Table 2.

The risk factors of brucellosis.

Risk factors		Significance association with brucellosis	References
Animal Factors	Species	Cattle are more likely to be infected than buffalos	(81)
	Age of animals	Sero-positive animals are more likely to be older age than calves	(82)
	Sex	Female dairy animals are more likely to be infected than males	(83)
	Breed	Purebred animals are more likely to be seropositive than native breeds	(84)
	History of abortion	The history of abortion is related to seropositive cases	(85)
	Status of pregnancy	The late stage of pregnancy is more likely to be seropositive	(86)
	History of retained placenta	The history of retained placenta is linked with seropositive cases	(87)
Pathogen factors		Intracellular replication Inhibition of bactericidal activity	(88)
		Intracellular replication Phagocytosis inhibition	(89, 90)
Occupational factors		Veterinarians, laboratory workers, farmers, butchers, abattoir workers	(91)
Management factors	Herd size	Larger herds are positively associated with seropositivity	(92)
	Mixed herd	Cattle being housed with goats and/or sheep are more likely to be seropositive	(92)
	Breeding method	Breeding by artificial insemination is positively co-related with seropositivity	(92, 93)
	Distance between herds	Herds located close to one another are positively associated with seropositivity	(92)
	Introduction of a new animal from an unknown source	The introduction of new animals from unknown sources is positively associated with seropositivity	(77)
	Clean drinking water	Lack of clean drinking water for animals is positively associated with seropositivity	(94)
	Clean and hygiene	Insufficient manure removal and dirtiness in farms are positively associated with seropositivity	(94)
	Routine milk diagnosis	Herds that are not routinely tested for Brucella infection were positively co-related with seropositivity	(30)
Human Factors	Age of owner	Cattle and buffalo belonging to older age group owners (above 40 years) are positively associated with seropositivity	(95)
	Awareness	Cattle and buffalo belong to farmers who have knowledge and awareness about diseases, particularly brucellosis is negatively correlated with seropositivity.	(58)
Agro-ecological factors	Origin	Sero-positivity differs in different parts of a country	(96)
	Presence of dogs, cats, and wildlife	Their presence is suspected as a source of infection	(97)