Careful examination of multiple smears may be necessary, since Babesia may infect less than 1% of circulating red blood cells, thus be easily overlooked. Serologic testing for antibodies against Babesia (both IgG and IgM) can detect low-level infection in cases with a high clinical suspicion, but negative blood film examinations. Serology is also useful for differentiating babesiosis from malaria in cases where people are at risk for both infections. Since detectable antibody responses require about a week after infection to develop, serologic testing may be falsely negative early in the disease course. A polymerase chain reaction (PCR) test has been developed for the detection of Babesia from the peripheral blood. PCR may be at least as sensitive and specific as blood-film examination in diagnosing babesiosis, though it is also significantly more expensive. Most often, PCR testing is used in conjunction with blood film examination and possibly serologic testing. Other laboratory findings include decreased numbers of red blood cells and platelets on complete blood count. In animals, babesiosis is suspected by observation of clinical signs (hemoglobinuria and anemia) in animals in endemic areas. Diagnosis is confirmed by observation of merozoites on thin film blood smear examined at maximum magnification under oil using Romonovski stains (methylene blue and eosin). This is a routine part of the veterinary examination of dogs and ruminants in regions where babesiosis is endemic. Babesia canis and B. bigemina are "large Babesia species" that form paired merozoites in the erythrocytes, commonly described as resembling "two pears hanging together", rather than the "Maltese cross" of the "small Babesia species". Their merozoites are around twice the size of small ones. Cerebral babesiosis is suspected in vivo when neurological signs (often severe) are seen in cattle that are positive for B. bovis on blood smear, but this has yet to be proven scientifically. Outspoken red discoloration of the grey matter post mortem further strengthens suspicion of cerebral babesiosis. Diagnosis is confirmed post mortem by observation of Babesia-infected erythrocytes sludged in the cerebral cortical capillaries in a brain smear. Treatment Treatment of asymptomatic carriers should be considered if parasites are still detected after 3 months. In mild-to-moderate babesiosis, the treatment of choice is a combination of atovaquone and azithromycin. This regimen is preferred to clindamycin and quinine because it has fewer side effects. The standard course is 7 to 10 days, but this is extended to at least 6 weeks in people