Biomedical subjects

Jan H Richardus

Publications and source records attributed to Jan H Richardus.

17 recordsLinked to original sources

PubMed2006

Association of SARS susceptibility with single nucleic acid polymorphisms of OAS1 and MxA genes: a case-control study.

BACKGROUND: Host genetic factors may play a role in susceptibility and resistance to SARS associated coronavirus (SARS-CoV) infection. The study was carried out to investigate the association between the genetic polymorphisms of 2',5'-oligoadenylate synthetase 1 (OAS1) gene as well as myxovirus resistance 1 (MxA) gene and susceptibility to SARS in Chinese Han population. METHODS: A hospital-based case-control study was conducted. A collective of 66 SARS cases and 64 close contact uninfected controls were enrolled in this study. End point real time polymerase chain reaction (PCR) and PCR-based Restriction Fragment Length Polymorphism (RFLP) analysis were used to detect the single nucleic polymorphisms (SNPs) in OAS1 and MxA genes. Information on other factors associated with SARS infection was collected using a pre-tested questionnaire. Univariate and multivariate logistic analyses were conducted. RESULTS: One polymorphism in the 3'-untranslated region (3'-UTR) of the OAS1 gene was associated with SARS infection. Compared to AA genotype, AG and GG genotypes were found associated with a protective effect on SARS infection with ORs (95% CI) of 0.42 (0.20-0.89) and 0.30 (0.09-0.97), respectively. Also, a GT genotype at position 88 in the MxA gene promoter was associated with increased susceptibility to SARS infection compared to a GG genotype (OR = 3.06, 95% CI: 1.25-7.50). The associations of AG genotype in OAS1 and GT genotype in MxA remained significant in multivariate analyses after adjusting for SARS protective measures (OR = 0.38, 95% CI: 0.14-0.98 and OR = 3.22, 95% CI: 1.13-9.18, respectively). CONCLUSION: SNPs in the OAS1 3'-UTR and MxA promoter region appear associated with host susceptibility to SARS in Chinese Han population.

2',5'-Oligoadenylate Synthetase↗

PubMed2006

Lessons learned from a population-based chlamydia screening pilot.

We evaluated process organization and response optimization in a home-based Chlamydia trachomatis (Ct) screening project in the Netherlands among 15- to 29-year-old women and men. The method used was computer-supported data flow, from population sampling to informing participants of the result. A new test kit or a letter reminded non-respondents after six weeks. Fifteen-year olds required parental consent. Urine arrived at the laboratory within 29 days from invitation, and four (1-11) days after collection, indicating good specimen quality. Test kits had a higher response than letters (15 versus 10%). Response in 15-year olds was 33%; with 2% Ct infected sexually active 15 year olds. In Conclusion, purpose made computer software is essential for an efficient screening programme. Sending urine by mail does not impair diagnostics. Reminders are necessary and effective after four weeks. Necessary parental consent for under 16-year olds should not be a deterrent to offer Ct screening to this age group.

Adolescent↗

PubMed2006

Natural Anaplasma phagocytophilum infection of ticks and rodents from a forest area of Jilin Province, China.

Polymerase chain reaction integrated with sequence analysis was carried out to investigate the natural Anaplasma phagocytophilum infection in ticks and rodents from a forest area of Jilin Province, China. Four (4.0%) of 100 Ixodes persulcatus and 2 (0.7%) of 286 Dermacentor silvarum ticks collected by flagging vegetation were positive. Nine (8.8%) of 102 rodents were infected, as well as 2 (2.8%) of 71 I. persulcatus parasitizing on 25 rodents. The nucleotide sequences of 1442-bp A. phagocytophilum 16S rRNA gene amplified from rodents and ticks were identical to each other and to that previously reported in Heilongjiang Province of China (GenBank accession no. AF205140), but different from those of other countries. The sequences of 357-bp partial citrate synthase gene from the above specimens were homologic, and varied from known A. phagocytophilum agents. These findings add new information on the ecologic features of A. phagocytophilum and indicate the threat of anaplasmosis in the area.

Anaplasma phagocytophilum↗

PubMed2005

Physical distance, genetic relationship, age, and leprosy classification are independent risk factors for leprosy in contacts of patients with leprosy.

BACKGROUND: Close contacts of patients with leprosy have a higher risk of developing leprosy. Several risk factors have been identified, including genetic relationship and physical distance. Their independent contributions to the risk of developing leprosy, however, have never been sufficiently quantified. METHODS: Logistic-regression analysis was performed on intake data from a prospective cohort study of 1037 patients newly diagnosed as having leprosy and their 21,870 contacts. RESULTS: Higher age showed an increased risk, with a bimodal distribution. Contacts of patients with paucibacillary (PB) leprosy with 2-5 lesions (PB2-5) and those with multibacillary (MB) leprosy had a higher risk than did contacts of patients with single-lesion PB leprosy. The core household group had a higher risk than other contacts living under the same roof and next-door neighbors, who again had a higher risk than neighbors of neighbors. A close genetic relationship indicated an increased risk when blood-related children, parents, and siblings were pooled together. CONCLUSIONS: Age of the contact, the disease classification of the index patient, and physical and genetic distance were independently associated with the risk of a contact acquiring leprosy. Contact surveys in leprosy should be not only focused on household contacts but also extended to neighbors and consanguineous relatives, especially when the patient has PB2-5 or MB leprosy.

Adolescent↗

PubMed2005

Paired, quantitative measurements of hepatitis B virus DNA in saliva, urine and serum of chronic hepatitis B patients.

OBJECTIVES: Despite an abundance of epidemiological evidence for horizontal transmission of hepatitis B virus (HBV), the transmission route remains to be fully elucidated. In a new approach, we evaluated quantitative HBV DNA content in serum, saliva and urine as a first step in exploring possible modes of horizontal transmission. METHODS: In an outpatient setting of an academic hospital, paired serum, saliva and urine samples were collected from 150 chronically infected HBV patients. A validated HBV DNA TaqMan assay was used to quantitatively measure HBV DNA. RESULTS: Mean log HBV DNA in serum was 5.8 (range, undetectable to 10.0 log HBV DNA) copies/ml, 50% of the patients had an HBV DNA above 10 copies/ml in serum. Mean log HBV DNA level in saliva was 3.2 (range, undetectable to 7.5) copies/ml, 15% had an HBV DNA above 10 copies/ml in saliva. Mean log HBV DNA level in urine was 2.6 (range, undetectable to 5.4) copies/ml and 1% had an HBV DNA above 10 copies/ml in urine. A high, non-linear correlation was shown between HBV DNA in serum and saliva (Spearman's rho 0.82) and between serum and urine (Spearman's rho 0.74). CONCLUSIONS: The significant amounts of HBV DNA found in saliva and urine in chronic HBV patients with high viraemia in serum may have implications for the understanding of hepatitis B epidemiology. The potential infectivity of these body fluids may provide an explanation for the 20% of cases of infection obtained through horizontal transmission for which the origin of infection is yet unknown.

Adult↗

PubMed2005

Management of Chlamydia cases and their partners: results from a home-based screening program organized by municipal public health services with referral to regular health care.

BACKGROUND: We evaluated the management of Chlamydia trachomatis cases and partners found in a systematic home-based chlamydia screening project in the Netherlands among 15- to 29-year-old women and men, organized by the Municipal Public Health Services (MHS). METHODS: Infected participants (165/8339 = 2%) were referred to regular curative services. The treating physician provided feedback on treatment and partner notification. RESULTS: Including the effect of a reminder, the treatment rate of all index cases was 91% (150/165); among persons with non-Dutch ethnicity, 81% (25/31). The majority of cases (82%) consulted the general practitioner for treatment as opposed to sexually transmitted disease/MHS clinics (18%). Eighty-five percent of cases were treated within 2 weeks. The confirmed treatment rate of partners in the last 6 months was 49% (86/176); 57% (81/141) for current versus 14% (5/35) for other partners. Patient referral was advised in an additional 18% (25/141) of current partners and in 9% (3/35) of other partners (potential treatment). CONCLUSION: Home-based chlamydia screening and treatment through regular treatment facilities has proven to be effective in the Netherlands. The necessity of a reminder to increase treatment rate and the lower treatment rate in non-Dutch high-risk groups deserve attention. Low confirmed treatment rate of current partners carries the potential of reinfection, and patient-delivered treatment should be expanded.

Adolescent↗

PubMed2005

Acceptability and consequences of screening for chlamydia trachomatis by home-based urine testing.

OBJECTIVE: The objective of this study was to study the acceptability and consequences of home-based chlamydia (CT) screening by Municipal Health Services (MHS) among 15- to 29-year-old participants. STUDY: This study consisted of a cross-section of 156 CT-positives and 600 random sampled CT-negatives after receiving the result of their CT test. RESULTS: Thirty-eight percent of the men and 59% of the women responded. The screening method was well-accepted. Seventy percent (52) of the CT-positives were surprised about their result. Infected women more often than men reported a feeling of being dirty and of anxiety about infertility. Curiosity for the CT result was decisive for participation in 68% and perception of personal risk was poor. The willingness to be tested regularly was determined by present chlamydial infection, young age, multiple lifetime partners, short relationship, and earlier test for chlamydia. CONCLUSIONS: Chlamydia screening organised by MHS is acceptable for future screening. Participants with an elevated risk are interested in screening as long as test kits are easily available. Counseling with focus on effects of CT, especially on women, is essential. Alternative approaches are needed to motivate men and non-Dutch high-risk groups.

Adolescent↗

PubMed2005

Close contacts with leprosy in newly diagnosed leprosy patients in a high and low endemic area: comparison between Bangladesh and Thailand.

BACKGROUND: As part of a larger study of the role of close contacts in the transmission of M. leprae, we explored whether the proportion of newly detected cases with a family history of leprosy differs with different incidence rates of leprosy in a population. METHODS: Retrospective analysis was performed of contacts of all new leprosy patients diagnosed during a 10-yr period in well-established leprosy control programs in Thailand and Bangladesh. By our definition, a contact group consisted of the new case and of past and present cases who were relatives and in-laws of the new case. For a new case, the nearest index case was defined on the basis of time of onset of symptoms for the cases in the contact group, in combination with the level of closeness of contact between these cases and the new case. Three contact levels were distinguished. In Bangladesh these levels were defined as 'kitchen contact'; 'house contact'; and 'non-house contact'. In Thailand comparable levels were defined as 'house contact'; 'compound contact'; and 'neighbor contact'. RESULTS: In Bangladesh 1333, and in Thailand 129 new patients were included. The average new case detection rate over 10 yrs was 50 per 100,000 general population per year in Bangladesh, and 1.5 per 100,000 in Thailand. In the high endemic area 25% of newly detected cases were known to belong to a contact group and were not the index case of this group, whereas in the low endemic area 62% of newly detected cases had these characteristics. The distribution of the nearest index cases over the three contact levels was comparable in both areas. Just over half of the nearest index cases were found within the immediate family unit ('kitchen' in Bangladesh; 'house' in Thailand). CONCLUSION: The results indicate that in a low endemic area a higher proportion of newly detected leprosy cases have a family history of leprosy compared to a high endemic area. Different contact levels and their relative risks to contract leprosy need to be established more precisely. In high endemic situations the circle of contacts that should be surveyed may need to be wider than currently practiced.

Adolescent↗

PubMed2004

Incidence of acute nerve function impairment and reactions in leprosy: a prospective cohort analysis after 5 years of follow-up.

BACKGROUND: Nerve function impairment (NFI) is the key outcome of the pathological processes of infection with Mycobacterium leprae, which can continue after completion of multidrug therapy (MDT) and lead to disability after leprosy patients are released from treatment. The objective of this study was to assess the need for and duration of surveillance of NFI. METHODS: Prospective cohort study of 2664 new leprosy patients in Bangladesh, with an observation period of 36 months in paucibacillary (PB) patients, and 60 months in multibacillary (MB) patients. Incidence rates (IR) were calculated with the number of patients developing NFI, type 1 and type 2 reactions, and silent neuritis for the first time after registration as the numerator, and cumulative person-years at risk (PYAR) as the denominator. Survival curves to the first event of NFI were also calculated. RESULTS: The IR of first event of NFI amongst MB patients was 16.1 per 100 PYAR, with 121/357 (34%) developing NFI during the observation period. Of the 121 with a first event of NFI, 77 (64%) had this within a year after registration, 35 (29%) in the second year, and the remaining 9 (7%) after 2 years. The IR of first event of NFI amongst PB patients was 0.9 per 100 PYAR, with 54/2153 (2.5%) developing NFI during the observation period. Of the 54 with a first event of NFI, 48 (89%) had this within a year after registration, 3 (5.5%) in the second year, and the remaining 3 (5.5%) cases after 2 years. The percentage of PB patients with no NFI at registration surviving without developing NFI during the observation period was 99% and for PB patients with NFI at registration 92%. In MB patients without NFI at registration, the percentage surviving with no NFI during the observation period was 84% and for MB patients with NFI at registration only 36%. CONCLUSION: New episodes of NFI and reactions after registration are common, in particular in MB patients with long-standing NFI at registration. The study highlights the importance of continuing surveillance for NFI of this risk group after registration for 2 years. Active surveillance beyond 2 years is not indicated.

Acute Disease↗

PubMed2004

Trends in leprosy case detection worldwide since 1985.

Trends in case detection and case detection rate (CDR) since 1985 are described at regional and national levels. Annual case detection by WHO Region was available for 1994-2000. Using different sources, complete time series for case detection were constructed for 1985-1998 for a group of 33 endemic countries cumulatively (top 33), and for 14 individual countries (top 14). Population statistics were used to derive CDRs. India contributed 79% to global case detection in 1998. Africa, the Americas and South-East Asia each contributed about 30% when India is excluded. During 1994-2000, case detection did not decrease in these three WHO Regions. The 33 countries contributed 99% and 98% to global case detection in 1994 and 1998, respectively. Cumulative case detection for the top 33 minus India gradually increased, overall almost doubling. The contribution of the top 14 to case detection of the top 33 hardly changed over time, equalling 96% in 1998 (81% when India is excluded). In terms of annual case detection, Brazil was always ranked second after India; it accounted for 27% of 1998 case detection in the top 33 except India. In 1998, seven of the top 14 countries--including India and Brazil--had CDRs above 2 per 10,000. The CDR did not exceed 1 per 10,000 for the other half. Decreasing tendencies in CDR, either for the whole period or in the 1990s, are observed for four of the top 14 countries (Guinea and three Western Pacific countries: China, Vietnam and the Philippines). In conclusion, there is no general decline in case detection to date, and several important countries still have high CDRs. Prevalence is an irrelevant indicator for monitoring epidemiological changes in leprosy. Trends in the transmission and incidence of leprosy are still completely unclear, necessitating further research. The target to eliminate leprosy as a public health problem, defined as a prevalence of less than 1 per 10,000, is therefore also an inadequate yardstick for decision making on leprosy control.

Africa↗

PubMed2004

The future incidence of leprosy: a scenario analysis.

OBJECTIVE: To investigate the impact of the current strategy for the elimination of leprosy on its incidence and to assess the consequences of failure to sustain this strategy. METHODS: Scenarios for assessing the impact of the elimination strategy were implemented in a computer simulation program. The scenarios reflected the assumptions made regarding contagiousness, transmission and bacille Calmette-Guerin (BCG) vaccination. The trend in case detection rate for the main countries in which leprosy was endemic during 1985-98 was fitted, and incidence up to 2020 was projected. FINDINGS: Owing to the gradual shortening of delays in detection up to 1998, and because of the low relapse rate that occurs with multidrug treatment MDT, incidence is predicted to decrease beyond 2000 in all scenarios. The annual decline was a few per cent higher when favourable assumptions were made about protection and coverage of BCG vaccination. Overall, the predicted annual decline in incidences ranged from 2% to 12%. CONCLUSION: The elimination strategy reduces transmission, but the decline may be slow. Relaxation of control after 2005 is unjustified given the uncertainty about the rate of decline and the adverse effects of longer delays in detection. A long-term strategy for leprosy control should be adopted.

BCG Vaccine↗

PubMed2003

Differences in perinatal mortality and suboptimal care between 10 European regions: results of an international audit.

OBJECTIVE: A European concerted action (the EuroNatal study) investigated the background of differences in perinatal mortality between countries of Europe. The study aimed to determine the contribution of differences in quality of care, by looking at differences in the presence of suboptimal factors in individual cases of perinatal death. DESIGN: Retrospective audit study. SETTING: Regions of 10 European countries. POPULATION: 1619 cases of perinatal death. METHODS: Perinatal deaths between 1993 and 1998 in regions of 10 European countries were identified. Reviewed were singleton fetal deaths (28 or more weeks of gestational age), intrapartum deaths (28 or more weeks) and neonatal deaths (34 or more weeks). Deaths with (major) congenital anomalies were excluded. Cases were blinded for region and an international audit panel reviewed them using explicit audit criteria. MAIN OUTCOME MEASURES: Presence of suboptimal factors. RESULTS: The audit covered 1619 cases of perinatal death, representing 90% of eligible cases in the regions. Consensus was reached on 1543 (95%) cases. In 715 (46%) of these cases, suboptimal factors, which possibly or probably had contributed to the fatal outcome, were identified. The percentage of cases with such suboptimal care factors was significantly lower in the Finnish and Swedish regions compared with the remaining regions of Spain, the Netherlands, Scotland, Belgium, Denmark, Norway, Greece and England. Failure to detect severe IUGR (10% of all cases) and smoking in combination with severe IUGR and/or placental abruption (12%) was the most frequent suboptimal factor. There was a positive association between the proportion of cases with suboptimal factors and the overall perinatal mortality rate in the regions. CONCLUSIONS: The findings of this international audit suggest that differences exist between the regions of the 10 European countries in the quality of antenatal, intrapartum and neonatal care, and that these differences contribute to the explanation of differences in perinatal mortality between these countries. The background to these differences in quality of care needs further investigation.

Abruptio Placentae↗

PubMed2003

A clinical prediction rule for nerve function impairment in leprosy patients-revisited after 5 years of follow-up.

Nerve function impairment (NFI) commonly occurs during or after chemotherapy in leprosy. We previously described a clinical prediction rule to estimate the risk of NFI occurring within 2 years of diagnosis, based on 2510 patients who are followed up in the Bangladesh Acute Nerve Damage Study (BANDS). This prediction rule assigns new leprosy patients to one of three risk groups based on leprosy group and the presence or absence of NFI at registration. Updated data with up to 5 years of follow-up showed that 95% of all NFI occurred within 2 years. This study confirms the validity of the rule and supports the conclusion that there is little value for the detection of NFI in extending follow-up beyond 2 years.

Adolescent↗

PubMed2003

The prognostic importance of detecting mild sensory impairment in leprosy: a randomized controlled trial (TRIPOD 2).

This study was designed to investigate whether leprosy patients diagnosed with mild sensory impairment have a better prognosis when treated with steroids than similarly impaired patients treated with placebo. A multi-centre, randomized, double-blind, placebo-controlled trial was conducted in Nepal and Bangladesh. Patients were eligible if they had a confirmed leprosy diagnosis, were between 15 and 50 years old, had mild sensory impairment of the ulnar or posterior tibial nerve of less than 6 months duration and did not require steroids for other reasons. 'Mild impairment' was defined as 'impaired on the Semmes-Weinstein monofilament test, but testing normal on the ballpen sensory test'. Subjects were randomized to either prednisolone treatment starting at 40 mg per day, tapering over 4 months, or placebo. Nerve function was monitored monthly. Any patient who deteriorated was taken out of the trial and was put on full-dose steroid treatment. Outcome assessment was done at 4, 6, 9 and 12 months from the start of the treatment. Outcome measures were the proportion of patients needing full-dose prednisolone and the Semmes-Weinstein sum scores. Each patient contributed only one nerve to the analysis. Seventy-five patients had nerves eligible for analysis, of whom 41 (55%) and 34 (45%) were allocated to the prednisolone and placebo arms, respectively. At 4 months, three patients in the prednisolone arm (7%) and six in the placebo arm (18%) had an outcome event requiring full dose steroids. At 12 months, these proportions had almost reversed, 11 (27%) and 6 (18%) in the treatment and placebo arms, respectively. In the latter group, 75% had recovered spontaneously after 12 months. Prednisolone treatment of sensory impairment of the ulnar and posterior tibial nerves detectable with the monofilament test, but not with the ballpen test, did not improve the long-term outcome in terms of recovery of touch sensibility, not did it reduce the risk of leprosy reactions or nerve function impairment beyond the initial 4-month treatment phase. Two unexpected main findings were the strong tendency of mild sensory impairment to recover spontaneously and the fact that patients with mild sensory impairment without any other signs or symptoms of reaction or nerve function impairment are relatively rare.

Adult↗

PubMed2003

Treatment with corticosteroids of long-standing nerve function impairment in leprosy: a randomized controlled trial (TRIPOD 3).

Some leprosy patients with long-standing nerve function impairment (NFI) appear to have responded favourably to treatment with corticosteroids. This study investigated whether patients with untreated NFI between 6 and 24 months duration and who are given standard regimen corticosteroid therapy, will have a better treatment outcome than a placebo group. A multicentre, randomized, double-blind placebo-controlled trial was conducted in Nepal and Bangladesh. Subjects were randomised to either prednisolone treatment starting at 40 mg/day, tapered by 5 mg every 2 weeks, and completed after 16 weeks, or placebo. Outcome assessments were at 4, 6, 9, and 12 months from the start of treatment. 92 MB patients on MDT were recruited, of whom 40 (45%) received prednisolone and 52 (55%) placebo treatment. No demonstrable additional improvement in nerve function, or in preventing further leprosy reaction events was seen in the prednisolone group. Overall, improvement of nerve function at 12 months was seen in about 50% of patients in both groups. Analysis of subgroups according to nerve (ulnar and posterior tibial), duration of NFI, and sensory and motor function, also did not reveal any differences between the treatment and placebo groups. There was however, indication of less deterioration of nerve function in the prednisolone group. Finally, there was no difference in the occurrence of adverse events between both groups. The trial confirms current practice not to treat long-standing NFI with prednisolone. Spontaneous recovery of nerve function appears to be a common phenomenon in leprosy. Leprosy reactions and new NFI occurred in a third of the study group, emphasizing the need to keep patients under regular surveillance during MDT, and, where possible, after completion of MDT.

Adolescent↗

PubMed2003

Adverse events of standardized regimens of corticosteroids for prophylaxis and treatment of nerve function impairment in leprosy: results from the 'TRIPOD' trials.

Reactions in leprosy causing nerve function impairment (NFI) are increasingly treated with standardized regimens of corticosteroids, often under field conditions. Safety concerns led to an assessment of adverse events of corticosteroids, based on data of three trials studying prevention of NFI (the TRIPOD study). A multicentre, randomized, double-blind placebo-controlled trial was conducted in leprosy control programmes in Nepal and Bangladesh. Treatment was with prednisolone according to fixed schedules for 16 weeks, starting in one trial with 20 mg/day (prophylactic regimen: total dosage 1.96 g) and in the other two trials with 40 mg/day (therapeutic regimen: total dosage 2.52 g). Minor adverse events were defined as moon face, fungal infections, acne, and gastric pain requiring antacid. Major adverse events were defined as psychosis, peptic ulcer, glaucoma, cataract, diabetes and hypertension. Also, the occurrence of infected plantar, palmar, and corneal ulceration was monitored, together with occurrence of TB. Considering all three trials together, minor adverse events were observed in 130/815 patients (16%). Of these, 51/414 (12%) were in the placebo group and 79/401 (20%) in the prednisolone group. The relative risk for minor adverse events in the prednisolone group was 1.6 (P = 0.004). Adverse events with a significantly increased risk were acne, fungal infections and gastric pain. Major adverse events were observed in 15/815 patients (2%); 7/414 (2%) in the placebo group and 8/401 (2%) in the prednisolone group. No major adverse events had a significantly increased risk in the prednisolone arm of the trials. No cases of TB were observed in 300 patients who could be followed-up for 24 months. Standardized regimens of corticosteroids for both prophylaxis and treatment of reactions and NFI in leprosy under field conditions in developing countries are safe when a standard pre-treatment examination is performed, treatment for minor conditions can be carried out by field staff, referral for specialized medical care is possible, and sufficient follow-up is done during and after treatment.

Adolescent↗

PubMed2002

Disappearance of leprosy from Norway: an exploration of critical factors using an epidemiological modelling approach.

BACKGROUND: By the middle of the 19th century, leprosy was a serious public health problem in Norway. By 1920, new cases only rarely occurred. This study aims to explain the disappearance of leprosy from Norway. METHODS: Data from the National Leprosy Registry of Norway and population censuses were used. The patient data include year of birth, onset of disease, registration, hospital admission, death, and emigration. The Norwegian data were analysed using epidemiological models of disease transmission and control. RESULTS: The time trend in leprosy new case detection in Norway can be reproduced adequately. The shift in new case detection towards older ages which occurred over time is accounted for by assuming that infected individuals may have a very long incubation period. The decline cannot be explained fully by the Norwegian policy of isolation of patients: an autonomous decrease in transmission, reflecting improvements in for instance living conditions, must also be assumed. The estimated contribution of the isolation policy to the decline in new case detection very much depends on assumptions made on build-up of contagiousness during the incubation period and waning of transmission opportunities due to rapid transmission to close contacts. CONCLUSION: The impact of isolation on interruption of transmission remains uncertain. This uncertainty also applies to contemporary leprosy control that mainly relies on chemotherapy treatment. Further research is needed to establish the impact of leprosy interventions on transmission.

Adolescent↗