Seroprevalence of Brucellosis among Patients Attending a District Hospital in Rwanda

Serological and bacterial prevalence of Brucella spp. in suspected patients: a risk factor analysis in North Khorasan, Iran

Background and Objectives

Brucellosis, a zoonotic bacterial disease caused by Brucella, affects humans and domestic animals, leading to significant economic loss. This study examined suspected cases in North Khorasan, Iran, to understand the prevalence of infection and its characteristics in this region.

Materials and Methods

Blood specimens were collected from 200 patients suspected of brucellosis after obtaining informed consent. Serum samples were tested using RBPT, Wright, and 2-ME agglutination tests. Blood samples were cultured on Brucella agar, and positive cultures underwent biotyping and PCR assays. A questionnaire identified correlated risk factors.

Results

RBPT, Wright, and 2-ME tests showed 25% brucellosis seroprevalence in symptomatic patients. In contrast, the prevalence was 2.5% among those with positive blood cultures. Notably, all culture-positive patients were also serologically positive, with titers exceeding 1:320 in Wright and 2-ME tests. Most positive cases were in people in their 30s, with B. melitensis biovar 1 identified as the causative agent, and the results were confirmed by multiplex PCR. Significant risk factors include contact with livestock and consumption of raw milk (P < 0.0001).

Conclusion

The findings highlighted the importance of comprehensive diagnostic approaches for accurate identification of brucellosis. Furthermore, education regarding close contact with animals and pasteurization of dairy products is essential for controlling human brucellosis.

Human Brucellosis: An Observational Study From a Tertiary Care Centre in North India

AIM

The main aim/objective of this study was to detect and characterize the Brucella species from patients having complaints of joint pain and also to know the potential causes of human brucellosis. In our study, we focused on joint pain symptoms that may be due to arthralgia or arthritis.  Introduction: Brucellosis is a neglected zoonotic disease that affects both humans and animals. In humans, brucellosis begins with chronic illness leading to great financial losses from not being able to work well and continued treatment costs, but few such studies have come from northern India. Joint pain is the common presentation of brucellosis and there are several risk factors associated with brucellosis.

METHODS

A total of 200 blood samples were collected from the participants having joints pain from September 2019 to September 2021 at Gandhi Memorial & Associated Hospitals of King George's Medical University, Lucknow, India, and tested by serology for anti-Brucella IgM and IgG enzyme-linked immunosorbent assay (ELISA), molecular tests byreverse transcriptase-polymerase chain reaction (RT-PCR), conventional polymerase chain reaction (PCR), and automated blood culture system. The anti-Brucella IgM and IgG ELISA were performed using the kit from NovaTec Immundiagnostica GmbH (Dietzenbach, Germany). Isolation of DNA was carried out using the QIAamp DNA Mini kit (QIAGEN, Hilden, Germany), and the primers and probes specific for targeted regions (BCSP31 and IS711 gene) in the Brucella genome were procured from Eurofins Scientific SE (Luxembourg, France), and for internal control from CDC.

RESULT

The study showed 19 (9.5%) and 23 (11.5%) positive results by anti-Brucella IgM ELISA and anti-Brucella IgG, respectively, and of these, one (0.5%) was positive for both anti-Brucella IgM and anti-Brucella IgG ELISA. Out of 19 anti-Brucella IgM ELISA positive, eight (4%) samples were positive for PCR/RT-PCR and that was negative for anti-Brucella IgG ELISA. All blood culture reports of all patients were negative.  Conclusion: Anti-Brucella IgM ELISA was more accurate than anti-Brucella IgG ELISA in detecting human brucellosis. Consumption of animal products (i.e. milk, a dairy product of cow, buffalo, goat, and meat of goat) and contact with animals were the main risk factors that were identified for Brucella disease.

Presence of Brucella spp. in Milk and Dairy Products: A Comprehensive Review and Its Perspectives

Consuming raw milk and milk-based products that have not been produced under strict control conditions can cause brucellosis, a highly contagious zoonotic disease. It is a significant global public health concern, particularly in regions with poor management and limited resources, such as Latin America, North and East Africa, the Middle East, and South and Central Asia. The study aims to summarize the occurrence of human brucellosis linked to milk and milk products and the presence of Brucella species in dairy foods. To achieve this goal, a meta-analysis was conducted on 69 studies ranging from 2001 to 2022, which were categorized into two groups: the incidence of Brucella species in milk and milk products and the prevalence of human brucellosis resulting from the consumption of contaminated milk. The following milk and milk products showed the highest incidence of Brucella species: cow milk (1.86%–81.7%), buffalo milk (10.4%–61.67%), camel milk (0%–24%), goat milk (0%–88.8%), and cheese (0%–39.1%). Consuming unpasteurized milk and milk products has been identified as the leading cause of human brucellosis, with incidence rates varying from 33.9% to 100%. Several human brucellosis cases have been linked to consuming raw milk and cheese in Spain, Israel, and other countries. Various serological techniques are employed to detect Brucella-specific antibodies in milk. The milk ring test (MRT) and enzyme-linked immunoassay (ELISA) are the two most widely utilized methods for detecting these antibodies in milk. Recently developed dual biosensors are a powerful approach for early diagnosis of Brucella from milk. Real-time PCR can rapidly detect organisms, reducing the risk of lab contamination and false positive results. To prevent and control brucellosis, essential steps include proper pasteurization of milk and dairy products, using the milk ring test (MRT) to detect Brucella in individual and bulk milk, immunization, education, and increasing public awareness of the disease. The consumption of raw milk and milk-made products that are not produced under strictly controlled conditions poses a significant risk to human health, mainly due to the high incidence of Brucella contamination. Therefore, ensuring strict control measures in producing milk and milk-made products is crucial to preventing the spread of this disease and safeguarding human health.

Seroprevalence and Associated Risk Factors of Brucellosis Among Human Population in Duhok City, Iraq

Purpose

Brucellosis is a zoonotic disease that contributes to severe global health and economic issues. In this study, the Rose Bengal Test (RBT), a crucial diagnostic tool for brucellosis in Duhok city, was evaluated in order to offer updated epidemiological data on this disease.

Patients and Methods

A total of 339 patients suffered from fever and seeking medical attention in the private medical health center in Duhok city, Iraq, were enrolled after taking ethical approval from committee at Faculty of Sciences, University of Zakho and a verbal consent from each enrolled patient for using his/her blood and data. The blood specimens were tested for Brucella spp. Antibodies using the RBT and blood cultures, followed by spp. determination. A questionnaire form was designed to detect the associated risk factors.

Results

Prevalence of brucellosis was 12.6% among participants with a probable diagnosis and 10.3% among those with a confirmed diagnosis (positive blood culture). Most of the positive cases were between the ages of 20 to 40 years. A highly significant (P < 0.0001) association was found between brucellosis with both consuming raw milk and having contact with cattle. The most common species identified were Brucella melitensis (57.1%) and Brucella abortus (42.7%).

Conclusion

Brucellosis is a significant cause of fever in the current study and can be detected using the RBT. Human brucellosis can be reduced by minimizing the chances of contact with cattle and consuming boiled or pasteurized milk.

Seroprevalence of brucellosis and molecular characterization of Brucella spp. from slaughtered cattle in Rwanda

Bovine brucellosis is endemic in Rwanda, although, there is a paucity of documented evidence about the disease in slaughtered cattle. A cross-sectional study was conducted in slaughtered cattle (n = 300) to determine the seroprevalence of anti-Brucella antibodies using the Rose Bengal Test (RBT), and indirect enzyme-linked immunosorbent assay (i-ELISA). Corresponding tissues were cultured onto a modified Centro de Investigación y Tecnología Agroalimentaria (CITA) selective medium and analysed for Brucella spp. using the 16S-23S ribosomal interspacer region (ITS), AMOS, and Bruce-ladder PCR assays. The seroprevalence was 20.7% (62/300) with RBT, 2.9% (8/300) with i-ELISA, and 2.9% (8/300) using both tests in series. Brucella-specific 16S-23S ribosomal DNA interspace region (ITS) PCR detected Brucella DNA in 5.6% (17/300; Brucella culture prevalence). AMOS-PCR assay identified mixed B. abortus and B. melitensis (n = 3), B. abortus (n = 3) and B. melitensis (n = 5) while Bruce-ladder PCR also identified B. abortus (n = 5) and B. melitensis (n = 6). The gold standard culture method combined with PCR confirmation identified 5.6% Brucella cultures and this culture prevalence is higher than the more sensitive seroprevalence of 2.9%. This emphasizes the need to validate the serological tests in Rwanda. The mixed infection caused by B. abortus and B. melitensis in slaughtered cattle indicates cross-infection and poses a risk of exposure potential to abattoir workers. It is essential to urgently strengthen a coordinated national bovine brucellosis vaccination and initiate a test-and-slaughter program that is not presently applicable in Rwanda.

Molecular characterization of Brucella spp. from seropositive herds of cattle farmed at the wildlife-livestock-human interface in Rwanda

Seroprevalence studies showed that brucellosis is prevalent in cattle in Rwanda with no recent study on the characterization of Brucella spp. Therefore, this study aimed to characterize Brucella spp. in seropositive herds of cattle farmed at the wildlife–livestock–human interface. Whole blood samples (n = 118), milk (n = 41), and vaginal swabs (n = 51) were collected from 64 seropositive herds. All samples (n = 210) were inoculated onto modified Centro de Investigacion y Tecnologia Agroalimentaria (CITA) selective medium. Cultures were analyzed to detect Brucella spp. using 16S−23S ribosomal DNA interspacer region (ITS) PCR, the Brucella cultures were speciated using AMOS and Bruce-ladder PCR assays. Brucella spp. were detected in 16.7% (35/210) of the samples established from the samples using ITS-PCR. The AMOS PCR assay identified mixed Brucella abortus and B. melitensis (n = 6), B. abortus (n = 7), and B. melitensis (n = 1) from cultures from blood samples; mixed B. abortus and B. melitensis (n = 1) and B. abortus (n = 4) from cultures from milk samples; mixed B. abortus and B. melitensis (n = 6), B. abortus (n = 8), and B. melitensis (n = 1) from cultures from vaginal swabs. Bruce-ladder PCR assay confirmed B. abortus and B. melitensis cultures. The isolation of Brucella spp. was significantly associated with districts, with the Nyagatare district having more isolates than other districts (p = 0.01). This study identified single or mixed B. abortus and B. melitensis infections in cattle samples in Rwanda, which emphasizes the need to improve brucellosis control at the wildlife–livestock–human interface and raise the awareness of cattle keepers, abattoir workers, laboratory personnel, and consumers of cattle products.

Sero-prevalence and risk factors of Brucella presence in farm bulk milk from open and zero grazing cattle production systems in Rwanda

BACKGROUND

Animal and human brucelloses have been reported in Rwanda, human brucellosis being linked to drinking inadequately heat-treated milk. However, information on Brucella detection and prevalence in milk produced in Rwanda is limited.

OBJECTIVES

To determine the sero-prevalence and risk factors of Brucella in farm bulk milk from zero and open grazing cattle production systems in Rwanda.

METHODS

A total of 330 farm bulk milk samples were collected from 198 zero grazing farms and 132 open grazing farms in a cross-sectional study in Rwanda. Sero-prevalence of Brucella in milk was analysed using indirect enzyme-linked immunosorbent assay. A questionnaire was administered to farmers to determine the risk factors of milk contamination with Brucella.

RESULTS

Anti-Brucella antibodies were prevalent in 19.7% (95% confidence interval (CI), 15.5-24.4) of the 330 collected farm bulk milk. Sero-prevalence was significantly higher (p < 0.05) in open grazing farms (37.9% [50/132]) than in zero grazing farms (7.6% [15/198]). Practising open grazing system (odds ratio, OR = 69.5; 95% CI = 1.6-3033.6), history of abortion (OR = 19.5; 95% CI = 8.1-46.8) and placenta retention (OR = 4.2; 95% CI = 1.7-10.3) were the significant risk factors for the presence of anti-Brucella antibodies in milk.

CONCLUSION

Notably, more than a third of farm bulk milk from open grazing farms in Rwanda contains Brucella antibodies. Considering the zoonotic nature of Brucella, there is a need to reinforce brucellosis control programs in the country.

Brucellosis: Prevalence with reference to East African community countries - A rapid review

Brucellosis is a zoonotic disease which is endemic to certain regions of the world including Sub-Saharan Africa. The aim of this article is to provide a recent and rapid review on brucellosis prevalence in East African Community (EAC) countries. Literature was obtained using Google Scholar search engine and screened for relevancy and fulfilment of criteria to 1, 17, 4, 4, 30 and 29 articles retained for brucellosis prevalence in Burundi, Kenya, Rwanda, South Sudan, Tanzania and Uganda. Recent literature (published in the last decade 2010 to 2019) was considered for prevalence results in this review. In EAC, livestock had an animal-level prevalence of 0.2% to 43.8%, 0.0% to 20.0% and 0.0% to 13.8% for cattle, goats and sheep respectively. In humans, the prevalence varied mostly between 0.0% and 35.8%. In conclusion, brucellosis is quite prevalent in the region. The reported prevalence calls for plans or more efforts from individual member countries and from EAC, as a region, to control brucellosis.

Seroprevalence of and Risk Factors Associated with Exposure to Brucella Spp. in Dairy Cattle in Three Different Agroecological Zones in Rwanda

Livestock production is a key element for poverty alleviation, food security, and economic growth in Rwanda. In 2017, the national average milk production per cow was about 2.5 L per day; in 2020-2021, it is projected to increase to 3.5 L per day if improvement interventions including those designed to reduce the burden of brucellosis in cattle are implemented. The objective of the study reported here was to estimate the seroprevalence of and identify risk factors associated with dairy farms and cattle classified as seropositive to Brucella spp. in three different agroecological zones in Rwanda. Most study farms (40/85 or 47%) had one head of cattle only. Using the Rose Bengal test, the seroprevalence of brucellosis was 28/85 or 33% (95% CI = 24%, 43%) at the farm level and 63/465 or 14% (95% CI = 11%, 17%) at the animal level. Using logistic regression, at the farm level, the presence of seropositive cattle was associated with herd size (2-45 cattle, odds ratio = 21.2; 95% CI = 2.4, 184.5) (46-220 cattle, OR = 288.5; 95% CI = 24.3, 3,423.1) compared with farms with one animal, after controlling for main breed (local breeds, crossbreeds) on the farm. In addition, the odds of testing seropositive were 10.7 (95% CI = 2.3, 49.1) and 149.5 (95% CI = 19.3, 1,158.7) times higher in farms in Nyabihu district and Nyagatare district, respectively, than in farms in Muhanga district, after controlling for main breed on the farm. The odds of seropositivity to Brucella spp. were 2.8 times higher in farms with mostly local breeds, than in those with mostly crossbreeds; but the association was confounded by herd size and geographic location. At the animal level, the odds of seropositivity to Brucella spp. were 2.6 times higher in adult cattle than in young cattle (95% CI = 1.1, 6.3). Finally, we observed a high frequency of adult cattle (86%) and a high seroprevalence of brucellosis in adult cattle (25%) in Nyagatare; an indication that, in the absence of culling and other control measures, Brucella spp. infection pressure can be relatively constant and a steady source of disease transmission in pastoral systems in that district.

Seroprevalence and Associated Risk Factors of Bovine Brucellosis at the Wildlife-Livestock-Human Interface in Rwanda

Bovine brucellosis is endemic in Rwanda; however, little information is available on seroprevalence and risk factors. Therefore, a cross-sectional study was conducted among cattle farmed at the wildlife-livestock-human interface (n = 1691) in five districts and one peri-urban district (n = 216). Cattle were screened using the Rose Bengal test, then the results were confirmed by indirect enzyme-linked immunesorbent assay. Potential risk factors were determined with a questionnaire and analyzed for their association with seropositivity. In all districts, the animal and herd-level seroprevalence was 7.4% (141/1907) and 28.9% (61/212), respectively, 8.3% (141/1691) and 30.9% (61/198) at the interface, and 0.0% (0/216) in peri-urban areas. Among the potential risk factors, old age (≥5 years), cattle farmed close to wildlife, herds of cattle and small ruminants, history of abortions, and replacement animals were significantly associated with brucellosis (p < 0.05). Low awareness of zoonotic brucellosis, assisting calving without biosafety protection, drinking raw milk, and manual milking were each observed in more than 21.7% of cattle keepers whose herds were seropositive. This study confirmed brucellosis endemicity in cattle farmed close to wildlife in Rwanda, suggesting the need to focus control efforts in these areas. Educated farmers with a high awareness of zoonotic brucellosis had low bovine brucellosis seropositivity, which emphasizes the importance of education.

Human brucellosis caused by raw dairy products: A review on the occurrence, major risk factors and prevention

Despite considerable efforts made to address the issue of brucellosis worldwide, its prevalence in dairy products remains difficult to estimate and represents an important public health issue in many areas of the globe today. This is partly explained by the increasing tendency for consumption of raw dairy products, making the prevention and control of this zoonosis even more critical. This review summarizes reports published since the early 2000s on human brucellosis caused by contaminated dairy products and the systems of evaluation and assessment which are used to improve the diagnosis, surveillance, control and prevention of the disease. For this purpose, five comprehensive electronic databases were investigated and relevant studies were identified for systematic review. The design and quality of the studies revealed notable variation, especially in the methods used for the detection and characterization of Brucella spp. This report provides helpful information about the health risk associated with the consumption of raw milk and relevant preventive strategies.

Prevalence and risk factors for brucellosis seropositivity in cattle in Nyagatare District, Eastern Province, Rwanda

A survey involving 120 small-scale dairy farmers was carried out to assess risk factors associated with brucellosis in cattle from selected sectors of Nyagatare District, Rwanda. A sample of cattle from nine selected sectors of Nyagatare was tested for brucellosis using the Rose Bengal Test. Of the respondents, 57.5% were unaware of brucellosis as a disease, 85.8% did not screen new additions to the herd for brucellosis and 82.5% did not remove brucellosis seropositive animals from the herd. The prevalence of brucellosis in herds with cows with no history of abortion was 38.5% and 17.0% in those with a history of abortion. None of the respondents disinfected abortion sites or vaccinated against brucellosis. The prevalence of brucellosis in cows with a history of retained placenta was 36% and 2% in those with no history of retained placenta. Of the respondents, 62.5% reportedly fed foetal membranes to dogs. About 65.8% of the respondents with brucellosis-positive animals reported a calving interval longer than 1 year. Katabagemu (28.6%) had the highest prevalence of brucellosis seropositivity while Karama had none. Brucellosis in cows (21.4%) was significantly higher than that in heifers (12.8%) (p < 0.05), but there was no significant difference between heifers and bulls or between bulls and cows (p > 0.05). The occurrence of brucellosis in herds with 40-70 cattle (26.9%) was significantly greater than the 14.9% of herds with 10-39 cattle (p < 0.05). Seropositivity to brucellosis in cross-breed cattle (23.6%) was significantly greater than that in indigenous cattle (13.8%) (p < 0.05). There was no significant difference in the overall prevalence of brucellosis in cattle from different grazing systems (p > 0.05). Seropositivity to brucellosis was significantly different (p < 0.05) between the fourth parity (32.5%) and first parity (14.3%) cows. The findings in this study confirmed the existence of brucellosis as a problem in Nyagatare and the authors recommend that farmer education on the epidemiology, risk factors and mitigation of the disease be undertaken as a matter of urgency.