[GMS-JE-Net - Message:20] Nipah and Hendra viral encephalitis
Stephane P. Rousseau (RCU)
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Nipah and Hendra viral encephalitis
INTRODUCTION
Hendra and Nipah viruses are two related zoonotic pathogens that have emerged in the Asia-Pacific region. Hendra virus caused a disease affecting horses and humans in Australia in 1994 and 1995 and has since then caused sporadic infections in horses and humans, while Nipah virus caused an outbreak of infection in pigs and humans in Malaysia and Singapore between 1998 and 1999, and outbreaks of infection in humans in Bangladesh from 2001 to 2004 and in West Bengal, India in 2001 [1-12]. Both are RNA viruses belonging to the Paramyxoviridae family. Since they share antigenic, serological, and ultrastructural characteristics and differ from other paramyxoviruses, they have been grouped under the genus henipavirus [13-16].
NIPAH VIRUS
Nipah virus was initially discovered when it caused an outbreak of viral encephalitis among pig farmers in Malaysia. The virus was named after a village in Malaysia, where the infected patient lived. There have also been several outbreaks of acute Nipah encephalitis in various districts in Bangladesh as well as in the neighboring district of Siliguri in India [12,17].
Epidemiology — The outbreak in Malaysia was initially thought to be Japanese encephalitis (JE), which is endemic in Asia. However, certain features were against this diagnosis: the occurrence of encephalitis among adults rather than children, the clustering of cases in the same household, and a history of illness in pigs belonging to the affected farmers [6,8]. Furthermore, a high number of patients had been vaccinated against JE [6,8]. (See "Arthropod-borne encephalitides", section on 'Japanese encephalitis virus'.)
Animal reservoirs — The primary animal reservoirs of henipaviruses are bats of the genus Pteropus [18-23]. Antibodies against Nipah antigens were found in bats from Malaysia and Bangladesh, and the virus was isolated from urine of bats of the species P. hypomelanus roosting in the East Coast of Malaysia [9,18,22]. Since then, serological evidence of Nipah virus infection have been found in 23 species of bats from 10 genera in regions as widely spread as Yunan and Hainan Island in China, Cambodia, Thailand, India, Madagascar, and Ghana in West Africa [23].
Unlike in JE, Nipah-infected pigs had clinical disease manifested by neurologic and respiratory symptoms [24,25]. The mode of transmission between pigs is probably through direct contact with infected fluid such as urine, saliva, pharyngeal and bronchial secretions. Other domestic animals such as cats and dogs have also been shown to have a positive serology for Nipah virus [8].
_______________________
Stéphane P. Rousseau (Mr)
Regional
Coordinator
Regional Coordination Unit (RCU)
Asian Development
Bank
Greater Mekong Subregion
Communicable Diseases Control
Project
Room 2104, 21st Floor,
Thanh Cong Tower,
57 Lang Ha
Street,
Ba Dinh District, Hanoi – VIET NAM
Tel: +844 3514 79 33
Fax:
+844 3514 80 12
Email: gms.c...@gmail.com
Website:
www.gms-cdc.org/
Skype: rcu_gms_cdc
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