Abstract
Background Leptospirosis is an anthropozoonotic reemerging neglected infectious disease underreported in most developing countries. A cross-sectional study was performed between 17 and 23 February 2014 to estimate the seroprevalence of leptospirosis among high-risk populations in Casablanca (Morocco). Methods A total of 490 human serum samples (97.6% males) were collected in 3 high-risk occupational sites including the biggest meat slaughterhouse (n = 208), a poultry market (n = 121), and the fish market (n = 161). A total of 125 human blood samples were also collected from the general population and used in this study as a control group. To detect the presence of anti-Leptospira, sera were screened with in-house IgG and IgM enzyme-linked immunosorbent assay (ELISA). Positive samples were tested by Microscopic Agglutination Technique (MAT) using a panel of 24 serovar cultures and cut point of 1 : 25. Results Seroprevalence of leptospirosis among the control group was 10.4% (13/125). A high seropositivity among the overall seroprevalence of 24.1% (118/490) was observed in the high-risk groups of which 7.3% (36/490), 13.7% (67/490), and 3.1% (15/490) were for anti-Leptospira IgM, IgG, and both IgG and IgM antibodies, respectively. Most of the positive individuals were occupationally involved in poultry (37.2%), followed by the market fish (26.1%) and the meat slaughterhouse (14.9%) workers. Among all ELISA-positive serum samples, 20.3% (n = 24) had positive MAT responses, of which the Icterohaemorrhagiae (n = 7) is the most common infecting serogroup followed by Javanica (4), Australis (2), and Sejroe, Mini, and Panama (one in each). In the remaining 8 MAT-positive sera, MAT showed equal titers against more than one serogroup. Conclusion Individuals engaged in risk activities are often exposed to leptospiral infection. Therefore, control and prevention policies toward these populations are necessary.
Highlights
Leptospirosis, caused by pathogenic members of genus Leptospira, is the most widespread bacterial zoonosis [1]
In 2014, the Direction of Epidemiology and Disease Control and Institut Pasteur du Maroc in collaboration with the local authorities decided to carry out a seroepidemiological investigation on the suspected sites of Casablanca. e objective of this investigation was to estimate the seroprevalence of Leptospira spp. among various human high-risk groups and to determine the pathogenicity of Leptospira serovars. is study aimed to generate information on risk factors related to this disease to promote public awareness since extensive professional activities are undertaken without adequate hygienic conditions
In the absence of any data about estimates of the seroprevalence of leptospirosis in Morocco, we considered first a convenience global sample of about 500 individuals in the 3 high-risk occupational sites based on 80% power, a type I error of 5%, a 10% nonresponse rate, and an expected seroprevalence around 12% according to published international studies [12,13,14]
Summary
Leptospirosis, caused by pathogenic members of genus Leptospira, is the most widespread bacterial zoonosis [1] This reemergence sickness is likely influenced by environmental conditions, such as occupation conditions, urbanization, and poverty [2, 3]. Poor housing conditions, and limited access to education and health increase the risk of human infection in urban areas [4, 5]. In most African countries including Morocco, lack of data about this disease may be the consequence of lack of awareness of the disease among physicians, and nonspecific symptoms, limited access to diagnosis, and leptospirosis burden assessment studies. Similar results were previously/recently reported in temperate countries In this Moroccan study, a seasonal increase of cases was observed during the summerautumn period with regular epidemic peaks in some provinces with highest rate (17.0%). In 2014, the Direction of Epidemiology and Disease Control and Institut Pasteur du Maroc in collaboration with the local authorities decided to carry out a seroepidemiological investigation on the suspected sites of Casablanca. e objective of this investigation was to estimate the seroprevalence of Leptospira spp. among various human high-risk groups and to determine the pathogenicity of Leptospira serovars. is study aimed to generate information on risk factors related to this disease to promote public awareness since extensive professional activities are undertaken without adequate hygienic conditions
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