Evolution of the Global Burden of Viral Infections from Unsafe Medical Injections, 2000–2010
2010. PLoS ONE 9(6): e99677. doi:10.1371/journal.pone.0099677
Evolution of the Global Burden of Viral Infections from Unsafe Medical Injections, 2000-2010
Jacques Pe pin 0 1 2 3 4 5 6 7 8
Claire Nour Abou Chakra 0 1 2 3 4 5 6 7 8
Eric Pe pin 0 1 2 3 4 5 6 7 8
Vincent Nault 0 1 2 3 4 5 6 7 8
Louis Valiquette 0 1 2 3 4 5 6 7 8
Dimitrios Paraskevis, University of Athens, Medical School, Greece
0 Department of Microbiology and Infectious Diseases, Universite de Sherbrooke , Sherbrooke, Que bec , Canada
1 Antigua and Barbuda , Argentina, Bahamas, Barbados, Belize, Brazil, Chile, Colombia , Costa Rica , Dominica , Dominican Republic , El Salvador, Grenada, Guyana, Honduras, Jamaica, Mexico, Panama, Paraguay , Saint Kitts and Nevis , Saint Lucia, Saint Vincent and the Grenadines, Suriname, Trinidad and Tobago, Uruguay , Venezuela
2 Botswana , Burundi , Central African Republic , Congo, Co te d'Ivoire , Democratic Republic of the Congo, Eritrea, Ethiopia, Kenya, Lesotho, Malawi, Mozambique, Namibia, Rwanda, South Africa, Swaziland, Uganda, Tanzania, Zambia , Zimbabwe
3 Algeria , Angola, Benin , Burkina Faso , Cameroon , Cape Verde , Chad, Comoros , Equatorial Guinea , Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Madagascar, Mali, Mauritania, Mauritius, Niger, Nigeria , Sao Tome and Principe , Senegal, Seychelles, Sierra Leone , Togo
4 Cambodia , China, Cook Islands, Fiji, Kiribati, Lao, Malaysia , Marshall Islands , Micronesia, Mongolia, Nauru, Niue, Palau , Papua New Guinea , Philippines , Republic of Korea, Samoa , Solomon Islands , Tonga, Tuvalu, Vanuatu , Viet Nam
5 Belarus , Estonia, Hungary, Kazakhstan, Latvia, Lithuania , Republic of Moldova, Russian Federation , Ukraine
6 Albania , Armenia, Azerbaijan, Bosnia and Herzegovina, Bulgaria, Georgia, Kyrgyzstan, Poland, Romania, Slovakia, Tajikistan, Macedonia, Turkey, Turkmenistan, Uzbekistan , Yugoslavia
7 Afghanistan , Djibouti, Egypt, Iraq, Morocco, Pakistan, Somalia, Sudan , Yemen
8 Bolivia , Ecuador, Guatemala, Haiti, Nicaragua , Peru
Background: In 2000, the World Health Organization estimated that, in developing and transitional countries, unsafe injections accounted for respectively 5%, 32% and 40% of new infections with HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV). Safe injection campaigns were organized worldwide. The present study sought to measure the progress in reducing the transmission of these viruses through unsafe injections over the subsequent decade. Methods: A mass action model was updated, to recalculate the number of injection-related HIV, HCV and HBV infections acquired in 2000 and provide estimates for 2010. Data about the annual number of unsafe injections were updated. HIV prevalence in various regions in 2000 and 2010 were calculated from UNAIDS data. The ratio of HIV prevalence in healthcare settings compared to the general population was estimated from a literature review. Improved regional estimates of the prevalence of HCV seropositivity, HBsAg and HBeAg antigenemia were used for 2000 and 2010. For HIV and HCV, revised estimates of the probability of transmission per episode of unsafe injection were used, with low and high values allowing sensitivity analyses. Results: Despite a 13% population growth, there was a reduction of respectively 87% and 83% in the absolute numbers of HIV and HCV infections transmitted through injections. For HBV, the reduction was more marked (91%) due to the additional impact of vaccination. While injections-related cases had accounted for 4.6%-9.1% of newly acquired HIV infections in 2000, this proportion decreased to 0.7%-1.3% in 2010, when unsafe injections caused between 16,939 and 33,877 HIV infections, between 157,592 and 315,120 HCV infections, and 1,679,745 HBV infections. Conclusion: From 2000 to 2010, substantial progress was made in reducing the burden of HIV, HCV and HBV infections transmitted through injections. In some regions, their elimination might become a reasonable public health goal.
Injections made with a syringe and/or a needle previously used
on another patient carry a risk of transmission of blood-borne
viruses when equipment is re-used without adequate sterilization
and correspond to an overwhelming majority of unsafe injections,
while use of multi-dose medication vials represents a smaller part
of the problem. In 2000, the World Health Organization (WHO)
estimated that, in developing and transitional countries, unsafe
injections accounted for 5% of new HIV infections, 32% of new
hepatitis B virus (HBV) infections and 40% of new hepatitis C
virus (HCV) infections . These estimates were based on a
mass action model, in which the incidence of each blood-borne
virus acquired from unsafe injections, Iu, is a product of the size
of the susceptible population, ps (those not yet infected and, in the
case of HBV, not yet vaccinated), the probability of transmission
during an unsafe injection, pt, the probability that injection
equipment is re-used, pr, the prevalence of the infection in the
population, pv, and the number of injections performed per
person-year, n, as follows: Iu = ps * [1-(1- pt * pr * pv)n].
Since then, the Safe Infection Global Network, ministries of
health and other stakeholders have attempted to reduce the
infectious risks associated with injections . We reported
elsewhere the changes from 2000 to 2010 in the number of
unsafe injections per person-year, which decreased from 1.35 to
0.16 . Here we attempted to quantify the evolution of the
number of cases of injections-related HIV, HCV and HBV
infections during that period. We first sought to recalculate the
number of injection-related infections in 2000, using the same
model but altering some parameters based on relevant information
which has accrued since the previous work, and then we calculated
the same outcomes for 2010, using updated epidemiological data.
To allow comparisons, regions as defined in the 2000 Global
Burden of Diseases (GBD) study were used (Table 1), excluding
four high-income regions where unsafe injections are thought to be
uncommon (North America/Cuba, Western Europe, Japan/
Australia/New Zealand and other developed countries mostly in
the Middle East) .
Table 1. Regions of the world (developing and transitional economies) as defined during the 2000 Global Burden of Diseases
Indonesia, Sri Lanka, Thailand.
Bangladesh, Bhutan, Democratic Peoples Republic of Korea, India, Maldives, Myanmar, Nepal
Number of unsafe injections per person per year
No change was made in the average number of unsafe injections
per person per year in 2000 . For 2010, in several regions
there were reductions in unsafe injections, mostly through a lower
proportion of re-use, and these figures were used for all three
blood-borne viruses . Given the lack of injections data for the
three countries that constituted region SEAR B, extrapolations
were made from India, Vietnam and Cambodia. Population
figures were updated . Changes in parameters specific for each
virus are described below.
Revised estimate of the probability of transmission per
unsafe healthcare injection, pt
The probability of transmission of HIV, HCV and HBV per
episode of unsafe healthcare injection cannot be measured
directly, so that two proxies must be used: the risk of transmission
during a needle stick injury in healthcare workers (HCW) and the
risk of transmission per episode of needle/syringe sharing by
injection drug users (IDU).
For HCV, the pt for HCW injuries previously used (1.8%),
generally accepted at the time, was overestimated because early
studies had used unreliable diagnostic assays. A review published
in 2002 estimated this pt at 0.5% (59 infections after 11324
injuries) . For HIV, the pt for HCW injuries is generally
estimated to be 0.32%, based on follow-up after 6202 exposures
. A 2006 meta-analysis estimated this risk at 0.24% .
The risk of transmission of HIV per episode of sharing of needles
and/or syringes was estimated at between 0.63% and 1.57%
When comparing unsafe injections to needle stick injuries,
competing factors must be considered. Actions associated with an
injection (inserting a needle deep into a muscle, and pushing its
content with the plunger) may enhance the risk compared to
HCW injuries, which are generally superficial. But on the other
hand, one third of HCW injuries occur after a needle had been
placed in the patients vein (to draw blood, to insert an intravenous
line, etc.) . Most healthcare injections being made
intramuscularly or subcutaneously, the amount of blood from
the index patient that ends up in the needle/syringe is lower than
when a HCW manipulated a needle deliberately inserted into a
patients vein. Furthermore, the pt during unsafe injections must
be lower than in IDU, among whom the potential transfer of
viruses occurs from vein to vein.
Thus, the pt of HIV (1.2%) and HCV (1.8%) per episode of
contaminated healthcare injection used for 2000 were presumably
overestimated [1,3]. It is more prudent to use, for each virus, a low
estimate, corresponding to the probability of transmission during a
needle stick injury to a HCW, and a high estimate which probably
should be not more than double the low one. For HIV, this
corresponds to 0.32% and 0.64%, nearly identical to the 0.24%
0.65% proposed elsewhere in a meta-analysis , our high value
for medical injections being close to the lower estimates (0.63%) of
the transmission risk among IDU. For HCV, the same approach
yields values of 0.5% and 1.0%.
The probability of HBV transmission during an unsafe injection
had been assumed to be 6% for HBeAg-negative source patients
and 30% for HBeAg-positive patients, in line with other estimates,
and we used the same values given that this has not been studied
further in recent years [1,3,19,20]. However, it had been
arbitrarily assumed that in most regions 20% of the
HBsAgpositive individuals were HBeAg-positive, yielding an overall
pt = 10.8%, while elsewhere 50% were HBeAg-positive, for an
overall pt = 18% [1,3]. We rather calculated region-specific values
of pt, based on estimates of the proportion of HBeAg antigenemic
Revised estimates of HIV prevalence in 2000 and
estimates for 2010
UNAIDS revised retrospectively its measures of national HIV
prevalence when Demographic and Health Surveys (DHS), with
HIV testing on capillary blood, revealed that in several countries
the prevalence (previously measured through surveys of pregnant
women) had been overestimated because of an under-sampling of
rural populations and an overestimate of the prevalence in men
[21,22]. The regional estimates of HIV prevalence for 2000 were
recalculated, and those for 2010 were calculated the same way.
From UNAIDS data for 2001 (revised figures) and 2009 , we
extrapolated to 2000 and 2010, based on the mean annual
changes in prevalence. Assuming that in most primary care
settings children and adults are treated with the same pool of
needles and syringes, the overall prevalence was calculated (and
not merely among those aged 1549 years).
Estimation of HIV prevalence in healthcare settings
Previous calculations had used the HIV prevalence in the
general population and assumed that prevalence among patients
attending healthcare facilities was the same [1,3]. However,
HIVinfected patients develop symptoms for which they seek care and
receive injections. Consequently, in certain healthcare settings, for
instance patients hospitalized in a medical ward, the HIV
prevalence is much higher than in the general population, as
pointed out by Reid . That effect, although less marked, is also
present in primary care settings, even if a substantial fraction of
their caseload corresponds to children, because HIV-infected
children are also more likely to attend outpatient services than the
seronegatives. Furthermore, in some primary care centers a
substantial fraction of the caseload consists of patients with
sexually transmitted infections, further enhancing HIV prevalence.
Furthermore, the propensity of HIV-infected patients to attend
a health facility increases as the disease progresses and so does
their viremia, hence their infectiousness. We assumed that this
latter phenomenon was intrinsically tailored in within the
estimates of the efficacy of transmission to HCW, and no further
adjustments were made.
We reasoned that, worldwide, most injections (and most unsafe
injections) are given to outpatients in primary care facilities:
forprofit clinics (operated by physicians, nurses or unqualified
personnel), governmental health centers, facilities run by
nonprofit organizations, outpatient departments of hospitals, etc. We
assumed that, with regard to the syringes/needles used, patients
treated in such facilities represent a single population (a mix of
children and adults), rather than two distinct compartments each
with their own pool of syringes/needles.
To identify relevant studies, Medline searches were performed
(Appendix S1) and the US Census Bureau database was searched
, seeking reports about patients in healthcare settings in
developing/transitional countries published since 1995. The goal
being to obtain measures of HIV prevalence among unselected,
consecutive patients attending healthcare facilities, studies that
represented obvious biases one way or the other were excluded, for
instance measures among: i) inpatients, in which the HIV-infected
would be much over-represented compared to outpatient settings;
ii) patients presenting with conditions strongly associated with HIV
infection (tuberculosis, pneumonia, etc.); iii) patients attending
sexually transmitted diseases clinics or facilities for voluntary
testing where the HIV-infected are over-represented; iv) antenatal
clinic attendees and blood donors, since these visits are not
prompted by ongoing symptoms. Furthermore, were excluded
studies where the HIV status had been determined by a single test,
studies with fewer than 200 participants, or with unavailable full
A total of 4052 titles and abstracts were scanned for full-text
review and potential inclusion. Ultimately, 16 studies fulfilled all of
the inclusion criteria and presented no exclusion criterion .
These measures of healthcare prevalence were compared with
measures of HIV prevalence in the population of the same city or
region. In some locations, this was possible through a DHS
measure . The prevalence in men and women combined was
used, except for an all-women study in Uganda  for which the
female prevalence was used as comparator. When the study
population had been limited to some age groups the prevalence in
age groups as close as possible was used as comparator. The
comparator prevalence was adjusted for the interval that had
elapsed between the study and the corresponding DHS, based on
estimates for the variation in HIV prevalence between 2001 and
2009 . For the paediatric studies, regional estimates made by
the South African Department of Health for children aged 214
years were used as comparator . For the other studies, our
comparator prevalence was based on surveys of HIV among
antenatal clinic attendees of the same location , generally
available for the same year as the study itself. To translate this into
a prevalence for the whole adult population, an adjustment took
into consideration differences in prevalence between men and
women, based on UNAIDS estimates in that particular country
Novel information on the prevalence of HCV and HBV in
Researchers recently estimated the prevalence of HCV
seropositivity and HBsAg antigenemia in various regions in 1990 and
2005, for each sex and age stratum, based on a review of
respectively 232 and 396 scientific papers and mathematical
modelling [42,43]. These estimates seemed more evidence-based
than the empirical ones previously used . We calculated the
annual variation in the prevalence of HCV seropositivity and
HBsAg antigenemia between 1990 and 2005, to extrapolate the
prevalence in 2000 and 2010. To calculate the overall regional
prevalence, the populations of each age stratum were used as
weights . As the data for 1990 and 2005 were presented along a
revised classification of countries (GBD 2010), the latter was
converted into prevalence for GBD 2000 regions, according to the
proportions of each 2000 region that came from each 2010 region.
No adjustment was made for a potentially higher prevalence in
healthcare settings, which seems unlikely given that only a
minority of HCV-infected and HBV-infected persons develop
A similar exercise measured, in each region, the proportion of
HBsAg-positive individuals who are HBeAg-positive, based on
fewer publications . Prevalence of HBeAg antigenemia among
HBsAg-positive individuals was much higher in young children
and decreased steadily with older age; geographic variations were
In many low-income countries, HBV vaccine was introduced
into the immunisation programme during the 20002010 decade,
and the fraction of recipients of unsafe injections susceptible to
iatrogenic HBV infection decreased progressively among children
and adolescents. The proportions of the population of various age
groups deemed non-susceptible through vaccination or natural
infection were not altered for 2000, but had to be corrected for
2010. WHO collates data provided by member states concerning
the proportion of infants who have received the third dose of HBV
vaccine by the age of 12 months . For each country,
immunisation rates were calculated for two age strata, 0-4 years
and 514 years, and translated into proportions of susceptibility
(ps) to HBV infection for each region, allowing for natural
infections as well. For individuals older than 14 years, the same ps
as in the 2000 model [1,3] were used.
The revisions in HIV prevalence in the overall population had
only a modest impact on the estimated regional prevalence for
2000 [1,3]. For the prevalence in healthcare settings, thirteen
studies contained data about adults, two presented paediatric data,
and one had included both children and adults. Most studies had
been performed in Africa, two in India and one in Haiti. HIV
prevalence among study populations varied widely. The ratio
between the prevalence among patients attending a healthcare
facility and that in the comparator in each of 16 studies is shown in
Supporting Information, Table S1. The means of these ratios was
2.48 for studies with adults, 2.69 for the paediatric studies, and
2.52 overall. This latter figure was multiplied by the prevalence in
the overall population to derive the prevalence in healthcare
settings, for each region, in 2000 and 2010 (Table 2). In 2010, this
prevalence decreased in AFR E, and increased in EMR D and
Hepatitis C prevalence
The revised estimates of regional prevalence of HCV
seropositivity for 2000 are displayed in Table 3 along with the data for
2010. Compared to the previously used data [1,3], there was
relatively little change in regional HCV prevalence for 2000. In
2010, prevalence increased in six regions.
Hepatitis B prevalence
The revised estimates of regional prevalence of HBsAg and
HBeAg for 2000 are shown in Table 4. For the high-prevalence
regions, the revised estimates of prevalence of HBsAg antigenemia
were lower than before . The revised proportions of the
HBsAgpositives who were HBeAg antigenemic in 2000 were generally
higher than in the original model, except for the two regions where
this prevalence had been arbitrarily estimated at 50%. Since
HBeAg antigenemia has a profound influence on the pt for HBV,
the regional pt varied accordingly. Table 4 also displays the data
for 2010. In all but one region, the prevalence of HBsAg
antigenemia decreased. There was a modest reduction in the
proportion of HBsAg-positive individuals who were HBeAg
Estimates of HIV infections transmitted through unsafe
injections in 2000 and 2010
Table 5 shows the revised estimates of HIV infections
transmitted through unsafe injections in 2000, based on the same
model but with HIV prevalence in health care settings as pv and
with the two revised pt values. Our higher estimate for 2000,
based on pt = 0.64%, yielded estimates similar to those presented
initially [1,3], with roughly a quarter of a million HIV infections
acquired through unsafe injections. Naturally, the estimates with
pt = 0.32% yielded figures that were half the other measure. Based
on previously mentioned assumptions, between 133,328 and
266,405 HIV infections were acquired worldwide through
unsterile injections in 2000. Region SEAR D (mostly India) had
represented more than half of the global number of
injectionsrelated cases of HIV, to a large extent because it was estimated
that 75% of injections in SEAR D were made with re-used needles
and syringes, based on a survey in India . Despite a much
higher pv, the contribution of sub-Saharan Africa was lower than
SEAR D, because of fewer injections and less frequent re-use.
Using UNAIDS revised data as denominators, in developing and
transitional economies, between 4.6% and 9.1% of all new HIV
infections in 2000 were caused by unsafe injections .
For 2010, the main changes in parameters were in the number
of unsafe injections per person per year  and the HIV
prevalence in healthcare settings. The same two values of pt were
used. Between 16,939 and 33,877 HIV infections were acquired
through unsafe injections worldwide (Table 5). Sub-Saharan
Africa represented 48% of such cases, while the contribution of
SEAR D decreased to 18%. Compared to 2000, the number of
injections-related HIV infections acquired worldwide decreased by
87% in 2010, when between 0.7% and 1.3% of all new HIV
infections were so acquired .
Estimates of HCV infections transmitted through unsafe
injections in 2000 and 2010
Table 6 shows the revised estimates of HCV infections
transmitted through unsafe injections in 2000, based on the
revised measures of prevalence and the two values of pt. We
estimated that in 2000 between 952,111 and 1,867,904 HCV
infections were injections-related. Again, the higher estimate for all
ten regions was similar to the one generated previously [1,3], even
if the regional distribution varied. Table 6 also displays the results
for 2010, using the same pt values, the updated regional
prevalence and the updated numbers of unsafe injections . In
2010, between 157,592 and 315,120 HCV infections were
acquired from unsafe injections, about one third of which occurred
in EMR D and another third in WPR B.
Estimates of HBV infections transmitted through unsafe
injections in 2000 and 2010
Table 7 displays the estimates of HBV infections transmitted
through unsafe injections in 2000, using the same HBeAg-specific
HIV prevalence in 2000
HIV prevalence in 2010
Previous estimates for 2000a
Current estimates for 2000b
Estimates for 2010b
aUsed in Hauri et al., and Hutin et al.1,3
bDerived from data available in Hanafiah et al.42
values of pt applied on the revised estimates of the prevalence of
HBsAg and HBeAg antigenemia. Although the regional figures
varied along with modifications in the prevalence of antigenemia,
the total for all ten regions was again similar to the one calculated
previously for 2000, with 19,710,444 HBV infections acquired
from injections. Table 7 also shows the results for 2010, based on
the same values of pt and the updated estimates of the number of
unsafe injections and of the prevalence of HBsAg and HBeAg
antigenemia in 2010 . Compared to 2000, there was a 91%
reduction in the number of injections-related HBV infections, to
1,679,745 new infections.
The main finding of this study is that, between 2000 and 2010,
there has been a reduction of respectively 87% and 83% in the
estimated number of cases of HIV and HCV infections
transmitted through unsafe injections. In the case of HBV, the
reduction was more marked (91%) due to the additional impact of
the rolling out of vaccination in most of the world.
We used the mathematical model developed previously [1,3],
because the main goal was to measure the relative reduction (2010
versus 2000) in injections-related HIV, HCV and HBV infections,
but also because this model did not seem to be flawed, even if by
definition all models are imperfect. A number of decisions about
how to use it could be debated, however. First, random mixing
between all age groups was assumed. That probably occurs in
most private outpatient facilities, but less so in large hospitals.
What proportion of injections worldwide is made through two
distinct compartments, one for children and the other for adults
remains unknown. Second, in our calculation of the relative
prevalence of HIV in healthcare settings, inpatients data were
excluded, lowering this estimate. What proportion of injections
worldwide is given to outpatients versus inpatients remains
unclear, and there might be a better compliance with single-use
syringes and needles in hospital settings. Third, the values of pt
could be endlessly debated. Some authors argue that this
probability is much higher than the values that we used [23,47],
but it does not seem plausible that transmission could be several
Previous estimates for 2000a
Current estimates for 2000b
Estimates for 2010b
Prevalence of HBsAg HBsAg+ who are
Prevalence of HBsAg HBsAg+ who are
Prevalence of HBsAg HBsAg+ who are
aUsed in Hauri et al., and Hutin et al.1,3
bDerived from data available in Ott et al.43,44
Revised estimates pt = 0.32%
Revised estimates pt = 0.64%
Estimates pt = 0.32%
Estimates pt = 0.64%
aUsed in Hauri et al., and Hutin et al.1,3
aUsed in Hauri et al., and Hutin et al.1,3
fold more common during IM or SC unsafe medical injections
than through IV injections of recreational drugs among addicts.
Finally, potential biases in the measures of unsafe injections have
been discussed elsewhere . Apart from the latter, these sources
of imprecision would be expected to have little impact on the
measures of the relative reduction in the iatrogenic transmission of
viruses over time.
Given that sampling variation and other imprecisions existed at
various degrees for the five parameters used in the model, it was
not possible to calculate confidence intervals around the absolute
number of infections, and we elected to rather present sensitivity
analyses for HIV and HCV based on two values of pt, the one
parameter for which there was no direct measurement. HBV
transmission during needle stick injuries has been little studied
during the last 30 years using modern serological assays,
precluding meaningful sensitivity analyses. In the future,
modelbased estimates could be complemented by the inclusion of
children within the DHS of some countries, allowing a
measurement of relatively recent non-sexual transmission of HIV and
HCV, and of natural infections with HBV.
Of the three blood-borne viruses evaluated in the current study,
HIV generally elicits most controversy [23,46,47]. There are
reasons to believe that the revised measures for 2000 are improved
compared to the prior version [1,3]. The HIV prevalence in
various regions of the world is better defined because it is now
based, in many countries, on surveys of a representative sample of
the nations population. For the first time, an attempt was made to
measure the relative prevalence of HIV in healthcare settings. And
it seems likely that the two measures of pt, 0.32% and 0.64%,
which now provide a sensitivity analysis, would be accepted by
most experts. Ultimately, the number of injections-related HIV
infections estimated previously for 2000 (256,152) [1,3] was similar
to our higher figure (266,405, if pt = 0.64%), while our low
estimate (133,328, if pt = 0.32%) represented half of that measure.
Despite the 13% population growth, the number of
injectionsrelated HIV infections decreased to only 16,93933,877 in 2010, a
remarkable public health achievement, and the fraction of new
Revised estimates pt = 0.5%
Revised estimates pt = 1.0%
Estimates pt = 0.5%
Estimates pt = 1.0%
Previous estimates,a 2000
Current estimates, 2000
Estimates for 2010
aUsed in Hauri et al., and Hutin et al.1,3
cases of HIV infection acquired through unsafe injections
decreased to 0.7%1.3% of the worldwide total of new infections
in 2010, compared to 4.6%9.1% ten years earlier. Most of this
was driven by the reduction in the average number of unsafe
injections, but decreasing HIV prevalence also impacted
favourably in East and Southern Africa. We did not attempt to model the
effect of the deployment of antiretrovirals on pt. This may need to
be considered in the future, as the suppression of viremia lowers
infectiousness but on the other hand prolongs survival, hence the
duration of infectiousness.
The number of cases of HCV infections acquired from unsafe
injections also declined substantially. Again our high estimate for
2000 was similar to the previous one [1,3]. By 2010, the number of
HCV infections from unsterile injections had dropped by 83%.
The effect of the reduction in unsafe injections was attenuated by
the population growth and the increasing prevalence in some
densely populated regions . The latter changes in HCV
prevalence are likely multi-factorial: incomplete screening of blood
donors, ongoing transmission among IDUs, and persistent
transmission by parenteral modes other than injections. The
long-term survival of most HCV-seropositive individuals also
impacts on prevalence.
The progress with injections-related HBV infections was even
more marked, at 91%. Several factors, attenuated only by the
population growth, led to this reduction: fewer unsafe injections,
lower prevalence of HBsAg and HBeAg antigenemia, and lower
susceptibility to HBV through vaccination. Independently of any
further progress in injection safety, this trend will continue as the
immunised cohorts get older, producing direct and indirect effects.
And as the HBsAg-positive subpopulation ages, it is also less prone
to be HBeAg antigenemic, further reducing transmission.
Given this progress, the cost per additional case of
injectionsrelated HIV, HCV and HBV infections averted will increase, as is
true for all disease control initiatives. We argue that these efforts
should be maintained or expanded, even if more expensive, for
two reasons. First, a moral imperative: iatrogenic infections with
HIV, HCV and HBV are unacceptable, and go against a
Hippocratic principle: first, do no harm. Second, as treatments
against HIV and HCV are increasingly deployed in developing
countries and transitional economies, incremental funding for the
prevention of the remaining iatrogenic infections may generate
savings. Elimination of these risks could become a reasonable goal
in sub-Saharan Africa and Latin America. Such an achievement in
Africa could remove half of the remaining burden of
injectionsrelated HIV infections worldwide.
However, other modes of iatrogenic transmission of
bloodborne viruses, not covered by the current work, persist and will
need to be addressed in the future. For instance, use of multi-dose
medication vials, phlebotomies with re-used needles, dental care
with improper sterilisation of instruments, unscreened
transfusions, ritual scarifications and circumcisions performed by
traditional practitioners all continue unabated, and should be
included within ongoing efforts to reduce infectious risks for
patients worldwide. Better measurement of such exposures and of
their impact on viral dynamics is an essential first step, and the
inclusion of children within demographic and health surveys could
provide much needed data.
Table S1 Estimation of the ratio of HIV prevalence in
healthcare settings compared to the general population.
Appendix S1 Strategies to identify relevant publications
for the comparison of HIV prevalence in healthcare
setting with that of the general population.
We are indebted to Yvan Hutin for his helpful comments and suggestions.
Conceived and designed the experiments: JP. Performed the experiments:
JP CNAC EP VN LV. Analyzed the data: JP CNAC EP VN LV.
Contributed reagents/materials/analysis tools: CNAC EP VN LV. Wrote
the paper: JP CNAC EP VN LV.
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