Statistical analyses included descriptive statistics presented as numbers (percentages) for categorical variables and medians (interquartile ranges [IQRs]) for continuous variables. The percentage of participants with HEV infection was defined as the number with an initial positive result for IgM or IgG against HEV divided by the total number of evaluable study participants. To compare characteristics among those with and without HEV infection, we used Fisher exact testing for categorical variables and rank-sum testing for continuous variables. A multivariate logistic regression model was used to identify factors associated with HEV infection. All analyses were performed by using Stata version 10.0 (StataCorp LP, College Station, TX, USA).

Among 4,410 HIV-infected persons, 458 (10%) had increased ALT levels at least 1 time during 32,468 person-years of follow-up. Among these, serum samples were available for HEV testing for 194 (42%) participants, among whom median age was 34 (IQR 30–40) years, 95% were male, and 42% were white (Table 1). The median ALT level was 440 (IQR 322–812) IU/mL. At the ALT spike, participants had been infected with HIV for a median duration of 5 (IQR 2–9) years; median CD4 cell count was 436 (IQR 239–627) cells/mm³, median plasma HIV RNA level was 13,581 (IQR 762–71,586) copies/mL, and 28% of participants were receiving antiretroviral therapy.

Samples for HEV testing were available at a median of 27 (IQR 0–104) days after the increase in ALT level. For 13 (6.7%) participants, IgM and/or IgG against HEV were present at the time closest to the ALT increase; antibody prevalence among those with elevated ALT levels did not increase during the HIV epidemic (χ² 0.76, p = 0.68). The 13 HIV-infected persons who were HEV seropositive (IgM or IgG at ALT spike) were similar to the 181 who were HEV seronegative in terms of demographics, military duty status, laboratory data, and overseas travel (Table 1). HEV-seropositive persons had higher plasma HIV RNA levels (4.7 vs. 4.1 log₁₀ copies/mL, p = 0.04) and the association with lower CD4 cell counts was borderline (median 217 vs. 439 cells/mm³, p = 0.07). In the multivariate logistic regression model adjusted for age, plasma HIV RNA levels remained significantly associated with HEV seropositivity (odds ratio 1.96 per log₁₀, 95% CI 1.04–3.71, p = 0.04).

Additional testing was conducted for all 13 participants with IgM or IgG against HEV or with HEV RNA at the time of ALT increase (Figure 1). HEV RNA was detected in 1 participant who also seroconverted (IgG) at the time of ALT increase. According to samples collected at or near ALT spike and after ALT spike, 5 more participants seroconverted. One participant had IgM detectable in all 3 samples (at or near ALT spike, after ALT spike, and at follow-up); the participant did not seroconvert, and HEV RNA was not detectable in any sample. In total, 7 (3.6%, 95% CI 1.6%–7.6%) of the 194 HIV-infected persons had evidence of acute HEV infection at time of ALT spike (Figure 2). HEV was deemed not to be the cause of the ALT spike for 5 participants with evidence of prior HEV infection because IgG positivity preceded the ALT increase. For 1 participant, IgM was found in only 1 sample; all other samples were negative for IgM, IgG, and HEV RNA. Because of unconfirmed positive follow-up results, this participant was excluded from further analysis.

For the 7 participants with acute HEV infection (Table 2), HEV was not considered during the ALT increase, and HEV testing was not conducted as part of clinical care. No significant differences in clinical or laboratory characteristics were found among the 7 participants with acute HEV infection and those without evidence of HEV infection (data not shown). Chronic HEV infection did not develop in any participant.

HEV seropositivity did not increase over the course of the HIV epidemic. Despite increasing reports of HEV among HIV-infected persons and the general population (1,3,7–10), this increase is probably associated with increased recognition and testing. Recent studies in the United States and Europe have shown that HEV seroprevalence is stable or decreasing (1,11).

HEV infections among HIV-infected persons have been reported (3,7–9,12); however, whether this population is at increased risk for HEV infection remains uncertain. Recent studies from Europe suggest that HIV-infected persons or other immunocompromised persons are not at increased risk of acquiring HEV infections (7–9,12). Nonetheless, these groups are at higher risk for chronic HEV infection (2,7,13).

We propose that a diagnosis of HEV infection be considered for persons with viral-like hepatitis. Serologic test results may be negative despite ongoing HEV infection; hence, for HIV-infected persons (especially those with low CD4 cell counts), PCR testing for HEV RNA should be conducted (7). Because HEV infection may be fulminant in the presence of underlying liver disease (common among HIV-infected persons) (14) and may lead to chronic infection in immunosuppressed persons (2,13), testing should be considered for these persons as treatment options for HEV infection evolve. Moreover, chronic HEV infection may be averted by reducing the level of immunosuppression (15) and use of highly active antiretroviral therapy (3,8), but more data are needed to support these measures.