The role of blood vessels and lungs in the dissemination of Naegleria fowleri following intranasal inoculation in mice
Jaroli, K.L.; McCosh, J.K.; Howard, M.J.
Folia Parasitologica 49(3): 183-188
2002
ISSN/ISBN: 0015-5683 PMID: 12418810 Document Number: 548247
Primary amoebic meningoencephalitis (PAM) was induced in mice by intranasal inoculation of Naegleria fowleri to study the role of blood vessels and lungs in the early and later stages of this disease. Upon culturing blood and lung tissue obtained at 24-, 36-, 48-, 72-, 96- and 120-h time periods, it was found that amoebae grew only from blood and lung tissue obtained at 96 and 120 h time periods. Paraffin sections of the head revealed small foci of acute inflammation and amoebae within the olfactory bulb of the central nervous system (CNS) at 24 h. Amoebae were not observed within blood vessels of the CNS until 96 and 120 h. Also, amoebae were observed within the connective tissue surrounding blood vessels and sutures of the skull, bone marrow and venous sinusoids between the skull bone tables at 96 and 120 h. No amoebae or acute inflammatory reactions were observed in the lung sections from any time period and indirect immunofluorescence microscopy was negative for N. fowleri. This study provides evidence that neither blood vessels nor lungs provide routes for N. fowleri to the CNS during the early stages of PAM and that amoebae enter the veins of the CNS and bone marrow during later stages of the disease.