Coffee and energy drink use patterns in college freshmen: associations with adverse health behaviors and risk factors

Background

Public health concern over college students mixing caffeine-containing energy drinks (EDs) and alcohol has contributed to an array of ED-focused research studies. One review found consistent associations between ED use and heavy/problem drinking as well as other drug use and risky behaviors (Nutr Rev 72:87–97, 2014). The extent to which similar patterns exist for other sources of caffeine is not known. The present study examined associations between coffee and ED consumption and alcohol, tobacco and other drug use; alcohol use problems; and parental substance abuse and mental health problems in a sample of college freshmen.

Methods

Subjects were N = 1986 freshmen at an urban university who completed an on-line survey about demographics; caffeine; alcohol, tobacco and other drug use; and family history. The sample was 61% female and 53% White. Chi-square analyses and multivariable binary or ordinal logistic regression were used to compare substance use, problem alcohol behavior, and familial risk measures across 3 caffeine use groups: ED (with or without Coffee) (ED + Co; N = 350); Coffee but no ED (Co; N = 761); and neither coffee nor ED (NoCE; N = 875) use.

Results

After adjusting for gender and race, the 3 caffeine use groups differed on 8 of 9 symptoms for alcohol dependence. In all cases, the ED + Co group was most likely to endorse the symptom, followed by the Co group and finally the NoCE group (all p < .002). A similar pattern was found for: use 6+ times of 5 other classes of drugs (all p < .05); extent of personal and peer smoking (all p < .001); and paternal problems with alcohol, drugs and anxiety/depression as well as maternal alcohol problems and depression/anxiety (p < .04).

Conclusions

The response pattern was ubiquitous, with ED + Co most likely, Co intermediate, and NoCE least likely to endorse a broad range of substance use, problem alcohol behaviors, and familial risk factors. The finding that the Co group differed from both the ED + Co and NoCE groups on 8 measures and from the NoCE group on one additional measure underscores the importance of looking at coffee in addition to EDs when considering associations between caffeine and other risky behaviors.

Analysis of Nicotine and Non-nicotine Tobacco Constituents in Aqueous Smoke/Aerosol Extracts by UHPLC and Ultraperformance Convergence Chromatography-Tandem Mass Spectrometry

The non-nicotine constituents of tobacco may alter the reinforcing effects of nicotine, but the quantitative and qualitative profiles of these chemicals in tobacco products such as electronic cigarettes (e-cigarettes), cigars, and waterpipe tobacco are not well characterized. The objective of this work was to develop and validate analytical methods to utilize saline both as an extraction solvent for smoke condensates from cigarettes, little cigars, and waterpipe tobacco and aerosols from e-cigarettes and as a delivery vehicle of nicotine and non-nicotine constitents for nonclinical pharmacological studies. Ultrahigh-performance liquid chromatography was used to analyze nicotine and acetaldehyde, and a novel ultraperformance convergence chromatography-tandem mass spectrometry method was developed to analyze anabasine, anatabine, cotinine, myosmine, nornicotine, harmane, and norharmane. Linearity was confirmed for each standard curve with correlation coefficients (r) ≥ 0.99, and relative errors (RE) for the standards were ≤±10% over the calibration ranges. Method validation was performed by preparing triplicate samples in saline to mimic the composition and concentration of each analyte in the smoke or aerosol condensate and were used to determine method accuracy and precision. Relative standard deviation values were ≤15% and mean RE ≤15% for each analyte at each concentration level. Selectivity of the methods was demonstrated by the absence of peaks in blank vehicle or diluent samples. Storage stability was assessed over ∼45 days. Precision (%RSD ≤ 13) and recovery (percent of day 0 ≥ 80%) indicated that the saline formulations of all four products could be considered stable for up to ∼45 days at 4-8 °C. Therefore, the use of saline both as an extraction solvent and as a delivery vehicle adds versatility and improved performance in the study of the pharmacological effects of constituents from mainstream smoke and aerosols generated from cigarettes, little cigars, waterpipes, and e-cigarettes.

Demographic and sexual risk predictors of delay discounting of condom-protected sex

Objective: Sexual delay discounting describes the decreased likelihood of condom-protected sex if a condom is not immediately available, which can be quantitatively summarised using the Sexual Delay Discounting Task (SDDT). The present studies determined the extent to which condom use likelihood as assessed by the SDDT is associated with self-reported sexual risk behaviours and demographics in two online samples of adults. Design: Study 1 (n = 767) assessed demographics, sexual risk behaviour, and delay discounting, and examined relations between these variables using correlation and regression. Study 2 (n = 267) examined whether real-world instances of unprotected sex because a condom was not immediately available predicted greater sexual discounting. Main outcome measures: Sexual delay discounting, condom use. Results: Both studies observed significant positive relations between sexual delay discounting and self-reported sexual risk behaviours, and found that males tended to show greater sexual discounting. In Study 2, 46% of the sample self-reported having unprotected sex because a condom was not immediately available, and these individuals showed significantly greater sexual delay discounting. Conclusion: These results extend prior findings by demonstrating that delay is a critical variable underlying real-life sexual risk behaviour among non-clinical samples. The SDDT is an ecologically valid measure of these processes.

Comparison of cigarette, little cigar, and waterpipe tobacco smoke condensate and e-cigarette aerosol condensate in a self-administration model

The pharmacological effects of tobacco products are primarily mediated by nicotine; however, research suggests that several non-nicotine tobacco constituents may alter the reinforcing effects of nicotine. This study evaluated the reinforcing effects of aqueous solutions of smoke/aerosol condensate from cigarettes, little cigars, electronic cigarettes (e-cigarettes), and waterpipe tobacco in a self-administration procedure to determine if abuse liability of these tobacco products differed. Adult male Sprague-Dawley rats (n = 64 total) were trained to self-administer intravenous nicotine (30 μg/kg/infusion) on a fixed ratio 5 schedule of reinforcement. Following nicotine dose-effect assessment (1, 7.5, 15, and 30 μg/kg/infusion), rats were given access to smoke/aerosol condensate derived from their assigned tobacco product. Rats responded for smoke/aerosol condensate containing 1, 7.5, 15, and 30 μg/kg/infusion nicotine, with the ratio of nicotine:non-nicotine constituents held constant across doses for each tobacco product. Responding for nicotine or smoke/aerosol condensate was also assessed on a progressive ratio schedule of reinforcement. Cigarette, little cigar, and e-cigarette smoke/aerosol condensates shifted the nicotine dose-effect curve leftward, whereas waterpipe tobacco smoke condensate shifted the dose-effect curve rightward. Smoke/aerosol condensate from all tobacco products produced similar levels of responding compared to nicotine alone during the progressive ratio phase. Results suggest that non-nicotine constituents in cigarettes, little cigars, and e-cigarettes differentially enhance nicotine's reinforcing potency. In contrast, waterpipe tobacco blunted nicotine's reinforcing potency, suggesting that it may contain unique constituents that dampen nicotine's reinforcing effects.

Alcohol use disorders are associated with increased HIV risk behaviors in cocaine-dependent methadone patients

People who inject drugs (PWID) are at increased risk of HIV infection. Although methadone maintenance therapy can help lower this risk, many methadone patients continue to engage in HIV risk behaviors, especially patients who use cocaine and alcohol. The purpose of the current study was to investigate relations between alcohol use disorders and HIV risk behavior in 239 cocaine-dependent methadone patients participating in a randomized controlled trial of a behavioral intervention to promote cocaine abstinence. Past 3-month HIV Risk-taking Behavior Scale (HRBS) scores were compared between cocaine-dependent methadone patients who met DSM-IV-TR diagnostic criteria for alcohol abuse or dependence and those who did not meet these criteria. No significant differences in HRBS drug subscale scores were observed between participants with and without alcohol use disorders, indicating risky drug use was similar between groups. However, alcohol use disorder was significantly associated with HRBS sex subscale scores (t=2.59, p=0.01), indicating participants with alcohol use disorders were more likely to engage in risky sexual behavior. Item-level analyses of the sex-related HRBS questions showed participants with alcohol use disorders were significantly more likely than participants without alcohol use disorders to have unprotected sex, engage in transactional (paid) sex, and have anal sex. Interventions are needed to reduce risky sexual behavior and attenuate the spread of HIV in this high-risk population.

Effects of caffeine on alcohol reinforcement: beverage choice, self-administration, and subjective ratings

RATIONALE

Combining alcohol and caffeine is associated with increased alcohol consumption, but no prospective experimental studies have examined whether added caffeine increases alcohol consumption.

OBJECTIVES

This study examined how caffeine alters alcohol self-administration and subjective reinforcing effects in healthy adults.

METHODS

Thirty-one participants completed six double-blind alcohol self-administration sessions: three sessions with alcohol only (e.g., beverage A) and three sessions with alcohol and caffeine (e.g., beverage B). Participants chose which beverage to consume on a subsequent session (e.g., beverage A or B). The effects of caffeine on overall beverage choice, number of self-administered drinks, subjective ratings (e.g., Biphasic Alcohol Effects Scale), and psychomotor performance were examined.

RESULTS

A majority of participants (65%) chose to drink the alcohol beverage containing caffeine on their final self-administration session. Caffeine did not increase the number of self-administered drinks. Caffeine significantly increased stimulant effects, decreased sedative effects, and attenuated decreases in psychomotor performance attributable to alcohol. Relative to nonchoosers, caffeine choosers reported overall lower stimulant ratings and reported greater drinking behavior prior to the study.

CONCLUSIONS

Although caffeine did not increase the number of self-administered drinks, most participants chose the alcohol beverage containing caffeine. Given the differences in subjective ratings and pre-existing differences in self-reported alcohol consumption for caffeine choosers and nonchoosers, these data suggest that decreased stimulant effects of alcohol and heavier self-reported drinking may predict subsequent choice of combined caffeine and alcohol beverages. These predictors may identify individuals who would benefit from efforts to reduce risk behaviors associated with combining alcohol and caffeine.

Weekly Energy Drink Use Is Positively Associated with Delay Discounting and Risk Behavior in a Nationwide Sample of Young Adults

Background: Energy drink use is associated with increased risk behavior among adolescents and college students. This study examined this relationship in a nationwide sample of young adults and also examined relations between energy drink use and delay discounting. Methods: Participants were 874 U.S. adults 18-28 years of age with past 30-day consumption of caffeine and alcohol. Participants completed an online survey of energy drink use, drug use, sexual activity, alcohol misuse (alcohol use disorders identification test [AUDIT]), sensation seeking (four-item Brief Sensation Seeking Scale [BSSS-4]), and delay discounting of monetary rewards and condom use. Results: Over one-third of participants (n = 303) reported consuming energy drinks at least once per week. Weekly energy drink users were more likely than less-than-weekly energy drink users to report a recent history of risk behaviors, including cigarette smoking (56% vs. 28%, p < 0.0001), illicit stimulant use (22% vs. 6%, p < 0.0001), and unprotected sex (63% vs. 45%, p < 0.0001). Covariate-adjusted analyses found that weekly energy drink users did not have significantly higher BSSS-4 scores (3.5 vs. 3.1, p = 0.098), but they had higher mean AUDIT scores (8.0 vs. 4.8, p < 0.0001), and they more steeply discounted delayed monetary rewards. Although weekly energy drink users did not show steeper discounting of delayed condom use, they showed a lower likelihood of using a condom when one was immediately available. Conclusions: This study extends findings that energy drink use is associated with risk behavior, and it is the first study to show that energy drink use is associated with monetary delay discounting.

Smartphone applications to reduce alcohol consumption and help patients with alcohol use disorder: a state-of-the-art review

Hazardous drinking and alcohol use disorder (AUD) are substantial contributors to USA and global morbidity and mortality. Patient self-management and continuing care are needed to combat these public health threats. However, services are rarely provided to patients outside of clinic settings or following brief intervention. Smartphone applications (“apps”) may help narrow the divide between traditional health care and patient needs. The purpose of this review is to identify and summarize smartphone apps to reduce alcohol consumption or treat AUD that have been evaluated for feasibility, acceptability, and/or efficacy. We searched two research databases for peer-reviewed journal articles published in English that evaluated smartphone apps to decrease alcohol consumption or treat AUD. We identified six apps. Two of these apps (A-CHESS and LBMI-A) promoted self-reported reductions in alcohol use, two (Promillekoll and PartyPlanner) failed to promote self-reported reductions in alcohol use, and two (HealthCall-S and Chimpshop) require further evaluation and testing before any conclusions regarding efficacy can be made. In summary, few evaluations of smartphone apps to reduce alcohol consumption or treat AUD have been reported in the scientific literature. Although advances in smartphone technology hold promise for disseminating interventions among hazardous drinkers and individuals with AUD, more systematic evaluations are necessary to ensure that smartphone apps are clinically useful.

A mobile-phone-based breath carbon monoxide meter to detect cigarette smoking

INTRODUCTION

Mobile phones hold considerable promise for delivering evidence-based smoking cessation interventions that require frequent and objective assessment of smoking status via breath carbon monoxide (Breath CO) measurement. However, there are currently no commercially available mobile-phone-based Breath CO meters. We developed a mobile-phone-based Breath CO meter prototype that attaches to and communicates with a smartphone through an audio port. We then evaluated the reliability and the validity of Breath CO measures collected with the mobile meter prototype and assessed the usability and acceptability of the meter.

METHODS

Participants included 20 regular smokers (≥10 cigarettes/day), 20 light smokers (<10 cigarettes/day), and 20 nonsmokers. Expired air samples were collected 4 times from each participant: twice with the mobile meter and twice with a commercially available Breath CO meter.

RESULTS

Measures calculated by the mobile meter correlated strongly with measures calculated by the commercial meter (r = .96, p < .001). Additionally, the mobile meter accurately distinguished between smokers and nonsmokers. The area under the receiver-operating characteristic curve for the mobile meter was 94.7%, and the meter had a combined sensitivity and specificity of 1.86 at an abstinence threshold of ≤6 ppm. Responses on an acceptability survey indicated that smokers liked the meter and would be interested in using it during a quit attempt.

CONCLUSIONS

The results of our study suggest that a mobile-phone-based Breath CO meter is a reliable, valid, and acceptable device for distinguishing between smokers and nonsmokers.

The ABCs of incentive-based treatment in health care: a behavior analytic framework to inform research and practice

Behavior plays an important role in health promotion. Exercise, smoking cessation, medication adherence, and other healthy behavior can help prevent, or even treat, some diseases. Consequently, interventions that promote healthy behavior have become increasingly common in health care settings. Many of these interventions award incentives contingent upon preventive health-related behavior. Incentive-based interventions vary considerably along several dimensions, including who is targeted in the intervention, which behavior is targeted, and what type of incentive is used. More research on the quantitative and qualitative features of many of these variables is still needed to inform treatment. However, extensive literature on basic and applied behavior analytic research is currently available to help guide the study and practice of incentive-based treatment in health care. In this integrated review, we discuss how behavior analytic research and theory can help treatment providers design and implement incentive-based interventions that promote healthy behavior.

Caffeine Use Disorder: A Comprehensive Review and Research Agenda

Caffeine is the most commonly used drug in the world. Although consumption of low to moderate doses of caffeine is generally safe, an increasing number of clinical studies are showing that some caffeine users become dependent on the drug and are unable to reduce consumption despite knowledge of recurrent health problems associated with continued use. Thus, the World Health Organization and some health care professionals recognize caffeine dependence as a clinical disorder. In this comprehensive literature review, we summarize published research on the biological evidence for caffeine dependence; we provide a systematic review of the prevalence of caffeine dependence and rates of endorsement of clinically meaningful indicators of distress and functional impairment among habitual caffeine users; we discuss the diagnostic criteria for Caffeine Use Disorder-a condition for further study included in the Diagnostic and Statistical Manual of Mental Disorders (5^th ed.); and we outline a research agenda to help guide future clinical, epidemiological, and genetic investigations of caffeine dependence. Numerous controlled laboratory investigations reviewed in this article show that caffeine produces behavioral and physiological effects similar to other drugs of dependence. Moreover, several recent clinical studies indicate that caffeine dependence is a clinically meaningful disorder that affects a nontrivial proportion of caffeine users. Nevertheless, more research is needed to determine the reliability, validity, and prevalence of this clinically important health problem.

Investigating group contingencies to promote brief abstinence from cigarette smoking

In contingency management (CM), monetary incentives are contingent on evidence of drug abstinence. Typically, incentives (e.g., "vouchers" exchangeable for goods or services) are contingent on individual performance. We programmed vouchers contingent on group performance to investigate whether these contingencies would promote brief abstinence from cigarette smoking. Thirty-two participants were divided into small teams (n = 3 per team). During three 5-day within-subject experimental conditions, participants submitted video recordings of breath carbon monoxide (CO) measures twice daily via Motiv8 Systems, an Internet-based remote monitoring application. During the interdependent contingency condition, participants earned vouchers each time they and their teammates submitted breath CO samples indicative of abstinence (i.e., negative samples). During the independent contingency condition, participants earned vouchers each time they submitted negative samples, regardless of their teammates' performance. During the no vouchers condition, no monetary incentives were contingent on abstinence. In addition, half of the participants (n = 16) could communicate with their teammates through an online peer support forum. Although forum access did not appear to promote smoking abstinence, monetary incentives did promote brief abstinence. Significantly more negative samples were submitted when vouchers were contingent on individual performance (56%) or team performance (53%) relative to when no vouchers were available (35%; F = 6.9, p = .002). The results show that interdependent contingencies can promote brief abstinence from cigarette smoking. Moreover, the results suggest that these contingencies may help lower treatment costs and promote social support.

Internet-based group contingency management to promote abstinence from cigarette smoking: a feasibility study

BACKGROUND

In contingency management (CM) interventions, monetary consequences are contingent on evidence of drug abstinence. Typically, these consequences are contingent on individual performance. Consequences contingent on group performance may promote social support (e.g., praise).

METHODS

Thus, to combine social support with the monetary incentives of CM, we integrated independent and interdependent group contingencies of reinforcement into an Internet-based intervention to promote smoking abstinence. Breath carbon monoxide (CO) measures were compared between treatment conditions and a baseline control condition. Thirteen participants were divided into 5 groups or "teams" (n=2-3 per team). Each participant submitted video recordings of CO measurement twice daily via the Internet. Teammates could monitor each other's progress and communicate with one another through an online peer support forum. During a 4-day tapering condition, vouchers exchangeable for goods were contingent on gradual reductions in breath CO. During a 10-day abstinence induction condition, vouchers were contingent on abstinence (CO≤4ppm). In both treatment conditions, concurrent independent and interdependent group contingencies were arranged (i.e., a mixed contingency arrangement).

RESULTS

Less than 1% of CO samples submitted during baseline were≤4ppm, compared to 57% submitted during abstinence induction. Sixty-five percent of participants' comments on the online peer support forum were rated as positive by independent observers. Participants rated the intervention favorably on a treatment acceptability questionnaire.

CONCLUSION

The results suggest that the intervention is feasible and acceptable for promoting abstinence from cigarette smoking.

The effect of 5 years of annual treatment with ivermectin (Mectizan) on the prevalence and morbidity of onchocerciasis in the village of Gami in the Central African Republic

To assess the impact of 5 years of annual community treatment with ivermectin (Mectizan) on the prevalence of onchocerciasis and onchocerciasis-associated morbidity, data collected, before and after such treatment, in the village of Gami, in a hyper-endemic area of the Central African Republic, were analysed. Skin snips from all the villagers treated in 1990 and/or 1995 were used to assess the prevalence and intensity of infection with Onchocerca volvulus. Ocular and dermatological morbidity was assessed by ophthalmological and clinical examinations of the same subjects. Following the five annual treatments, there was a reduction in the prevalence of infection and a dramatic decrease in the microfilarial load of the community. The prevalences of pruritus, onchocercal nodules and impaired vision were all significantly reduced. The results emphasise the long-term benefits of the mass-treatment programmes, particularly for children aged <10 years.

DNA in situ hybridization on polytene chromosomes of Simulium sanctipauli at loci relevant to insecticide resistance

A DNA technique for in situ hybridization developed by Kumar & Collins (1994) for use on polytene chromosomes of adult Anopheles mosquitoes (Diptera: Culicidae) was modified for use with Simulium larval salivary gland chromosomes (Diptera: Simuliidae). Cloned fragments of several Simulium genes (coding for aspartate amino transferase, cytochrome P450 and DNA polymerase) were successfully mapped physically by assigning specific band locations in Simulim sanctipauli V. & D. This represents the first attempt at locating genes beyond the resolution of linkage to inversions in any blackfly species.

The Mectizan Donation Programme--a 10-year report

In the 10 years since 1987 when Merck & Co. announced a plan to donate its safe and effective microfilaricide, Mectizan (ivermectin, MSD), to treat onchocerciasis wherever and for as long as needed, more than 96 million treatments have been enabled in community-based treatment programmes in all 34 countries, in Africa, the Middle East, and Latin America, where the disease is endemic. It is expected that donations enabling some 33 million treatments will be approved in 1997. Since the beginning of the donation programme, it is estimated that some 19-20 million people have received at least one dose of the drug and that many have received their sixth, seventh, eighth, or even ninth annual dose.

Biochemical and molecular characterization of Leishmania parasites isolated from an endemic focus in eastern Sudan

Twelve Leishmania isolates from visceral leishmaniasis patients in eastern Sudan were characterized using isoenzyme analysis, Southern blotting and polymerase chain reaction (PCR) 'fingerprinting'. Isoenzyme analysis revealed the presence of 3 zymodemes: MON-18, MON-30 and MON-82, corresponding to Leishmania donovani sensu stricto, L. infantum and L. archibaldi (still of uncertain taxonomic status), respectively. Southern blotting and PCR 'fingerprinting' revealed identical patterns for all 3 zymodemes, which were indistinguishable from those of L. donovani s.s.

The direct agglutination test for diagnosis of visceral leishmaniasis under field conditions in Sudan: comparison of aqueous and freeze-dried antigens

The performance of the direct agglutination test (DAT) was evaluated under field conditions in an endemic area of visceral leishmaniasis in eastern Sudan, using aqueous (Aq) antigen which has to be kept refrigerated and a newly developed freeze-dried (FD) antigen which is stable at ambient temperature. Both antigens compared well, with 92-98% of readings being identical or only with one dilution difference in titre. FD antigen gave titres that were identical with Aq antigen in 73% of samples, higher in 19%, and lower in 8%. Owing to high ambient temperatures and low humidity, microtitre plate wells dried out during the standard procedures for elution and incubation. However, shortening the elution time from 12 to 4 h proved possible for both antigens; incubation could be reduced from 24 to 10 h for Aq antigen, after which the plates could still be read. Incubation with FD antigen required 18 h and the plates needed to be kept cool because of evaporation. Despite the longer procedure with the FD antigen, the DAT can be completed in 24 h and the use of this stable antigen, that does not require refrigeration, is a major improvement in performing the DAT under unfavourable field conditions.

Sensitivity of a polymerase chain reaction-based assay to detect Onchocerca volvulus DNA in skin biopsies

A polymerase chain reaction (PCR) of a 150-bp tandem repeat of Onchocerca volvulus (O-150) combined with Southern-blot hybridization to species-specific DNA probes was employed for DNA detection. O-150 was amplified from parasites originating from Uganda, Benin, Cameroon, Liberia, Ghana, Burkina Faso, Mali, and Zaire and was successfully hybridized to digoxigenin-labeled oligonucleotides. To investigate the sensitivity of the PCR, 2 skin biopsies were taken from each of 227 persons from Uganda with proven O. volvulus infections but with low microfilaria (mf) densities due to ivermectin treatment. One biopsy was tested by PCR and the other was digested using collagenase to assess the total number of mf. The PCR revealed 76.2% of the samples to be positive, and the collagenase method showed that 78.9% were positive, indicating similar sensitivity for the two methods. It is probable that for both techniques the biopsy must contain at least one live mf or fragments of a dead mf. In this study, no free or circulating O. volvulus DNA could be detected in skin biopsies by PCR.

Sudanese mucosal leishmaniasis: epidemiology, clinical features, diagnosis, immune responses and treatment

The epidemiology, clinical features, pathology, immune responses, diagnosis and treatment of 14 patients with mucosal leishmaniasis in the Sudan are described. The condition occurred mainly in adult males, particularly in certain closely related tribes from the western Sudan. It affected the mucosa of the upper respiratory tract and/or the oral mucosa and sometimes followed treated kala azar. The parasites were sometimes confined to the mucosa, sometimes spread to the lymph nodes, and rarely infected the bone marrow and spleen. One of the 2 patients with both visceral and mucosal leishmaniasis differed from classical kala azar cases; his infection was longer lasting, he was leishmanin positive, and his peripheral mononuclear cells proliferated in response to leishmanial antigens. Mucosal leishmaniasis following treated kala azar is a similar phenomenon to post-kala azar dermal leishmaniasis and post-kala azar uveitis. Post-kala azar mucosal leishmaniasis can therefore be added to the other post-kala azar leishmanial infections. Using the polymerase chain reaction, Southern blot analysis with specific probes, and isoenzyme characterization, the causative parasite was identified as Leishmania donovani in 4 patients and as L. major in one. Unlike American mucocutaneous leishmaniasis, mucosal leishmaniasis in the Sudan was not preceded or accompanied by cutaneous lesions and the response to pentavalent antimony or ketoconazole was good.

Visceral leishmaniasis: use of the polymerase chain reaction in an epidemiological study in Baringo District, Kenya

The polymerase chain reaction was applied to capillary blood spots dried on filter paper from 20 parasitologically proved cases of visceral leishmaniasis (VL), 21 subclinical cases, and 11 healthy controls in a longitudinal study of anthroponotic VL in Baringo District, Kenya. Leishmania deoxyribonucleic acid (DNA) was detected 10.5 months before diagnosis and up to 3 years after diagnosis and apparently successful treatment. Subclinical cases can have detectable circulating parasite DNA in their blood. These findings may indicate that subclinical cases can be a reservoir and formerly treated VL patients can remain a reservoir for a long time. Xenodiagnosis should be performed on subclinical cases and former VL patients to establish their role in transmission of VL in Kenya.

Leish-KIT, a stable direct agglutination test based on freeze-dried antigen for serodiagnosis of visceral leishmaniasis

In order to increase the application potential of the direct agglutination test (DAT) for the detection of anti-Leishmania antibodies in human serum samples, we developed an antigen based on stained and freeze-dried Leishmania donovani promastigotes. We describe here the evaluation of the performance of the DAT based on this freeze-dried antigen. It was shown that the freeze-dried antigen remains fully active, even after storage at 56 degrees C for 18 months. With a cutoff value of 1:1,600, the sensitivity of the DAT was shown to be 92% and the specificity of the test was 99.7%, which were comparable with the results found for the DAT based on liquid antigen. The major advantages of the freeze-dried antigen are that the production of a large batch of this antigen allows reproducible results in the DAT over a long period of time and that the freeze-dried antigen can be stored at ambient temperature, which, as was shown, makes the test a valuable diagnostic tool for use in the field.

Genomic fingerprinting of Onchocerca species using random amplified polymorphic DNA

A method based on amplification of genomic DNA by decamer primers of random nucleotide sequence was used to obtain DNA fingerprints from different species of the genus Onchocerca. Each of the 20 primers tested allowed a clear distinction between the different species of the genus on an agarose gel. The technique offers the potential to construct species or strain specific probes and oligonucleotides PCR primers from the species specific fragments. A combination of these primers or others could be useful as population markers.

Development and application of the polymerase chain reaction for the detection and identification of Leishmania parasites in clinical material

Detection, diagnosis and identification of Leishmaniasis may be difficult owing to low numbers of parasites present in clinical samples. The PCR has improved the sensitivity and specificity of diagnosis of several infectious diseases. A leishmania specific PCR assay was developed based on the SSUrRNA genes which amplifies DNA of all Leishmania species. Point mutations occurring within the rRNA genes allow differentiation of the Leishmania complexes using primers constructed with the 3/ ends complementary to the specific point mutations present in the SSU rRNA genes of the Leishmania species. Biopsy material, blood, lesion impressions and blood spots on filter paper can be used in the assay. In a longitudinal study on the incidence rates of VL, subclinical cases and PKDL in an endemic region of Sudan, filter paper blood spots from proven and suspected VL patients, PKDL and control samples from an endemic region in Sudan are being taken. The blood spots were analyzed in the DAT and by PCR and results compared with clinical and parasitological data. The first results indicate that the PCR on blood spots is a simple and sensitive means of detecting active VL; in PKDL patients parasites are detectable in the skin.

Onchocerca volvulus: application of the polymerase chain reaction to identification and strain differentiation of the parasite

Previous studies have demonstrated that the genome of Onchocerca volvulus contains a variable tandemly repeated DNA sequence family with a unit length of 150 bp. The variability of the 150-bp family has been exploited to develop O. volvulus strain and species specific DNA probes. Application of these DNA probes to the study of the epidemiologically most significant life cycle stages of the parasite has been confounded by several obstacles. These include the relative insensitivity of some of the DNA probes and the difficulty in releasing genomic DNA from infective larvae and skin microfilariae in a form that may be directly detected by hybridization to the probes. DNA sequence comparison of 18 known examples of the 150-bp repeat has been used to develop two populations of degenerate oligonucleotides. These oligonucleotides have been shown to support the amplification of the 150-bp repeat family from Onchocerca DNA, using the polymerase chain reaction. Both strain and species specific members of the repeat family are faithfully amplified, allowing characterization of a parasite on the basis of hybridization of the PCR amplification products to the previously developed DNA probes. This method is shown to be applicable to all diagnostically important forms of the parasite, including adults, infective larvae, and skin microfilariae. In addition, the method is capable of detecting O. volvulus infective larvae directly in extracts of blackfly vectors.

The onchocerciasis focus at Kinsuka/Kinshasa (Republic of Zaire) in 1985. I. Entomological aspect

The entomological aspect of the onchocerciasis focus at Kinsuka/Kinshasa has not been studied since vector control was carried out in 1948. As in 1940, larvae of Simulium damnosum s.l. are located in the arm of the Zaire River flowing between Mimosa Island and the Zairian bank. They are, however, scarce. Cytotaxonomic studies showed that the S. squamosum group was the only member of the S. damnosum complex present in the region of Kinshasa. Physico-chemical analysis of the water at breeding sites determined that S. squamosum larvae develop in neutral or acid water with a conductivity of less than 50 micronhos cm-1 and a low concentration of dissolved salts. Longitudinal study showed that the 'annual biting rate' (ABR) and the 'annual transmission potential' (ATP) fluctuate from 2406-5999 bites man-1 year-1 and from 120-236 infective larvae man-1 year-1 respectively. The low transmission rate at Kinsuka is mainly due to the low level of the biting population occurring during the main river rising. The increase in Kinsuka's population has reinforced this situation by 'diluting' the parasite in the human reservoir.

Biotechnology as applied to vectors and vector control

Vector borne diseases remain some of the major public health problems in the developing world. In this review some of the current applications of biotechnology to vectors and vector control and some of the possible future applications are discussed.

Cloning and characterization of an Onchocerca volvulus specific DNA sequence

A cloned sequence, pOvs134, was isolated from a genomic library prepared from Onchocerca volvulus of savanna origin in the plasmid pUC9. pOvs134 hybridizes to all the geographic isolates of O. volvulus tested from both the New and the Old World, but not to the species Onchocerca gibsoni, Onchocerca gutturosa, Onchocerca ochengi, Onchocerca cervicalis, the filarial parasites Brugia malayi, or Dirofilaria immitis, nor to human or simuliid DNA. As little as 250 pg of DNA can be detected on a dot blot hybridization, suggesting that pOvs134 is sensitive enough to detect a single third stage larva. DNA sequence analysis of the inserted DNA of pOvs134 revealed that it consisted of twelve examples of a 149-bp repeat. The sequence of this repeat is strikingly similar to that of two O. volvulus genomic clones previously described, one of which has been reported to be specific for forest form O. volvulus, and one of which hybridizes to genomic DNA of several species of Onchocerca. These results suggest that the 149-bp repeat sequence is highly repeated in the genome of O. volvulus, and that variants of this repeat with different specificities exist.

Simulium (Edwardsellum) rasyani n.sp., the Yemen species of the Simulium damnosum complex

The examination of the polytene chromosomes of the Yemen representative of the Simulium damnosum complex revealed hitherto unknown arrangements distinct enough to justify the description of this form as the new species Simulium (Edwardsellum) rasyani. The newly recognized inversion II L-60.65 was always present and found to be homozygous in 62% and heterozygous in 38% of the 106 larvae which were examined. A short description is given of the morphology of the females, males, larvae and pupae. Populations from the five permanent Wadis Kabir, Rasyan, Al Barh, Zabid, and Surdud were genetically and morphologically very uniform.

Following movements of resistant populations of Simulium soubrense/sanctipauli (Diptera: Simuliidae) by means of chromosome inversions

Following larval insecticide treatment, resistance to the organophosphates temephos and chlorphorxim appeared in a population of the Simulium soubrense/sanctipauli group of the S. damnosum complex on the Bandama Rivers, Ivory Coast. Resistant populations were subsequently identified from other river basins in the north of Ivory Coast. A small chromosomal rearrangement, IIL-A, was found to be associated with resistant populations. Monitoring the presence of this inversion was used to detect the spread or resistance eastwards into untreated areas.

Variation and distribution of forms of Simulium soubrense and S. sanctipauli in West Africa

Examination of specimens from savanna areas of Togo and Benin attributable to Simulium soubrense and S. sanctipauli according to the criteria of Vajime and Dunbar (1975) revealed hitherto undescribed features. Cytological examination showed many larvae with the arrangement IIL- 4.6/4.6.7, heterozygous for the 'diagnostic' inversion and 86% of the males possessed a previously undescribed inversion IIS-6b. The occurrence of such larvae in Togo and Benin was associated in adult males with records of a type of scutal pattern which is described and termed Type IV. This pattern is one extreme of a range of scutal pattern variation in the males of the S. soubrense/S. sanctipauli sub-group, which was separated into four arbitrary classes and specimens were scored as Type I, II, III or IV. The distribution of these different types of male scutal pattern, based on collections made in West Africa between 1963 and 1981, is presented. Type I and II patterns predominated in forest areas and Type IV in savanna. Many female flies which occurred together with the latter possessed pale wing tufts. In the light of the above and additional evidence, derived from the progeny of individual females, and because the 'diagnostic' inversion for S. soubrense and S. sanctipauli together with a previously undescribed sequence IIL-6 occurred in Hardy-Weinberg equilibrium, it was concluded that the populations in Togo and Benin are a single interbreeding group. This group is described as a new form, named the Beffa form, of the S. soubrense/S. sanctipauli subgroup of the S. damnosum s.l. complex and its possible taxonomic status is discussed.

Identification of a laboratory mating form of the Simulium damnosum Theobald complex in West Africa

Larvae and pupae of Simulium damnosum s.l. were collected from the Begba rapids on the Mono river. Emerging adults were induced to mate, blood feed and oviposit. Six out of 13 discrete egg batches counted were fertile. The F1 females did not blood feed and thus no F2 eggs were obtained. Larvae from the breeding site and the F1 generation were identified as being the Beffa form of the S. sanctipauli/S. soubrense group. This form appears to be the only member of the S. damnosum complex in West Africa which mates in the laboratory and is almost certainly the same form as that colonized by Simmons and Edman (1982). The mating behaviour of West African S. damnosum s.l. described by several authors is similar to that observed in the Beffa form, and the possibility that earlier reports referred to the Beffa form is discussed.

Enzymes for species identification in the Simulium damnosum complex form West Africa

An electrophoretic survey of 44 enzyme systems of the Simulium damnosum complex has revealed only two that are of value in species diagnosis, namely PGM and trehalase. S. yahense has a unique PGM variant, and S. yahense and S. squamosum have a different trehalase variant from S. sirbanum, S. damnosum s.s., S. sanctipauli and S. soubrense. Examination of S. damnosum s.l. from Mali, Ivory Coast and Ghana has shown that PGM and trehalase can be used to distinguish accurately adult S. yahense from S. squamosum and these two from S. sirbanum, S. damnosm s.s., S. sanctipauli and S. soubrense.