Question

West Nile virus is capable of infecting many different organisms (humans, birds, raccoons, and so on). This information indicates that West Nile virus

	a.	is capable of fecal-oral transmission.
	b.	has a narrow host range.
	c.	has a narrow tissue tropism.
	d.	has a broad host range.

Answer 1

Ans:- D. Has a broad Host range.

West Nile Virus has an extremely broad host range. It replicates in birds, reptiles, amphibians, mammals, mosquitoes and ticks.It causes disease in humans, horses, and several species of birds. Most infected individuals show few signs of illness, but some develop severe neurological illness which can be fatal.

Rest of the Options are not appropriate because:-

WNV was detected in multiple tissues, including novel sites such as the skin, duodenum and pancreas, but the tropism was identical for the two strains which denotes not as narrow .

Mosquito bites are the usual source of WNV for mammals, reptiles and amphibians. When environmental conditions favor high viral amplification, significant numbers of “bridge vector” mosquitoes (mosquitoes that feed on both birds and mammals) become infected in the late summer, and can transmit the virus to humans, horses and other incidental hosts.

Though, some species of birds can shed WNV in oral and cloacal secretions, and may transmit the virus directly. Direct transmission during close contact has also been reported in alligators, possibly via fecal shedding of virus. Chipmunks, squirrels and raccoons can also shed WNV in feces, oral secretions and/or urine. WNV has been found in the urine of experimentally infected hamsters, and in very small amounts in the oral and/or cloacal fluids of experimentally infected North American bullfrogs (Rana catesbeiana) and green iguanas (Iguana iguana).

That's the above reasons, Options A) , B) & C) are not truely appropriate like D).