Patients infected by HCV frequently question whether their infection can be transmitted to their sexual partners, and whether HCV can be transmitted through sexual relations. Common sense suggests that HCV like HBV and HIV can be transmitted through sexual contact, but what is the degree of risk? Does it depend on the population studied? Can risk behavior alter contamination potential^27,34,74?

Classically, parenteral exposition unites many risk factors that are relevant for HCV transmission, such as the use of illegal drugs, hemodialysis, blood transfusion and blood derivatives, tattoos, organ transplants, acupuncture, sharing of straws for drug inhalation, and accidents in health-care workers^{12,26,49,58,71,89}.

Convincing evidence for the sexual transmission of HCV requires a history of couples having lived together in sexual activity, the absence of other opportunities for infection, and genetic evidence on the virus, demonstrating that both partners are infected by a virus with very similar genomic sequences. The possession of quality information concerning these questions can aid in providing answers to these issues. However, few studies meet these criteria satisfactorily^22,69,85.

ALTER et al. (1989)² presented the first study in which the possibility of HCV transmission was discussed, and considered multiple sex partners as a risk factor. However, the contribution of sexually transmitted HCV remains controversial. In the United States, the Centers for Disease control and Prevention (CDC) estimates that between 20 to 25% of the transmission indexes are associated with sexual contact, although the numbers discussed worldwide fluctuate since many different population are involved^2,15,48.

The information available on the sexual transmission of HCV varies considerably; the numbers reported lying between zero and 27%. However, the majority of studies mention rates of between zero and 3%. These low indexes, associated with rare risk factors, suggest that sexual transmission presents a minimal or negligible risk^{18,30,31,44,49,51,54,69,82,83,92}.

Studies that discuss specific groups, such as those who attend clinics for sexually transmitted diseases like drug abusers, homosexuals and sex workers, reveal findings that differ from those of the general population, and the risks of sexual transmission of HCV increase considerably^{12,15,18,23,25,26,37,51,61,65,68,69,83,85,91} .

GAMBOTTI et al. (2005)²⁷ identified 29 cases of acute hepatitis C that occurred between 2001 and 2004 in a population of positive HIV men who had sex with other males, and performed risk behavior such as unprotected sex or sex with multiple partners, revealing percentages of seroconversion for HCV above that of the general population²⁷.

In analyzing a cohort of 1,038 homosexual males, BODSWORTH et al. (1996)⁴ found 7.6% to be positive for anti-HCV, and suggested that immunological suppression caused by HIV might facilitate acquisition of the infection. Investigators such as FILIPPINI et al. (2001)²³ affirm that the risk of sexual transmission is greater in the case of HIV-HCV co-infection^4,23.

In a review article, BONACINI & PUOTI (2000)⁵ presented that stable partners of HCV infected patients have a higher risk of HCV infection than partners of HCV negative index case. HIV coinfection in the index case was initially thought to enhance sexual transmission. However, other studies did not confirm this initial impression⁵.

In Canada, when investigating the risk of sexual transmission of HCV and HIV among users of non-injectable drugs and their sexual partners, it was noted that in groups with low risk behavior the potential existed for the sexual transmission of HCV⁵⁶.

When considering patients attended at hepatology clinics and who do not belong to groups with risk behavior, but who are HCV carriers, and their sexual partners, what might be the risk of these, non-carrier partners becoming infected through sexual activity? This question must be considered and evaluated carefully^69,76,92.

One group that arouses much curiosity is the HCV positive patients who do not present an identifiable risk factor for HCV infection, which is on average of 30-40% of patients. Probably sexual transmission, like other forms of human contact can play a significant role within this group of patients^{6,16,28,30,39,57,68,76}.

In Australia, where notifications of Hepatitis C cases were evaluated, the risk factors related to HCV transmission showed indexes of less than 2%. The research mentions that seropositivity between sexual partners was greater than between other individuals who had non-sexual contact and resided in the same household¹⁹.

NEUMAYR et al. (1999)⁵⁷, after evaluating genotypes among eight couples, reported just two in agreement, only one of who presented another evident risk factor, showing that sexual transmission is possible but infrequent among monogamous mates of chronic HCV carriers. KAO et al. (1996)³⁸ found an index of 17% among 100 positive anti-HCV couples. Of these, 11 presented the same 1b genotype^38,57.

TANAKA et al. (1997)⁸² observed that the spouses of sex partners who were HCV carriers showed a 2-fold risk of contracting the disease than the spouses of partners who were HCV negative. SOTO et al. (1994)⁷⁹, in a multicentric study, evaluated 423 heterosexual partners with a case index reactive for anti-HCV, and suggested that the infection could be transmitted sexually, but with little efficiency. However, co-infection by HIV may increase these values. MARINCOVICH et al. (2003)⁴⁴, on evaluating a cohort of 171 heterosexuals, initially seropositive for HCV and HIV, suggested that the sexual transmission of HCV is extremely low or even null, and no couple in the population studied converted seropositively for HCV^44,79,82.

The sexual and intrafamilial transmission of HBV has been well documented, but the same issue for HCV does not appear to have been established. We also know that the transmission of HBV and HIV is considerably greater than that of HCV; however, the number of people who could acquire Hepatitis C by sexual means should not be neglected^{10,15,17,23,24,28,40,51,85,86}.

Comparison between sex partners and other family members residing with the same household, having a HCV carrier as a reference, shows that intrafamilial contact is an important factor in the transmission of HCV. Cultural habits differ from one population to another and can interfere in the results of epidemiological studies that involve HCV transmission.

In a study by DIAGO et al. (1996)¹⁷ the incidence of anti-HCV for sex partners of index cases was 7.6% (30/394), and for other members of the family was 3.3% (34/1057)¹⁷.

In CHANG'S et al. study (1994)¹⁰ of 307 families of HCV-carrier patients, 28% presented anti-HCV positive mates, a higher percentage, compared to children and other household contacts of HCV index case (6.4%) (r < 0.001). Anti-HCV positivity was 23% in husbands who presented wives as an index case, and 29% in wives who presented husbands as an index case¹⁰.

Identification, the means of transmission, and evaluation of HCV prevalence among family members are very important factors as concern prevention of the dissemination of HCV infection in endemic areas⁷³.

Egypt is a country endemic for HCV infection. In one population study, 669 parturient women were investigated of whom 94 were positive in tests for detecting anti-HCV antibodies subsequently 35 genomic sequences of HCV were genotyped and the homologies among them established. The outcome was that 33 sequences exhibited the same genotype, 30 showed 100% similarity, two 97% and one 91% similarity. The NS3 region of the HCV genome was also sequenced. The index for children was low compared to couples. In this study, sexual transmission seems to play an important role in the intrafamilial transmission of HCV^41,43.

OKAYAMA et al. (2002)⁶⁰ evaluated 973 subjects in Japan in an area considered to be endemic for HCV, showing that 23% were anti-HCV positive. This population was accompanied, and in an 11-month period, 14 partners seroconverted. Of these, five had a history of being with a mate who was a HCV carrier, and six did not. There was no statistically correlation, and sexual transmission was not considered likely⁶⁰.

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