West nile virus is an arbovirus that can be transmitted by birds because they develop viremia when infected. in contrast, infected humans cannot spread the disease because they do not develop viremia. why is viremia associated with the ability to transmit the disease? a. if there are no (or only very few) viral particles in the blood, then they are not picked up by vectors feeding on the blood in sufficient amounts to cause infection. b. the virus is only found within red blood cells if there is no viremia, so it cannot be spread by mosquitoes that do not consume those cells. c. direct contact with blood is required for infection. if there are no viral particles in the blood, then infection can't occur using this mechanism. d. because white blood cells are found in the blood, any virus in the blood would be attacked by the immune system. with no viral particles available for the immune system to attack, the virus cannot be spread.

Research cheetahs on the internet what has contributed to this animal becoming "endangered" or "threatened." what animal you have chosen? -cheetah how long has the animal been endangered or threatened? what has contributed to this animal’s endangered or threatened status? why is it important to save this animal from extinction? after researching and gathering facts, write a 350-word letter from the point of view of an animal rights' activist. be sure to include at least five facts that you learned from your research.

In 1959, doctors began using the powerful antibiotic methicillin to treat infections of staphylococcus aureus, but within two years, methicillin-resistant strains of s. aureus (mrsa) appeared. how did the resistant strains of s. aureus emerge? in 1959, doctors began using the powerful antibiotic methicillin to treat infections of staphylococcus aureus, but within two years, methicillin-resistant strains of s. aureus (mrsa) appeared. how did the resistant strains of s. aureus emerge? staphylococcus aureus bacteria that were able to synthesize cell walls using a protein that was not affected by methicillin survived the methicillin treatments and reproduced at higher rates than did other individuals. over time, these resistant individuals became increasingly common. in response to treatment of staphylococcus aureus infections with methicillin, some bacteria began to synthesize cell walls using a protein that was not affected by methicillin. these bacteria survived the methicillin treatments and reproduced at higher rates than did other individuals. over time, these resistant individuals became increasingly common. in response to treatment of staphylococcus aureus infections with methicillin, bacterial populations gradually began to synthesize cell walls using a protein that was not affected by methicillin.

What causes eclipses? check all that apply. earth's rotation on its axis moon's shadow covering the sun earth's shadow covering the moon earth's orbit and moon's orbit occasionally aligning the moon and sun's gravity pulling in the same direction