|Year : 2018 | Volume
| Issue : 2 | Page : 168-175
Seroprevalence of leptospirosis among people in Shabramant Village, Egypt
Amgad A Elzahaby1, Samy Zaky1, Nawal A Hafez Hassanain2, El-Sayed R Hassan3, Mohey A Hafez Hassanain2, Mohamed Hegazy1, Ahmed M Maher2
1 Department of Tropical Medicine, Faculty of Medicine, Al-Azhar University, Cairo, Egypt
2 Department of Zoonotic Diseases, National Research Centre (NRC), Cairo, Egypt
3 Department of Microbiology, Head of Leptospirosis Unit, Animal Reproduction Researches Institute (ARRI), Giza, Egypt
|Date of Submission||09-Feb-2017|
|Date of Acceptance||21-Feb-2017|
|Date of Web Publication||27-Feb-2019|
Ahmed M Maher
Assistant researcher of Zoonotic Diseases, National Research Centre (NRC), 71513, Cairo
Source of Support: None, Conflict of Interest: None
Background Leptospirosis is considered as the most common zoonosis in the world. Leptospirosis has a multiorgan affection that can affect nearly any organ in a classical, rare or unusual presentation and complications. This may include hepatic, renal, pulmonary, meninges and cardiac affections.
Aim The purposes of this study were estimating leptospiral infection prevalence among people living in Shabramant village at El-Giza Governorate and identifying associated environmental and behavioral risk factors for the infection.
Patients and methods This study was designed to be a cross-sectional study conducted during the period from June 2013 to May 2014. Our study included 100 participants based on history taking and laboratory investigations; a structured questionnaire was administered to collect information on individuals’ potential risk factors for leptospiral infection. Microagglutination test was performed using five Leptospira serovars: Leptospira int. icterohaemorrhagiae, Leptospira int. canicola, Leptospira int. pomona, Leptospira int. grippotyphosa and Leptospira int. wolffi to determine the presence of leptospiral antibodies and their titers in the sera of investigated patients.
Results Our study found leptospirosis disease to be common among studied cases (44%), and L. icterohemorrhagiae was the only serovar detected among the studied cases. Middle-aged female patients were predominantly affected (52.6%); hence, age and sex can be regarded as risk factors of leptospirosis. Coinfections by other pathogens were also noted in this study; 22.2% of the 44 cases included had positivity for hepatitis C virus antibodies, which can be regarded as a risk factor for acquiring this disease. Also, living close to places inhabited by rodents and animals was considered as an important risk factor for exposure to such infections, and measures should be developed to minimize exposure to these animals.
Conclusion It can be concluded that leptospirosis is an important neglected zoonotic disease despite its high prevalence. We recommend adding Leptospira infection to the list of possible diseases among febrile patients and increasing the awareness of the fever hospital clinicians about leptospirosis.
Keywords: occupational disease, prevalence, risk exposure, rodents
|How to cite this article:|
Elzahaby AA, Zaky S, Hafez Hassanain NA, Hassan ESR, Hafez Hassanain MA, Hegazy M, Maher AM. Seroprevalence of leptospirosis among people in Shabramant Village, Egypt. Al-Azhar Assiut Med J 2018;16:168-75
|How to cite this URL:|
Elzahaby AA, Zaky S, Hafez Hassanain NA, Hassan ESR, Hafez Hassanain MA, Hegazy M, Maher AM. Seroprevalence of leptospirosis among people in Shabramant Village, Egypt. Al-Azhar Assiut Med J [serial online] 2018 [cited 2020 Jul 6];16:168-75. Available from: http://www.azmj.eg.net/text.asp?2018/16/2/168/253081
| Introduction|| |
Leptospirosis is one of the world’s most widespread zoonoses, caused by pathogenic spirochetes of the genus Leptospira . Being spread by the urine of animals, the bacteria enter body through abraded skin, conjunctivae or mucous membranes, after which they disseminate throughout the body. The infection is common in regions characterized by high rainfall or close contact with livestock or wild animals. Because of increased rainfall and global warming, leptospirosis is re-emerging, especially in urban areas, where slums are rapidly growing .
Leptospirosis occurs in several countries, but the incidence is variable and marked underreporting is very common. Generally, there is a higher incidence in tropical areas. Leptospira is also encountered in a variety of wild and domestic animals, but rodents, cattle, dogs and pigs are the predominant hosts in many countries . Different serogroups predominate in different countries, but Leptospira icterohaemorrhagiae is encountered in the majority of countries .
The usual presentations of leptospirosis are highly variable . Leptospirosis has been misdiagnosed by other diseases such as dengue fever disease, typhoid fever, influenza, encephalitis, yellow fever disease and malaria. However, asymptomatic disease is also common (≥60–70%) in endemic regions. Most patients develop a mild febrile illness with rather nonspecific symptoms such as fever, myalgia and headache. A proportion of patients, however, develop rapidly progressing and severe complications, with a fatality rate up 70% in patients with severe pulmonary complications . Other presentations include pulmonary hemorrhage, iritis, noncalculuscholecystitis and myocarditis .
Because of the diverse symptoms similar to various other diseases, leptospirosis is difficult to be diagnosed clinically alone. Hence, laboratory investigations are required for confirmation. The reference serological test is the microagglutination test (MAT). The MAT antigens used reflect the most prevalent serotypes in the country. Other tests include enzyme-linked immunosorbent assay and the dipstick test .
Available data on the incidence and prevalence of leptospirosis in the Middle East are limited . In Egypt, a pilot study was conducted ∼25 years ago revealing that 9% of sera collected from persons living in contact with carrier animals were seropositive for different Leptospira serogroups , and an earlier study by Tawfik  reported that 13% of the collected rodents’ sera were reactive for Leptospira. Moreover, surveillance of Leptospira in animals has been carried out in Mahalla, and the findings of this study suggested that wild and domestic mammals are important sources of leptospires in Mahalla city . Hatem and Samir  recorded a recent outbreak of leptospirosis in sheep as the first epidemic in northern Egypt up till now.
Therefore, the purposes of this study were estimating leptospiral infection prevalence among people living in Shabramant village at El-Giza Governorate and identifying associated environmental and behavioral risk factors for the infection.
| Patients and methods|| |
A random cross-sectional survey was carried out in Shabramant village in El-Giza Governorate, from June 2013 to May 2014. Shabramant population of about 60000, and is located about 20 km southwest of the Cairo capital city; this village was selected because it is located near streams of water, many villagers are engaged in work such as vegetable and fruit gardening, livestock farming, fishing and weaving. Houses are usually built high floored on high wooden or concrete poles, with floors and walls of wood or bamboo. Roofing is of thatch, leaves and recently of corrugated tinplate. Cattle and buffalo are reared both in sheds and free ranges around the village. Livestock, goats and chickens are also kept by many households, and they are usually reared free around the houses. We conducted our study on 100 participants based on history taking and laboratory investigations after obtaining written consent form from them. For all enrolled patients who agreed to participate, one individual face-to-face interview was carried out with each person included in the sample, using a structured questionnaire to collect information on that person’s potential risk factors for leptospiral infection, such as occupation, ownership of different kinds of animals, activities associated with water and livestock and the environmental conditions of the house and the village. After the interview, a blood sample was drawn after signing a consent form approved by the Ethics Committees of the National Research Centre. Frozen serum samples were sent to the laboratory of Animal Reproduction Researches Institute for serologic analysis of leptospiral antibodies.
All the studied cases were subjected to the following:
- Thorough history taking stressing on the presenting symptoms such as fever, abdominal pain and tenderness, jaundice, renal insufficiency, meningeal signs and severe pulmonary affection; history of exposure to risk factors including sewer workers, builders, farmers, any contact with rodents, especially rats, or contact with domestic animals and a history of other causes for fever and coinfections.
- Lab investigations, including complete blood picture, prothrombin time, liver function tests [alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum albumin and serum bilirubin; total and direct], renal function tests (urea nitrogen and serum creatinine) and viral markers [hepatitis C virus antibodies (HCV-Ab) and HBs-Ag].
- MAT which was performed in this study to determine the presence of leptospiral antibodies and their titers in the sera of investigated participants. It was carried out according to Faine et al. . Antigens were 4–7 days’ old live cultures of the five Leptospira serovars; Leptospira int. icterohaemorrhagiae, Leptospira int. canicola, Leptospira int. pomona, Leptospira int. grippotyphosa and Leptospira int. wolffi in Elinghausen and Mc cullough modified by Johnson and Harris (EMJH) medium at 30°C. Agglutination was examined by dark-field microscopy. The agglutination was considered positive if at least 50% of the screened leptospires were agglutinated, whereas negative results were considered as free motile leptospires with no clumps. Any reactions that were positive on the screening assay would have to be titrated. A reactive MAT was determined by titers up to 1 : 200 . The reported endpoint titers were calculated as the reciprocal of the highest serum dilutions that agglutinated at least 50% of the cells for each serovar used .
The data were processed and analyzed using the statistical package for social sciences program (SPSS; SPSS Inc., Chicago, Illinois, USA). Statistical tests used were description of quantitative variables in the form of mean±SD and description of qualitative variables by frequency and percentage. Student’s t-test of two independent samples was used to compare quantitative variables. The one-way analysis of variance test was used to compare more than two groups’ quantitative variables, χ2-test was used to compare qualitative variables and correlation coefficient test (r-test) was used to rank different variables against each other either directly or indirectly. Significance level (P) was greater than 0.05.
| Results|| |
[Table 1] shows the sociodemographic characteristics of the studied participants; the mean age of participants was in the late thirties; the majority of participants were women (57%). With regard to the occupation of the studied participants, most of them were farmers and housewives. [Table 2] represents ecological characteristics among the studied participants: 36% had nonconcrete ceiling in their houses, 37% were exposed to rodents, 29% showed the presence of barns and pens in their houses and 37% were in contact with nearby drains/canals. [Table 3] illustrates laboratory findings among the 100 studied participants in Shabramant village. [Table 4] displays the prevalence of leptospirosis among the studied participants, which was found to be 44%, and L. int. icterohemorrhagiaeis was the only serovar detected. [Table 5] shows that leptospirosis-positive cases occur in individuals in their late 30s (38.0±14.7) and female patients were predominant (52.6%); hence, age and sex can be regarded as risk factors for leptospirosis; with regard to occupation of the studied participants, most of the infected persons were farmers and housewives. Positive cases of leptospira Abs have a significant frequency associated with non concrete ceiling, exposure to rodents, presence of barns and nearby drain/canal ([Table 6]). [Table 7] shows that a positive medical history of acute febrile illness suggesting previous infections has low diagnostic characteristics in the diagnosis of leptospirosis cases. [Table 8] illustrates the impact of positive leptospirosis on laboratory abnormalities. On studying different risk factors among the studied samples in regression models, only exposure to rodents was the only significant factor for leptospiral infection ([Table 9]).
|Table 4 Serovar and titer of Leptospira in positive cases among the studied participants|
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|Table 5 Comparison between leptospirosis-positive and leptospirosis-negative cases regarding age, sex and occupation|
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|Table 6 Comparison between leptospiral antibody-positive and antibody-negative cases regarding ecological characteristics|
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|Table 7 The diagnostic characteristics of clinical symptoms suggesting previous infectionsa|
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|Table 9 Regression model for factors influencing infection with Leptospira|
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| Discussion|| |
Leptospirosis is an important zoonotic disease, caused by the pathogenic Leptospir a . Leptospirosis has been recognized as a re-emerging public health problem due to the amplified frequency in developing and developed countries .
Regarding the seroprevalence of Leptospira in our study, it was interesting that 44% of the studied patients were seropositive for Leptospira antibodies. To putting our results into a world wide prespective, the case of seroprevalence reported from high-hazard settings, for example, urban ghettos, tropical islands, and surge hazard ranges is about 40.9% in Thailand and 37% in Indonesia . Al-Robasi et al.  recorded a seroprevalence of Leptospira antibodies of 42% in Yemen. Recently, Samir et al.  reported that the seroprevalence of Leptospira antibodies was 49.7%.
Higher prevalences were demonstrated in studies conducted in Ethiopia (48%) , Tamil Nadu, India (58%) , Mazandaran Province, Iran (58%)  and Alto Mayo Valley in the Peruvian region of San Martín (64.6%) . However, lower prevalences were demonstrated by Kuriakose et al.  (29.6% in a midland rural area of Kerala State), Swai et al.  (15% in Tanga City, Tanzania) and Reis et al.  (15.4% in an urban slum in Brazil).
As regards to previous studies in Egypt, lower prevalences were recorded; Maronpot and Barsoum  reported a prevalence of Leptospira infection of 5.6% in 513 humans. In 2006, Naval Medical Research Unit-3 directed a study to define the percentage of Leptospira antibodies in fever hospitals in Egypt. Lower Egypt showed the highest percentage (24%) among patients with hepatitis . Also, Barakat et al.  reported the prevalence of infection to be ∼25.9% among the investigated hepatitis cases in Egypt.
Regarding the predominant serovar observed in the present study, L. icterohaemorrhagiae was the only Leptospira serovar observed and 27.3% of the studied leptospirosis cases had a titer of 1 : 400 and more (1 : 800 and 1 : 1600), suggestive of probable recent leptospirosis, and further emphasizes the potential public health relevance of serogroup L. icterohaemorrhagiae .
In Egypt, Ismail et al.  reported that L. icterohemorrhagiae was the major serotype present among the studied patients with acute febrile illness. Also, several investigators recorded that L. icterohemorrhagiae was the most prevalent infecting serovar: Juarez et al.  in Salvador, Brazil and Picardeau  in mainland, France and French Atlantic and Pacific territories. Moreover, Alarcón-Villaverde et al.  found that the most frequent serovars were L. icterohaemorrhagiae, Leptospira autumnalis, Leptospira australis, Leptospira Panama and L. Grippotyphosa, in Alto Mayo Valley in the Peruvian region of San Martín, Peru.
However, the finding of the present study is in contrast to several researches; Jansen et al.  in Germany, reported that serovar L. Grippotyphosa represented the most common infecting serovar; Swapna et al.  confirmed serovar Betaviae and Djasiman as major serovars in North Kerala; Padma and Mohammed  who found in his study in Kelantan that the most common pathogenic serovar recognized was Betaviae (12.3%). Furthermore, Poeppl et al.  stated that the patients’ sera reacted most commonly with serovars Canicola (16.5%) and Hardjo (11.8%); Khalili et al. , in Southeast Iran, registered a positive titer against only L. Grippotyphosa and Samsudin et al.  found that the most common serovar was Sarawak (37.0%) in Selangor.
In the present study, the demographic factors (age, sex and occupation) could be considered as potential risk factors of leptospiral infection; higher prevalence was noted in age group of late 30s. This finding is similar to results of studies conducted by Yanagihara et al.  who revealed that most of the leptospirosis cases occurred between the ages of 20 and 50 years.
In contrast, Anna and Tzimoula  recorded that most of the leptospirosis cases occurred between the ages of 50 and 69 years and Kanimozhi et al.  suggested that people in the senior age group (more than 60 years) are more susceptible to this disease, probably due to the lower immunity factor.
In this concurrent work, our findings showed a significant association between female sex and the seroprevalence of leptospiral antibodies and seropositivity among the studied participants, as 52.6% of women and 32.6% of men were seropositive for leptospiral antibodies (P=0.045). This is in agreement with the findings of Swapna et al. , Padma and Mohammed  and Kanimozhi et al. .
Our result concerning the sex contradicts that of other researches, which concluded that men are more often infected with Leptospira than women (Esmaeili et al. , Al-Robasi et al.  and Sakinah et al. ). Furthermore, Vimala et al.  found that the male-to-female ratio was 1 : 1, and concluded that leptospirosis is prevalent in men as well as women, and both are equally affected because of the fact that nowadays both of them are more exposed to the contaminated environment.
In the present work, people in occupations dealing with animals or its products (farmers) are more exposed to Leptospira, and there was a statistically significant association among positive cases (P<0.001). This is in agreement with findings of Alavi and Khoshkho , who found that greater than 33% of rice agriculturists in the area were seropositive for leptospirosis. Lau et al.  in their study in Fiji reported that working outdoors was associated with a higher risk of leptospiral infection, and the majority of outdoor work involves farming, as farmers are known to be at a high risk for leptospirosis in many parts of the world because of close contact with cattle and exposure to urine during milking and feeding, concluding that occupational exposure in the agricultural industry is likely to be an important source of leptospiral infection.
In contrast, our study is inconsistent with a study conducted by Swapna et al.  in Calicut, India, which reported that the highest seroprevalence was in hospital sanitary workers (46%), construction workers (28%) and sewage workers (26%). Furthermore, Alvarado-Esquivel et al.  found that the seroprevalence of Leptospira was significantly higher in meat workers than in others. The seroprevalence found in meat workers (17.7%) is also higher than the 4.4% seroprevalence found in waste pickers in the same city of Durango, Mexico .
Concerning other risk factors in the studied sample in regression models, we found that having nonconcrete ceiling, presence of barns or pens and nearby drain/canal are considered as risk factors and exposure to rodents is considered to be significant one (P<0.001).
A systematic review by Mwachui et al.  from a selection of 2723 unique publications containing information on leptospirosis identified 428 papers dealing with risk factors and 25 studies evaluating exposure to rodents. A majority of the studies were conducted in South America (10 studies) and on islands (eight studies), and concluded that rodents play a major role in the transmission of leptospirosis. Lau et al. stated that variables linked with the presence of Leptospira antibodies involved living in villages, working outdoors, living in rural areas, living less than 100 m from a major river and high cattle density in the district.
In contrast to this result, Hajikolaei et al.  conducted a study on the seroprevalence of leptospirosis in Iran and reported that rats have a lower chance of being exposed to leptospires.
Also, in our study, nonuse of personal protective equipments (PPE) and lack of previous knowledge of leptospirosis collectively were found to be risk factors for acquiring infection. Prabhu et al.  reported the use of PPE while the workers are at work: only 21 (19.8%) wore mask and mask-like clothes and 12 (11.3%) wore rubber gloves while working. Also, Sakinah et al.  reported that the prevalence of leptospiral antibodies was higher (41.2%) among respondents who did not use any protective equipment. However, Awosanya et al.  found that wearing of hand gloves or protective clothing and boots was not found to be protective against leptospirosis. Moreover, Sakinah et al.  reported that the number of respondents with poor knowledge about leptospirosis was higher than the number of respondents who had good knowledge in their study. However, De Araújo et al.  revealed that of the 257 people interviewed, 232 (90.3%) had previously heard about leptospirosis. Furthermore, Samarakoon and Gunawardena  conducted a descriptive study among 460 school students in Sri Lanka, among whom the awareness of leptospirosis was 100%.
The present study concerning laboratory findings of the studied participants showed that anemia was present in 27.3%, leukopenia in 20.5%, thrombocytopenia in 6.8%, high ALT in 22.7%, high AST in 31.8%, high total Bilirubin in 20.5% and high prothrombin time in 18.2% of Leptospira-seropositive cases, and no significant differences between leptospirosis-positive and leptospirosis-negative cases regarding laboratory abnormalities were recorded.
Greene et al.  stated that hepatic involvement in leptospirosis can vary from mild liver enzyme elevations with or without hyperbilirubinemia to severe liver failure with signs of hepatic encephalopathy. Kar et al.  reported that low platelet numbers (73.3%), high bilirubin (80%) and high AST and ALT (62 and 66%) were observed in leptospirosis-positive cases. Also Das et al.  showed that hemoglobin less than 10 g/dl was present in 26.3%, leukocytosis greater than 12 000/mm3 was present in 68.4% and elevated levels of both serum creatinine and ALT/AST were present in 34.2% of the cases. However, Dutta and Christopher  stated that most of the routine laboratory tests showed nonspecific findings.
In the present study, 24% of patients were HCV-Ab positive with insignificant differences between the positive and the negative Leptospira Ab groups. This is obviously higher than that found in the previous Egypt Health Issues Survey. Egypt Health Issues Survey-2015 was conducted on behalf of the Ministry of Health and Population by El-Zanaty and Associates, and ICF International  and reported that 10% of Egyptians aged 15–59 years were positive for HCV antibody testing, whereas only 7% were positive for HCV RNA. Also, Angnani et al.  reported serological evidence of both leptospirosis and hepatitis in 39.4% of their patients. Furthermore, Das et al.  demonstrated that 5.2% of their cases of leptospirosis were coinfected with HCV.
| Conclusion|| |
It can be concluded that leptospirosis is an important neglected zoonotic disease despite its high prevalence.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9]