Occupational Transmission

Health care workers should be at great risk of HIV infection. But, according to the CDC, not a single paramedic or surgeon has acquired HIV or AIDS through on the job exposure? How can this be, particularly when paramedics are at grave risk of exposure to foreign blood, and testing in emergency conditions is simply not an option?

Tomkins S, Ncube F. Occupational transmission of HIV: Summary of published reports. Health Protection Agency. 2005 Mar.

“Health care professionals are more susceptible than most members of the population to occupational hazards involving blood and other body fluids. The greatest hazard is associated with occupations involving perforating and cutting materials…Among medical professionals, surgeons present the highest risk because of their extensive use of needles and perforating instruments in surgical procedures. Plastic surgeons spend relatively more operating time suturing subcutaneous and skin than those involved in other surgical specialities…[they make] more use of more delicate materials such as skin hooks, thus maximizing the risk of perforations…This prospective study examined 1100 gloves from two groups. For group A, 390 gloves from 100 consecutive plastic surgery procedures were examined…For group B, 710 gloves from 100 major plastic surgeries were examined…Considering all the professionals involved in the surgeries, 4 gloves from 3 minor procedurs were peforated, as compared with 76 gloves from 49 major procedures…during 10 major procedures, the surgeons were aware of perforations and changed gloves…These cases were not included in the current study…major surgeries required 1 to 6 hours (average, 186 minutes) [yet, in the United States at least, with close to one million cases of AIDS reported, not one has been in a surgeon (without other risk factors)] ”

Barbosa MV et al. Risk of glove perforation in minor and major plastic surgery procedures. Aesthetic Plast Surg. 2003 Nov-Dec;27(6):481-4.

“The maintenance of seronegativity despite exposure to HIV has been observed in sexual partners of HIV infected persons [7 references given], infants born to HIV-infected mothers [3 references], commercial sex workers [4 references] and health care workers occupationally exposed to HIV-contaminated body fluids [2 references] ”

Makedonas G et al. HIV-specific CD8 T-cell activity in uninfected injection drug users is associated with maintenance of seronegativity. AIDS. 2002 Aug 16;16(12):1595-602.

“As of June 2000, CDC had received voluntary reports of 56 U.S. HCP [Health Care Personnel] with documented HIV seroconversion temporally associated with an occupational HIV exposure [but far fewer cases of AIDS, and not a single one in a paramedic or surgeon! And this is at a time when 765,559 AIDS cases had been reported, and presumably there had been many more cases of HIV infection] ”

Updated U.S. Public Health Service Guidelines for the Management of Occupational Exposures to HBV, HCV, and HIV and Recommendations for Postexposure Prophylaxis. MMWR. 2001 Jun 29;50(RR11):1-42
http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5011a1.htm.

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“To date, only one study has reported that zidovudine (ZDV) alone may protect from occupational post-exposure infection with an efficacy estimated at 81%. However, a retrospective case-control study is not the optimal design for assessing the efficacy of such strategies, thus limiting the significance of this observation...Three control animals were treated with placebo and four animals were treated, as recommended in humans, by the combination of ZDV (4.5 mg/kg), 3TC (2.5 mg/kg) and indinavir (20 mg/ kg) 4 h after experimental intravenous inoculation of SHIV89.6P [SIV/HIV mixture virus]...All the animals became infected, demonstrating that initiating this treatment as early as 4 h post-inoculation does not protect from intravenous inoculation of cell-free virus. ”

Le Grand et al. Post-exposure prophylaxis with highly active antiretroviral therapy could not protect macaques from infection with SIV/HIV chimera. AIDS. 2000 Aug 18;14(12):1864-6.

“More than 8 million health care workers in the United States work in hospitals and other health care settings. Precise national data are not available on the annual number of needlestick and other percutaneous injuries among health care workers; however, estimates indicate that 600,000 to 800,000 such injuries occur annually. About half of these injuries go unreported. Data from the EPINet system suggest that at an average hospital, workers incur approximately 30 needlestick injuries per 100 beds per year.

Most reported needlestick injuries involve nursing staff; but laboratory staff, physicians, housekeepers, and other health care workers are also injured. Some of these injuries expose workers to bloodborne pathogens that can cause infection. ”

NIOSH Alert: preventing needlestick injuries in health care settings. DHHS (NIOSH). 1999 Nov;2000-108.

“In 18 cases [of occupational exposure] HIV infection occurred in spite of a complete or partial course of PEP with zidovudine [AZT] ”

Ippolito G et al. Occupational human immunodeficiency virus infection in health care workers: worldwide cases through September 1997. Clin Infect Dis. 1999 Feb;28(2):365-83.

“We conducted a case-control study of health care workers with occupational, percutaneous exposure to HIV-infected blood. The case patients were [33] who became seropositive after exposure to HIV…in France, Italy, the United Kingdom, and the United States. The controls were [665 US] health care workers…who were exposed to HIV but did not seroconvert…analysis…showed that significant risk factors for seroconversion were deep injury (odds ratio= 15), injury with a device that was visibly contaminated with the source patient's blood (odds ratio= 6.2), a procedure involving a needle placed in the source patient's artery or vein (odds ratio=4.3), and exposure to a source patient who died of the acquired immunodeficiency syndrome within two months afterward (odds ratio=5.6)…By univariate analysis, there was no significant difference between case patients and controls in the use of zidovudine after exposure (9 of 33 case patients, or 27 %, vs. 247 of 679 controls, or 36 %)…[However, after adjustment for all the other variables significantly associated with seroconversion] the case patients were significantly less likely than the controls to have taken zidovudine after the exposure (odds ratio=0.19). ”

Cardo DM et al. A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group. N Engl J Med. 1997 Nov 20;337(21):1485-90.

“Env-specific T helper responses evaluated in a total of 28 HIV seronegative, PCR negative HCW [health care workers] with HIV exposures [of which 10 had taken AZT], indicated that 21 of them (75%) showed responses to two or more of the five peptides [proteins believed to be from HIV] and in certain individuals these responses were observed more than 23 wk after exposure. Surprisingly, 24% (9/38) of HCW with HIV negative exposures exhibited responses to the peptides in contrast to 9% (3/33) in healthy blood donors…and the difference between the groups were statistically significant. It cannot be ruled out that some of the exposures to negative fluids were actually to fluids from HIV-infected individuals who had not yet seroconverted [or that the 'HIV' proteins are not actually specific for this virus] ”

Pinto LA et al. ENV-specific cytotoxic T lymphocyte responses in HIV seronegative health care workers occupationally exposed to HIV-contaminated body fluids. J Clin Invest. 1995 Aug;96(2):867-76.

“PBMCs [peripheral blood mononuclear cells] from 8 health care workers with high-risk exposures and 9 control health care workers were studied…None of the HIV-exposed health care workers became infected as determined by negative HIV antibody and polymerase chain reaction analysis after follow-up evaluation that ranged from 8 to 64 weeks ”

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Clerici M et al. HIV-specific T-helper activity in seronegative health care workers exposed to contaminated blood. JAMA. 1994 Jan 5;271(1):42-6.

“[this study included US health care workers exposed] to blood from a patient with documented HIV infection [81% had AIDS] as a result of percutaneous injury (for example, a needlestick or a cut from a sharp object), contamination of mucous membranes, or contamination of nonintact skin…1245 workers were enrolled and tested for HIV antibody at baseline [as soon as possible after the exposure] and at least 180 days after exposure…4 seroconverted to HIV…From October 1988 to Jun 1992, the period when use of zidovudine [AZT] was studied, 848 workers were enrolled. Postexposure zidovudine was used by 265 (31%) of these workers…in doses range from 200 to 1800 mg/day and for periods of 1 to 180 days…The proportion of enrolled workers using zidovudine increased from 5% in the fourth quarter of 1988 to 50% in the third quarter of 1990 and has been stable subsequently…no seroconversions occurred among 301 workers not using zidovudine, and 1 seroconversion occurred among 143 workers using zidovudine…176 (75%) reported one or more symptoms, most commonly nausea, malaise or fatigue, or headache. Symptoms were reported less frequently among workers who did not use zidovudine…Of 175 workers who completed 21 or more days of [AZT] prophylaxis, 51 (29%) had paired hemograms at least 21 days apart…7 (14%) had a 10% or greater reduction in hemoglobin or hematocrit values…74 (31%) of workers did not complete their planned regime of zidovudine because of adverse symptoms (73) or reduction in hemoglobin level (1)…28 (12%) of workers were absent from work for periods ranging from 1 to 49 days because of adverse events attributed to zidovudine…because of uncertainty about efficacy and safety, the Public Health Service concluded in January 1990 that a recommendation for or against the use of posexposure zidovudine could not be made. ”

Tokars JI et al. Surveillance of HIV infection and zidovudine use among health care workers after occupational exposure to HIV-infected blood. The CDC Cooperative Needlestick Surveillance Group. Ann Intern Med. 1993 Jun 15;118(12):913-9.

“Our analyses show that the available data are consistent with both the dental transmission hypothesis [from dentist Acer to Kimberly Bergalis and other patients] and the null hypothesis [that all Acer’s patients became HIV-positive independently] and do not yet distinguish between the two. Much of the difficulty lies in the decision of Ou et al to focus on the small, highly variable C2-V3 region. ”

DeBry RW et al. Dental HIV transmission?. Nature. 1993 Feb 25;361:691.

“Of 19 seropositive health-care workers, 10 reported a definitive nonoccupational risk for HIV-1. Of the other 9, 1 nursing student had no patient exposure, 2 could not be fully evaluated…and 3 reported highly suggestive nonoccupational exposures but could not be definitely classified into HIV risk categories. The remaining 3 seropositive donors had HIV infection that was probably occupation-related.”

Petersen LR, Doll LS. Human immunodeficiency virus type 1-infected blood donors: epidemiologic, laboratory, and donation characteristics. The HIV Blood Donor Study Group. Transfusion. 1991 Oct;31(8):698-703.

“The risk of HIV-1 infection associated with a single needle stick is estimated to be less than 0.4%. ”

Lange JM et al. Failure of zidovudine prophylaxis after accidental exposure to HIV-1. N Engl J Med. 1990 May 10;322(19):1375-7.

“From Oct 15 through 25, 1984, 2400 Mama Yemo Hospital employees were enrolled in [this] study…Three personal medical factors were significiantly associated with seropositivity: (1) receiving a blood transfusion, (2) being hospitalized during the previous ten years, and (3) receiving medical injections during the previous three years. Workers who reported receiving five or more injections had a significantly higher seroprevalence than those reporting one to four injections…Seropositivity was not associated with reported occupational exposures to patients or their blood. Seropositivity did not vary significantly by extent of exposure among those reporting patient contact, blood contact, blood drawing, or accidental needle sticks…Data on nurses were analyzed separately since their likelihood of exposure to HIV-infected patients was considered high…Seropositivity was not associated with occupational exposures. In addition, no association was observed between seropositivity and hospital service, number of patient and blood contacts, type of blood contacts, or number of accidental needle sticks during the past year. ”

Mann JM et al. HIV seroprevalence among hospital workers in Kinshasa, Zaire. Lack of association with occupational exposure. JAMA. 1986 Dec 12;256(22):3099-102