Essam Mohammed Alastot, Hassan A. Al-Shamahy

Medical Microbiology and Clinical Immunology, Faculty of Medicine and Health Sciences, Sana’a University, Yemen



Zoonotic infections can be work-related risks to people who labor in nearby connection with animals. The goals of present study were to find out the prevalence of leptospira antibodies and impact factors of leptospirosis among this risk groups in Sana'a city.  A 267 serum samples were assembled from the study groups and a written record was completed for all workers to record individual and behavioral information. The sera were tested for leptospirosis IgG antibodies by commercial ELISA technique. The acquired data illustrated that 100% of individuals did not employ at all personal protective equipments (masks, gloves, overalls and boots) and 100% of participants had absolutely not used disinfectants to their blades and hands, while 10% be aware of they were at risk of zoonotic infections like leptospirosis only. The seroprevalence of leptospirosis was 41.3%.  There was highly significant associated between positive of IgG antibodies and older age (median>27 years) (OR= 3 times, PV<0.001), work history median > 8 years (OR=2.8 times, PV<0.001) and history of >5 times cut in the last year (OR=3.7, PV<0.001). In conclusion: the present of leptospira IgG antibodies among slaughter-house workers and butchers in Sana'a city is relatively common, similar to that reported previously from Yemen, and from neighboring countries among risk groups. Encouraging universities in Yemen to undertake active disease surveillance because these efforts will eventually allow policy makers and other authorities to convert knowledge into policy by set appropriate evidence foundation priorities in the field of Leptospirosis disease control and prevention.

Keywords: Butchers, leptospirosis, Sana'a city-Yemen, Seroprevalence, slaughter house workers.


Numerous zoonotic diseases are occupational risks be opposite by persons who approach into close contact with animals and their carcasses. The possibility of get in touch with animal pathogens whilst working depends on a variety of aspects, for instance the health of the animals, the kind of job executed the incidence of make contact with animals, and/or their tissues and carcasses, the employ of personal and environmental protective measures, and the manners and levels of awareness of the people at risk1. Slaughterhouse workers and butchers are on elevated risk of contracting zoonosis. In Yemen, previous studies have recognized zoonosis similar to leptospirosis and brucellosis, such as potential occupational hazards for slaughterhouse workers2,3. Leptospirosis is a widespread  infections that  involves both humans and animals1.  Leptospira spp., can be spreading to humans throughout broken skin or mucous membranes by making contact with tissues, body fluids, and organs of infected animals, or by ingestion of food or water contaminated by the urine of infected animals4.  In humans, leptospirosis cause a wide variety of signs including fever, jaundice meningo-encephalitis,  kidney failure myocarditis, myalgia, conjunctivitis, meningitis, and pulmonary haemorrhage with respiratory failure, which occasionally outcomes in fatality5.  Leptospirosis is an occupational hazard with farmers, butchers and slaughterhouse workers4.  Since butchers and slaughterhouse workers are in contact with animals; and their body fluids and tissues, they are at great hazard of contracting zoonosis6.  Trade in considerable numbers of livestock from neighboring countries to Yemen, and reports of leptospirosis, Q fever and brucellosis eruption in neighboring countries3,7 encouraged us to assess the prevalence of leptospirosis and risk factors in slaughterhouse workers  and butchers in Sana'a city, Yemen.


This cross sectional study was completed in the Faculty of Medicine and Health Sciences in the Medical Microbiology Department at the Sana'a University, during the period from July 2017 to September 2017 on 267 butchers and slaughterhouse workers in Sana'a City-Yemen. The blood specimens were collected from slaughterhouse workers and butchers subsequent get their consent, 2 ml of whole blood were collected by venipuncture in a disposable syringe and transferred immediately to plane tube, sera were separated from this tube by centrifugation following clotting of blood, and sera were reserved at -200C. Sera of participants were examined to the present of Leptospirosis antibody (IgG) by a commercial ELISA technique (Serion/Verion Co, Germany).

Data collection   

 Data were collected by predesigned questionnaire. Data including demographic data of the patients, clinical information, potential risk factors of leptospirosis and laboratory results.

Ethical approval

We obtained written consent from all cases. Assent was taken from participants before collecting the specimens. The study proposal was evaluated and approved by the Ethics Committee of Faculty of Medicine and Health Sciences, Sana’a University.


In the present study, 267 blood specimens were taken from butchers and slaughterhouse workers live in Sana'a city, Yemen. The median age (range) and work duration time of contributors in this study were 27 years (14 years to 66 years) and 8 years (2 years to 41 years), in that order. All workers were males.  All 267 (100%) workers were directly involved in carrying and handling of animal remains; animal slaughtering and examining the carcasses. All workers were in direct contact with cattle (including calves), goats and sheep throughout their daily activities. Besides 80% of the individuals described a history of splashing with animal body fluids and viscera several times into worker's face and 95.5% onto other parts of their bodies. Additionally 71.2% of our study subjects had an incidence of  hand cut or other parts cut at least 5 times during their work within the last year. As well, 100% of workers did not use any personal protective equipments as overalls,  masks, gloves, and boots). What's more, 100% of workers had never applied disinfectants to their hands and knives, whilst 10% knew they were at risk of zoonosis as leptospirosis.  41.3% of workers had positive titer of anti-Leptospira IgG. Considering the risk factors, there were associations between the older age of the workers and the prevalence of leptospirosis in which median age >27 years shows a highly significant odd ratio (OR=3, 95%CI=1.7-5.2, PV<0.001). Also, there was a significant correlation between seroprevalence of leptospirosis and work history >8 years ratio (OR=2.8, 95%CI=1.6-4.8, PV<0.001). A marginally significant correlation between positive leptospirosis and splashing of animal secretions into body (OR: 3.6, 95% CI: 0.7-35, pv=0.07). There was a significant association between leptospirosis and history of >5 times cut in the last year (OR=3.7, 95%, CI=2 -6.9, PV<0.001).


Leptospirosis is important unnoticed zoonosis worldwide, with a complicated epidemiology. The disease have an effect on domestic and wild mammals; and human. Due to the range of clinical symptoms and obscurity of developing diagnostic confirmatory laboratory methods, leptospirosis continues inadequately explore, especially in country like Yemen in which facilities and resources for laboratory diagnosis is not available. Leptospirosis is considered an occupational disease of people employ in agriculture, animal slaughtering, forestry and sewage works4. In addition in recent years, leptospirosis is recognized as public health problem worldwide due to increased in mortality and morbidity of it in various countries7. For this reason we investigated leptospirosis in one of these risk groups. To our knowledge, the present study is one of  the first study assess the Leptospira antibodies in butchers and slaughter house workers in Sana'a city and second study to assess the prevalence of Leptospira antibodies in popula­tions at risk in Yemen after Al-Robasi et al. in (2015) whom done it among populations at risk in Hodeida Governorate, Yemen3. The total seroprevalence of leptospirosis according to positive Leptospira IgG antibod­ies (cut off > 30 IU/ml) in our study group was 41.3%.  This result is similar to previously seroprevalence studies reported in Yemen Hodeida in which the rate was 42%3. Also similar findings were demonstrated in studies conduct­ed in Thailand: 12.7- 40% 8, in Indonesia: 37%9.  Ethiopia: 48%10, in India: 58%11, and in Iran: 58%12. Nevertheless, dissimilar findings were found among popula­tion at risk in Colombia as 19% 13, in Tanzania: 15%14.

 Leptospirosis infection affects both adults and children everywhere7,15,16.  When age of our slaughter house works and butchers was considered, the maximum rate of Leptospira IgG antibodies was found among older age group (median age >27 years) (50.9%) with associated OR equal to 3 (pv<0.001). This result is similar to findings in previous studies in Yemen among risk groups in Hodeida3 which reported that higher prevalence of leptospirosis were in the 4th and 5th decades. Also the present results were similar with the results from the other parts of the world, in Iran, they confirmed that the highest seropositivity were present in aged range from  40-50 years 15  , but different from that  in Chile, in which they show that the maximum rate of leptospirosis  depend  on antibodies result was in younger age (21-40 years)16,  and in India the majority were obtained in the 35-44 years old7.  These results can be explained with that the increasing of prevalence rate with increasing age could indicate an accumulation risk of infection over time. The long duration of occupational exposure is more favorable for the transmission of Leptospira spp. than shorter duration. There was significant rise of the rate of Leptospira antibodies in longer occupational duration (work history median >8 years (table 2).  Separate surveys were done among butchers and workers of slaughterhouse in Iran17,18,19, Brazil20, Mexico21 and New Zealand22 found the same results. These results can be explained by the longer exposure to occupational risks.

The reasonably significant high seropositivity rate in our study is fascinating, because there is not human leptospirosis case has been recorded from Sana'a city and not any of the Leptospira IgG antibodies positive workers in our study had clinical signs and symptoms of leptospirosis. On the other hand, clinical human cases of leptospirosis  have been reported from Oman and Saudi Arabia  which share borders with Yemen7.


Separately from occupational factors, other factors as admittance to supplies of safe water and crucial hygiene can be part of the cause to infection risks. The risk of leptospirosis to slaughterhouse workers and butchers possibly will be determined more accurately by integrated the general population samples as a control group, which unluckily was impossible at the time of the study. An additional, disadvantage of the present study was absent of golden standard tests for approval of leptospirosis diagnosis. The present survey gives important data on the health situation of slaughterhouse workers and butchers in Sana'a city, Yemen, this is can be helpful for health policy makers in planning. Furthermore our universities should be coordinate with the Leptospirosis Burden Epidemiology Reference Group (LERG) in WHO to clear the situation of leptospirosis in Yemen.


Authors acknowledge the financial support of Sana'a University, Yemen.


"No conflict of interest associated with this work”.


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Table 1: The frequency of  Leptospira antibodies level by IU/ml among slaughter-house workers and butchers in Sana'a city, 2017.




  No            %



>30 U/ml



Definite  Leptospira infections

Less than  30 U/ml



Definite rejection for Leptospira infections





Table 2: Analysis of risk factors associated with the seroprevalence (>30 IU/ml) of Leptospira IgG antibodies among butchers and slaughter-house workers in Sana'a city, Yemen, 2017.





Leptospira IgG antibodies >30 IU/ml n=110

No            %


95% CI



Age (median=27 years)

≤27 years n=102







>27 years n=165







Work history (median=8 years)

≤ 8 years n=102







>8 years n=165







Splashing of animal secretions


No n=52







Yes n=215








No n=12







Yes n=255







Occupational injury (cutting hand or other organs)

≤ 5 times n=77







>5 times n=190







OR-Odds ratio = Relative risk

95%CI-95% Confidence intervals

χ 2- Chi-square = 3.9  or more is significant

pv- Probability value = 0.05 or less  is significant