Simulation study on radiation fields around targets to apply CR-39 for photo-neutron measurement in electron accelerator near the threshold energy.

Photo-neutron production in electron accelerator near the threshold energy has been studied by Monte Carlo simulation using the FLUKA code. A pencil beam of 10 MeV electron was incident normally on W, Ta, Pb and Bi targets and a CR-39 detector attached to the target was used as scoring region. In the simulation, photon and neutron spectra, yield and their spatial distribution, fast neutron fluence above 100 keV, total dose and neutron dose deposition were estimated for these metallic targets. The photon emission was found to be forward peaked whereas the neutron emission was isotropic in nature. The photon yield was found to be 5 to 6 orders of magnitude higher than that of neutrons. In W and Ta, the photon yield is maximum for 1.5 mm thickness whereas for Pb and Bi, the photon yield is highest at 2 and 2.5 mm respectively. The total neutron yield was highest for W and lowest for Pb whereas highest number of fast neutrons above 100 keV was for W followed by Bi, Pb and Ta. Production of significant number of fast neutrons above 100 keV suggests the possibility of the use of CR-39 detector for measurement of these neutrons. The total dose deposition was found to be highest for Bi followed by Pb, Ta and W whereas the neutron dose equivalent was highest for W followed by Pb, Bi and Ta. This simulation study will be useful for neutron dosimetry, estimation of source term, implementation of CR-39 for measurement and other radiation protection aspects in the vicinity of an electron accelerator.

The effect of cytotoxic agents on the passive transfer of cell-mediated immunity.

A system involving the passive transfer of committed lymphoid cells from Listeria-immune donors has been used to study the phases of the immune response which are sensitive to the immunosuppressive action of various cytotoxic agents. The agents investigated included cyclophosphamide, vinblastine, methotrexate, azathioprine, and X-irradiation. Complete suppression of passive immunization was obtained by the administration of cyclophosphamide or vinblastine to recipients at the time of cell transfer or by prior X-irradiation of recipients a day before cell transfer. Methotrexate was only partially suppressive, whereas azathioprine had no effect at all. The donor cell responsible for the transfer of immunity to recipients was shown to be a resting cell which is sensitive to the action of cyclophosphamide but not to vinblastine. The results of this investigation suggest that the donor cells undergo multiplication in the tissues of the recipient, presumably in response to specific stimulation by Listeria antigens. This in turn results in the activation of host macrophages. The immunosuppressive action of cyclophosphamide, vinblastine, and irradiation in the cell-transfer system has been discussed in relation to a direct cytotoxic action on the immune lymphoid cells of the donor and specific interference with their proliferation in the recipient, as well as impairment of macrophage production on the part of the recipient itself.

The effect of cytotoxic agents on the primary immune response to Listeria monocytogenes.

Four drugs, representing four different categories of cytotoxic agents, were studied for their effect on the immune response to Listeria infection in mice. The development of the host's immune response is revealed by a progressive change in the slope of the bacterial growth curve in spleen and liver. It has its onset at 24 hr in untreated mice, but in the presence of effective immunosuppression the organism multiples uninterruptedly until the animal dies from overwhelming infection. When administered as single injections at the time of infection, cyclophosphamide, vinblastine, and azathioprine all produced an effective immunosuppression, characterized by continuous bacterial multiplication. Methotrexate was also immunosuppressive, but unlike the others its effects were reversible. They could be sustained, however, by further treatment. Studies of the time-response relationship indicated that cyclophosphamide was highly active over a broad time-span ranging from 2 days before infection to 4 days after infection. Vinblastine on the other hand was maximally active when given on the day of infection, while methotrexate had its greatest effect when given 48 hr after infection. These differences indicate that these three drugs act on different cell populations involved in the host's immune response. The effects observed have been discussed in relation to what is known of the modes of action of the drugs tested. An observation of interest was the phenomenon of enhanced immunity in animals treated with cyclophosphamide or vinblastine 7-11 days before, and with methotrexate 4 days before infection; reactive hyperplasia of lymphoid tissue following withdrawal of drug was again advanced as an explanation for the occurrence of this paradoxical effect. The experimental model employed is simple, requiring only routine bacteriological facilities and minimal equipment. It seems to offer a useful means of assessing the immunosuppressive activity of drugs and of determining the time-course of their action; it could also be of value in the screening of anticancer agents.

Prenatal allergic sensitization to helminth antigens in offspring of parasite-infected mothers.

Total and filaria-specific immunoglobulin E (IgE) levels were studied in cord blood from infants born in Madras, India, where filariasis and intestinal helminth infections are highly endemic. Increased total IgE levels were observed in 82% of 57 cord sera tested (geometric mean 12.6 ng/ml; range 1-1,900 ng/ml). 33 of these sera also contained IgE antibodies specific for filarial antigens as determined by solid-phase radioimmunoassay. Comparison of ratios of filaria-specific IgE to total IgE in paired maternal and cord sera suggested that cord blood IgE was derived from the fetus in most cases and not from transplacental antibody transfer. Our results suggest that prenatal allergic sensitization to helminth parasites occurs in the tropics. Such sensitization may contribute to the heterogeneity in host immune response and disease expression noted in filariasis and other helminth infections.

Generation and application of LET calibration curve for neutron dosimetry using CR-39 detector and microwave induced chemical etching.

Microwave induced chemical etching (MICE) has been established as a faster and improved technique compared to other contemporary etching techniques for the development of tracks in a CR-39 detector. However, the methodology could not be applied for LET (linear energy transfer) spectrometry due to lack of a calibration curve using this method. For this purpose, a new LET calibration curve in the range of 12 keV/µm-799 keV/µm was generated considering different ions such as H, Li, C, O, and F on CR-39 having different LETs in water. An empirical relation was established from the obtained calibration curve for determining the value of LET (in water) from the value of V, the ratio of track etch rate to bulk etch rate. For application of this calibration curve in neutron dosimetry, CR-39 detectors were irradiated to neutrons generated from 120 and 142 MeV 16O+27Al systems followed by a similar MICE procedure. The absorbed dose (DLET) and the dose equivalent (HLET) were obtained from the LET spectra and were found to be 13% and 10% higher for 142 MeV 16O+27Al system than those for 120 MeV 16O+27Al system, respectively. The outcome of the study demonstrates the possibility of using the MICE technique for neutron dose estimation by CR-39 via LET spectrometry.

Rate of hospitalization and inpatient care costs for HIV-1-infected patients in Pune, India.

BACKGROUND: The transition of human immunodeficiency virus (HIV) infection to acquired immune deficiency syndrome (AIDS) has begun in India, and an increase in AIDS-related hospitalizations and deaths is an anticipated challenge. We estimated the rates of hospitalization and inpatient care costs for HIV-1-infected patients. METHODS: Data were analysed on 381 HIV-1-infected persons enrolled in a HIV-1 discordant couples' cohort between September 2002 and March 2004. Inpatient care costs were extracted from select hospitals where the study patients were hospitalized and the average cost per hospitalization was calculated. RESULTS: A majority of the patients were in an advanced state of HIV-1 disease with the median CD4 counts being 207 cells/cmm (range: 4-1131 cells/cmm). In all, 63 participants who did not receive antiretroviral therapy required hospitalization, 53 due to HIV-1-related illnesses and the remaining 10 due to worsening of pre-existing conditions. The overall HIV-1-related hospitalization rate was 34.2 per 100 person-years (95% CI: 26.94-42.93). The median duration of HIV-1-related hospitalization was 10 days (range 2-48 days) and the median cost was Rs 17,464 (range: Rs 400-63,891). CONCLUSION: It is necessary to strengthen the inpatient care infrastructure and supporting diagnostic set-up, and work out economically optimized treatment algorithms for HIV-1-infected patients. Although this analysis does not cover all costs and may not be generalizable, these baseline data might be a useful reference while planning related studies accompanying the government-sponsored programme to roll out antiretroviral therapy to AIDS patients.

Selection of neutron-absorbing materials to improve the low-energy response of a Zr-based extended neutron monitor using Monte Carlo simulations.

Monte Carlo simulations have been carried out using the FLUKA code to improve the neutron ambient dose equivalent [H*(10)] response of the ZReC (zirconium-lined portable neutron counter responding satisfactorily to neutrons up to 1 GeV) by introducing various neutron absorbers in the system such as cadmium, gadolinium, natural boron, enriched (10)B and borated polythene. It was found that ZReC can be effectively used as a portable neutron monitor by introducing any one of the following perforated layers: 5 mm thick natural boron, 0.5 mm thick enriched (10)B or 1 cm high-density polythene mixed with 50 % boron by weight. The integral response of the instrument was also calculated for some typical reference neutron fields. The relative ambient dose equivalent response of the said system is also found comparable with that of the existing LINUS neutron monitor.

Effects of high neutron doses and duration of the chemical etching on the optical properties of CR-39.

Effects of the duration of chemical etching on the transmittance, absorbance and optical band gap width of the CR-39 (Polyallyl diglycol carbonate) detectors irradiated to high neutron doses (12.7, 22.1, 36.0 and 43.5 Sv) were studied. The neutrons were produced by bombardment of a thick Be target with 12 MeV protons of different fluences. The unirradiated and neutron-irradiated CR-39 detectors were subjected to a stepwise chemical etching at 1h intervals. After each step, the transmission spectra of the detectors were recorded in the range from 200 to 900 nm, and the absorbances and optical band gap widths were determined. The effect of the etching on the light transmittance of unirradiated detectors was insignificant, whereas it was very significant in the case of the irradiated detectors. The dependence of the optical absorbance on the neutron dose is linear at short etching periods, but exponential at longer ones. The optical band gap narrows with increasing etching time. It is more significant for the irradiated dosimeters than for the unirradiated ones. The rate of the narrowing of the optical band gap with increasing neutron dose increases with increasing duration of the etching.

The epidemiology of AIDS in the Vellore region, southern India.

OBJECTIVE: To describe the epidemiology of patients with AIDS in Vellore region, Southern India. DESIGN AND METHODS: Sixty-one patients with AIDS were diagnosed and treated between July 1987 and June 1992. Information on their demographic characteristics and probable modes of acquiring HIV infection was collected at interviews with them and their spouses. RESULTS: There was a progressive increase in the number of patients seen over the 5 years. The mean ages of the 51 men and the 10 women were 33 and 29 years, respectively. Of the 44 patients from our district (population, 5 million), 28 were from Vellore town and 10 from rural areas. Forty-seven (92%) men had frequently used prostitutes. Of the women, four were prostitutes, one had had multiple sex partners and five had not had extramarital sexual contact. One man and one woman had no other risk factor except blood transfusion. Thirty-one (51%) patients had died by August 1992. CONCLUSION: The AIDS epidemic in this region is in its early ascending phase, with a doubling time of approximately 1 year. Most men with AIDS were infected by heterosexual contact with prostitutes, while some women were prostitutes themselves. Together with the male-to-female ratio of 5:1, these results suggest that the male population at risk has sex with a much smaller population of female prostitutes, constituting the major chain of transmission. HIV infection is occurring in both urban and rural populations.

PIP: Between July 1987 and June 1992 physicians diagnosed AIDS in 61 patients at the Christian Medical College Hospital in Vellore, India. They noted that there were 200 AIDS cases reported in the same period in the region, but they extrapolated AIDS cases to be 7656. Yet even the figure of 7656 was likely to be an underestimate, because this hospital does not treat most patients in the district or in the town. The number of cases at this hospital doubled each year. The mean age of the 51 men was 33 years, and 29 years for the 10 women (male-to-female ratio - 5:1). 23% of cases were from rural areas. Most cases (71% for men and 80% for women) were married and lived with their spouses. 47 (92%) of the men had had sexual intercourse with prostitutes, suggesting that this was the leading means of HIV transmission. 4 married women were prostitutes and their husbands knew and/or encouraged them to work as prostitutes. 4 other married women had had no extramarital sexual affairs and were infected by their HIV positive husbands who had had sexual intercourse with prostitutes. The only risk factor for 2 patients was blood transfusion. The most common signs and symptoms of AIDS included considerable weight loss (62%), fever for more than 30 days (56%), tuberculosis (52%), oral candidiasis (41%), and chronic diarrhea (31%). By August 1992, 31 (51%) patients had died.

The human immunodeficiency virus epidemic in India. Current magnitude and future projections.

Since the first case of the human immunodeficiency virus (HIV) infection was documented in India in 1986, there has been an explosive increase in HIV transmission. In this review we describe the chronology of the HIV epidemic in India, preliminary information about the clinical presentation of the acquired immunodeficiency syndrome (AIDS), the biological and behavioral aspects of HIV transmission in the Indian setting, and projections regarding the future of the HIV epidemic in India. Using recent data obtained by searching the computerized literature and published abstracts, conference proceedings, and publications from the government of India, we show that India is experiencing a major epidemic of HIV transmission in high-risk populations of commercial sex workers, sexually transmitted disease clinic patients, intravenous drug users, and commercial blood donors. There is also evidence of recent spread of the epidemic from these high-risk groups to other risk groups in India, and from urban centers to rural populations. It is estimated that 1.6 million people are currently infected with HIV in India. At the present rate of transmission, India will have the largest number of HIV-infected individuals of any country in the world by the end of this decade, with more than 5 million infected individuals. Because limited data are available, comprehensive and well-designed epidemiologic surveys are urgently needed to adequately characterize the HIV epidemic in India and to help implement targeted and effective educational and prevention-oriented programs.

PIP: A review of government publications, conference proceedings, and computerized literature and published abstracts reveals an explosive increase in human immunodeficiency virus (HIV) in India since the first case was identified in 1986. In fact, if present rates of transmission persist, India will have more than 5 million HIV-infected persons by the year 2000--the largest number in the world. By 1990, at least 40% of Bombay's 50,000 commercial sex workers were infected. Other high-risk groups include sexually transmitted disease clinic patients, intravenous drug users, and commercial blood donors. The lack of a uniform case definition for AIDS or of a standardized national program to register AIDS cases have impeded research on the natural history of the disease in India. Co-infection with tuberculosis appears to be the predominant clinical pattern. Community awareness of AIDS has been limited by a 50-60% literacy rate, poor access to the mass media in rural areas, and government neglect of AIDS education. Knowledge about HIV and its transmission is alarmingly low, even among health workers. Before 1991, government responses to AIDS were limited to calls for quarantine, the restriction of foreigners, denial of health care to HIV-infected patients, and offers to pay infected prostitutes to retire. Preparation in 1991 of a government document, "Strategic Plan for Prevention and Control of AIDS in India 1992-96," represented a major reversal and a commitment to provide the necessary resources to contain the spread of the epidemic. International aid will be required, however, for the diagnosis and treatment of opportunistic infections, maintenance of an HIV surveillance program, provision of a safe blood supply, prospective studies, and an aggressive educational campaign for health workers and the public.

Human immunodeficiency virus infection in the blood donors of Delhi, India.

In the present study, blood from paid and unpaid donors was screened for the presence of HIV infection using a competitive ELISA test. None of the 8,000 unpaid donors but 4 (0.23%) of the 1,700 paid donors showed evidence of HIV infection. All of these four ELISA-positive samples were confirmed by the Western blot test. The present study indicates that HIV infection has entered the group of paid donors in the Delhi metropolitan area. Careful donor screening, discouraging use of paid donors, and stringent screening of donated units of blood has become mandatory in India to prevent HIV transmission through blood and blood products.

PIP: In Delhi, India, researchers collected sera from 1700 paid blood donors between January-February 1989 and from 8000 voluntary blood donors between September 1, 1988-February 28, 1989. Laboratory personnel screened all the sera for HIV antibodies using a competitive ELISA test. Any samples found to be reactive were tested again using the ELISA technique. Laboratory personnel determined reactivity a 2nd time in 4 samples. They confirmed that these 4 samples were positive for HIV by the Western blot test. The 4 positive samples came from paid donors (.23%), while no positives occurred in the volunteer group. Characteristics of the paid donors included male, 50% unemployed, illiterate, and median age of 28 years. 95% of the volunteers were males. Also volunteers were generally literate and educated. 3 of the 4 HIV positive donors were daily-wage unskilled laborers who went from city to city seeking employment. To sustain themselves or support their families, they would donate their blood often. All 3 have had sex with prostitutes. The 4th donor could not be found. Even though the prevalence of HIV is low among prostitutes in INdia, they are the largest risk group and prevalence is climbing. Since paid blood donors are usually transient, they can spread HIV to prostitutes of other cities as well as to recipients of their donated blood. 2 possible targets of intervention include educating the public to not accept blood from professional blood donors since their blood is not tested for HIV and educating prostitutes on methods of prevention of HIV infection.

HIV serosurveillance among prostitutes and patients from a sexually transmitted diseases clinic in Delhi, India.

Screening of 701 prostitutes in Delhi for HIV antibodies by a competitive ELISA test and supplementary Western blot test showed that only one of them was infected. Of the 4,572 samples from the patients attending a sexually transmitted disease clinic in Delhi, none showed evidence of HIV infection. In contrast to this low frequency of HIV infection in Delhi, a much higher frequency has been reported to the Indian Council of Medical Research from major metropolitan centers on the coast of India, namely, Bombay and Madras and their surrounding areas. It is possible that the infection is making inroads from these coastal areas to the interior of the country.

Randomised controlled clinical trial of short course chemotherapy in abdominal tuberculosis: a five-year report.

OBJECTIVES: To assess and compare the efficacy of a 6-month short-course chemotherapy regimen (SCC) with that of a 12-month standard regimen in the treatment of abdominal tuberculosis. DESIGN AND SUBJECTS: A total of 193 adult patients with evidence of abdominal tuberculosis were randomly allocated to one of two daily regimens: 1) a 6-month SCC regimen with rifampicin, isoniazid and pyrazinamide for 2 months followed by rifampicin with isoniazid for another 4 months (6R series) and 2) and 12-month standard regimen of ethambutol and isoniazid with streptomycin supplemented for 2 weeks (12E series). Surgery was undertaken only for patients suspected to have obstruction or perforation of the intestine. RESULTS: A total of 163 (85 6R, 78 12E) patients were available for efficacy analysis after exclusion of 30 patients for various reasons. At the end of treatment clinical status was normal in 84 (99%) in 6R patients and in 73 (94%) in 12E patients. Of these, 147 patients completed follow-up for 5 years; none had relapsed requiring treatment for abdominal tuberculosis. CONCLUSION: A 6-month SCC regimen has been found to be as effective as the standard 12-month regimen in the treatment of all forms of abdominal tuberculosis.

Reduced lymphocyte response to mitogens in patients with Bancroftian filariasis.

Peripheral blood lymphocytes from patients with acute and chronic Wuchereria bancrofti infections responded poorly to concanavalin A, phytohaemagglutinin and pokeweed mitogen when cultured in heat-inactivated pooled normal serum. The lymphocyte response to mitogens in carriers of microfilariae (mff) were normal. The suppression of transformation to mitogens was not reversible by the removal of plastic adherent cells. Incubation with mitogens and the adult filarial worm antigen (BmA) did not alter the mitogen response either in control subjects or in filarial patients. The possible mechanism of immunosuppression is discussed.

Localization of a peripheral patch: the role of blur and spatial frequency.

Peripheral vision serves to direct our attention and fixation to objects of interest. This requires that the visual system be capable of accurately localizing peripherally presented targets having different spatial structures. The question we address is "to what extent does stimulus spatial structure influence the precision of peripheral localization?" To address this issue, we measured the precision of spatial localization (with reference to a foveal target) for a single Gaussian or Gabor patch briefly presented in the periphery. For both stimuli, we find that when the standard deviation of the stimulus envelope (SD) is less than 1/5 the stimulus eccentricity, localization thresholds are independent of SD and are approximately 1/50 of eccentricity. For larger values of SD, localization thresholds increase linearly with increasing SD, and are approximately 1/5 of SD. The results hold over a range of eccentricities (from 2.5 to 10 deg) and stimulus contrasts (from near detection threshold to 80%). In addition, for Gabor patches, the results are independent of frequency, phase and orientation of the carrier.

Long-range dichoptic interactions in the human visual cortex in the region corresponding to the blind spot.

The region of the visual field of one eye that corresponds to the blind spot of the contralateral eye is believed to be monocular. We measured dichoptic contour interaction in this region of the visual field in humans by having observers report the orientation of a test letter "T" presented to this region, in the presence of flanking T's presented around the blind spot of the fellow eye. A large drop in performance was seen because of the flanks, showing clearly the existence of dichoptic contour interaction in this "monocular" region of the visual field. This suggests that the cortical representation of the region of the visual field that corresponds to the contralateral eye's blind spot is not strictly monocular. The absence of direct retinal afferents from one eye to this region of cortex suggests the involvement of horizontal cortical connections in the contour interaction phenomenon. Our estimates of the extent of contour interaction in mm of striate cortex are comparable to the reported lengths of the long-range horizontal connections in the striate cortex of monkeys. Our results are consistent with the proposition that long-range horizontal connections of the striate cortex may mediate the contour interaction phenomenon.

Looking behind a pathological blind spot in human retina.

Recent work suggests that dichoptic lateral interactions occur in the region of the visual field of one eye that corresponds to the physiological blind spot in the other eye (Tripathy, S. P., & Levi, D. M. (1994). The two-dimensional shape of spatial interaction zones in the parafovea. Vision Research, 34, 1127-1138.) Here we ask whether dichoptic lateral interactions occur in the region of the visual field of one eye that corresponds to a pathological blind spot, a retinal coloboma in the other eye. To address this question we had the observer report the orientation of a letter 'T' presented within this region in the presence of flanking 'T's presented to the other eye around the coloboma. A large drop in performance was seen due to the flanks, showing the existence of dichoptic lateral interactions in this monocular region. The presence of these dichoptic interactions in a region lacking direct retinal afferents from one eye is consistent with the proposition that long-range horizontal connections of the primary visual cortex mediate these interactions.

Two-dot alignment across the physiological blind spot.

Three competing hypotheses have been proposed for the cortical representation of the blind spot. These are: (i) the regions surrounding the blind spot maintain their spatial values; (ii) the opposite sides of the blind spot are represented adjacently at the cortex, so that the blind spot is "sewn-up"; and (iii) the blind spot is sewn-up with compensation occurring in the immediate surround of the blind spot, so that spatial values are distorted only in the immediate surround of the blind spot. To distinguish between these hypotheses we used a two-dot alignment task, with the two dots straddling the blind spot at varying dot separations. Thresholds in the two-dot alignment task are limited by the cortical separation of the two dots. When thresholds for alignment across the blind spot are compared with thresholds over intact retina at the same eccentricity, the three hypotheses predict: (i) no change in thresholds; (ii) a lowering of thresholds; and (iii) a lowering of thresholds but only at separations slightly greater than the diameter of the blind spot. Thresholds across the blind spot were closely similar to thresholds across intact retina. The results do not support a sewing-up (with or without compensation) of the blind spot. Rather, our results are consistent with a preservation of spatial values around the blind spot.

Detecting collinear dots in noise.

We estimated the sensitivity for detecting a row of collinear target elements (usually dots) by measuring the maximum density of randomly positioned noise elements that allowed 75% correct detection of the orientation of alignment (binary choice: horizontal versus vertical) of the target elements. We varied the number of target elements, their mode of generation, and their accuracy of positioning. As reported previously (Moulden (1994) Higher-order processing in the visual system. Ciba Foundation Symposium 184. Chichester: Wiley), target detection improved rapidly until the number of target elements reached about seven, and then improved more slowly beyond this point. However, this break was reduced (and often removed entirely) when the target array was formed by repositioning pre-existing noise elements lying close to the target location, rather than by superimposition of additional target elements onto the noise array. This almost linear slope of improvement, coupled with the observation that target detection was disrupted more by random jitter of target elements at right angles to their axis of alignment than by jittering along this axis, argues against a two-stage process of perceptual grouping (Moulden, 1994) and supports instead an explanation based on the operation of a single mechanism. This single mechanism explanation is further supported by the observation that intrinsic positional uncertainty (estimated from the results of jitter experiments) was independent of target element number. Additional experiments showed that target detection is facilitated by aperiodic noise dots that fall close to the target axis. The results are discussed in relation to alternative explanations of perceptual grouping.

Epidemic of herpes zoster following HIV epidemic in Manipur, India.

Since 1989, injecting drug use (IDU) related HIV infection has affected thousands of young adults in Manipur, a north eastern state of India bordering Myanmar following a similar kind of epidemic in adjoining countries like Thailand and Myanmar. During a clinical surveillance of a group of HIV positive IDUs for a natural history study at Manipur, herpes zoster (HZ) emerged as the most specific early HIV related illness (positive predictive value of 100%) in patients belonging to the age group of 12-45 years. Data collected from the dermatology departments of the two main hospitals of the state revealed that there had been an epidemic of HZ since 1990 (rate of 1990 being 11.3/1000 compared to 6.5/1000 in 1989, P value < 0.0001) among males of 12-45 years. The epidemic of HZ has been attributed to the preceding epidemic of IDU related HIV in the same age and gender group occurring 1 year earlier. HZ should be recognised as a marker condition similar to tuberculosis indicating the necessity of screening for HIV in regions where the dual problem of IDU and HIV exist in young adults.