Abstract & Commentary

Emerging Nipah Virus causes Outbreak in Bangladesh Linked to Bat Reservoir

By Joseph F. John, MD, FACP, FIDSA, FSHEA, Associate Chief of Staff for Education, Ralph H. Johnson Veterans Administration Medical Center; Professor of Medicine, Medical University of South Carolina, Charleston, is Co-Editor for Infectious Disease Alert.

Dr. John reports no financial relationship to this field of study.

Source: Lowe L, et al. Characterization of Nipah Virus from outbreaks in Bangladesh 2008-2010. Emerg Infect Dis 2012;18:248255.

It has been over 10 years since a deadly paramyxovirus known as the Nipah virus emerged in Asia. Over the subsequent decade there has been multiple outbreaks. Some traditional practices like drinking raw date sap are hard to break. The year's first outbreak in Bangladesh (Jipurhat) this year resulted in death in all six affected individuals. The incubation is about 5-7 days and the attack begins with fever, changes in cognition and seizures. Health care workers are urged to wash their hands frequently when caring for patients with Nipah virus infection.

Bats and ("flying foxes") get access to palm sap collecting jars and denial of such access is the major public health remedy currently applied. A recent publication from the CDC and the International Centre for Diarrheal Diseases in Bangladesh discusses a way to compare Nipah viruses. In the paper the full genome sequence of 2 viruses were reported and partial sequences from virus from 3 patients. A proposed standardized scheme evolved out of these genomic studies. Using the N-terminal region of the N gene open reading frame, there are 25 distinct nucleotides (nt) that "universally differentiate the genotypes." The M proteins are highly conserved among the genotypes from Malaysia versus Bangladesh and India.

Phylogenetic analysis disclosed two major groups designated M for Malaysia and Cambodia and B for Bangladesh and India. What are known as the topologies and branching patterns in the phylogenetic trees are very similar for the comparison of whole gene sequences reported earlier. (Arankalle, VA, et al. Emerg Infect Dis 2011;17:907-9). So this new shortened method of classifying Nipah Viruses should work well towards standardization.

Commentary

Emerging viruses are always of interest especially when they have a known zoonotic connection. In the case of Nipah, there were early devastating outbreaks around some exposure to horses but the seminal reservoir now appears to be bats. Why the virus has not jumped continents more of late is not known but the high case fatality rate for people on the subcontinent makes this infection of grave concern.

Clearly local, regional and national infection control measures need to be honed. The current genomic classification, as well, offers a way to detect the rapid emergence of new strain, their spread and the surveillance of the virus in bats. The 729-nt region used here for comparing strains is small enough for one PCR reaction and allows a sufficient amount of variability.

The technical and creative power of the CDC scientists as well as their international counterparts provide some measure of assurance that our current process for assessing new viruses--like Nipah-- will serve the world's need for detecting and characterizing new viruses and new strains of existing virus. These two reports—one from a local epidemic and the other from international study groups—serve as a model for public health research and responses to new deadly viral infections.