Out of more than 200 known cases of naegleria infections in the US in past 40 years, only two people survived.
Under the Emerging and Vector Borne Disease Control Initiative, the Department of Microbiology of University of Karachi, recently organised a panel discussion entitled ‘Avoiding Waterborne Protozoal Encephalitis during Ramazan’. The panel consisted of basic and clinical microbiologists, parasitologists, immunologists, including Chairperson Prof Dr Shahana Urooj Kazmi, Prof Dr Fasihuddin Ansari, Dr Farooq Haseeb, Dr Zaid Pirzada, Dr Abdul Wahab, Dr Adnan Khan and Dr Fouzia.
Majority of experts expressed their deep concern and sympathy with the increasing number of victims who lost their life in Karachi hospitals in a short span of illness due to lethal infection with a rare protozoan human pathogen, the free-living waterborne amoeboflagellate naegleria fowleri the cause of primary amoebic meningoencephalitis.
Commenting on the unusual lifecycle of naegleria, Prof Kazmi said that it was capable of carrying out its full life cycle without the intervention of a parasitic stage. The molecular repertoire responsible for the cytolytic and brain tissue-destructive activity and the molecular mechanism of invasion and pathogenesis of primary amoebic meningoencephalitis were still unclear.
Pathogenicity has been associated with phospholipases, degrading lipid rich cell membranes, undefined hemolytic factors and a secreted cysteine proteinase, which forms pores in target membranes of prokaryotes and human cells resulting in enormous tissue-destruction and cell killing.
Two pore-forming polypeptides known as negliapores isolated from highly virulent trophozoites of naegleria fowleri exhibited antimicrobial and cytolytic properties against human immune system cells, Natural Killer (NK) and T cells.
She further said that free-living, bacteria-feeding amoeboflagellate naegleria fowleri was distributed worldwide in soil and warm pools of water, including thermal pools of hot industrial waste water, also isolated from mineral water in Mexico. N fowleri is a facultative protozoan parasite and was not bacteria or virus as reported in media.
Causes human infection by entering through nasal passages and olfactory neuroepithelium during swimming and bathing in hot baths or hot springs, sniffing water in nasal area to clean or irrigate sinuses. Within the brain they multiply by binary fission, provoke inflammation, severe headache, neck rigidity, mental confusion, drowsiness followed by coma and death due to extensive destruction of brain tissue.
She said this rapidly fatal infection, known as ‘Primary Amoebic Meningoencephalitis’ usually results in death within 72 hours after the onset of symptoms. Out of more than 200 known cases of naegleria infections in the United States in past 40 years only two people survived.
Water and Sanitation Related Diseases and the Environment: Challenges, Interventions and Preventive Measures
Janine M. H. Selendy
Paperback | 552 pages | October 2011