Seroepidemiological survey of bovine brucellosis in selected Fulani Herds in Kwara State , Nigeria

Objective: Brucellosis is a bacterial zoonotic disease caused by members of the genus Brucella. It causes economic loss and ill health among animals and humans. This study was conducted to determine the prevalence of brucellosis in cattle particularly in White Fulani breed of cattle in Kwara State, Nigeria. Materials and methods: A total of 120 blood samples were collected randomly from the cattle in Kwara State of Nigeria. Sera were separated from the blood samples. The serum was used for the identification of antibodies against Brucella present in it. Three screening tests namely Bovine Brucella Antibody Test (BBAT; ImmunoCombR), Rose Bengal Plate Test (RBPT) and Serum Agglutination Test (SAT) were used for the identification purpose. Results: Based on BBAT, 13.3% (n=16/120) cattle were positive for brucellosis. Similary, 14.2% (n=17/120) and 3.3% (n=4/120 cattle were found to be positive for RBPT and SAT, respectively. The affected cattle were mainly of White Fulani breed with few cross-bred. Conclusion: Results of this study indicates that brucella antibody is circulating in cattle examined in the study area. This calls for urgent public health intervention and routine screening of other domestic animals as well.


INTRODUCTION
Brucellosis is a zoonotic disease that seriously affects animal health, public health and international trade.The disease poses a formidable threat to profitable livestock production through decreased milk production, weight loss, loss of young ones, infertility and lameness (Ross et al, 1994;Muriuki et al., 1997;Godfoid et al., 2005).The disease can be transmitted to human causing "Undulant Fever".Brucellosis in animals and humans has since been identified as an important problem in many countries like Nigeria (Falade et al., 1995), Sudan (Elhassan et al., 2015;Ebrahim et al., 2016), Iran (Gharekhani et al., 2016), Kwuait (El-Gohary et al., 2016) and India (Mohamand et al., 2014).
Bovine brucellosis is usually caused by Brucella abortus, less frequently by B. melitensis and occasionally by B. suis (El-Gohary et al., 2016).Brucellosis was first diagnosed in human in 1887 (Ocholi et al., 2004).The infection is common in countries that do not have effective public health and domestic animal health program such as in most countries of Asia, Africa, The Caribbean, Mexico, South and Central America, Middle East and The Mediterrean.It is a rare disease in the USA, Israel, UK, Australia and South Africa because of successful implementation of effective animal disease control programs (Ocholi et al., 2004 Brucellosis is commonly transmitted to susceptible animal by direct or indirect contacts (Esuruoso, 1974).Aborted fetus, placental membrane, vaginal discharge or other fluid present after an infected animal has aborted or calved may be contaminated with Brucella organism.Another source of infection is through an infected bull during normal service or artificial insemination, excretion through the colostrum and uterine discharges.Also, wild animals infected with brucellosis can transmit the disease to domestic livestock population (Davis et al., 1990;Schelling et al., 2003).
The incubation period of brucellosis could be 2 weeks to 1 year or longer.The most obvious signs in pregnant animal are abortion or birth of weak calves, reduction in milk production, delayed conception; not all infected cows abort but those that do usually abort between the fifth and seventh month of pregnancy.Other signs include lower fertility with poor conception rates, retained placenta and arthritis.In brucellosis, the affected animal remains as carrier for life (Bale et al., 2010).
Knowledge on prevalence of brucellosis is of paramount importance as far as public health is concerned (Bale et al., 2010).This study gathered current information to contribute in understanding the epidemiology of brucellosis.Also, findings from this study will be used to recommend some forms of community intervention to minimize the health problem associated with brucellosis in both humans and animals.Based on the results of this study, the prevalence of brucellosis in Kwara State could be clarified and would primarily help to create awareness to livestock officers, livestock keepers and to the community people.
This study was conducted with the general objective of establishing the status of bovine brucellosis in Kwara State, North-Central Zone, Nigeria.Provide inputs for evidence-based disease control in the country as it relates to brucellosis.This study investigated the prevalence of brucellosis in cattle and determined the current status of bovine brucellosis in Kwara State.This study will improve the understanding of the epidemiology of bovine and human brucellosis in Kwara State, Nigeria.

Ethical statement:
The experiments were conducted as per the guidelines of American Veterinary Medical Association providing minimal discomfort to the animals during blood collection.

Study area:
The study was conducted in Kwara State, North-Central Zone, Nigeria, an area lying between latitude 8 °25 ' N to 8 °32'N and longitude 4 °30'E to 4 °41'E.The area is closer to the confluence of the rivers Niger and Benue, the two rivers that demarcate the Northern and Southern regions of Nigeria (Olorunfemi and Odita, 1998).Ilorin the state capital has a small industrial activity base and the inhabitants are predominantly civil servants or small business operators.The city is 50.2Km in area and is situated approximately 420 Km from Federal Capital Territory.It is strategically located as the gateway between the Southern and Northern areas of the country which makes it easily accessible to all parts of the country by air, road and rail transportation (Aiyedun, 2011).
Table1: Distribution of sampled cattle with respect to sex and breed of cattle in the study area.

Sampling method and specimen collection:
Necessary consent from the owner was obtained before collecting data from the selected Fulani herds.10% of the herd size was randomly screened in each farm for this study.Approximately 10 mL of blood was collected aseptically from the jugular vein of properly restrained animal using sterile needle and vacutainer tubes.On each farm, blood was collected randomly from cattle aging equal or >1 year old.The samples were left at room temperature overnight to allow clotting for serum separation.Serum was collected from the vacutainer tubes using a disposable plastic Pasteur pipette, dispensed to an Eppendorf tube and stored in a cool-box in the field.Eppendorf tubes were then stored in the freezer at -20°C.

Bovine brucella antibody test (BBAT):
The commercially available Bovine Brucella Antibody Test Kit (Catalog number: 50BBA103) was obtained from Biogal Laboratories UK.The test was performed as per the procedures/protocols indicated by the manufacturer.

Rose Bengal plate test (RBPT):
The test was performed by placing one drop (0.03 mL) of antigen on each square of hand rule enamel strip.One drop (0.03 mL) of the serum sample was placed alongside the antigen.The antigen and serum were thoroughly mixed using sterile tooth pick.The enamel strip was placed on the rocking machine for 4 min.The test was examined for agglutination.A known positive and negative sera were included in the test.The result was either negative (no agglutination) or positive (agglutination).Positive reaction was also considered as either weak or strong based on the degree of agglutination (Mousa et al., 1988;Godfoid et al., 2010).
Serum agglutination test (SAT): 0.5 mL of phenol saline was dispended each into five test tubes and 0.3 mL of serum sample was added and mixed gently without making any froth.0.5 mL was transferred from the first tube to the next test tube and carried on to the last test tube, finally 0.5 mL was discarded from the last tube.It was incubated at 37 o C for 20 h.The standard positive and negative tests were set up along with the test sera, and finally the degree of agglutination in each tube was read (Kozukeev et al., 2003).
). Brucellae are Gram-negative coccobacilli or short rods with straight or slightly convex in shape, and rounded ends.The genus Brucella comprises of six classical species namely B. abortus B. melitensis, B. suis, B. ovis, B.canis, and B. neotomae.Seven biovars are recognized for B. abortus, three for B. melitensis and five for B. suis.B. abortus, B. melitensis, B. suis, and B. neotomae generally occur in smooth form, while B. ovis and B. canis are invariable rough species (Nielsen et al., 2004).

Table 2 :
The distribution of B. abortus antibody in cattle in the study areas using BBAT(Immunocomb), RBPT and SAT.However, positive tests for Brucella antibodies does not necessarily mean that the animals have current or active infection at the time of sampling.It may be a result of past infection resulting in a "self-limiting disease".This showed that cattle indiscriminately roamed from one area to the other in search of pasture on a daily basis predisposes them to diseases including brucellosis.Also, stress and inadequate water encourages the animal to come down with diseases.The fundamental reason for the high prevalence recorded in this study may be connected with nomadic nature of the pastoral Fulanis, poor farm management and biosecurity practices in the North-Central geopolitical zone.Although female White Fulani cattle showed as positive animals mostly, sex may not have any role in the results obtained because majority of tested animals were of this type.CONCLUSIONThis study confirms that brucellosis particularly bovine brucellosis is prevailing among Fulani herds in Kwara State, Nigeria.Being a zoonotic infection, brucellosis may make an occupational hazard to the cattle farmers and other related personnel.Appropriate actions should be taken by the government and other private bodies considering routine screening, awareness and education.
(Muma et al., 2007;Al-Majali et al., 2009) al., 2009).The prevalence could not reflect the past or present exposure to Brucella organisms because vaccination against brucellosis using B. abortus S19 was not previously practiced.