AIDS as STD 
Review paper 
AIDS IN THE CONTEXT OF SEXUALLY 
TRANSMITTED DISEASES 
M. Matičič, J. Tomažič and L. Vidmar 
SUMMARY 
The predominant mode of human immunodeficiency virus (HIV) transmission throughout the world is 
sexual. The sexual contact with an infected person is estimated to account for nearly 90% of HIV infected 
cases worldwide. The risk of HIV transmission, practicing unprotected sexual contact with an infected person, 
depends on several factors: the mode of sexual intercourse, state of the disease in infected partner, virulence 
of the virus, age and gender of an uninfected partner and coexistence of other sexually transmitted diseases 
(STDs). There exists also an apparent influence of HIV infection and immunosuppression on the transmission, 
clinical manifestation, or natural histm:y of other STDs. Awareness of HIV/STD risk is important in all 
contexts of sexuality, underlying the strategies of prevention and puhlic health intervention. Safer sex messages 
which include reducing the number of sexual partners, avoiding unprotected sexual practices and using 
condoms are of extreme importance. 
KEY WORDS 
HW infection, AIDS, sexual transmission, cofactors, sexually transmitted diseases 
INTRODUCTION 
HIV infection is spreading dramatically around 
the globe, is increasingly spread by heterosexual 
behaviours and is ultimately lethal. Current treatment 
of HIV infection is only of modest benefit, and 
intense efforts to create an HIV vaccine have been 
thwarted to date by the antigenic variability of the 
virus (1). 
The modes of transmission of HIV have not 
expanded significantly beyond those described or 
predicted early in the epidemic: sexual contact, 
parenteral transmission, or perinatal transmission 
from an infected mother (2). In a global sense, the 
predominant mode of HIV transmission throughout 
162 
the world is sexual and accounts for nearly 90% of 
HIV infected cases (3). Heterosexual and bisexual 
transmission is more common in developing countries, 
and homosexual transmission is more common in 
industrialized countries, where in the foreseeable 
future heterosexual transmission represents a serious 
threat to so called second generation of infected 
(4). Heterosexual contact accounts for about 75% of 
worldwide infected (5). 
HIV IN GENITAL TRACT SECRETIONS 
HIV can be detected by several methods .in genital 
tract secretions both as free and intracellular virus. 
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AIDS as STD 
The shedding of a virus in an infected person 
changes depending on the stage of illness, antiviral 
chemotherapy etc. 
Semen is an important vehicle for sexual transmission 
of HIV (6). The virus was found in seminal plasma 
and mostly in CD4+ lymphocytes. However, only in 
32% of seropositive men HIV was cultured from 
semen (6). Leucocytospermia significantly influences 
the increased shedding of HIV. HIV positive 
lymphocytes were also found in testis, prostatic 
gland, epididimis and <listal urethra, the latter being 
of great importance for transmission of HIV. 
In women's genital tract HIV can be detected in 
cervicovaginal secretions (predominantly in cervical), 
in HIV positive CD4 cervical cells and in inflammatory 
secretions. 
Semen of HIV infected men contains more virus 
than cervicovaginal secretions in HIV infected women. 
FACTORS INFLUENCING THE 
SEXUAL TRANSMISSION OF HIV 
The transmission of HIV virus by sexual contact 
(genito-genital or ano-genital) is relatively low. Por 
example, the risk of transmission of Neisseria 
gonorrhoeae from an infected female prostitute, in 
a single sexual exposure was estimated to be 22-
25 % (7). Overall "risk-per-sex-act" of HIV taking 
into account heterosexual and homosexual intercourse 
was estimated to be 0.1 to 0.2% (2, 8). However, 
some persons become HIV infected after a single 
risk sexual encounter, whereas others may remain 
uninfected despite hundreds of unprotected risk 
sexual contacts. This indicates that the likelihood of 
HIV infection may be substantially affected by intrinsic 
properties of either the HIV infected partner, the 
virus itself, or the uninfected partner (7, 9) . 
The risk of HIV transmission practicing unprotected 
sexual contact with an infected person, depends on 
the mode of sexual intercourse, stage of the disease 
in infected partner, virulence of the virus, age and 
gender of an uninfected partner and coexistence of 
other STDs in both partners. 
Mode of sexual intercourse 
The average appearance of sexual transmission of 
HIV is small, from 1 per 100 in receptive anal 
intercourse, to even 1 per 1500 in female-to-male 
transmission. 
Unprotected receptive anal intercourse is the 
most effective mode of sexual transmission of 
HIV (10). 
acta dermatovenerologica A.P A. Vol 4, 95, No 3 
Most heterosexual transmissions occur through 
vaginal intercourse although anal intercourse may 
further increase the risk for women (2). Male-to-
female transmission is more efficient than female-
to-male transmission, but the efficiency of the latter 
can be greatly enhanced in the presence of well 
defined risk factors, including more advanced 
immunodeficiency in the infected partner, the presence 
of conventional STDs in either partner, sex during 
menses etc (Table 1) (9, 11, 12, 13). It is most 
likely that a sustained heterosexual epidemic in the 
Third World is only possible because of a common 
occurrence of such amplifying factors. The cumulative 
incidence of heterosexual transmission of HIV in a 
couple, where an infected man practices unprotected 
sex for a longer period of tirne, is estimated to be 
20% (9). 
Table l. Factors associated with heterosexual trans-
mission of HIV (9). 
Factor male to female 
female to male 
Lack of condom Yes Yes 
Anal intercourse Yes No 
Sex during menses No Yes 
Number of sexual contacts Yes Yes 
Advanced disease state Yes Yes 
Zidovudine decreases risk Possibly Unknown 
Genital sores, infections Yes Yes 
Oral contraceptives Yes Unknown 
Intrauterine contraceptive device Possibly Unknown 
Receptive oral intercourse also constitutes a risk 
for persons of either gender, whose insertive partner 
is HIV positive, although the risk may be less than 
one sixth of the one of receptive anal intercourse 
(9). 
A very small number of cases of female-to-female 
transmission have been reported. 
Stage of the disease in HIV infected partner 
The risk of transmission appears to be higher if 
the HIV infected person already has AIDS or a 
CD4+ T celi count less than 400 per mm3 (7). Men 
and women have been found to be more infective 
also around the period of seroconversion, when 
body fluids are flooded with HIV. So, the HIV 
positive person is most infectious in a very early 
and in late period of infection (14). 
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AIDS as STD 
Virulence of the virus 
Certain vira! strains have also been suggested to 
be more infectious than other (7). HIV virus manifests 
a high degree of genetic variability in vivo, and 
genetically different isolates can be recovered from 
the same HIV infected person at different times 
and even at the same tirne. 
Table 2. Association of sexually transmitted diseases 
and HIV infection (15). 
Disease Increased risk for Oinical course 
HIV acquisition exacerbated in 
HIV + patient 
Neisseria gonorrhoeae +/- +/-
Trichomonas vaginalis + 
Haemophilus ducreyi + + 
Chlamydia trachomatis + +/-
Syphilis + + 
Herpes simplex virus + + 
Granuloma inguinale + +/-
Human papillomavirus +/- + 
Lymphogranuloma + +/-
venereum 
Hepatitis B virus + 
Age and gender of an uninfected partner 
The risk of HIV infection is higher in females. 
Young women and women over 45 years of age are 
the two populations at higher risk. In the puberty, 
iminature cervix and vaginal mucosa do not represent 
an efficient barrier against infection. In women in 
and after the period of menopause the physiological 
changes occur, making the mucosa thinner (9). 
Coexistence of other STDs 
There exists now a solid evidence from prospective 
epidemiologic and clinical virologic studies that both, 
genital ulcers (including chancroid, syphilis and genital 
herpes), as well as nonulcerative STDs (such as 
gonorrhoea, chlamydial infection or trichomoniasis) 
enhance the sexual transmission of HIV (Table 2) 
(13, 15). 
Genital ulcerative diseases increase the risk of 
HIV transmission during a single sexual act by a 
factor as high as 10 to 100 (16). Nonulcerative 
STDs are far more common than ulcerative in most 
populations and so their contribution to the sexual 
spread of HIV may also be higher, even if their 
relative risk is probably smaller (17). These findings 
are supported by perhaps more compelling recent 
data showing that urethritis and cervicitis can enhance 
genital shedding of HIV provirus, potentially increasing 
the inoculum of HIV delivered sexually, and that 
cervicitis treatment reduces shedding of the virus. 
HIV infection and related immunosuppression have 
had severa! reported effects on the transmission, 
clinical manifestations and natural history of other 
STDs: increased cervical and anal shedding of human 
papilloma virus (HPV) and increased risk and post-
therapy recurrence of cervical displasia and cancer; 
more severe, persistent genital and rectal herpes, 
with emergence of Acyclovir-resistant herpes simplex 
virus (HSV); shift in the therapeutic resistance of 
genital ulcers and neurosyphilis; increased risk of 
gonorrhoea; and increased risk and severity of pelvic 
inflammatory diseases (PID) (18, 19). 
CONCLUSION 
The mutual reinforcement of HIV and other STDs 
represents a growing threat to HIV/STD prevention. 
So, awareness of HIV/STD risk is important in 
every context of sexuality, especially in the strategies 
of prevention and public health intervention. Safer 
sex messages, which include reducing the number of 
sexual partners, avoiding unprotected penetrative sexual 
practices and using condoms are of extreme 
importance. 
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AUTHORS' ADDRESSES 
Mojca Matičič, MD, specialist of interna! medicine, Dpt of Infectious Diseases 
Oinical Centre Ljubljana, Japljeva 2, 61000 Ljubljana, Slovenia 
Janez Tomažič, MD, MS, specialist of interna} medicine, same address 
Ludvik Vidmar, MD, Head Dpt. of infectious diseases, Clinical Centre 
Japljeva 2, 61000 Ljubljana, Slovenia 
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