic Slide Agglutination test (MSAT), Microscopic Agglutination Test (MAT) and Faine’s criteria in the diagnosis of leptospirosis.

English

BACKGROUND: Concomitant infection of leptospirosis with dengue has been reported in places where these diseases are endemic and leptospirosis may be overlooked in such cases. Recognition of leptospirosis is especially important since antimicrobial agents can reduce its severity and duration. Failure to identify leptospirosis in these patients will result in high mortality rate for this infection. Hence this study was conducted to have a detailed knowledge and awareness about the concomitant infection of leptospirosis with dengue. MATERIALS AND METHODS: Patients admitted to the medical ward of Government General Hospital, Chennai with fever of ≥ 5days and of the age group twelve years and above were evaluated for leptospirosis by doing the screening test MSAT (Macroscopic Slide Agglutination Test). All patients who tested positive for MSAT were further confirmed by MAT (Microscopic Agglutination Test). Those patients who tested positive for leptospirosis were investigated for concomitant infection with dengue utilising IgM ELISA. Patients positive for both leptospirosis and dengue were taken up for the study and were evaluated for relevant clinical features and laboratory profile. RESULTS: 143 patients were found to be positive for leptospirosis and among them 4 (2.8%) patients were positive for the concomitant dengue infection. In the four concomitant infection patients, two were males and two were females, all in the age group of 20 to 30 years. Fever and myalgia were the predominant symptoms in these patients. Thrombocytopenia was seen in 3 (75%) patients. With fluid resuscitation, platelet transfusion, appropriate drug and supportive therapy all the four patients recovered. No mortality was observed in this study. CONCLUSION: Increased awareness of concomitant infection and an enhanced ability to diagnose it early in illness is necessary so that appropriate treatment and supportive measures can be given to reduce the morbidity and mortality. Leptospiral illness may be a significant component in patients with concomitant infections and hence it is essential to evaluate for leptospirosis in all

Study on the Prevalence of Leptospirosis among Fever Cases Reported from Private Clinics in the Urban areas of Villupuram District, Tamil Nadu, India

ObjectivesTo know the prevalence of leptospirosis cases reported in private clinics among fever cases in Villupuram District, Tamil Nadu, India to know its real magnitude of the problem and to diagnose Leptospirosis among fever cases from differential diagnosis.Methods1502 Blood serum samples collected from three urban towns namely Kallakurichi (Latitude: 11° 73′ N; Longitude: 78° 97′ E), Villupuram (Latitude: 11° 75′ N; Longitude: 79° 92′ E) and Thindivanam (Latitude: 12° 25′ N; Longitude: 79° 65′ E) in fifteen clinics based on case definition of leptospirosis delineated by the National Vector Borne Disease Control Programme (NVBDCP), Government of India. Samples were tested in the laboratory of the Zonal Entomological Team (ZET), Cuddalore with Macroscopic Slide Agglutination Test (MSAT) and Ig-M ELISA.ResultThere were 65 positive cases detected from 1502 blood serum samples in both MSAT and Ig-M ELISA. It could be known that there was 4% cases contributed from private clinics among fever cases. From this study, further it was known that all age groups of people affected irrespective of sexes based on their living condition associated with the environment prevailed of the disease.ConclusionFrom this study, it was quantified that 4% of cases reported in private clinics among fever cases and its findings ascertained both the importance of differential diagnosis as well as reports that should be included to the Government for knowing its real magnitude for planning.

Leptospirosis in vellore: a clinical and serological study.

Leptospirosis is a severe spirochetal zoonosis in the world. It is considered an occupational disease of persons engaged in agriculture, sewage works, forestry, and animal slaughtering. A study was conducted with an objective of assessing the seroprevalence of leptospirosis in and around Vellore district, Tamil Nadu. The study was based on the signs and symptoms of the patients reporting fever in Vellore Municipal Clinic (Urban Malarial Scheme). Blood samples were collected from 129 patients. Animal studies were conducted from 24 rodents captured form the market place of the Vellore municipality. In the ZET (Zonal Entomological Team, Vellore) Laboratory the sera were examined by macroscopic slide agglutination test (MSAT). In the MAST, totally 10 positive leptospiral cases from human beings and 10 positive leptospiral cases from rats (Rattus rattus and Rattus norvegicus) were found out. Then both positive cases of leptospiral vials were labeled, sealed, and sent to the Leptospirosis Research Laboratory, Madhavaram, Chennai, for further serovars examination. Among the various serovars identified autumnalis was more prevalent. Our findings showed that the age groups between 15 and 55 years showed more susceptibility. Particularly the adults were more infected. The majority of seropositive individuals in the cases had only subclinical infection. Rodents were abundant and contributed to enzootic and endemic prevalence of leptospirosis.

Leptospirosis in children in Mumbai slums.

There is limited data available on symptomatic leptospirosis in Indian children. We report an outbreak of leptospirosis that occurred in children living in slums following heavy rainfall and flooding. This hospital-based prospective study was conducted from July to August 2001. Diagnosis of acute leptospirosis was suspected by following the Indian Leptospirosis Society working definition for leptospirosis. Diagnosis was confirmed by detecting anti-Leptospira antibodies, using either a Leptospira genus-specific latex agglutination assay or a dipstick assay or by a macroscopic slide agglutination test. Thirty (32%) out of 93 children admitted had acute leptospirosis. Fever, bodyache, chills, abdominal pain, headache, vomiting, cough, hepatosplenomegaly, edema and crepitations were the common presenting signs and symptoms. Twenty - two children had anicteric leptospirosis and 8 had Weil disease. Response to penicillin treatment was good in all except in one child with Weil disease who died of renal failure within 3 hours of admission. Leptospirosis has emerged as an infectious disease in Mumbai. During monsoon, parents should ensure that their child does not have contact with the contaminated flood water.

The use of a formolised antigen as a screening test for leptospiral antibodies in horses.

SummarySix hundred and thirty‐two equine serums were examined for the presence of leptospiral antibodies. A positive reaction to one or more antigenic pools of a formolised leptospiral antigen (used in the rapid macroscopic slide agglutination test) was recorded in 41% of cases.One hundred samples were tested with 5 formolised antigen pools and 19 live antigens (by the microscopic agglutination test). Of 20 samples in which the live antigen test suggested leptospiral infection with serotypes known to occur in the region, 17 (85%) were confirmed with the formolised antigens.When the results of both tests were compared, there was agreement in 42 samples (30 positive and 12 negative). Forty‐one samples produced equivocal results and 17 gave doubtful reactions to the formolised antigens, 15 of which were negative to the live antigens.Dilution of the serums 1:1 with normal saline or heat inactivation had no effect in increasing the specificity between the formolised and live antigens. Agreement between operators in the use of the formolised antigen was poor. It is concluded that the formolised antigen has too wide a divergence to be of use for screening horse serums.

Leptospirosis in man and rodents on Taiwan.

SummaryA survey for leptospirosis in man and wild rodents in Taiwan, by serologic and cultural techniques, revealed that 3.22% of 8,362 school children were positive by the macroscopic slide-agglutination test of Galton et al.13 The number of positive reactions dropped to 1.94% when the microscopical agglutination-lysis test was employed.A group of 65 patients with illnesses suggestive of leptospirosis were studied. Ten (15.4%) were serologically positive, and in two (3.08%) L. canicola was isolated by culture.Of 586 rodents studied, 38 (6.48%) were positive by the macroscopic slide-agglutination test, and 20 were positive by culture. R. norvegicus were more often positive although they represented only 32% of the trapped population, and 18 of 193 (9.32%) animals were positive. Only two of 282 (representing 48.5% of the trapped population) R. rattus had positive cultures (0.71%).

A Macroscopic-Slide Agglutination Test for the Presumptive Diagnosis of Furunculosis in Fish

A Macroscopic-Slide Agglutination Test for the Presumptive Diagnosis of Furunculosis in Fish

Serologic Evidence of L. Australis a in a Georgia Patient

T HE SEROTYPE Leptospira australis A Ballico was first isolated by Cotter and Sawers (1) in 1934 in northern Queensland, Australia. It was reported recently by Derrick and others (2) as the second most common serotype in Australia and accounted for 87 percent of the leptospirosis cases that occurred in canefield workers. The principal animal carrier was found to be a native rat, Rattus conatus (3). In addition, this serotype was isolated from the kidney of a dog in Makasar by Mochtar (4) and from hedgehogs and yellowthroated mice, Apodeinus flavicollis, in Czechoslovakia by Kmety (5). No evidence of L. australis A infection was found in the United States until 1955, when two cultures isolated from raccoons in Decatur County, Ga. (6), were identified in the Communicable Disease Center's Leptospira Research Laboratory (7). Subsequently, presumptive identification has been made of 3 other isolations from raccoons and 1 from an opossum in southwestern Georgia. In August 1956 a macroscopic slide agglutination test antigen was prepared from the first L. australis A strain isolated in southwestern Georgia. The antigen was incorporated into the battery of leptospiral antigens used to screen all human and animal serums examined in the laboratory. Routine use of this antigen led to the detection of L. australis A antibodies in serum from a patient in October 1957. The history of the patient's illness and the subsequent epidemiological investigation are described in this report.

A Study of the Whole Yeast Cell Agglutination Test in Rabbits Experimentally Infected with Histoplasma Capsulatum

Summary It was found that whole yeast cells of Histoplasma capsulatum grown on brain heart infusion agar at 37°C could be used as the antigen in a tube agglutination test with sera from rabbits experimentally infected with H. capsulatum. Very low or negative agglutinin titers were obtained with sera from infected rabbits using the commonly used incubation temperatures of 25, 37 or 52°C. Overnight refrigeration of tubes (4°C) resulted in slightly increased titers. Greater agglutinin titers were demonstrable in tubes that had been centrifuged, and it was found that an incubation period was not necessary using this technique. The method of choice was, therefore, to centrifuge the tubes immediately after mixing antigen with serum. Yeast cells from 3 strains of the fungus were shown to be useful agglutinogens, exhibiting approximately equal combining power. An additional strain was found to agglutinate spontaneously in normal human and rabbit sera. The methods used for inactivation (heat, formalin, and phenol) were found to have an effect upon the agglutinating ability of cells from the different strains, but no one method seemed to be the best for all strains tested. In sera from rabbits experimentally infected with H. capsulatum, agglutinin titers were found to rise rapidly during the first week of the disease, reach a maximum by the end of the second week, and become negative at the end of a 9 week period. Complement fixation tests using whole cell antigens were also positive after 1 week, but reached a peak at 6 weeks and remained positive in high titers at the end of 13 weeks. The histoplasma agglutination antigen when tested in sera of rabbits experimentally infected with Blastomyces dermatitidis, Sporotrichum schenckii, Candida albicans and Coccidioides immitis, gave positive results only with B. dermatitidis. No differences in specificity of the antigens were noted after treatment with formalin and phenol or heat inactivation. A macroscopic slide agglutination test is described which proved of value in “screening” rabbit sera for the presence of antibodies against yeast cells of H. capsulatum.