Brucella spp. are known for causing which of the following conditions?

Brucella spp. are primarily responsible for causing undulant fever, also known as brucellosis. This condition is characterized by recurrent fevers that can vary in intensity and may show a cyclic pattern. Infection with Brucella occurs often through the consumption of unpasteurized dairy products or through contact with infected animals, leading to systemic symptoms including fever, malaise, and often myalgia.

The other conditions listed are caused by different pathogens. Whooping cough is caused by Bordetella pertussis, pinkeye is typically due to bacterial or viral infections affecting the conjunctiva, and pneumonia can result from various bacteria, viruses, or fungi but is not specifically associated with Brucella spp. Thus, understanding the specific diseases linked to various pathogens helps in distinguishing the role of Brucella in human health.