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The direct fluorescent antibody test (DFA), is performed in all rabies reference laboratories across Latin America and the Caribbean (LAC). Despite DFA being a critical capacity in the control of rabies, there is not a standardized protocol in the region. We describe the results of the first inter-laboratory proficiency exercise of national rabies laboratories in LAC countries as part of the regional efforts towards dog-maintained rabies elimination in the American region. Twenty three laboratories affiliated to the Ministries of Health and Ministries of Agriculture participated in this exercise. In addition, the laboratories completed an online questionnaire to assess laboratory practices. Answers to the online questionnaire indicated large variability in the laboratories throughput, equipment used, protocols availability, quality control standards and biosafety requirements. Our results will inform actions to improve and harmonize laboratory rabies capacities across LAC in support for the regional efforts towards elimination of dog-maintained rabies., Author summary The incidence of dog-maintained rabies in Latin America has showed a significant reduction in the last 30 years. Although several countries have achieved its elimination there are still focalized areas in the region where rabies remain endemic. Many factors, including poverty, geographic and environmental features, as well as social, cultural, political and economic variables, have limited the effective implementation of canine rabies control programs in these endemic areas. Critical to the goal of control and elimination of rabies is a robust laboratory diagnostic capacity. This report presents the results of an Inter-laboratory proficiency testing exercise for rabies diagnosis by direct fluorescent antibody test among laboratories across Latin America and the Caribbean (LAC). Our results indicate that although all laboratories can perform the direct fluorescent antibody test, there are substantial differences in the overall results and test interpretation. This study identified important gaps in standardization and/or harmonization between laboratories which could be overcome and corrected with appropriate DFA protocols standardized across the LAC, including its broad distribution and proper training.

Bats are natural reservoirs for the majority of lyssaviruses globally, and are unique among mammals in having exceptional sociality and longevity. Given these facets, and the recognized status of bats as reservoirs for rabies viruses (RABVs) in the Americas, individual bats may experience repeated exposure to RABV during their lifetime. Nevertheless, little information exists with regard to within-host infection dynamics and the role of immunological memory that may result from abortive RABV infection in bats. In this study, a cohort of big brown bats (Eptesicus fuscus) was infected intramuscularly in the left and right masseter muscles with varying doses [10(-0.1)-10(4.9) median mouse intracerebral lethal doses (MICLD(50))] of an E. fuscus RABV variant isolated from a naturally infected big brown bat. Surviving bats were infected a second time at 175 days post-(primary) infection with a dose (10(3.9)-10(4.9) MICLD(50)) of the same RABV variant. Surviving bats were infected a third time at either 175 or 305 days post-(secondary) infection with a dose (10(4.9) MICLD(50)) of the same RABV variant. When correcting for dose, similar mortality was observed following primary and secondary infection, but reduced mortality was observed following the third and last RABV challenge, despite infection with a high viral dose. Inducible RABV-neutralizing antibody titres post-infection were ephemeral among infected individuals, and dropped below levels of detection in several bats between subsequent infections. These results suggest that long-term repeated infection of bats may confer significant immunological memory and reduced susceptibility to RABV infection.

Despite progress in vaccine development in the past century the mechanisms behind immune responses elicited by rabies biologics or via natural infection remain largely unknown. In this study, we compared protection elicited by standard, early, or delayed prophylaxis with a reduced number of vaccine doses using inactivated and live-attenuated vaccines. Two-month-old Syrian hamsters, 4-week-old ICR mice or adult rhesus macaques were inoculated with canine rabies virus variants. Thereafter, prophylaxis was initiated 6 h, 1, 2, 3, 4, 5, 6 or 7 days post-exposure (p.e.). One or several doses of inactivated (HDCV), or reverse genetically attenuated (live), or gamma-irradiated (inactivated)-ERAG333 vaccines were administered intramuscularly. The dynamics of virus spread were measured over time in the rodent models. Rabies virus reached the spinal cord at day 4 and brain at day 6 p.e. All hamsters succumbed in groups in which live ERAG333 was delayed until days 5 and 6 p.e. However, 78%, 44%, 56% and 22% of hamsters survived when one dose of live ERAG333 was administered 6 h, 1, 2, 3, and 4 days p.e., respectively. Similarly, 67% survived when inactivated ERAG333 was administered at 24 h p.e. All hamsters succumbed when standard prophylaxis (the Essen regimen) was delayed until days 3–6, but 67% and 33% of hamsters survived when PEP began 1 or 2 days p.e., respectively. Macaques were protected by one dose of attenuated ERAG333 at 24 h p.e. The highly attenuated (live) and inactivated ERAG333 vaccines elicited potent protective immune responses, even when prophylaxis initiation was delayed. When 2–5 doses of commercial vaccine and HRIG were administered according to the Essen scheme, 89–100% of the animals survived. Reduced vaccine schedules provided efficacious intervention, regardless of the total number of vaccine doses administered.

Infected persons had slept in an infested cabin., In February 2006, a diagnosis of sylvatic epidemic typhus in a counselor at a wilderness camp in Pennsylvania prompted a retrospective investigation. From January 2004 through January 2006, 3 more cases were identified. All had been counselors at the camp and had experienced febrile illness with myalgia, chills, and sweats; 2 had been hospitalized. All patients had slept in the same cabin and reported having seen and heard flying squirrels inside the wall adjacent to their bed. Serum from each patient had evidence of infection with Rickettsia prowazekii. Analysis of blood and tissue from 14 southern flying squirrels trapped in the woodlands around the cabin indicated that 71% were infected with R. prowazekii. Education and control measures to exclude flying squirrels from housing are essential to reduce the likelihood of sylvatic epidemic typhus.