The nymph is the primary vector and feeds for hours to days. Sporozoites are injected from the tick salivary gland to the hosts bloodstream. It enters erythrocytes, forms trophozoites and merozoites and then destroys the erythrocyte and infects new red blood cells. The schizogony is asynchronous, unlike that seen in malaria. There is therefore no classic patterns of fever.
Most patients are asymptomatic.
After a 1-3 week incubation, there might be malaise, fatigue, anorexia, chills, fever, headache, myalgias, arthalgias, nausea, vomiting, abdominal pain, depression, dark urine, photophobia, conjunctival injection, sore throat, cough. The child may have had exposure to sick chickens. Influenza A H5N1 was identified, a virus previously only known in birds. This virus seemed to have crossed the avian-human species barrier without prior adaptation in another mammalian species. The fear, without this mixing, was that this strain would be so different from prior strains that the population at large would have no immunity and would potentially cause a pandemic equal to or worse than the Swine Flu Pandemic of 1918.