|Year : 2020 | Volume
| Issue : 2 | Page : 107-112
Seroprevalence and factors associated with risk of human brucellosis among febrile patients attending health-care facilities in Bauchi, North-Eastern Nigeria
Hafiz Halilu1, Fatima J Giwa2, Saad A Ahmed3, Mu'awiyyah B Sufiyan4, Amina I Mohammed5
1 Nigeria Field Epidemiology and Laboratory Training Program, Abuja, Nigeria
2 Department of Medical Microbiology, Ahmadu Bello University, Zaria, Nigeria
3 Department of Pathology, Ahmadu Bello University, Zaria, Nigeria
4 Department of Community Medicine, Ahmadu Bello University, Zaria, Nigeria
5 Department of Medical Microbiology, Aminu Kano Teaching Hospital, Kano, Nigeria
|Date of Submission||30-Jun-2020|
|Date of Decision||09-Jul-2020|
|Date of Acceptance||09-Sep-2020|
|Date of Web Publication||31-Dec-2020|
Mr. Hafiz Halilu
Nigeria Field Epidemiology and Laboratory Training Program, Abuja
Source of Support: None, Conflict of Interest: None
Background: Brucellosis is a neglected underdiagnosed zoonotic disease of worldwide distribution with varying symptoms similar to those occurring in other febrile illnesses. A recent screening survey conducted among butchers in Bauchi state reported a high prevalence
of human brucellosis; however, its burden among patients with other febrile illnesses is unknown. We determine the seroprevalence and factors associated with risk of brucellosis among febrile patients attending health-care facilities (HCFs) in Bauchi metropolis, North-Eastern Nigeria. Methodology: We conducted a hospital-based descriptive cross-sectional study of 382 participants using a multistage sampling technique. Brucella antibodies were detected using Rose Bengal plate test, and a questionnaire was used to identify risk factors associated with human brucellosis. Data analyses were conducted using Epi Info version 7.0. Bivariate and multivariate analyses were conducted at
P = 0.05. Results: Fifty-seven (14.9%) of the 382 febrile patients tested had Brucella antibodies. Males: female ratio was 1.1:1, and the mean age was 29.9 (standard deviation ± 12.03). Age, sex, occupational status, keeping animals, having ever milked an animal, handling animals
during birth, and consuming unpasteurized milk or meat were found to be significantly associated with brucellosis on bivariate analysis. Conclusions: Up to 14.9% of the febrile patients attending HCFs in Bauchi metropolis had Brucella antibodies. Age, occupational status, consuming unpasteurized milk or meat, handling animals during birth, and lack of awareness on zoonosis remained independent predictors for brucellosis. Therefore, conducting routine serological screening tests for Brucella antibodies in all febrile patients presenting to HCFs will assist in its diagnosis and proper management.
Keywords: Brucellosis, febrile patients, North-Eastern Nigeria, prevalence, risk factors
|How to cite this article:|
Halilu H, Giwa FJ, Ahmed SA, Sufiyan MB, Mohammed AI. Seroprevalence and factors associated with risk of human brucellosis among febrile patients attending health-care facilities in Bauchi, North-Eastern Nigeria. Ann Trop Pathol 2020;11:107-12
|How to cite this URL:|
Halilu H, Giwa FJ, Ahmed SA, Sufiyan MB, Mohammed AI. Seroprevalence and factors associated with risk of human brucellosis among febrile patients attending health-care facilities in Bauchi, North-Eastern Nigeria. Ann Trop Pathol [serial online] 2020 [cited 2021 Apr 21];11:107-12. Available from: https://www.atpjournal.org/text.asp?2020/11/2/107/305695
| Introduction|| |
Brucellosis is a neglected, underdiagnosed zoonotic disease of worldwide distribution. It can cause severe illness in humans and substantial economic losses in livestock production. The disease can be chronic and is capable of affecting any organ or system. Brucella can be transmitted to humans in several ways including the consumption of unpasteurized dairy products, inhalation of the microorganisms as well as transmission through the skin. The disease remained the world's most common bacterial zoonosis for decades. In the year 2015, it was enlisted as the second zoonotic infection of public health concern, with over half a million new cases reported annually.
Brucellosis is predominantly an occupational disease of those working with infected animals or their tissues but can also infect consumers of unpasteurized dairy products and hunters who unknowingly handle infected animals. A study of brucellosis in low- and middle-income countries revealed that ingestion of unpasteurized dairy products and exposure through direct contact with infected animal fluids or tissues, especially the placenta from aborted animals, were the main risk factors for transmission of the infection. The consumption of local delicacies such as milk products (e.g., cheese and yoghurt) and locally roasted meat/barbecue was found to have a positive relationship with contracting recent Brucella infection and increasing the risk of having miscarriage threefold, respectively.
Prevalence rates in some countries are exceeding 10 cases per 100,000 population. The disease is largely occupational, and the majority of the cases are males between the ages of 20 and 45 years. Brucellosis is prevalent in many regions of the world, including Latin America, the Middle East, the Mediterranean Basin, Africa, and Asia. In Northern and sub-Saharan African countries, brucellosis prevalence varies within countries, and the incidence ranges from 0.28 to 71/100,000 populations. In Nigeria, the prevalence of human brucellosis reported by different researchers ranges from 7.6% to 55%, mostly focused on occupationally exposed groups with varying reported results.,
Brucellosis poses considerable challenges for clinicians in both human and animal health. Clinical signs and symptoms of human brucellosis are nonspecific and highly variable, and these symptoms also occur with common nonzoonotic diseases, such as malaria and typhoid fever, which are likely to be considered more readily by clinicians. There is an increasing report of febrile illnesses across Nigeria and other sub-Saharan African countries, which are not malaria or typhoid fever.,,
A previous study showed that bovine brucellosis is prevalent among cattle slaughtered in Bauchi state. A recent report also revealed a high prevalence of human brucellosis among herders and butchers in the state. It is important, therefore, to determine whether these cases of febrile illnesses are brucellosis or otherwise for proper patient management. We sought to determine the burden of human brucellosis among febrile patients in Bauchi metropolis and its associated risk factors which will help in the proper management of patients with febrile illnesses.
| Methodology|| |
Bauchi state is located in North-Eastern Nigeria. The predominant economic occupation in Bauchi state, especially in rural communities, is agriculture (including livestock keeping) which provides direct and indirect jobs to thousands of people. Bauchi state has a high population of livestock including its domestication and a high rate of consumption of raw/unprocessed milk, which are risk factors for brucellosis.
This was a hospital-based descriptive cross-sectional study.
Febrile patients aged 16 years and above presenting to selected health-care facilities (HCFs) and private clinics were enrolled.
Inclusion and exclusion criteria
Febrile patients aged 16 years and above presenting to public tertiary, secondary, primary, or private health facilities (HFs) with temperature of 38°C or more were included. The study excluded patients with known underlying chronic illnesses (cancer, HIV, and tuberculosis patients) and those on admission (inpatients).
Sample size determination
The sample size was determined using the Leslie Kish formula for cross-sectional studies, where a sample size of 335 was obtained using a prevalence of 32.5% from a previous study. After correction for a 20% nonresponse rate, the sample size became 400. A total of 400 patients were recruited for this study, however, only 387 participants consented giving a 96.8% response rate. Furthermore, 387 blood samples were collected, of which only 382 were found to be acceptable for testing.
A multistage sampling technique was used to select the study participants. There are 11 political wards in Bauchi metropolis and 11 public and 20 private HFs.
Stage 1: Selection of ward
A simple random sampling technique by balloting was used to select five wards from the 11 wards that made up the metropolis. The following wards were selected: Dan-Iya, Hardo, Dan-Amar A, Makama B, and Dan-Dango.
Stage 2: Selection of health facilities from the selected wards
HFs from the selected wards were stratified into public and private facilities before the selection was carried out. They were then selected by equal allocation to public and private facilities; one public and one private health facilities were selected from each selected ward using simple random sampling by balloting, making a total of two facilities from every ward and a total of ten facilities from all the five wards.
Stage 3: Selection of the respondents from the selected health facilities
Based on the patient's flow/attendance in the HFs, the average number of patients with fever seen in the outpatients' departments per facility per day was obtained which ranges from 15 to 30/day, Abubakar Tafawa Balewa University Teaching Hospital (ATBUTH) 30, Specialist Hospital Bauchi 30, Infectious Diseases Hospital Bayara 22, Tashar-Babaye Primary Health Care Centre 24, Yalwa Primary Health Care Centre 15, Ni'ima Clinic 30, Remee Clinic 22, Durum PHCC 22, Al-Manzoor Clinic 22, and Kainuwa Clinic 24. A total of average fever cases seen per day in all the 10 HFs were 241. The sample size was divided between the facilities based on proportionate allocation. Using systematic sampling, every fifth patient was selected from each HF everyday (depending on the average number of the febrile patients seen daily in that facility) among patients presenting with fever till the required sample size was reached. For ATBUTH 50, Specialist Hospital Bauchi 50, Infectious Diseases Hospital Bayara 36, Tashar-Babaye Primary Health Care Centre 40, Yalwa Primary Health Care Centre 25, Ni'ima Clinic 50, Remee Clinic 36, Durum PHCC 36 Al-Manzoor Clinic 36, and Kainuwa Clinic 40.
A pretested, interviewer-administered structured questionnaire with five sections was used to collect data on sociodemographics of the participants (sex, ethnicity, age, residential local government area, and occupational status). Risk factors for brucellosis and other zoonoses were also assessed from the questionnaire.
The samples were collected by trained medical laboratory technicians who were recruited as research assistants. Sterile vacutainers were used to collect 3 ml of blood from each patient aseptically. The skin was cleaned in concentric circles of increasing diameter with 70% ethanol and left to dry.
Three milliliters of blood was drawn from the vein and dispensed in a plain bottle. This was labeled using a unique patient identifier (ID), location, and the date of sample collection and then transported in iceboxes at 4°C to ATBUTH, after which it was spun at 1500 rpm for about 5 min, and the serum was extracted into cryovials and stored at −20°C.
Rose Bengal plate test
The Rose Bengal plate test (IDvet, 310, Rue Louis Pasteur, Grabels, France) was used to detect Brucella antibodies. This antigen is a bacterial suspension of Brucella stained with Rose Bengal and buffered at pH 3.6 and contains 0.95 g/L of sodium azide. The reagent was obtained from the Veterinary Public Health Laboratory at Ahmadu Bello University Zaria, and the test was conducted according to the manufacturer's instructions. All tests were run using positive and negative controls.
Epi Info version 7 Developed by Centers for Disease Control and Prevention (CDC) and MS Excel 2007 were used for data analysis. Data were presented as frequencies, proportions, and summary measures of statistics in tables. The variables analyzed include sociodemographic characteristics, risk factors, and serology result for brucellosis. Bivariate and multivariate analysis (using logistic regression) was carried out. The confidence level was set at 95%, and P < 0.05 was considered statistically significant.
Ethical clearance with protocol approval number NRECC/12/05/2013/2018/57 was obtained from the Bauchi State Ministry of Health Operational Research Advisory Committee and ATBUTH Bauchi Ethical Committee with assigned number 0054/2018. Informed and written consent was obtained from the participants before enrollment. Collected data were kept confidential; study ID numbers were used for patient identification to ensure utmost confidentiality.
| Results|| |
A total of 400 patients were recruited for this study with a 96.8% response rate; 387 blood samples were collected, of which 382 were found acceptable for testing. The age and sex distribution of the participants is shown in [Table 1]. Two hundred participants (52.4%) were recruited from government-owned HCFs [Figure 1]. The prevalence of brucellosis was 14.9% among febrile patients attending outpatients' departments from the ten selected HFs in Bauchi metropolis (n = 382). Among males, the prevalence was 19.3% (n = 197), while it was 10.3% in females (n = 185). The study found a prevalence of 26.2% among participants that were aged 35 years and above (n = 130). The prevalence of brucellosis was 20.2% among participants with no awareness on zoonoses. A prevalence of 34.7% was also observed (n = 72) in participants who consumed raw or unpasteurized milk or meat and a prevalence of 62.5% among participants who handled animals during birth (n = 32). A prevalence of 42.9% was also observed among study participants who had ever milked animals (n = 56). The seropositivity of brucellosis was found to be 23.4% (n = 201) among patients who reported to have kept animals (either at home farm or both) [Table 2].
|Table 1: Sociodemographic characteristics of the study participants (n =382)|
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|Table 2: Risk factors for brucellosis among febrile patients attending health-care facilities in Bauchi metropolis between March and June 2019 (n =382)|
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|Figure 1: Distribution of study participants selected from different health facilities and their result status|
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After multivariate analysis using multiple logistic regression, age (being 35 years or younger), low educational level, involving in a high-risk occupation, consuming raw/unpasteurized milk or meat, handling animals during birth, and lack of awareness on zoonoses remained independent predictors for brucellosis among study participants. However, sex, keeping animals, and having ever milked an animal were not statistically significant predictors for brucellosis [Table 2].
| Discussion|| |
In this study, the seroprevalence of human brucellosis among febrile patients attending different HCFs in Bauchi metropolis was about 50%. This could be due to previous exposure or current infection. This is lower than reports seen from a similar work which was done in Gombe, Gombe State, North-Eastern Nigeria, which reported 32.5%. Similarly, Ogbodo and Isiofia reported a prevalence of 26.8% among patients tested for malaria in a private medical laboratory in Enugu, south-eastern region of Nigeria. This prevalence for brucellosis in a city not known for pastoral activities is quite high and could be attributed to the serological method used which is known to give false-positive results. The findings of this study were, however, higher than that of another study conducted in Borno State, North-Eastern Nigeria, by Baba et al. among patients with pyrexia of unknown origin (PUO) who reported a prevalence of 5.2%. This could be attributed to the fact that Borno State though in the same region is less agrarian due to its unique climatic and weather condition compared to Bauchi state. This indicates that geographical location and other factors like pastoral activities may also influence prevalence. Similarly, Pathak et al. reported a prevalence of 4.25% among people with PUO in the Goa region of India. Our study findings were consistent with that obtained in a hospital-based study done in Uganda which reported a prevalence of 13.3% and 17%., Another study by Zein and Sabahelkhier in Northern Sudan among high-risk groups also found a prevalence of 15.3%. The prevalence found in this study was, however, lower than the reported prevalence of 40.0% in a study conducted in Libya. The low prevalence of brucellosis found in this study could be attributed to the area of the study which is urban, and brucellosis being a zoonotic disease could be more common in rural areas where keeping animals is one of the common practices among rural dwellers, where methods of rearing animals, hygiene measures, and limited awareness of communities on zoonotic diseases could be more prominent.
We found that a higher prevalence of human brucellosis was influenced by the presence of brucellosis in domestic animals; we demonstrated a higher seroprevalence among patients who kept animals and were five times more likely to develop brucellosis (P < 0.001) compared to those who did not which is supported by findings in the Middle East in 2002 by Refai.
In this study, males were two times more likely to develop brucellosis compared to females (P = 0.001). This is in concordance with studies conducted in Egypt, Kuwait, Saudi Arabia, and India,,, in which males had a higher rate of infection than females, but contrary to findings in South Sudan by Madut et al. , who reported that males and females had a similar prevalence of brucellosis. This could be due to the fact that in Muslim communities of Northern Nigeria, females are less involved in agricultural and pastoral activities, but in Southern Sudan communities, females have equal opportunities of handling animals, which potentially exposes them to the same level of risk of acquiring brucellosis as their male counterparts.
The prevalence of brucellosis was higher among patients aged 35 years and above, a finding which corresponds to that of a recent study also by Madut et al . in Southern Sudan and that of Kudi et al. , which found a high prevalence within the age group of 31–40 years. Individuals within this age group play a major role in rearing animals in addition to performing other tasks such as milking cows and slaughtering of cattle. This could expose such individuals to the risk of acquiring brucellosis, which may be responsible for the high prevalence of the disease among this age group.
The prevalence of brucellosis was also found to be higher among occupationally high-risk groups such as veterinarians, herders, butchers, abattoir workers, and laboratory workers. Using bivariate analysis, these groups were six times more likely to develop brucellosis compared to those in low-risk occupational groups. This could be attributed to their interaction with animals as a result of their occupation which is also in agreement with findings by Aworh et al . in Abuja, Nigeria, Zein and Sabahekheier in Northern State of Sudan, and Tumwine et al . in Uganda.,, The independent predictors for brucellosis using multiple regression analysis were age (35 years or more), low educational level, occupation, consuming raw/unpasteurized milk or meat, handling animals during birth, and lack of awareness on zoonoses.
This could be attributed to direct contact with infected animals or consumption of infected products, which is consistent with the findings of a study by Refai et al. which showed that the consumption of unpasteurized dairy products and delivery methods of animals enhanced the spread of the disease. In addition, a study by Omer et al. showed that the consumption of raw meat increased the risk of getting infected. Our findings showed that educational level was not an important risk factor which is in concordance with a case–control study conducted by Sofian et al. in Iran. It is, however, in contrast with the studies by Njeru et al. among febrile patients seeking treatment in remote hospitals in North-Eastern Kenya and Arif et al. in Pakistan which shows that low level of education is a significant risk factor for human brucellosis., This study shows that lack of awareness on zoonosis in general and brucellosis in particular is an important risk factor for human brucellosis as documented by Arif et al. in five districts of Punjab and two districts of Sindh of Pakistan and Mufinda et al. in Namibe Province of Angola.
| Conclusions|| |
Brucella antibodies from febrile patients attending various health-care facilities in Bauchi metropolis were found to be high (about 15%). Risk factors associated with developing brucellosis were keeping animals and involving in occupations related to handling of animals or their raw products. The major independent predictors for brucellosis in Bauchi metropolis were consumption of infected animal products and animal handling during parturition.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]