Sweat of infected patients may contain hepatitis C: inapparent parenteral transmission

OB/GYN News, Dec 15, 2003 by Bruce Jancin

BARCELONA, SPAIN -- Hepatitis C virus actively replicates in the healthy epidermis and sweat glands of chronically infected patients--and more important, is secreted in their sweat, Dr. M. Isabel Longo said at the 12th Congress of the European Academy of Dermatology and Venereology.

This finding lends support to the hypothesis--admittedly unproven and controversial--that many cases of hepatitis C virus (HCV) infection in individuals without any of the recognized risk factors might be due to inapparent parenteral transmission through minor skin abrasions, added Dr. Longo, a dermatologist at Gregorio Maranon Hospital in Madrid.

The major known routes of HCV transmission are parenteral. They include intravenous drug use and tattooing. But in numerous epidemiologic studies, 10@% of HCV-infected individuals do not have any of the recognized risk factors for the disease. And it is in this group where the recent finding by Dr. Longo and her colleagues that HCV is secreted in sweat takes on relevance regarding the potential etiology of infection.

She reported on 15 patients with HCV and no other medical conditions and 10 control subjects with hepatitis due to causes other than HCV. All participants underwent biopsies of healthy-looking skin. The tissue specimens were analyzed for the presence of HCV by in situ hybridization, reverse transcriptase-polymerase chain reaction, and immunohistochemistry.

HCV RNA was consistently detected in the epidermis of infected patients. The epidermal involvement was restricted to keratinocytes, of which 6% were infected by HCV.

HCV was also detected in dermal sebaceous and sweat glands of infected patients. Nearly 10% of epithelial cells in the basal glandular coil of eccrine sweat glands were infected, and 4.2% demonstrated evidence of active HCV replication. The degree of a patient's viremia correlated positively with the percentage of epithelial sweat gland cells that were infected, she noted.

All 10 sweat samples from HCV-infected patients proved positive for encapsulated HCV RNA. The concentration of HCV in sweat was roughly 100-fold less than in serum.

Is this sweat infectious? The answer to this critical question is as yet unknown. But the finding that HCV is present in the sweat of chronically infected individuals takes on added significance in light of a Centers for Disease Control and Prevention report earner this year, Dr. Longo said.

In the CDC report, Dr. Elise M. Beltrami of the CDC's National Center for Infectious Diseases in Atlanta provided details of a case of simultaneous transmission of HCV and HIV from a nursing home patient to a health care worker who had no known risk factors for either disease. Viral genotyping demonstrated that the viruses from both individuals were very closely related.

The health care worker had markedly chapped and abraded hands and had not consistently worn gloves in providing patient care. The most likely scenario is that HCV and HIV infections were transmitted from the nursing home patient by way of the health care worker's nonintact skin, according to Dr. Beltrami and her coinvestigators (Am. J. Infect. Control 31[3]:168-75, 2003).

Individuals with psoriasis, eczema, or other disorders that adversely affect the integrity of the skin's barrier function may possibly be at increased risk for HCV infection. The same might apply to patients who have recently undergone surgery, Dr. Longo said.