Friday, May 1, 2009

Part 7 HIV Multiple choice questions

31q: which subtype of the M group of HIV-1 viruses is most common in south and southeast asia ?

a. A subtype of M group of HIV-1
b. CRF01_AE
c. CRF02_AG
d. D subtype of M group of HIV-1

32q: which of the following is not a mode of transmission of HIV ?

a. sexual contact
b. needle prick
c. mosquito bite
d. transfusion of infected fresh frozen plasma

33q: why is there a strong association between HIV transmission and receptive anal intercourse ?

Answer: There is a strong association of HIV transmission with receptive anal intercourse, probably because only a thin, fragile rectal mucosal membrane separates the deposited semen from potentially susceptible cells in and beneath the mucosa and trauma may be associated with anal intercourse. Anal douching and sexual practices that traumatize the rectal mucosa also increase the likelihood of infection.
It is likely that anal intercourse provides at least two modalities of infection: (1) direct inoculation into blood in cases of traumatic tears in the mucosa; and (2) infection of susceptible target cells, such as Langerhans cells, in the mucosal layer in the absence of trauma .

34q: why is the male to female transmission of HIV usually more efficient than female to male transmission ?

Answer: Studies in the United States and Europe have found that male-to-female HIV transmission is usually more efficient than female-to-male transmission, but small numbers of HIV-positive female index partners limit conclusive sex-specific estimates of transmission probabilities per sex act.
The differences in reported transmission rates between men and women may be due in part to the prolonged exposure to infected seminal fluid of the vaginal and cervical mucosa, as well as the endometrium (when semen enters through the cervical os). By comparison, the penis and urethral orifice are exposed relatively briefly to infected vaginal fluid.

35q: which of the following is the chief predictor of heterosexual transmission of HIV
( as per studies conducted in Uganda ) ?

a. duration of sexual intercourse
b. plasma viremia
c. presence of other Sexually transmitted diseases
d. genetic makeup

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