Estimating HIV-1 transmission efficiency through unsafe medical injections

Abstract

Summary:The transmission ef® ciency of HIV-1 through unsafe medical injections can be estimated from seroconversions among health care workers (HCWs) after percutaneous exposures and documented iatrogenic outbreaks. Data from a case± control study of seroconversion after percutaneous exposures among US and European HCWs shows an average rate of seroconversion after deep injuries Ð arguably comparable to unsafe injections Ð of 2.3%. Information from an iatrogenic HIV outbreak in a Romanian orphanage suggests a transmission ef® ciency of 2± 7%. Even these estimates may be too low to explain the rapid spread of HIV among Russian and Libyan children in iatrogenic outbreaks discovered in 1988 and 1998, respectively. In countries in sub-Saharan Africa and elsewhere with high HIV prevalence and large numbers of unsafe injections, personal risk as well as the share of the HIV epidemic associated with unsafe injections may be an order of magnitude higher that many experts have supposed.

Transmission of HIV-1 infection in sub-Saharan Africa and effect of elimination of unsafe injections

“…6 Injections given with reused equipment are more common in the Middle East and south Asia than in subSaharan Africa, where the results of population-based surveys indicate that an estimated 2·1 injections are given per person per year, of which about 18% (approximate 95% CI [13][14][15][16][17][18][19][20][21][22][23] are given with reused equipment. This proportion is considerably less than the 50% of injections cited by Gisselquist and colleagues, 7 and results in a mean of 0·4 potentially unsafe injections per person per year. 6 Most injections in sub-Saharan Africa are given intramuscularly, and blood contamination of needles after use for intramuscular injection is infrequent.…”

“…7 Even if one accepts their calculations and assumptions, unusual outbreaks are likely to have higher than usual transmission efficiency. The Russian outbreak was a result of a combination of intramuscular and intravenous (catheter and possibly transfusion) exposures; 22 the Romanian outbreak involved the sequential, immediate use of large-bore needles in children; and there are few epidemiological data from the Libyan outbreak.…”

“…19,20 Gisselquist and colleagues use two arguments to arrive at their much higher estimated risk of transmission efficiency of 2·3%. 7 A case-control study 21 on occupational risk of HIV-1 infection identified several factors that increase the risk of infection, including deep injury, visible blood on the device, any procedure involving drawing blood from an artery or vein in the source patient, and terminal illness of the source patient. Gisselquist and colleagues used the proportion of cases and controls in the study that reported a deep injury to estimate the risk after a deep injury as 2·3%.…”

HIV infections in sub-Saharan Africa not explained by sexual or vertical transmission

“…Furthermore, many health care workers were treated with zidovudine for post-exposure prophylaxis, which reportedly reduced seroconversion rates by over 80% 95 . Because medical injections occasion a deep injury and are not countered by antivirals, HIV transmission during unsafe injections may well be an order of magnitude greater than 0.3% 96 .…”

Quantifying HIV-1 transmission due to contaminated injections

“…A lthough controversial, recent suggestions that HIV-1 (HIV)-contaminated (hereafter referred to as "contaminated") injections might be a major, but largely overlooked, route of HIV transmission in sub-Saharan Africa, should be considered seriously (1,2). If true, there would be profound implications for HIV control policy in the region.…”