Intravenous Inoculation of a Bat-Associated Rabies Virus Causes Lethal Encephalopathy in Mice through Invasion of the Brain via Neurosecretory Hypothalamic Fibers

The majority of rabies virus (RV) infections are caused by bites or scratches from rabid carnivores or bats. Usually, RV utilizes the retrograde transport within the neuronal network to spread from the infection site to the central nervous system (CNS) where it replicates in neuronal somata and infects other neurons via trans-synaptic spread. We speculate that in addition to the neuronal transport of the virus, hematogenous spread from the site of infection directly to the brain after accidental spill over into the vascular system might represent an alternative way for RV to invade the CNS. So far, it is unknown whether hematogenous spread has any relevance in RV pathogenesis. To determine whether certain RV variants might have the capacity to invade the CNS from the periphery via hematogenous spread, we infected mice either intramuscularly (i.m.) or intravenously (i.v.) with the dog-associated RV DOG4 or the silver-haired bat-associated RV SB. In addition to monitoring the progression of clinical signs of rabies we used immunohistochemistry and quantitative reverse transcription polymerase chain reaction (qRT-PCR) to follow the spread of the virus from the infection site to the brain. In contrast to i.m. infection where both variants caused a lethal encephalopathy, only i.v. infection with SB resulted in the development of a lethal infection. While qRT-PCR did not reveal major differences in virus loads in spinal cord or brain at different times after i.m. or i.v. infection of SB, immunohistochemical analysis showed that only i.v. administered SB directly infected the forebrain. The earliest affected regions were those hypothalamic nuclei, which are connected by neurosecretory fibers to the circumventricular organs neurohypophysis and median eminence. Our data suggest that hematogenous spread of SB can lead to a fatal encephalopathy through direct retrograde invasion of the CNS at the neurovascular interface of the hypothalamus-hypophysis system. This alternative mode of virus spread has implications for the post exposure prophylaxis of rabies, particularly with silver-haired bat-associated RV

Wetland related livelihoods, institutions and incentives for conservation in the Great Ruaha River Wetland System

Wetlands are among the world’s most productive environments and of tremendous economic benefits to society. Though wetland utilization for household agriculture and wetland resource extraction for household income generation may be the two most important factors driving wetland  degradation in Tanzania the furtiveness of small decisions makes mitigation efforts exceedingly difficult. Like other families throughout the  world, the decision that Tanzanian families make in regard to the use of wetland resources are strongly influenced by desire to improve their livelihoods. The importance of trade to household economies and as a  determinant of wetland resources status prompts an examination of the potential for using marketbased incentives and relevant institutions to enhance household incomes while conserving wetland biodiversity.  Balanced utilization of wetland ecosystems can be achieved if wetland related livelihoods, institutions and incentives for their management are  well planned, in place and understood by stakeholders. This study was conducted in Malolo B and Msosa villages in the Great Ruaha River wetland system to determine the existing wetland related livelihoods, institutions and incentives for management. The major wetland based livelihoods in order of magnitude are associated with use of wetlands for agriculture,  source of water for various uses, fishing, source of construction material such as for roofing, game meat, earth brick making, fodder/use of wetlands for livestock grazing. About 95% of the population in wetland adjacent communities are involved in agricultural production. The main  institutions involved in wetlands management are grouped in different categories based on the roles they play in wetlands management. These  include connectors, whistle blowers, enforcement, information exchange, management, education and capacity building, lobbying, entrepreneurs,following and reinforcing, leading, rule creation, funding, wrecking and  caring, spiritual. The major incentives for wetlands conservation include clear clear land tenure), alternative income generating activities, joint management and stakeholder participation and privatization of wetland management