Combining citizen science and molecular diagnostic methods to investigate the prevalence of Borrelia burgdorferi s.l. and Borrelia miyamotoi in tick pools across Great Britain

Lyme disease is the most common tick-borne disease and is caused by a group of bacteria known as Borrelia burgdorferi sensu lato (s.l.) complex. Sharing the same genus as B. burgdorferi, Borrelia miyamotoi is a distinct genotype that causes relapsing fever disease. This emerging tick-borne disease is increasingly becoming a concern in public health. To investigate the prevalence of B. burgdorferi s.l. and B. miyamotoi in ticks first, we developed a PCR (Bmer-qPCR) that targets the phage terminase large subunit (terL) gene carried by B. miyamotoi. A similar approach had been used successfully in developing Ter-qPCR for detecting B. burgdorferi s.l. The terL protein functions as an enzyme in packaging phage DNA. Analytical validation of the Bmer-qPCR confirmed its specificity, efficiency and sensitivity. Second, we designed a citizen science-based approach to detect 838 ticks collected from numerous sites across Great Britain. Finally, we applied Bmer-qPCR and Ter-qPCR to 153 tick pools and revealed that the prevalence of B. burgdorferi s.l. and B. miyamotoi was dependent on their geographical locations, i.e. Scotland showed a higher rate of B. burgdorferi s.l. and lower rate of B. miyamotoi carriage as compared to those of the England data. A pattern of diminishing rate of B. miyamotoi carriage from southern England to northern Scotland was visible. Together, the citizen science-based approach provided an estimation of the carriage rate of B. burgdorferi s.l. and B. miyamotoi in tick pools and a potential spreading pattern of B. miyamotoi from the south to the north of Great Britain. Our findings underscore the power of combining citizen science with the molecular diagnostic method to reveal hidden pattern of pathogen-host-environment interplay. Our approach can provide a powerful tool to elucidate the ecology of tick-borne diseases and may offer guidance for pathogen control initiatives. In an era of limited resources, monitoring pathogens requires both field and laboratory support. Citizen science approaches provide a method to empower the public for sample collection. Coupling citizen science approaches with laboratory diagnostic tests can make real-time monitoring of pathogen distribution and prevalence possible.

Targeting Multicopy Prophage Genes for the Increased Detection of Borrelia burgdorferi Sensu Lato (s.l.), the Causative Agents of Lyme Disease, in Blood

The successful treatment of Lyme disease (LD) is contingent on accurate diagnosis. However, current laboratory detection assays lack sensitivity in the early stages of the disease. Because delayed diagnosis of LD incurs high healthcare costs and great suffering, new highly sensitive tests are in need. To overcome these challenges, we developed an internally controlled quantitative PCR (Ter-qPCR) that targets the multicopy terminase large subunit (terL) gene encoded by prophages that are only found in LD-causing bacteria. The terL protein helps phages pack their DNA. Strikingly, the detection limit of the Ter-qPCR was analytically estimated to be 22 copies and one bacterial cell in bacteria spiked blood. Furthermore, significant quantitative differences was observed in terms of the amount of terL detected in healthy individuals and patients with either early or late disease. Together, the data suggests that the prophage-targeting PCR has significant power to improve success detection for LD. After rigorous clinical validation, this new test could deliver a step-change in the detection of LD. Prophage encoded markers are prevalent in many other pathogenic bacteria rendering this approach highly applicable to bacterial identification in general.

[Measuring drug affordability (Senegal)]

This article presents the results of a global survey on drug accessibility conducted in Senegal in 2001. The original tool we developed to measure drug affordability for this study considered 5 marker diseases and their corresponding medical treatments and determined the theoretical amount that each population quintile can devote to the purchase of these treatments at market prices without damaging their economic status (affordability threshold). These results were then compared with those obtained as part of a field survey of 987 patients at 41 health centres and 51 private chemists (pharmacists). The main results show that the population's ability to afford treatment is low (less than 40% at public sector prices and a little over 20% at private sector prices) and that even at the lowest market prices (public sector) 20% to 60% of the population cannot afford treatments for the most common illnesses. The field survey shows, moreover, that these results are exacerbated by four external factors: additional illness-associated expenditures (i.e., transportation costs, doctor visits), lack of compliance with government-set drug prices, prescription habits and dispensing practices. When these added costs are taken into account, less than 20% of the population can actually pay the public-sector treatment costs for the marker diseases, let alone the private sector prices. This tool is also useful for highlighting the insufficiencies of the strategies adopted for the target diseases (inconsistency between pricing policies and health priorities) and for providing a baseline measurement (at t0) of different socioeconomic groups' access to given treatments. Improvement or deterioration can then be assessed with measurements at times t1, t2...tn.

[Why drug prices are high in sub-Saharan Africa. Analysis of price structure: the case of Senegal]

This article seeks to shed light on the reasons for the lack of correlation between the price of drugs in this very poor sub-Saharan country and the population's ability to pay for them. The analysis is based on: (i) a comparison between the wholesale (exclusive of VAT and other taxes) and government-fixed retail prices and the corresponding prices of the same drugs in their country of origin (France); (ii) a description of the price-setting mechanisms in Senegal in both the public and private sectors; and (iii) an evaluation of public-sector retail price in Senegal, by end users and prescribing professionals in both sectors. The study found that: (i) patient expenditure would be one-fifth as high if all the drugs in the sample were sold at their government-fixed public-sector retail prices; (ii) the most cost effective drugs are sold at fixed retail prices higher than those of drugs not reimbursed by the national health insurance in France because considered less cost-effective; (iii) the mechanism for setting public retail prices seems to be unrelated to public health objectives, does not consider specific population groups, target diseases, or the drugs' therapeutic value, and therefore cannot be considered an effective tool for implementing national drug policies. Instead, the incentives of this mechanism lead retailers to sell the most expensive drugs first, to generate the highest possible margins. It does not prioritize the essential generic drugs that health authorities have placed at the centre of their pharmaceutical policy.

Comparison of the safety and immunogenicity of the lyophilized Mérieux seed and the World Health Organization working reference BCG vaccines in school-aged children in Senegal

In order to validate two new lots of Mérieux BCG vaccine (Mérieux seed derived from strain 1072), a calibration study was performed to compare their safety and immunogenicity to a full dose of the WHO-reference BCG vaccine (Tokyo strain 172) as well as the WHO-reference vaccine given at 1/10 of its normal concentration, in an open, randomized, four-arm, multicenter study in Senegal. A total of 1041 healthy Senegalese children aged 8-10 years were screened for participation in this study, of whom 548 had a negative Mantoux test and complied with inclusion and exclusion criteria. These children were randomly allocated a single dose of one of the following vaccines: full-dose Mérieux BCG vaccine (lot E0650); full-dose Mérieux BCG vaccine (lot E0624); full-dose WHO-reference vaccine (Tokyo strain 172); or 1/10 dose WHO-reference vaccine. A follow-up examination, including a tuberculin test, was performed 10-12 weeks after BCG vaccination for 465 (85%) children: 236 Mérieux BCG vaccine (117 lot E0650; 119 lot E0624); 115 full-dose WHO; 114 1/10 dose WHO. The percentage of subjects with a positive tuberculin test after vaccination was significantly lower (P < 0.001) in the 1/10 dose group (81.5%) compared to the other three groups (> 96%). The mean induration diameter was significantly smaller in subjects who received the low-dose of WHO vaccine compared to the others, according to analyses considering all subjects vaccinated, as well as only those subjects with a positive tuberculin test after vaccination. More children in the low-dose group did not have a vaccination scar, and the mean diameter of scars was smaller in this group. The rate of tuberculin reactions, the classification of reactions (Palmer and Edwards), and the characteristics of the vaccinal lesion were similar for the Mérieux BCG vaccines and the full-dose WHO-reference vaccine. All vaccines were safe, as evidenced by the absence of adenitis or suppurative adenitis during the course of the study. Results from this trial show that the two lots of Mérieux BCG vaccine behave equally as well as the full-dose WHO-reference BCG vaccine. The WHO-reference vaccine, given at 1/10 of its normal concentration was significantly less immunogenic, according to all parameters evaluated.

[Rabies in France, 100 years after Pasteur]

Pasteur's vaccination, a huge step forward in infectiology, remains the fundamental element in the fight against rabies. Since 1968, when rabid foxes reappeared in France there have been no domestic cases of human rabies, but from 1970 to 1993, 14 patients contaminated in enzootic areas (usually Africa) died from rabies in France. The new circulation conditions created by the European Union emphasizes the importance of the inactivated Pasteur vaccine cultivated on Vero cell lines. The classic protocol for post-exposure vaccinations is based on 5 intramuscular injections on day 0, 3, 7, 14 and 30. In 1988, the World Health Organization established new recommendations: the 2-1-1 schedule for post-exposure vaccination. Two injections are given on day 0 at two different sites followed by boosters on day 7 and day 21. Tested worldwide by independent laboratories, this schedule has been shown to effectively induce seroconversion when modern cell-culture vaccines are used. Although there is still a certain amount of debate on the new schedule, no failures have been recorded. The Centers for Disease Control in Atlanta recommend preventive vaccination for exposed professions based on primary and booster injections on day 0, 7, 28 and 365. Protection lasts for 3 years and may be prolonged with supplementary vaccinations. One hundred years ago, Pasteur taught us that we could protect the human population by fighting against animal contamination. Today's progress is the reward of such foresight--and a challenge to both human and veterinary medicine.

Simultaneous injection of hepatitis B vaccine with BCG and killed poliovirus vaccine

In most developing countries, hepatitis B virus is endemic and prevention has to be carried out early in life and on a mass scale. In these regions, simultaneous administration of multiple antigens is normal practice. We have therefore investigated the interaction of hepatitis B vaccine with BCG and inactivated polio vaccine. The serological antibody response to poliovirus and HBsAg as well as the cellular immune response to tuberculin post BCG immunization were assessed. The immune responses to HBsAg, BCG and polio vaccines injected simultaneously were comparable to those observed after separate administration of each vaccine. Moreover, no increase of adverse reactions was noted. Results confirmed that HB vaccine could be introduced into the WHO expanded programmes on immunization without impairing the expected protective efficacy against the targeted vaccine-preventable diseases.