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ANTIVIRALS
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On November 22 the National Institutes of Health issued a Note to Physicians recommending
that physicians closely monitor the CD4 counts of patients taking a combination of d4T plus AZT. The reason was that an
ongoing study (ACTG 290) found an unexpected decline in CD4 count of volunteers assigned to that combination, who also had much
prior experience with AZT.
An Australian team reports that therapy with the protease inhibitor ritonavir results
in a "dramatic and sustained" rise in CD8+ proliferation in HIV-positive patients.
Agouron Pharmaceuticals has filed a new drug application with the Food and Drug Administration
(US) for its anti-HIV drug nelfinavir (ViraceptTM) marking the first time a company has petitioned the FDA for a protease inhibitor
drug for both adults and children. Analysts say the market potential for such a drug is tremendous. The FDA has already approved
three drugs that fall under the same classification as Viracept: Merck & Co.'s Crixivan, Abbott's Norvir, and Roche Holding's
Invirase. A price has not yet been set for the new Agouron drug.
Vertically infected HIV-positive children experience a gradual reduction in viraemia
during early childhood from the very high values during the first year of life, according to Dr. Kenneth McIntosh of the Harvard
School of Public Health. By about five years of age, the levels of viraemia seen in these children are similar to those seen
in asymptomatic, horizontally infected adults.
In ACTG 290, volunteers had CD4 counts at study entry between 300 and 600, and had
a median of 34 months' use of AZT. Those assigned to the d4T plus AZT combination arm had an unexpected CD4 drop -- 20 cells at
week 4, to 82 cells at week 36. There were no unexpected CD4 declines in other arms of the study (d4T alone, ddI alone, and ddI
plus AZT). "No significant differences in adverse events, serious laboratory toxicitys, or HIV-related clinical events" were found in any of the groups. The ACTG has discontinued
the d4T plus AZT combination arm, and offered volunteers a new study arm with d4T alone for eight weeks, with very close
monitoring.
Another study (ACTG 298) also had a d4T plus AZT arm, but had no unexpected decline.
The only apparent difference is that in this study, the volunteers had less than 7 days of prior AZT experience.
No one knows why the CD4 decline occurred, and additional research is being done to
try to find out. Meanwhile, the Note to Physicians does not make any recommendation on whether or not to discontinue this combination,
but advises physicians to closely monitor CD4 counts of patients taking it.
Source: AIDS Treatment News 261.
These two drugs compete at an intracellular level of activation down cellular phosphorylation
pathways - this lends to lower levels of active drug at the site of action. Additionally, weak antagonism has been described
by a number of laboratories in vitro, particularly in the presence of AZT-resistant virus. These factors may result in
a poorer than expected antiviral effect from this combination. Both drugs are also most active in actively replicating cell populations
hence their range of activity overlaps. ddC, ddI and 3TC are all more active in resting cell populations.
Ritonavir Increases CD8+ Levels In HIV-Positive Patients
Dr. Andrew Carr of the University of South Wales in Sydney compared CD8+ levels in
HIV-positive subjects who received ritonavir monotherapy, nucleoside or non-nucleoside analogue reverse transcriptase inhibitors
either alone or in combination, or placebo. Dr. Carr noted a significant and sustained increase in CD8+ levels following protease
inhibitor therapy with ritonavir, but "...nucleoside or non-nucleoside analogue reverse transcriptase inhibitor therapy resulted
in no significant or sustained change." Higher doses of ritonavir resulted in an even more sustained CD8+ effect.
"The clinical significance of the CD8+ lymphocyte increases seen with protease inhibitor
therapy remains to be determined," the Sydney investigator noted. Dr. Carr writes that the increase in CD8+ response seen
with protease inhibitor therapy "...may result in greater and more sustained suppression of HIV replication by the immune system
leading to improved immunological and clinical benefit."
Ref: J Acquir Immune Defic Syndr Hum Retrovirol 1996;13:320-326.
Source: Aegis
CD8 lymphocyte count rises have been seen with all protease inhibitors (including
saquinavir and nelfinavir). It may reflect improved immune competence against some infections (viral , MTB) however it is unclear
how much of this response (as with CD4 increases) is due to trafficking of cells and how much may be expansion of functional cell
lines.
Agouron Pharmaceuticals Applies to Produce Anti-HIV Drug - Nelfinavir
Agouron is to be applauded for its inclusion of an indication for children in its initial licensing application, none of the three currently licensed PIs are indicated for use in children. However, see ATPs DocFax 13 for information on the deplorable current state of access to nelfinavir
in Europe. Trials are planned for combination trials of nelfinavir + saquinavir (enhanced oral formulation) at European specialist
centres.
This drug appears to be well tolerated (loose stools being the main adverse effect)
and probably will be launched as tid dosing. Dosing is with food. Cross-resistance has not been observed from first analysis of
resistant viruses from phase I/II studies, however indinavir and ritonavir select commonly for nelfinavir resistance. This drug
may, therefore, be best used early. Nelfinavir enhances saquinavir bioavailability 10-fold.
OPPORTUNISTIC ILLNESS
Aphthous Oroesophageal And Idiopathic Genital Ulcers In HIV-Positive Women: Pathophysiologic Similarities Reported
A multicentre group reports that "...the clinical presentation and course of idiopathic
genital and aphthous oroesophageal ulcers are similar...and share the same pathophysiology..." in HIV-positive women.
Dr. Rebecca Clark of LSU Medical Center in New Orleans and colleagues wanted to better
understand the clinical presentation of idiopathic genital ulcer disease in this patient group. They surveyed clinicians caring
for HIV-positive women and turned up 29 cases of idiopathic genital ulcer disease. Most of the HIV-positive women subsequently
studied were severely immunocompromised, negative for syphilis and HSV "...and/or negative for genital ulcer biopsy." Close
to 70% had progressed to AIDS. Dr. Clark found that 37% of the subjects had oral ulcers and 19% had genital ulcers that had progressed
to fistula formation. Most of the patients responded favourably to steroid treatment.
"Aphthous ulcer disease in HIV-infected women probably manifests as isolated oroesophageal
ulcers, isolated genital ulcers, or ulcers coexisting in both sites." Although uncommon, idiopathic genital ulcers in
HIV-positive women can cause severe morbidity, Dr. Clark told Reuters Health. The key points of this study, she said, are that treatment
for idiopathic genital ulcers should be the same as treatment for oroesophageal ulcers, and that physicians should look
for oroesophageal ulcers in women with idiopathic genital ulcers and vice versa.
"The results of this study suggest that aphthous genital ulcers often have a moderate
or good response to steroid therapy. Thalidomide has been recently found to significantly improve healing of aphthous oral ulcers
and, therefore, also may be of benefit in the treatment of idiopathic or presumed aphthous genital ulcers."
Ref: J Acquire Immune Defic Syndr Human Retrovirol 1996;13:343-347.
Source: Aegis
Similar pathophysiologic features have also been reported for some perianal ulcers.
Thalidomide is currently the most used treatment in London for apthous ulceration in AIDS.
Two Regimens Comparable For AIDS-Related Oesophageal Candidiasis
Italian researchers report that two regimens, fluconazole alone or itraconazole plus
flucytosine, are equally efficacious in the short-term treatment of AIDS patients with oesophageal candidiasis.
Dr. Giuseppe Barbaro of the University "La Sapienza" in Rome and colleagues in the
Candida Oesophagitis Multicentre Italian Study Group compared these two regimens in 85 HIV-positive subjects. All of the subjects
had an endoscopically confirmed first episode of oesophageal candidiasis. Dr. Barbaro's group randomised subjects to one of
three groups: fluconazole and placebo, itraconazole and flucytosine, or placebo and placebo.
"At the end of follow-up, endoscopic cure was observed in 89.8% of the fluconazole+placebo
group and in 94.8% of the itraconazole+flucytosine group...Clinical cure was observed in 94.8% of the fluconazole+placebo
group and in 97.3% of the itraconazole+flucytosine group." In both treatment groups, the side effects were minimal, and concomitant
zidovudine treatment did not affect the course of treatment or the incidence of relapse.
Dr. Barbaro concluded that "...the state of immunodeficiency of the patients represented
the principal factor responsible for treatment failure." The findings indicated to Dr. Barbaro that a synergistic therapeutic
association exists between itraconazole and flucytosine. He suggested that this combination may be useful for long-term treatment
of candidial oesophagitis.
Ref: Chest 1996;110:1507-1514
Source: Aegis.
Common regimens in the UK for threatment of candida are; ketoconazole 200mg bd for
5 days; fluconazole - single doses (150mg or higher) or 3 day courses of 50mg bd; itraconazole 200mg bd for 5 days. Fluconazole
resistant strains are increasingly common. Contrary to US recommendations, in the UK it is generally felt that episodic treatment
rather than continued prophylaxis is preferable to avoid selection of resistant strains.
Dosage Of Dapsone For PCP Prophylaxis In HIV-Positive Patients Determined
An international team of investigators has determined that 100-mg doses of dapsone
administered biweekly result in sustained plasma dapsone levels in most HIV-positive patients with Pneumocystis carinii pneumonia
(PCP).
Although trimethoprim-sulfamethoxazole (TMP-SMX) is the first-line treatment for PCP
prophylaxis, the high rate of adverse effects associated with this therapy has led researchers to explore treatment alternatives.
In the current study, Dr. Giorgio Gatti of the University of Genoa and a multicentre team investigated the pharmacokinetics
of dapsone. Dr. Gatti's group administered biweekly 100-mg doses of dapsone to 53 HIV-positive patients.
"Plasma concentration-versus-time curves indicated that the administration of 100
mg of dapsone biweekly is associated with sustained dapsone levels in the plasma of the majority of the patients," Dr. Gatti said.
Therefore, 100 mg of dapsone dosed biweekly appears to be an appropriate dosage for PCP prophylaxis in HIV-positive patients.
"Among the covariates [that] were tested for their influence on pharmacokinetic parameters,
concomitant administration of rifampin appeared to be the only significant factor that could be clinically relevant,"
he concluded. Therefore, dosage adjustments of dapsone may be necessary for patients concomitantly treated with rifampin.
Ref: Antimicrob Agents Chemother 1996;40:2743-2748.
Source: Aegis
Dapsone is a second choice PCP prophylaxis used only in people with established co-trimoxazole
intolerance. Current UK dose is most commonly 100mg daily. Twice weekly dosing of pyramethamine, and three times weekly
dosing with co-trimoxazole is used at some centres. Less frequent dosing of dapsone may encourage compliance.
Accelerated Neutrophil Apoptosis Occurs In HIV Infection
Neutrophils from AIDS patients are characterised by "...markedly accelerated apoptosis
ex vivo," according to researchers at the University of Illinois in Chicago.
Dr. David L. Pitrak and colleagues evaluated apoptosis of neutrophils isolated from
10 HIV-positive subjects who had CD4+ lymphocyte counts less than 200 per cubic meter and from seven healthy volunteers. The
HIV-positive subjects did not have signs of active infection. The Chicago team then determined rates of apoptosis using electron
microscopy, flow cytometry and DNA gel electrophoresis.
After three hours in culture, the AIDS patients' neutrophils "...exhibited significantly
greater apoptosis than controls," and the difference in rate of apoptosis continued to widen up to 18 hours. In addition,
cell viability was significantly decreased for the HIV-positive subjects at 18 hours compared with the controls.
"Despite the fact that the accelerated apoptosis appears to be an intrinsic property
of the [neutrophils] from AIDS patients, the process is not irreversible," the researchers report. Specifically, they found
that incubation of neutrophils with G-CSF significantly decreased apoptosis in vitro. This
suggests that "...cytokine therapy may be of potential clinical benefit..." by slowing
the loss of neutrophil function in patients with HIV infection.
Ref: J Clin Invest 1996;98:2714-2719.
Source: Aegis
Filgrastim Reverses Neutropenia In HIV Infection
Neutropenia is a common side effect of myelosuppressive treatment in HIV-positive
patients, according to a multicentre European group. In the current issue of AIDS, Dr. Philippe Hermans of Saint-Pierre University
Hospital in Brussels and his associates report that filgrastim, a lineage-specific growth factor, "...rapidly reverses neutropenia
and is subsequently able to maintain normal neutrophil counts in patients with HIV infection."
Dr. Hermans and investigators in the G-CSF 92105 Study Group evaluated the efficacy
and safety of filgrastim in 200 HIV-positive patients. In this open-label, multicentre study, subcutaneous filgrastim was administered
to the patients for 28 days. Most of the patients received one or more of the following drugs: ganciclovir, zidovudine,
co-trimoxazole or pyrimethamine, which were considered to be the cause of the neutropenia.
Ninety-eight percent of the subjects experienced a reversal of neutropenia within
a median of two days of treatment. "Most patients (96%) achieved reversal of neutropenia with a filgrastim dose of less than or
equal to 300 micrograms per day." Dr. Hermans found that filgrastim was well tolerated by the study subjects and had no adverse
effects on HIV replication or T-lymphocyte counts.
Based on these results, the team concludes that filgrastim treatment in HIV-positive
patients will permit "...greater use of myelosuppressive medications without the potentially life-threatening complications
of neutropenia. By permitting optimal therapy to be administered to patients, filgrastim could have an impact on current standard
of care and possibly even survival."
Ref: AIDS 1996;10:1627-1633.
Source: Aegis
Filgrastim is a recombinant preparation of Granulocyte Colony Stimulating Factor (G-CSF)
it is marketed under the brand name Neupogen in the UK. Guidelines vary from centre to centre on the use of G-CSF with cost
being a major issue. If a central venous line is present it may be used when neutrophils are <0.5, or <0.3 if there are no such
infection prone devices. It may be administered either s.c. or i.v.
Patients with low neutrophil counts are at increased risk of a range of bacterial
infections and these infections may progress more rapidly in neutropenic patients. Neutropenia is a common consequence of HIV infection
and is exascerbated by many of the drugs commonly used such as AZT, ganciclovir and co-trimoxazole.
VIRAL LOAD TESTING
Three HIV-1 RNA Assays: Pros And Cons Reported For Each
A team of French investigators compared the performance of the three assays that are
now commercially available for quantitation of plasma HIV-1 RNA. Overall, they found inherent strengths and weaknesses for each.
Dr. Michel Segondy of Centre Hospitalier Universitaire in Montpellier and colleagues
compared the reverse transcriptase-coupled polymerase chain reaction assay (Amplicor HIV-1 Monitor), the branched DNA (bDNA)
method (Quantiplex HIV-1 RNA), and the nucleic acid sequence-based assay (NASBA). Dr. Segondy used these tests to evaluate plasma
specimens from HIV-1-positive and HIV-1-negative subjects. The research team found that the bDNA method was the most reproducible
and that the NASBA test was the most sensitive. The defect of sensitivity observed with bDNA can be explained by the high detection
limit of this method...whereas Amplicor and NASBA have similar detection limits that are more than 20 times lower than the bDNA
detection limit."
Dr. Segondy also observed that "...the genetic variability of HIV-1 affects the quantitation
of HIV-1 RNA by the different techniques." For example, subtype A was not detected by Amplicor in plasma or in culture
supernatants of subtype A strains. NASBA did not detect HIV-1 RNA in the culture supernatants of subtype G strains. However,
the bDNA method detected HIV-1 RNA from all of the subtype reference strains.
Overall, he concluded that "...bDNA is a highly reproducible method that allows quantitation
of RNA from different HIV-1 subtypes...[but]...bDNA has a low sensitivity since, in our experience, HIV-1 RNA could not
be quantitated in more than 30% of the patient specimens."
Ref: J Med Virol 1996;50:293-302.
Source: Aegis
Shockingly, a basic HIV viral load assay is still not available at many UK HIV centres.
Some centres in London now have access to several assays and their use depends on several issues including clade detection,
cost, sensitivity, batch size and run time, and sample preparation. African, asian and South American patients may all have non-clade
B strains complicating the use of viral load assays.
PATHOGENESIS
Similarities Reported Between HIV-2 And HIV-1 Infection
European investigators report that HIV-2 infection appears to progress at the same
rate as HIV-1 infection. And in the December issue of AIDS, the multicentre group also notes that mutations seen in patients with
HIV-2 infection following zidovudine treatment are similar to those in patients with HIV-1 infection who develop zidovudine
resistance. "To our knowledge, this is the first description of mutations in HIV-2 possibly related to zidovudine," Dr. Albert
D.M.E. Osterhaus of Erasmus University in Rotterdam says.
Dr. Osterhaus and colleagues compared differences between 12 HIV-2-positive Western
European subjects and HIV-1-positive subjects.
"Although no data were available on place and duration of both HIV-1 and HIV-2 infection,
several observations prompted us to suggest that HIV-1 and HIV-2 infections in our population had a similar rate of disease
progression."
The ratio of asymptomatic and symptomatic subjects did not differ by the presence
of HIV-1 or HIV-2 infection. In addition, the "...rapid decline in CD4+ cell counts observed in the French individuals...over a
36-month observation period clearly showed that HIV-2 infection may also run a rapidly progressive course."
Dr. Osterhaus also hypothesised that SI virus phenotype, which is predictive of rate
of disease progression, may also be a prognostic marker for HIV-2 infection.
Ref: AIDS 1996:10:1649-1655.
Source: Aegis
Immunity To HIV Infection May Be CD8 T Cell-Dependent
Canadian researchers present "...clear experimental evidence that some multiply exposed,
HIV-1 negative individuals have in vivo protective immunity that is CD8 T cell-dependent."
There have been reports, Dr. Stan Houston and colleagues from the University of Alberta
in Edmonton explain, "...of individuals who have been frequently exposed to HIV-1 but remain seronegative for the virus."
In the current study, they used a humanised SCID/beige mouse model to examine the mechanism of this HIV-1 resistance in vivo.
"When the SCID/beige mice were reconstituted with peripheral blood lymphocytes from
two different multiply exposed HIV-1 seronegative individuals, the mice showed resistance to infection by two strains of HIV-1...although
the same peripheral blood lymphocytes were easily infected in vitro." When human CD8 T cells were depleted in the reconstituted
mice, they became susceptible to HIV-1 infection.
Therefore, the investigators conclude that in vivo protection against HIV-1 infection
requires the presence CD8 T cells. Understanding the mechanism of this protective effect, they point out, will be important
in designing prophylactic vaccines as well as immunotherapeutic regimens.
Ref: Proc Natl Acad Sci USA 1996;93:14720-14725.
Source: Aegis
HIV Infection Linked To Loss Of Primitive Haematopoietic Progenitors
French researchers report that a deficit of primitive haematopoietic cells may be
the underlying cause of HIV-related haematologic disorders.
The mechanism leading to haematologic abnormalities in HIV-1 infection are unclear
and may be multifactorial," explain Dr. Fawzia Louache and colleagues at the Institute Gustave Roussy in Villejuif. One hypothesis
suggested involves HIV-1 infection of the marrow stem-cell/progenitor compartment.
In the current study, Dr. Louache and colleagues used biologic assays and immunophenotyping
to evaluate the compartment of primitive haematopoietic cells in HIV-1-positive subjects. Specifically, they determined
the proportion of immature bone marrow cells expressing CD34 antigen in bone marrow aspirates from 21 HIV-1-positive subjects
with advanced infection and 10 healthy HIV-1-negative controls.
The mean percentage of CD34+ cells was not significantly different in the two groups.
However, in all samples from HIV-1-positive subjects most of these cells coexpressed CD38 antigen, indicating committed differentiation.
The investigators also used polymerase chain reaction assay to determine the presence
of HIV-1 in subsets of CD34+ cells. They could not detect the HIV-1 genome in any cell type, or in progeny from long-term culture.
Overall, the data indicate that "...haematologic disorders in HIV disease may be the
consequence of a deficit of primitive cells. However, direct infection of these cells by HIV-1 does not seem to be responsible
for this defect."
The authors also point out in their conclusion that other researchers are considering
the use of an intracellular vaccination to treat HIV-1 infection. Given the results of the current study, they believe that
"...these gene transfer approaches must be performed sufficiently early during HIV-1 disease to target enough haematopoietic stem
cells."
Ref: Blood 1996;88:4568-4578.
Source: Aegis
These findings may add support to the idea of a defect in the production or maturation
of lymphocytes being responsible for the reduced peripheral CD4 counts seen in HIV infection rather than increased destruction
of CD4 cells as reported in DocFax issue 13.
PAEDIATRICS
HIV Predominantly Infects CD45RO Cells in Neonates and Infants
HIV therapy for children and neonates should target the CD45RO T cell population,
researchers at the University of Florida report. John W. Sleasman and colleagues found that the number of HIV-infected cells was
10 times to 100 times higher among CD45R0 cell populations, compared to CD45RA cell populations. The finding suggests that "T cells
generally become infected after leaving the thymic environment," Sleasman said. The researchers suggest that directing antiretroviral
therapy to the relatively small population of CD45RO cells might restore normal memory T cell function and enhance clearance
of HIV-1.
Source: AIDS Daily Summary
In adults both memory and naive cell types are infected but it is the naive population
which appears to selectively decline. Interleukins may also have different effects in children relative to adults.
HIV RNA Levels Decline Gradually Over Time In Vertically Infected Children
Dr. McIntosh and a multicentre group studied the natural history of viraemia in vertically
HIV-infected children. They documented HIV titres in 48 children over time by measuring serum HIV RNA with the reverse
transcriptase-polymerase chain reaction test and the immune complex dissociated p24 antigen enzyme-linked immunosorbent assay.
Dr. McIntosh's team observed a "...downward trend...in subsets of children with all
degrees of immunodeficiency...[and]...the mean slope of repeated HIV RNA measurements in children was similarly in a downward
direction." Viral load in this study population "...fell gradually over time," which contrasts with patterns reported in adults
after primary infection, "...where the titre of extracellular virus falls quickly and abruptly."
If confirmed by larger studies, these results "...will be an important consideration
in interpreting HIV RNA copy numbers in paediatrics. Variations in viral load by age may have to be factored into decisions
about prognosis, as well as about institution of or changes in antiretroviral therapy."
Ref: Pediatr Infec Dis J 1996;15:1087-1091.
Source: Aegis
Levodopa Relieves Extrapyramidal Syndromes In HIV-Positive Children
"Levodopa is a useful adjunctive therapy in HIV-1-infected children with extrapyramidal
syndromes," according to a multicentre team.
"HIV-1 infection of the CNS can cause a well-defined encephalopathy in children termed
HIV-associated progressive encephalopathy," Dr. M. Mintz of the Robert Wood Johnson Medical School in Camden, NJ and colleagues
explain in the current issue of Neurology. The resulting neurologic deterioration includes progressive motor dysfunction
that frequently causes spasticity, along with cognitive and brain growth impairments.
In the current study, they describe the cases of five HIV-positive children with CNS
involvement. All of the children had extrapyramidal dysfunction, with symptoms that included rigidity, stiffness, impaired
movement, impaired speech, drooling, facial abnormalities and bradykinesia.
The team reports that "...levodopa therapy caused an initial improvement in all symptoms,
and the effect was sustained in most patients." In particular, levodopa treatment enhanced the children's motor function
and improved their quality of life. They conclude that "...levodopa therapy affords the clinician an important adjunctive
therapeutic modality for HIV-1-infected children with extrapyramidal/'parkinsonian-like'/rigid syndromes."
Ref: Neurology 1996;47:1583-1585.
Source: Aegis
Response To Hib Vaccine Decreased In HIV-Positive Children
Following initial vaccination with Hib conjugate vaccine, children with HIV infection
have a decreased antibody response compared with HIV-negative children, according to a multicentre European group.
Dr. Diana Gibb of the Institute of Child Health in London and colleagues investigated
immunogenicity following immunisation with Hib-tetanus conjugate vaccine in 48 vertically infected HIV-positive children and
36 HIV-negative children also born to HIV-positive mothers.
The UK team found that, one month after vaccination, 88% of the HIV-positive children
compared with 100% of the HIV-negative children had antibody titres of 1 microgram per millilitre or greater. One year after
vaccination, titres declined below this level in 43% of the HIV-positive children compared with 11% of the HIV-negative children.
"The rate of antibody titre decline was not significantly related to HIV disease status
or to either the age-related CD4 count at the time of immunisation or the change in age-adjusted CD4 count during the 12 months
after immunisation."
Dr. Gibb points out that further evaluation of the longevity of antibody response
in HIV-positive children is still needed, as is determination of the optimal timing of booster immunisation for this patient cohort.
Ref: Pediatr Infect Dis J 1996:15:1097-1101.
Source: Aegis
Poor response to a range of vaccines has also been reported in adults with HIV. Additionally,
vaccination may transiently increase viral replication; an important consideration for patients on therapy, especially
if below detectable.
EPIDEMIOLOGY
Spain's Unwelcome Distinction
Spain now has a higher AIDS rate than any other European country, with 180 cases per
1 million people. Following Spain are Italy, with 101 per million; France, with 89 per million; and Switzerland, with 87 per
million. More HIV-positive children are estimated to be born in Spain than in all the other 14 European Union countries combined.
"It is important we have a trans-border initiative to alert tourists to the risks they may be running," noted Peter Piot,
director of the United Nations Program on HIV/AIDS.
Ref: Lancet (12/07/96) Vol. 348, No. 9041, P. 1578
Source: AIDS Daily Summary