Incidence Of Subsequent Disease Research Articles

Risk Factors, Subsequent Disease Onset, and Prognostic Impact of Myocardial Infarction and Atrial Fibrillation.

BackgroundAlthough myocardial infarction (MI) and atrial fibrillation (AF) are frequent comorbidities and share common cardiovascular risk factors, the direction and strength of the association of the risk factors with disease onset, subsequent disease incidence, and mortality are not completely understood.Methods and ResultsIn pooled multivariable Cox regression analyses, we examined temporal relations of disease onset and identified predictors of MI, AF, and all‐cause mortality in 108 363 individuals (median age, 46.0 years; 48.2% men) free of MI and AF at baseline from 6 European population‐based cohorts. During a maximum follow‐up of 10.0 years, 3558 (3.3%) individuals were diagnosed exclusively with MI, 1922 (1.8%) with AF but no MI, and 491 (0.5%) individuals developed both MI and AF. Association of sex, systolic blood pressure, antihypertensive treatment, and diabetes appeared to be stronger with incident MI than with AF, whereas increasing age and body mass index showed a higher risk for incident AF. Total cholesterol and daily smoking were significantly related to incident MI but not AF. Combined population attributable fraction of cardiovascular risk factors was >70% for incident MI, whereas it was only 27% for AF. Subsequent MI after AF (hazard ratio [HR], 1.68; 95% CI, 1.03–2.74) and subsequent AF after MI (HR, 1.75; 95% CI, 1.31–2.34) both significantly increased overall mortality risk.ConclusionsWe observed different associations of cardiovascular risk factors with both diseases indicating distinct pathophysiological pathways. Subsequent diagnoses of MI and AF significantly increased mortality risk.

Risk factors, subsequent disease onset and prognostic impact of myocardial infarction and atrial fibrillation

Abstract Background Myocardial infarction (MI) is a known risk factor for incident atrial fibrillation (AF), while AF frequently complicates acute MI. Although both diseases share common cardiovascular risk factors, the direction and strength of the association of the risk factors with disease onset, subsequent disease incidence and mortality are not completely understood. Purpose Our goal was to define the temporal relationship of MI and AF and the association of cardiovascular risk factors with disease incidence in order to determine whether common clinical risk factors show different associations with incident MI or AF. We further aimed to investigate predictors of subsequent disease onset and the impact of subsequent disease diagnosis on mortality. Methods In pooled multivariable Cox regression analyses we examined temporal relations of disease onset and identified predictors of MI, AF and subsequent all-cause mortality in 108,363 individuals (median age 46.0 years, 48.2% men) free of MI and AF at baseline from six European population-based cohorts. Results Over a maximum follow-up of 10.0 years 3558 (3.3%) individuals were diagnosed exclusively with MI, 1922 (1.8%) with AF but no MI, and 491 (0.5%) individuals developed both MI and AF. Association of male sex, systolic blood pressure, antihypertensive treatment and diabetes mellitus appeared to be stronger with incident MI than with AF, whereas increasing age and body mass index showed a higher risk for incident AF. Total cholesterol and daily smoking were significantly related to incident MI but not AF. The combined population attributable fraction of the cardiovascular risk factors was over 70% for incident MI, whereas it was only about one quarter for incident AF. Subsequent MI after incident AF (hazard ratio1.68, 95% CI 1.03–2.74) and subsequent AF after MI (hazard ratio 1.75, 95% CI 1.31–2.34) both significantly increased overall mortality risk. Conclusions Subsequent diagnosis of MI and AF was associated with a significant increase in mortality, irrespective of the first event. We found different associations of common cardiovascular risk factors with incident MI and AF indicating distinct pathophysiological pathways in disease development. Funding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union's Horizon 2020 research and innovation programme (grant agreement No 847770, AFFECT-EU) European Union's Horizon 2020 research and innovation programme (grant agreement No 648131)

Effect of Kasugamycin, Oxytetracycline, and Streptomycin on In-orchard Population Dynamics of Erwinia amylovora on Apple Flower Stigmas.

We assessed the effect of three antibiotics (streptomycin, oxytetracycline, and kasugamycin) on populations of the fire blight pathogen Erwinia amylovora on apple flower stigmas during three field seasons. Application timing relative to E. amylovora presence on flower stigmas had little impact on population dynamics and subsequent disease incidence. Although E. amylovora populations on water-treated flowers increased to 106-7 cfu flower-1 after 4 to 5 days during each experiment, the antibiotics streptomycin and kasugamycin caused statistically significant reductions in stigma populations by as many as 4 to 5 logs over a 4- to 5-day period during two of the three experiments. In contrast, the effect of oxytetracycline on E. amylovora populations on stigmas was more variable, with reductions in E. amylovora populations only observed during one of the three experiments. In agreement with the population data, the disease incidence was significantly higher for oxytetracycline-treated flowers compared with the other antibiotic treatments during 2 of 3 years. Statistical analyses of the effects of weather parameters on antibiotic activity revealed that solar radiation and temperature negatively impacted the activity of both kasugamycin and oxytetracycline. We further assessed the potential for photodegradation of formulated kasugamycin (Kasumin 2L) and found that Kasumin 2L was susceptible to degradation in vitro after exposure to a 16-h photoperiod of daily light integrals (DLIs) varying from 6 to 35 mol⋅m-2⋅d-1. We further determined that exposure to three consecutive 16-h photoperiods of DLIs of 23 or 35 mol⋅m-2⋅d-1 reduced the available concentration of Kasumin 2L (assessed using a bioassay) from 100 μg⋅ml-1 to 10 to 20 μg⋅ml-1. Our results correlate the superior blossom blight control efficacy of kasugamycin and streptomycin with significant population reductions in E. amylovora on apple flower stigmas but indicate that, similar to oxytetracycline, kasugamycin is vulnerable to photodegradation, which would suggest that further considerations are necessary when applying this antibiotic.

Evaluating disease prediction models using a cohort whose covariate distribution differs from that of the target population.

Personal predictive models for disease development play important roles in chronic disease prevention. The performance of these models is evaluated by applying them to the baseline covariates of participants in external cohort studies, with model predictions compared to subjects' subsequent disease incidence. However, the covariate distribution among participants in a validation cohort may differ from that of the population for which the model will be used. Since estimates of predictive model performance depend on the distribution of covariates among the subjects to which it is applied, such differences can cause misleading estimates of model performance in the target population. We propose a method for addressing this problem by weighting the cohort subjects to make their covariate distribution better match that of the target population. Simulations show that the method provides accurate estimates of model performance in the target population, while un-weighted estimates may not. We illustrate the method by applying it to evaluate an ovarian cancer prediction model targeted to US women, using cohort data from participants in the California Teachers Study. The methods can be implemented using open-source code for public use as the R-package RMAP (Risk Model Assessment Package) available at http://stanford.edu/~ggong/rmap/ .

Flow ofBotrytis cinereainoculum between lettuce crop and soil

Botrytis cinereacauses grey mould, a disease common on many economically important crops. Although much attention is paid to the airborne inoculum of this fungus, as it sporulates abundantly in favourable conditions, knowledge on the abundance and genetic characteristics of soilborne inoculum could help improve control strategies. In this study, the soilborne inoculum ofB. cinereawas quantified in two greenhouses at different times before and after the cultivation of four successive lettuce crops. Between 0 and 1177 colony‐forming units (CFU) ofB. cinereaper gram of soil were recorded. There was no significant correlation between abundance of soilborne inoculum and subsequent disease incidence on lettuce (P = 0·11). Sixty‐five isolates collected from diseased plants and 66 isolates collected from the soil were investigated for their genetic diversity. The soil strains showed lower genetic diversity than the lettuce strains when considering the unbiased gene diversity within the nine microsatellite loci, the mean number of alleles per locus and the haplotypic diversity. The genetic differentiation between lettuce and soil strains decreased over three successive lettuce crops. At the same time, the genetic structure of the two groups of strains tended to become similar. These results are consistent with the hypothesis of a flow of inoculum between the lettuce crop and the soil, and vice versa. The study shows that grey mould management should pay more attention to the inoculum ofB. cinereapresent in the soil.

Prevalence of mumps antibodies in the Israeli population in relation to mumps vaccination policy and incidence of disease

We examined the prevalence of mumps antibodies in the Israeli population in relation to mumps vaccination policy and past and subsequent incidence of disease. The levels of specific IgG antibodies against mumps were tested in 3330 residual sera collected during 1997-1998 from an age-stratified population sample. Against the background of a consistent MMR vaccination coverage of >90%, the age- and sex-adjusted seropositivity to mumps was 77.0%. No significant differences between genders were found. Seropositivity in the 10-13 years age group, born just before the introduction of the MMR vaccine, was the lowest (59%). These birth cohorts were the target of an outbreak of mumps in 2005 that occurred among high-school students and military recruits. A trend of waning immunity was observed between the first and second vaccine doses. The seroepidemiological data demonstrate that immunity levels below the herd immunity threshold, along with social mixing and crowded conditions facilitated the occurrence of mumps outbreaks. Periodical serosurveys are an essential component in the evaluation of the vaccination policy against mumps.

Detection and quantification ofSpongospora subterranea f. sp.subterranea by PCR in host tissue and naturally infested soils

A polymerase chain reaction (PCR) assay using primers SsF and SsR designed from the internal transcribed spacer (ITS) regions ofSpongospora subterranea f. sp.subterranea was developed for the specific identification and quantification ofS. subterranea. These primers amplified a 434 bp product from DNA ofS. subterranea spore balls, but not from DNA of healthy potato, common scab tuber, and taxonomically related plasmodiophorids. This PCR assay was successfully used for the detection ofS. subterranea in naturally infected symptomatic and asymptomatic potato tubers.Spongospora subterranea in other infected symptomless host plants was detected by PCR. The PCR assay was modified with improved soil DNA extraction methods to detectS. subterranea in soil. The assay was sensitive, and one spore ball per gram of soil could be detected. Following the design of a heterologous competitor DNA template from the sequence of λDNA, a competitive PCR assay for the quantification ofS. subterranea in soil was developed and provided accurate quantification in the range of 1 to 104 spore balls per 0.25 g of soil. In a preliminary survey of naturally infested field soil samples, spore ball concentrations were estimated to vary from ca 0 to 3600 spore balls per 0.25-g soil sample by this competitive PCR assay. The spore ball levels were compared with the powdery scab disease incidence of potatoes in these fields, and a correlationship between spore ball levels and subsequent disease incidence was found. The PCR assays developed in this investigation can be routinely used to detect and quantifyS. subterranea in diseased plant tissue, asymptomatic plant tissue, and infested soil.

Incorporation of Temperature and Solar Radiation Thresholds to Modify a Lettuce Downy Mildew Warning System

ABSTRACT The effect of temperature on infection of lettuce by Bremia lactucae was investigated in controlled environment studies and in the field. In controlled conditions, lettuce seedlings inoculated with B. lactucae were incubated at 15, 20, 25, or 30 degrees C during a 4-h wet period immediately after inoculation or at the same temperatures during an 8-h dry period after the 4-h postinoculation wet period at 15 degrees C. High temperatures during wet and dry periods reduced subsequent disease incidence. Historical data from field studies in 1991 and 1992, in which days with or without infection had been identified, were analyzed by comparing average air temperatures during 0600 to 1000 and 1000 to 1400 Pacific standard time (PST) between the two groups of days. Days without infection had significantly higher temperatures (mean 21.4 degrees C) than days with infection (20.3 degrees C) during 1000 to 1400 PST (P < 0.01) but not during 0600 to 1000 PST. Therefore, temperature thresholds of 20 and 22 degrees C for the 3-h wet period after sunrise and the subsequent 4-h postpenetration period, respectively, were added to a previously developed disease warning system that predicts infection when morning leaf wetness lasts >/=4 h from 0600 PST. No infection was assumed to occur if average temperature during these periods exceeded the thresholds. Based on nonlinear regression and receiver operating characteristic curve analysis, the leaf wetness threshold of the previous warning system was also modified to >/=3-h leaf wetness (>/=0900 PST). Furthermore, by comparing solar radiation on days with infection and without infection, we determined that high solar radiation during 0500 to 0600 PST in conjunction with leaf wetness ending between 0900 and 1000 PST was associated with downy mildew infection. Therefore, instead of starting at 0600 PST, the calculation of the 3-h morning leaf wetness period was modified to start after sunrise, defined as the hour when measured solar radiation exceeded 8 W m(-2) (or 41 mumol m(-2) s(-1) for photon flux density). The modified warning system was compared with the previously developed system using historical weather and downy mildew data collected in coastal California. The modified system was more conservative when disease potential was high and recommended fewer fungicide applications when conditions were not conducive to downy mildew development.

Soil Sampling Techniques for Determining the Effect of Cultural Practices on Rhizoctonia oryzae-sativae Inoculum in Rice Field Soils.

Methods were evaluated to quantify sclerotia in rice fields affected with aggregate sheath spot disease. Recovered sclerotia were compared with disease ratings at harvest for paddies subjected to various postharvest cultural straw management practices. Sclerotial inoculum level was not always correlated with subsequent disease incidence in rice aggregate sheath spot disease, suggesting alternative sources of inoculum and other factors influencing disease development. Straw management practices affected the inoculum load of Rhizoctonia oryzae-sativae, as determined by methods recovering sclerotia from California rice field soil samples. Traditional wet sieving of soil samples was improved using a potassium carbonate solution to float heavier sclerotia that normally remained in the sediment. The relationship of inoculum in the soil from seedbeds and the incidence of resulting disease measured just before harvest was investigated over 3 years at three sites. A linear dose-response was found at only one site where the number of floating sclerotia was more strongly correlated with disease incidence than total number of sclerotia (floating plus nonfloating sclerotia). Floating sclerotia were more easily counted using a water floatation extraction (WFE) than were total sclerotia by using a potassium carbonate floatation extraction (PCFE) or a combination of the two assays (WFE + PCFE), and the WFE more accurately predicted disease incidence than did either PCFE or WFE + PCFE. All assays detected significant differences between inoculum levels as influenced by various straw residue management practices, with removal of straw residue significantly reducing number of soil-borne sclerotia.

Transnasal treatment of congenital choanal atresia with the KTP laser.

This retrospective analysis presents a minimally invasive method for a transnasal approach to treat bilateral and unilateral choanal atresia and stenosis in infants and children. We describe an advanced surgical technique that applies the use of a KTP laser and give recommendations for preoperative diagnosis and postoperative assessment. We report 13 cases of bilateral and unilateral choanal atresia or stenosis treated over a 3 1/2-year period. We used a transnasal approach and endoscopic control. For bilateral choanal atresia, the operation was performed within the first few days of birth. For unilateral choanal atresia or stenosis, surgery was performed several weeks after birth. In all cases, an intranasal stent was inserted. Our findings demonstrate that this transnasal approach provides significant benefits. A primary advantage is the diminished risk of intraoperative or postoperative complications. Additional benefits include lower rates of re-obstruction and a decreased incidence of subsequent disease, including chronic secretory otitis media.

Astrovirus diarrhea in Egyptian children.

This study describes the epidemiology of astrovirus diarrhea among a population-based cohort of 397 children aged <3 years residing in rural Egypt from 1995 to 1998. The age-specific incidence rates of astrovirus diarrheal episodes per person-year were 0.38 for infants aged <6 months, 0.40 for those aged 6-11 months, 0.16 for those aged 12-23 months, and 0.05 for those aged 24-35 months. The overall incidence rate of astrovirus diarrhea was the same as that of rotavirus diarrhea, 0.19 episodes per person-year. Astrovirus infection was pathogenic and associated with severe dehydration in 17% of the cases. The most frequent serotype was HAstV-1, and, in order of decreasing frequency, HAstV-5, HAstV-8 and HAstV-3, HAstV-6, HAstV-4, and HAstV-2. In determining whether astrovirus diarrhea was associated with a reduced incidence of subsequent disease, there was evidence to suggest HAstV-1 homotypic immunity but not heterotypic immunity. Because we observed 38% of the incidence of astrovirus diarrhea to occur in infants aged <6 months, a candidate astrovirus vaccine would have to confer immunity very early in life.

Curing of kiwifruit for control of postharvest infection by Botrytis cinerea

The effects of temperature and humidity during curing on subsequent infection levels of B. cinerea in kiwifruit were investigated in 1993 and 1994. After harvest, each fruit was inoculated with 25 000 spores in a 17 μl droplet of Tween 20. Dry conidial application was also included in 1994 experiments. The largest curing effect was obtained at 10°C. Disease incidence was highest at 0°C and the curing effect diminished at temperatures above 10°C. In 1994 a three day curing period was used and 10°C gave the lowest subsequent disease incidence. After twelve weeks of cool storage (1993) there was less disease in fruit cured at 89–95% relative humidity than at lower humidities. In 1994, comparable results were obtained. Firmness fluctuated with harvest and in general, decreased with storage, although a satisfactory firmness was maintained throughout cool storage for all treatments. For all experiments, weight loss increased with increased curing temperature or with decreased relative humidity.

Influence of Tillage Practices on Anthracnose Development and Distribution in Dry Bean Fields.

Three tillage practices-chiseling, rototilling, and moldboard plowing-were evaluated in 1993 and 1994 to determine their impact on initial disease development, distribution, and progression over time in a field of the susceptible kidney bean cultivar Horizon. The tillage treatments were administered in the spring in a field infested in 1992 with the bean anthracnose pathogen, Colletotrichum lindemuthianum race β. Initial disease incidence was highest in the chiseled plots, where more bean debris was left on the surface than in the other treatments. Significantly higher final disease incidence and area under the disease progress curve (AUDPC) occurred in the chiseled plots than in the rototilled and moldboard plowed plots. There was a significant correlation (r = 0.75) between the percentage of debris left on the surface and subsequent disease incidence on pods in the field. Anthracnose incidence or severity in the field was highly correlated with disease incidence on harvested pods (r values ranged between 0.87 and 0.98). Results from the ordinary runs analysis showed that anthracnose occurred randomly within the field early in the season, indicating that initial inoculum was from bean debris within the field. Later in the season, plant-to-plant spread resulted in a more clustered distribution of diseased plants.

Glutathione alterations in melon and tomato roots following treatment with chemicals which induce disease resistance to Fusarium wilt

Glutathione (GSH) has been implicated in the activation and regulation of the biosynthetic processes involved in plant defence. In this study, we examined whether herbicides which induce resistance to Fusarium sp. alter GSH concentrations in roots of cantaloupe melons and tomato. GSH levels were estimated spectrofluorimetrically in extracts from melon (8 days) and tomato (10 days) roots from plants grown in sand amended with various concentrations of the dinitroaniline herbicides trifluralin, oryzalin and dinitramine; the chloracetimide herbicide, acetochlor; and the chloracetimide safeners, flurazole and dichlormid. At the same time, treated and control tomato and melon seedlings were inoculated with their respective pathogens, Fusarium oxysporum f. sp. lycopersici and f. sp. melonis , and then planted into chemical-free Promix under controlled environmental conditions. Subsequent disease incidence was determined daily for 2 weeks. In dinitroaniline-treated tomato seedlings GSH levels were significantly higher than in control plants from the first harvest. This difference increased with time because herbicide treatment also reduced the rate of GSH decline. The extent of GSH increase was influenced by the chemical and the rate applied. All dinitroaniline treatments tested resulted in elevated levels of GSH in tomato and provided partial or complete protection against F. oxysporum f. sp. lycopersici Acetochlor, however, did not alter GSH levels in tomato, nor did it protect against F. oxysporum f. sp. lycopersici . In contrast, acetochlor was most effective in increasing GSH levels in melons and in providing protection against F. oxysporum f. sp. melonis . Oryzalin was the least effective in enhancing GSH and providing disease protection in melons. Neither dichlormid nor flurazole greatly altered GSH concentration or protected either plant species from disease. A highly significant inverse correlation was observed between the GSH levels and disease incidence with the chemicals tested.

The Harvard Mastery of Stress Study 35-year follow-up: prognostic significance of patterns of psychophysiological arousal and adaptation.

A 35-year prospective study was undertaken in 126 former college students to determine the predictive value of psychophysiological patterns previously recorded in response to repetitive laboratory stress experiments. Detailed health information has been obtained in 116 (92.1%) of these subjects. The emotion of "severe anxiety" expressed in one or more of the prior tests appeared to be a reliable marker for increased susceptibility not only to coronary heart disease but to overall future illness. This form of pathological anxiety, moreover, was frequently shown to be linked to marked conflict about hostile impulses. Contrariwise, neither anger-in nor anger-out was found to be associated with a higher incidence of subsequent disease. Failure to express emotion was observed in a variety of subjects who as a group exhibited no predisposition to sickness in later life. Psychological Mastery was predictive of favorable prognosis, but Physiological Mastery, contrary to expectations, did not show statistically significant advantages in that regard. Thus, the construct of "Mastery" itself as a determinant of prognosis was not fully supported by the findings in the present study. Cardiovascular hyperreactivity could not be confirmed as a major biologic mechanism responsible for cardiovascular disease. Such hyperresponses were common in association with "anger-in" without evidence of increased susceptibility to cardiovascular disease or other forms of illness. Further research is needed to identify pathophysiological pathways that may be activated by the emotion of severe anxiety in mediating its apparent relationship with total morbidity and mortality over time.

Pathogenic variability of downy mildew (Sclerospora graminicola) on pearl millet. II. Statistical techniques for analysis of data

SUMMARYDifferent cultivars of pearl millet were exposed to infection by asexual propagules of Sclerospora graminicola in Polythene tunnels. Subsequent incidence of disease was measured on one‐month old seedlings. The data consisted of binomial proportions based on differing total numbers of seedlings. It is shown how to utilise the logit link in the GLIM statistical package for analysis to compare variety performances. In addition the possibilities of interplot interference and intraplot variation were investigated using GLIM. Interplot interference occurred infrequently and did not affect the rank order of the cultivars in terms of their response to the fungus infection. Intraplot variation was also shown to be non significant in spite of proximity of some plants to the disease spreader plants. Once these potentially confounding phenomena were eliminated the cultivars could be compared directly with impunity. GLIM was also used to confirm that the type of symptom expression was a stable feature of each host genotype.

Cephalometric comparisons of the results of the Wardill-Kilner and Von Langenbeck palatoplasties: Samir E. Bishara, Hans Enemark, and Rosemary F. TharpCleft Palate J. 13:319–329, October, 1976

Although little is yet known about tuberculosis in Nepal itself because no records can bestudied there and no survey within the country has yet been carried out, the prevalence of radiographic tuberculous lesions and of positive tuberculin reactions in would-be Gurkha recruits suggests that the disease must be quite common in the districts of Nepal whence the British army draws its Gurkha recruits.In the army, the incidence of tuberculosis in Gurkhas is still high in spite of strict measures enforced to reduce it. Even in men who joined the army scince 1951, amongst whom all negative reactors on enlistment have been vaccinated with BCG, the incidence has been high compared with the rates shown by troops of other nationalities serving in the same area.A particularly high incidence is demonstrated in Gurkha recruits during their firstyear of army service. This has been due mainly to the large number of cases of primary tuberculosis which have occurred. It is suggested that many recruits are primarily infected on the journey they make from their homes to the recruiting depots in Nepal where they enlist. The conditions on this journey are highly conducive to the spread of respiratory infection, and tuberculosis is known to exist among the inmates of the rest houses along the routes and around the depots.Most cases in the Brigade of Gurkhas now occur in men who are already tuberculin positive when they enlist, having already acquired their primary infections in Nepal before joining the army. It is estimated that by the end of 1966, if the present rates continue, about 46 new cases of tuberculosis will occur each year, of which 40 will be in positive reactors and only five or six in vaccinated men. If future incidence is to be reduced it is on the positive reactors that particular attention must be directed.In the positive reactors a relationship is demonstrated between strong tuberculin sensitivityon enlisment and subsequent disease incidence. Not only has the incidence been considerably higher in the strong reactors, but they have provided the bulk of the disease which has occurred in the reactor group. The recruit who reacts strongly to tuberculin on enlistment appears to be at special risk of developing tuberculosis during his army service, and it is recommended that special measures, namely isoniazid prophylaxis, be taken to prevent the emergence of overt manifestations of tuberculous disease.The various factors which might have been responsible for the occurrence of disease in the positive reactors are examined. It is estimated that one in four cases in positive reactors has been due to exogenous infection acquired after contact with another infectious person. The sources of such infection are believed to exist most commonly in the following situations and in the following order: in Nepal itself, where soldiers return on leave once every three years; in the wives and families of soldiers; in the civilians of the countries where Gurkhas serve, and in other (infectious) soldiers.The endogenous exacerbation of already-existing latent foci has been responsible for three in four of the cases occurring in positive reactors. Such exacerbation can occur because individual resistance is low, or because environmental factors such as fatigue, stress and privation have upset the equilibrium existing between resistance and bacterial virulence.Since the various ‘environmental’ factors have been affected for the better rather thanfor the worse by military service, the conditions of life in the army cannot be held mainly responsible for the disease which has occurred in the positive reactors. It may be the case that the primary factor responsible for endogenous breakdown in Gurkhas is that many of them possess low levels of native or natural resistance. This may be because Nepal as a country is comaparatively young in its experience of tuberculosis and stocks still exist amongst the Gurkhas who are immunologically ill equipped to deal with endogenous progression of naturally acquired primary lesions.

Tuberculosis in the Gurkhas of Nepal

Summary Although little is yet known about tuberculosis in Nepal itself because no records can bestudied there and no survey within the country has yet been carried out, the prevalence of radiographic tuberculous lesions and of positive tuberculin reactions in would-be Gurkha recruits suggests that the disease must be quite common in the districts of Nepal whence the British army draws its Gurkha recruits. In the army, the incidence of tuberculosis in Gurkhas is still high in spite of strict measures enforced to reduce it. Even in men who joined the army scince 1951, amongst whom all negative reactors on enlistment have been vaccinated with BCG, the incidence has been high compared with the rates shown by troops of other nationalities serving in the same area. A particularly high incidence is demonstrated in Gurkha recruits during their firstyear of army service. This has been due mainly to the large number of cases of primary tuberculosis which have occurred. It is suggested that many recruits are primarily infected on the journey they make from their homes to the recruiting depots in Nepal where they enlist. The conditions on this journey are highly conducive to the spread of respiratory infection, and tuberculosis is known to exist among the inmates of the rest houses along the routes and around the depots. Most cases in the Brigade of Gurkhas now occur in men who are already tuberculin positive when they enlist, having already acquired their primary infections in Nepal before joining the army. It is estimated that by the end of 1966, if the present rates continue, about 46 new cases of tuberculosis will occur each year, of which 40 will be in positive reactors and only five or six in vaccinated men. If future incidence is to be reduced it is on the positive reactors that particular attention must be directed. In the positive reactors a relationship is demonstrated between strong tuberculin sensitivityon enlisment and subsequent disease incidence. Not only has the incidence been considerably higher in the strong reactors, but they have provided the bulk of the disease which has occurred in the reactor group. The recruit who reacts strongly to tuberculin on enlistment appears to be at special risk of developing tuberculosis during his army service, and it is recommended that special measures, namely isoniazid prophylaxis, be taken to prevent the emergence of overt manifestations of tuberculous disease. The various factors which might have been responsible for the occurrence of disease in the positive reactors are examined. It is estimated that one in four cases in positive reactors has been due to exogenous infection acquired after contact with another infectious person. The sources of such infection are believed to exist most commonly in the following situations and in the following order: in Nepal itself, where soldiers return on leave once every three years; in the wives and families of soldiers; in the civilians of the countries where Gurkhas serve, and in other (infectious) soldiers. The endogenous exacerbation of already-existing latent foci has been responsible for three in four of the cases occurring in positive reactors. Such exacerbation can occur because individual resistance is low, or because environmental factors such as fatigue, stress and privation have upset the equilibrium existing between resistance and bacterial virulence. Since the various ‘environmental’ factors have been affected for the better rather thanfor the worse by military service, the conditions of life in the army cannot be held mainly responsible for the disease which has occurred in the positive reactors. It may be the case that the primary factor responsible for endogenous breakdown in Gurkhas is that many of them possess low levels of native or natural resistance. This may be because Nepal as a country is comaparatively young in its experience of tuberculosis and stocks still exist amongst the Gurkhas who are immunologically ill equipped to deal with endogenous progression of naturally acquired primary lesions.