Abstract
Former illegal blood donation in the past decade has caused HIV outbreaks in some rural areas in China. Other HIV associated virus infections, such as human herpesvirus 8 (HHV8) in such areas are still not well defined. In order to explore HHV8 and HCV seroprevalence and potential risk factors in such areas, a cross-sectional study with 305 HIV positive and 315 HIV negative subjects recruited from a rural county in Shanxi province was conducted, where illegal blood collection was reported. Interview questionnaires and serum testing were carried out with these participants. HCV and HHV8 seroprevalence were found to be higher in HIV positive than negative group (76.4% vs. 2.5%; 15.4% vs. 4.8% respectively), while the difference in HBV seroprevalence was not significant. Co-infection with HCV and HHV8 was also more prevalent in the HIV positive group. HIV status (odds ratio [OR], 2.71; 95% confidence interval [CI], 1.16–6.30) and HBV status (OR, 2.56; 95%CI: 1.14–5.75) were independently associated with HHV8 infection. HIV status (OR, 23.03; 95%CI: 9.95–53.27) and blood/plasma selling history (OR, 14.57; 95%CI: 7.49–28.23) were strongly associated with HCV infection. These findings demonstrate that both HHV8 and HCV infections are prevalent in this community. HIV infection is an important risk factor for both HHV8 and HCV infection. HBV infection is associated with HHV8 infection but not with HCV infection. It is possible that HHV8 and HBV, but not HCV, may have similar mode of transmission in this population.
Keywords: HIV, HHV8, HCV, Illegal blood donor, Seroprevalence
INTRODUCTION
Human herpesvirus 8 (HHV8), also known as Kaposi’s sarcoma-associated herpesvirus (KSHV), a member of the gamma herpesvirus family, has consistently been found to be associated with all forms of Kaposi’s sarcoma (KS). It is also associated with other lymphoproliferative diseases such as primary effusion B-cell lymphomas (PELs) and multicentric Castleman's disease (MCD) [1]. HHV8 infection is not ubiquitous and the prevalence varies in different populations but is commonly found in HIV positive individuals. HHV8 seroprevalence is generally low to moderate in western countries, ranging from 3% to 23% [2–4]. However, in sub-Saharan Africa, seroprevalence can be as high as 50% in the general population, and is even higher in the HIV positive population [5–7]. Data from Asian countries suggests that HHV8 seroprevalence is generally low [8]. Several epidemiological studies have been conducted to study the route of transmission and risk factors involved in acquiring HHV-8 infection [9–11]. While salivary transmission has emerged to be one of the major routes of transmission, a recent study conducted in Uganda has clearly demonstrated that transmission via blood transfusion can occur, albeit inefficiently [12].
In addition to HHV8, unmonitored blood transfusion may also increase the risk for acquiring hepatotropic viral infections, such as hepatitis C virus (HCV) and HBV. These viruses have been known to share similar routes of transmission and risk factors with HIV. It has also been reported that HCV coinfection is very common among HIV positive populations [13, 14].
During early 1990s, illegal plasma and blood collection by commercial establishments was common in rural areas of central China, mainly as a mean for rural farmers to augment their household income [15]. Practices such as pooling of blood and re-infusion of red blood cells from donors with compatible blood types, exposed the blood donors to various blood borne pathogens including HIV. This practice had led to an outbreak of HIV in rural central China. Since the first outbreak of HCV infection among plasma donors in China in 1991, studies have shown a high seroprevalence of HCV in the illegal blood donor population [13, 16]. In contrast, very little is known about HHV8 epidemiology in China, especially in this unique high risk population. A few studies on HHV8 prevalence in mainland China and in Xinjiang Uygur autonomous region in Northwestern China, which is an endemic area for KS, have been reported [17, 18]. No seroprevalence studies of HHV8 have been conducted in areas of central China where a large number of illegal commercial blood/plasma donors reside, even though high prevalence of HCV and HIV has been observed in this area. The prevalence of HHV8 in this population and its correlation to HIV, HBV and HCV infection is not known.
Therefore, we conducted a cross-sectional epidemiological study to ascertain the seroprevalence of HHV8 and HCV among HIV infected patients and compared them to HIV negative individuals in a rural area in Shanxi province of Central China. To our knowledge, this is the first study to document HHV8 seroprevalence in this population. These findings will contribute to an enhanced awareness of HHV8 infection among these former blood donors.
MATERIALS AND METHODS
Study cohort and sample collection
The present study was conducted in Yun-cheng city, a rural prefecture area of Shanxi province in Central China, a community that harbors a large number of former illegal blood donors. The first case of HIV in a plasma donor for commercial gain from Yun-cheng city was reported in 1996. Since then 626 HIV/AIDS cases were reported by the end of 2004. Of these, 246 cases had died, 43 were untraceable.
A total of 620 subjects were included in the present study and all samples were collected in late 2004 through early 2005 for an observational study about the quality of life in this population. All samples were divided into two groups: a) HIV+ Group: All HIV-infected adults were recruited from the local clinic which offered free antiretroviral treatment program, as part of the national anti-HIV/AIDS campaign. Only adults participated in this study and 305 out of 326 cases (93.6%) gave consent. The rest 21 patients were unreachable, refused to be interviewed or provide blood sample. b) HIV− Group: This group included 315 HIV uninfected individuals who were randomly selected from a local community–based adult HIV screening program from a village in the study area.
Venous blood was drawn from each study subject, coded with a unique identification number and then transferred to the laboratory within 4 hours after collection. Plasma was aliquoted and stored at −70 °C. All assays were performed blindly and this study was approved by the Institutional Review Board of Fudan University, Shanghai, China.
Serological testing
a) HIV
All samples were screened with commercial enzyme-linked immunosorbent assay (ELISA; Abbott Laboratories) for HIV antibodies according to the manufacturers’ protocol. Samples tested positive by ELISA were confirmed by Western blotting.
b) HCV & HBV
ELISA for HBV surface antigen (HBsAg) and anti-HCV immunoglobulin G (IgG) antibodies was conducted to determine HBV and HCV infection status, according to the manufacturers’ protocol (Wantai Biomedical Co. Ltd, Beijing, China). All samples were assayed in duplicate.
c) HHV8
Plasma samples were tested by monoclonal antibody-enhanced immunofluoresence assay (IFA) as reported previously [19]. Briefly, two HHV8 serology tests were used. First, BC-3 cells, HHV8 positive and Epstein-Barr virus (EBV) negative B cell line (American Type Culture Collection, Manassas, VA.), stimulated by tetradecanoyl phorbol acetate (TPA) were fixed, permeabilized and used for monoclonal-enhanced immunofluorescence assay. Second, Spodoptera frugiperda clone 9 (Sf9) expressing three viral recombinant proteins, ORF73, ORF65 and K8.1, were used for testing. The procedure was similar to the BC-3 IFA. A sample was considered HHV-8-seropositive only if it was positive at a standard serum dilution of 1:40 utilizing both BC-3 and Sf9 assays. Each slide was read independently by two experienced laboratory workers.
Statistical analysis
Original questionnaire data and laboratory results were entered and managed with EpiData 3.0, and then transferred to SPSS v11.5 (Chicago, USA) for further analysis. Pearson Chi-square test and univariate logistic regression analyses were performed to explore correlates of HCV or HHV8 seropositivity. Multiple logistic regression analyses were conducted to identify risk factors for HCV or HHV8 prevalence after adjusting for potential confounders. Odds ratios (OR) with 95% confidence intervals (95% CI) were generated to determine whether a variable was independently associated with HCV or HHV8 prevalence. All p-values ≤0.05 were considered statistically significant. Mann-Whitney U test was used to assess the difference of geometric mean titers (GMTs) of HHV8 between the HIV+ and the HIV− groups. All statistical analyses were carried out using the SPSS software v11.5. Graphpad prism 5.0 (La Jolla, CA, USA) was used to construct figures.
RESULTS
Study cohort and characteristics
We enrolled 620 study participants (median age 43.0 years) from Yun-cheng city for the purposes of this study. The Han ethnic group is the major ethnic group in this province. The differences in ethnicity, age group, marital status, education and profession between the two groups were not significant. The HIV group was more likely to have multiple sex partners and individuals who had never used a condom. Seventy three percent of the HIV positive people sold blood/plasma at least once, 16.1% had a history of receiving blood transfusions, and 11.1% had history of surgery. The major demographic characteristics of all participants (305 HIV positive and 315 HIV negative subjects) are summarized in Table 1.
Table 1.
Characteristics of study participants.
| HIV + Group | HIV− Group | Total | |
|---|---|---|---|
| Gender (P=0.002) | |||
| Male | 165 (54.1%) | 132 (41.9%) | 297 (47.9%) |
| Female | 140 (45.9%) | 183 (58.1%) | 323 (52.1%) |
| Ethnicity (P=0.078) | |||
| Han | 302 (99.0%) | 315 (100.0%) | 617 (99.5%) |
| Others | 3 (0.9%) | 0 (0%) | 3 (0.5%) |
| Age group (P=0.029) | |||
| 19–29 | 10 (3.3%) | 18 (5.7%) | 28 (4.5%) |
| 30–49 | 224 (73.4%) | 201 (63.8%) | 425 (68.6%) |
| 50+ | 71 (23.3%) | 96 (30.5%) | 167 (26.9%) |
| Marital status (P=0.720) | |||
| Married | 292 (95.7%) | 302 (95.9%) | 594 (95.8%) |
| Single | 4 (1.3%) | 6 (1.9%) | 10 (1.6%) |
| Divorced/Widowed | 9 (3.0%) | 7 (2.2%) | 16 (2.6%) |
| Education (P=0.019) | |||
| Illiterate | 26 (8.5%) | 14 (4.4%) | 40 (6.5%) |
| Primary school | 109 (35.7%) | 111 (35.3%) | 220 (35.5%) |
| Middle school | 154 (50.5%) | 156 (49.5%) | 310 (50.0%) |
| High school or higher | 16 (5.2%) | 34 (10.8%) | 50 (8.1%) |
| Farmer (P=0.019) | |||
| Yes | 290 (95.1%) | 284 (90.2%) | 574 (92.6%) |
| No | 15 (5.0%) | 31 (9.1%) | 46 (7.4%) |
| Multiple sex partners (P=0.012) | |||
| Yes | 16 (5.2%) | 5 (1.6%) | 21 (3.4%) |
| No | 289 (94.8%) | 310 (98.4%) | 599 (96.6%) |
| Ever used condoms (P<0.001) | |||
| Yes | 256 (83.9%) | 290 (93.8%) | 546 (88.9%) |
| No | 49 (16.1%) | 19 (6.0%) | 68 (11.1%) |
| Ever had blood transfusion (P<0.001) | |||
| Yes | 49 (16.1%) | 16 (5.1%) | 65 (10.5%) |
| No | 256 (83.9%) | 299 (94.9%) | 555 (89.5%) |
| Ever donated blood/plasma (P<0.001) | |||
| Yes | 223 (73.1%) | 0 (0%) | 223 (35.9%) |
| No | 82 (26.9%) | 315 (100%) | 397 (64.1%) |
| Ever had a surgery (P<0.001) | |||
| Yes | 34 (11.1%) | 12 (3.8%) | 46 (7.5%) |
| No | 271 (88.9%) | 303 (96.2%) | 574 (92.5%) |
HHV8 serology and associated risks factors
We conducted logistic regression analysis for risk factors associated with HHV-8 seroprevalence in this population. HHV8 seroprevalence was significantly higher in the HIV positive than negative individuals (15.4% vs. 4.8%, respectively; P < 0.001). The univariate analysis showed that HIV infection, HBV infection and a history of blood/plasma donation were associated with HHV8 infection. Multiple logistic regression analysis indicated that HIV and HBV infection were independently associated with HHV8 infection (OR 2.71, 95% CI: 1.16–6.30 and OR 2.56, 95% CI: 1.14–5.75, respectively) (Table 2).
Table 2.
Seroprevalence and correlates of HHV8 infection among the study subjects
| Univariate analysis | Multivariate analysis | ||||
|---|---|---|---|---|---|
| Characteristics/Risk factor | Positive/Total (%) | OR 95%CI | p-value | OR (95%CI)* | p-value |
| Gender | |||||
| Male | 26/297(8.8%) | 1.00 | |||
| Female | 36/323 (11.1%) | 1.31 (0.77–2.22) | 0.323 | ||
| Age group | |||||
| 19–29 | 2/28 (7.1%) | 1.00 | |||
| 30–49 | 46/425 (10.8%) | 1.58 (0.36–6.86) | 0.543 | ||
| 50+ | 14/167 (8.4%) | 1.19 (0.26–5.54) | 0.825 | ||
| Education | |||||
| Illiterate | 4/40 (10.0%) | 1.00 | |||
| Elementary school | 26/220 (11.8%) | 1.21 (0.40–3.66) | 0.741 | ||
| Middle school | 28/310 (9.0%) | 0.89 (0.30–2.69) | 0.842 | ||
| High school or higher | 4/50 (8.0%) | 0.78 (0.18–3.35) | 0.741 | ||
| Farmer | |||||
| Yes | 58/574 (10.1%) | 1.00 | |||
| No | 4/46 (8.7%) | 0.85 (0.29–2.45) | 0.759 | ||
| Ever married | |||||
| Yes | 61/610 (10.0%) | 1.00 | |||
| No | 1/10 (10.0%) | 1.00 (0.12–8.03) | 1.000 | ||
| Multiple sex partners | |||||
| Yes | 2/21 (9.5%) | 0.95 (0.22–4.16) | 0.941 | ||
| No | 60/599 (10.0%) | 1.00 | |||
| Ever used condoms | |||||
| Yes | 56/546 (10.3%) | 1.18 (0.49–2.85) | 0.712 | ||
| No | 6/68 (8.8%) | 1.00 | |||
| HIV infection status | |||||
| Positive | 50/305 (15.4%) | 3.64 (1.99–6.67) | <0.001 | 2.71 (1.16–6.30) | 0.021** |
| Negative | 15/315 (4.8%) | 1.00 | 1.00 | ||
| HBsAg | |||||
| Positive | 9/45 (20.0%) | 2.46 (1.12–5.39) | 0.024 | 2.56 (1.14–5.75) | 0.022** |
| Negative | 53/575 (9.2%) | 1.00 | 1.00 | ||
| Ever had blood transfusion | |||||
| Yes | 8/685 (12.3%) | 1.30 (0.59–2.87) | 0.513 | ||
| No | 54/555 (9.7%) | 1.00 | |||
| Ever donated blood/plasma | |||||
| Yes | 37/223 (16.6%) | 2.96 (1.73–5.60) | <0.001 | 1.493 (0.71–3.18) | 0.299 |
| No | 25/397 (6.3%) | 1.00 | 1.00 | ||
Odds ratio and p-value obtained by multiple logistic regression model, which was adjusted for all demographic variables listed in this table. 95% CI: 95% confidence interval
HHV8 Antibody titer distribution
We also wanted to determine whether the geometric mean titer (GMT) of HHV8 antibodies differed between HIV+ and HIV− groups. Therefore, plasma from all HHV8 seropositive subjects was serially diluted and tested for IgG anti-HHV8 antibody titer. As shown in Figure 1, the GMT of HHV8 antibodies was 417.3 (95% CI: 319.5–545.1) for HIV positive group (n=47) and 403.2 (95% CI: 294.7–551.6) for HIV negative group (n=15). We did not observe any significant difference between the GMT of HHV8 antibodies between HIV infected and uninfected group (Mann-Whitney U=357.5, P=0.782).
Figure 1.
GMT of HHV8 antibodies in seropositive participants in the HIV positive and negative groups.
*Antibody titers were determined by IFA based on BC3 slides. GMT for both groups were calculated and compared. (Mann-Whitney U=357.5, P=0.782)
HCV serology and associated risk factors
HCV seroprevalence was significantly higher in the HIV positive than negative group (74.4% vs. 2.5%, respectively; P < 0.001). In the univariate analysis, gender, condom usage, HIV status, history of selling blood/plasma and history of surgery were found to associate with HCV infection. Multivariate analysis indicated that subjects who were HIV positive (OR 23.03; 95%CI 9.95–53.27) or those who had a history of selling blood/plasma (OR 14.57; 95%CI 7.49–28.23) were more likely to be HCV seropositive than those who were HIV negative or had no history of selling blood/plasma (Table 3).
Table 3.
Seroprevalence and correlates of HCV infection among the study subjects
| Univariate analysis | Multivariate analysis | ||||
|---|---|---|---|---|---|
| Characteristics/Risk factor | Positive/Total (%) | OR 95%CI | p-value | OR (95%CI)* | p-value |
| Gender | |||||
| Male | 142/297 (47.8%) | 1.00 | 1.00 | ||
| Female | 99/323 (30.7%) | 0.48 (0.35–0.67) | <0.001 | 0.82 (0.45–1.50) | 0.52 |
| Age group | |||||
| 19–29 | 7/28 (25.0%) | 1.00 | |||
| 30–49 | 167/425 (39.3%) | 1.94 (0.81–4.67) | 0.138 | ||
| 50− | 67/167 (40.1%) | 2.01 (0.81–4.99) | 0.133 | ||
| Education | |||||
| Illiterate | 19/40 (47.5%) | 1.00 | |||
| Elementary school | 91/220 (41.4%) | 0.78 (0.40–1.53) | 0.471 | ||
| Middle school | 123/310 (39.7%) | 0.73 (0.38–1.41) | 0.344 | ||
| High school or higher | 8/50 (16.0%) | 0.22 (0.08–0.56) | 0.002 | ||
| Farmer | |||||
| Yes | 230/574 (40.1%) | 1.00 | 1.00 | ||
| No | 11/46 (23.9%) | 0.47 (0.23–0.94) | 0.034 | 0.61 (0.17–2.17) | 0.45 |
| Ever married | |||||
| Yes | 237/610 (38.9%) | 1.00 | |||
| No | 4/10 (40.0%) | 1.05 (0.29–3.76) | 0.941 | ||
| Multiple sex partners | |||||
| Yes | 10/21 (47.6%) | 1.45 (0.61–3.46) | 0.405 | ||
| No | 231/599 (38.6%) | 1.00 | |||
| Ever used condoms | |||||
| Yes | 198/546 (36.3%) | 0.33 (0.20–0.56) | 0.001 | 0.69 (0.28–1.76) | 0.44 |
| No | 43/68 (63.2%) | 1.00 | 1.00 | ||
| HIV infection status | |||||
| Positive | 233/305 (76.4%) | 124.19 (58.66–262.91) | <0.001 | 23.03 (9.95–53.27) | <0.001** |
| Negative | 8/315 (2.5%) | 1.00 | 1.00 | ||
| HBsAg | |||||
| Positive | 16/45 (35.6%) | 0.86 (0.46–1.62) | 0.636 | ||
| Negative | 225/575 (39.1%) | 1.00 | |||
| Ever had blood transfusion | |||||
| Yes | 28/65 (43.1%) | 1.22 (0.72–2.04) | 0.463 | ||
| No | 213/555 (38.4%) | 1.00 | |||
| Ever donated blood/plasma | |||||
| Yes | 202/223 (90.2%) | 88.29 (50.54–154.20) | <0.001 | 14.57 (7.49–28.23) | <0.001** |
| No | 39/397 (9.8%) | 1.00 | 1.00 | ||
Odds ratio and p-value obtained by multiple logistic regression model, which was adjusted for all demographic variables listed in this table. 95% CI: 95% confidence interval
Coinfection of HBV, HCV and HHV8
The overall seroprevalence of HBV, HCV and HHV8 among the study subjects was 7.3% (45/620), 38.9% (241/620) and 10.0% (62/620), respectively. The seroprevalence of HBV, HCV and HHV8 was 7.5% (23/305), 76.4% (233/305) and 15.4% (47/305), respectively in the HIV positive group, and 7.0% (22/315), 2.5% (8/315) and 4.8% (15/315), respectively in the HIV negative group. Both HIV-infected and uninfected groups had no significant difference in prevalence of HBV (P=0.789) but had significant difference in prevalence of both HCV (P < 0.001) and HHV8 (P < 0.001). As shown in Table 4, 54 (17.7%) HIV-infected individuals were not coinfected with HBV, HCV or HHV8. However, 202 (66.2%) were coinfected with either one of the three viruses; 46 (15.1%) were coinfected with two viruses, and 3 (1.0%) were coinfected with all three viruses. Among the 202 HIV-infected individuals who were coinfected with only one of the above three viruses, 187 (92.6%) were coinfected with HCV (Table 4). Among the 46 HIV positive individuals with coinfections of two out of three viruses, 31 (67.4%) were coinfected with HCV and HHV8. For HIV-uninfected individuals, the majority (87.3%) were negative for all three viruses. Thirty-five (11.1% of 315) were coinfected with only one other virus, of which 51.4% were HBV-infected. Five (1.6%) were coinfected with two other viruses (HBV, HCV and/or HHV8), and none with all three viruses (Table 4).
Table 4.
Summary of infection by HBV, HCV and HHV8 in HIV positive and negative groups
| HIV+ Group (N=305) | HIV− Group (N=315) | |||
|---|---|---|---|---|
| Co-infected with | No. | Prevalence (%) |
No. | Prevalence (%) |
| None | 54* | 17.7 | 275 | 87.3 |
| Single virus only | ||||
| HBV | 5* | 1.6 | 18 | 5.7 |
| HCV | 187* | 61.3 | 6 | 1.9 |
| HHV8 | 10* | 3.3 | 11 | 3.5 |
| Dual viruses | ||||
| HBV+HCV | 12* | 3.9 | 1 | 0.3 |
| HBV+HHV8 | 3* | 1.0 | 3 | 1.0 |
| HCV+HHV8 | 31* | 10.2 | 1 | 0.3 |
| Triple viruses | ||||
| HBV+HCV+HHV8 | 3* | 1.0 | 0 | 0 |
These infections are HHV8, HCV or HBV plus HIV
DISCUSSION
Given the continuing spreading of the HIV/AIDS epidemic in China, HHV8, an important opportunistic infection could become a major public health concern in China. However, little information is available for the prevalence and transmission patterns of HHV8 among the Chinese population, which can be of great importance to HHV8 prevention and control in China and to HIV/AIDS care in particular. Therefore, studies to understand the modes of HHV8 transmission and risk factors for HHV8 acquisition in China are required.
The results from this study demonstrated a higher HHV8 seroprevalence (15.4%) in HIV positive group as compared to the HIV negative group (4.8%), which is consistent with other serological studies on epidemiology of HHV8 infection in Shandong area, a neighboring province in China [20]. HHV8 prevalence varies considerably in different regions of the country. It is reported to be 19.3% to 46.6% in the general population of Xinjiang, but only between 7.3% to 16.1% in other provinces in China [17, 18, 20, 21]. In support of other studies conducted in China, we also find that HHV8 infection is not ubiquitous in China. Compared with results from the Xinjiang area, our subjects have relatively low HHV8 prevalence. The reason for these differences may due to ethnicity, socioeconomic status, environmental characteristics and hygiene practices. Previous data have shown that both the ethnic and socioeconomic factors can influence HHV8 infection, even in the Han population in Xinjiang, which was regarded as a low risk group throughout China, although the HHV8 prevalence in the same ethnic group is higher than in other parts of China [17]. Interestingly, in our study, the HIV positive group was found to have a slightly higher anti-HHV8 antibody titer than the negative group, although the difference is not statistically significant.
As expected, we observed a very high level of coinfection with HCV in the HIV positive group (76.4%) and a much lower HCV prevalence in the HIV negative group (2.5%), which reflects the infection rate of general population in the rest of China. Since both HCV and HIV are transmitted via blood, with HCV being more infectious than HIV, it is not surprising that high HCV coinfection rate was detected in this study. Several studies on the HCV coinfection in former blood donors from other areas in China have shown similar results, demonstrating that the HCV prevalence can be as high as 78.6% to 86.3% among HIV positive subjects [13, 22, 23]. Our results further confirm that HCV infection is primarily blood-borne and is of public health importance to antiretroviral therapy (ART) in areas with illegal plasma/blood donors.
The current study results suggest that HIV infection was positively associated with both HHV8 and HCV infections. Furthermore, there is an association between HHV8 and HBV, but not between HHV8 and HCV coinfections. It is possible that factors associated with HBV transmission, such as close familial contact and sharing hygiene equipment are also potentially associated with HHV8 transmission. In fact, association between HHV8 and HBV infections has been reported in previous studies [12, 24]. Since the HIV transmission route and blood/plasma selling history were independently associated with HCV but not with HHV8 and HBV, it is likely that HHV8 transmission route in this population is not via blood and is different from HCV. The association between HIV and HHV8 co-infection could be due to immunosuppression which rendered HIV infected individuals more susceptible to HHV8 infection. A previous study on HHV8 transmission has shown that transmission of HHV8 via blood is inefficient [25]. In fact passive transfer of HHV8 antibody was even suggested to have a protective effect in HHV8 transmission [26]. In our study no association between sexual behavior, including multiple sex patterns, condom use and HHV8 positive status was observed. This is also consistent with several previous studies demonstrating that heterosexual transmission of HHV8 is rare [27, 28]. Together these findings support the hypothesis that common routes of transmission are rarely shared by HCV and HHV8 infections in this area, which deserve further intensive research.
In conclusion, both HHV8 and HCV infections are prevalent in this former illegal blood donating community, with HIV acting as an important factor for their coinfection. Our data demonstrates that HBV infection is associated with HHV8 infection but not with HCV infection. HHV8 and HBV, but not HCV, may have similar mode of transmission in this population. A number of studies have shown that HHV8 can be detected and potentially be transmitted via saliva contact [29, 30], it is possible that the saliva might play an important role in transmission in this study population. We are unable to delineate this route as saliva samples were not collected as a part of this study. Further, prospective studies on HHV8 seroprevalence and more extensive risk factor analysis, such as living arrangement, hygiene conditions and food sharing practices are needed to explore the epidemiology of HHV8 infection in this population.
Acknowledgments
TRANSPARENCY DECLARATION
This study was supported by grants from Chinese National Natural Science Foundation (30671880), Shanghai Municipal Education Committee (08ZZ02); the United States National Institutes of Health Fogarty International Center (D43 TW001492), NCI (CA75903) and NCRR COBRE grant (RR15635) to C.W.; TZ was a Fogarty Scholar.
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