Henipavirus

Henipavirus is a kind of the family Paramyxoviridae , order of the Mononegavirales containing two members, Hendravirus (Morbillivirus of équidés in the beginning) and Nipahvirus (the word henipavirus is a contraction of the two names of virus). The henipavirus are characterized by their large size (18,2 kilobases; Wang et al., 2001), their natural occurrence at the Bats Pteropid, and their recent emergence like pathogenic Zoonotic able to cause death at the animal domestic and the human S.

Virus of Hendra

Appearance

Hendravirus was discovered in September 1994 when it caused the death of thirty Chevaux and a trainer during the drive with Hendra, suburbs of Brisbane in the Queensland, in Australia.

Index puts, a mare, was placed with 23 other horses after being fallen Malade and died two days later. Then, 19 of the remaining horses are falls ills and 12 died about it. The trainer and a stable boy was implied by nourishing Index puts and both are falls ills within one week after the death of the mare. They presented then the symptoms of the Grippe. The stable boy recovered while the trainer died of respiratory and renal problems. The source of the virus was most probably the sneezes of Index Puts.

A second case occurred in August 1994 (preceding the first case chronologically) in the north of Mackay with 1000km of Brisbane, having for result the deaths of two horses and their owner (Field et al., 2001). The owner attended the autopsies of the horses and was allowed at the hospital three weeks after suffering of a meningitis. He recovered, but 14 month later, he developed central nervous system disorders and died. This case was diagnosed retrospectively by the presence of Hendravirus in the brain of the patient.

A serum monitoring of fauna in the sectors of manifestation of the virus was led and identified Chauves-souris pteropid like the most likely source of the virus of Hendra with a seroprevalence of 47%. None of the 46 other taken species was positive. Insulations of virus in the area and the urine of the Chauves-souris indicated that the transmission with the horses could be produced via the exposure to the urine or of the amniotic liquid of the bat (Halpin et al., 2000).

Other cases

Three additional incidents, with Cairns in the Queensland in January 1999 and October 2004, like in Townsville always in Queensland in December 2004, each case had like consequence the death of a horse. A veterinary surgeon implied in the autopsy of the horse of Townsville developed a disease related to this virus but recovered.

Distribution of the bats covering Townsville and Cairns, and the synchronization of the incidents indicates a seasonal model of the demonstrations probably related to the seasonal character of the births of these bat. Because there is no obviousness of transmission to human directly since the bats, one thinks that the human infection occurs only via one host.

Pathology

The bats are not affected by the infection of the virus of Hendra. The symptoms of the infection of the virus of Hendra for the human ones can be respiratory, including the Hémorragie and the edema pulmonary, or encephalitic having for result meningitis. The horses, the infection causes usually a pulmonary edema and the nasal congestion.

Virus of Nipah

Appearance

The first epidemics related to the Nipah virus took place in Singapore and in Malaysia in 1998. However the virus of Nipah was identified in 1999 when it because case of a neurological and respiratory disease to the farms of pig in peninsular Malaysia, having for result the death of 105 people out of 265 and the Euthanasie of a million pigs (Field et al., 2001). In Singapore, 11 cases whose mortal occurred with workmen of slaughter-house exposed to the imported pigs of the affected Malaysian farms.

The natural basin of the Nipah virus is the frugivorous bat of the pteropus type. Deforestation in Southeast Asia involved the destruction of its habitat. It thus migrated in order to find food. It took refuge towards the farms where it infected the food of the pigs. Indeed the virus is contained amongst other things in its saliva. The contaminated pig excretes by strong coughs the virus and contaminates in its turn the men. He is thus an intermediate host and also a powerful vector of the infection.

The symptoms of the infection of the Malaysian case were mainly encephalitic at the man and respiratory in the pigs. The posterior demonstrations caused respiratory diseases at the man, increasing the probability of the transmission human-with-human and indicating the existence of the more dangerous constraints of the virus.

Other cases

Six additional cases of virus of Nipah occurred since 1998, one in India and five with the Bangladesh. All the sites of these cases are in lower part of the zone of the species of Pteropus (Pteropus giganteus). As with the virus of Hendra, the synchronization of the demonstrations indicates a seasonal effect.

• January 31st, 2001 - February 23rd, Siliguri, India: 66 cases with a death rate of 74% (Chadha et al., 2006). 75% of patients were either the personnel of hospital, or of the people having returned visit with other patients in the hospital, indicating a transmission human-with-human.

• April-May 2001, zone of Meherpur, Bangladesh: 13 case with nine dead (mortality of 69%) (Hsu et al., 2004).

• January 2003, zone of Naogaon, Bangladesh: 12 cases with eight dead (mortality of 67%) (Hsu et al., 2004).

• January-February 2004, provinces of Manikganj and Rajbari, Bangladesh: 42 cases with 14 dead (mortality of 33%).

• February 19th - April 16th, 2004, zone of Faridpur, Bangladesh: 36 cases with 27 dead (mortality of 75%). The epidemiologic indices strongly suggest that these cases implied the transmission person to person virus of Nipah, which had not been previously confirmed. 92% of implied cases were narrowly in liaison with at least another person reached of the virus of Nipah. Two cases comprised a simple short exposure to a sick patient, including a driver of rickshaw which transported a patient to the hospital. Moreover, at least six cases implied the SARS which was not brought back previously for the disease of virus of Nipah at the man. This symptom is likely to have helped the human-with-human transmission by the great dispersion of droplet at the time of the sneezes.

• January 2005, zone of Tangail, Bangladesh: 32 cases with 12 dead (mortality of 38%). The virus could be contracted by date juice drink soiled by the excrements or the saliva of bats.

Eleven cases isolated from encéphalite which had with the virus of Nipah were also referred in Bangladesh since 2001.

The virus of Nipah was isolated in the bat from Lyle (Pteropus lylei) to the Kampuchea (Reynes et al, 2005) and the viral ARN was found in the urine and the saliva of the bat of Lyle and the larvae of Horsfield (Hipposideros larvartus) of Thailand (Wacharapluesadee, et al., 2005). The Kampuchean cases show that the virus is identical to 98% with the virus causing the cases of 1998. One observed no human infection or other species in Kampuchea or in Thailand.

Pathology

At the man, infected present fever, headaches and somnolence. Cough, the abdominal pain, nausea, the vomiting, the weakness, the problems with ingestion and the scrambled vision are relatively common. 1/4 of the patients had faintnesses and approximately 60% became comatose and have Pu to need respiratory assistance. The patients presenting of the serious forms of the disease, developed serious hypertension, a heart rate and a temperature very high.

The virus of Nipah is also known to cause encéphalites at the time of the relapses. Among the initial Malaysian cases, a patient presented a encéphalite approximately 53 months after his initial infection. There is no final treatment for the encéphalite of Nipah, independently of measurements of support, such as mechanical ventilation and the prevention of the secondary infection. The Ribavirin, an antiviral drug, was tested in the Malaysian infections and the results are encouraging, however studies are still necessary.

In the animals, particularly in the pigs, the virus causes respiratory and neurological syndromes.

Causes of appearance

The appearance of the henipavirus was done in parallel of the appearance of other zoonotic viruses in the recent decades. The viruses of the SARS and the Ebola (inter alia) also “were probably lodged” by bats and are able to infect a variety of other species. The appearance of each one of these viruses was related to an increase in the contacts between the bats and the human ones, implying an intermediate host sometimes. The increased contact is led by the human encroachment in the territory of the bats (in the case of Nipah, the porcine breedings are in the aforementioned territory) and by the movement of the bats towards the human populations due to the changes in the dietary habit and the loss of habitat.

It is obvious that the loss of habitat of the bats in South Asia and Australia (in particular along the east coast) as well as the encroachment of the human residences and agriculture in the remaining habitats, will create a greater contact between the men and the bats.

References

• Field, H., Young, P., Yob, J. Mr., Millets, J., Hall, L., Mackenzie, J. (2001). The natural history off Hendra and Nipah viruses. Microbes and Infection 3, 307-314.
• Halpin, K, Young, PL, Filed, HE, Mackenzie, JS. (2000). Insulation off Hendra virus from pteropid beat: natural tank Hendra virus has off. Journal off General Virology. 81: 1927-1932.
• Hsu VP, Hossain MJ, Parashar UD, Ali MM, Ksiazek TG, Kuzmin I, Niezgoda, M, Rupprecht, C, Bresee, J, Brieman, RF. (2004). Nipah virus encephalitis reemergence, Bangladesh. Emerging Infectious Disease 10 (12) 2082-2087. (in)
• Chadha, ms, James, AC, Lowe, L et al. (2006). Nipah virus-associated encephalitis outbreak, Siliguri, India. Emerging Infectious Diseases. 12 (2) (in)
• Reynes JM, Counor D, Ong S, Faure C, Seng V, Molia S, et al. (2005). Nipah virus in Lyle' S flying foxes, Cambodia. Emerging Infectious Diseases. 11 (7) (in)
• Wacharapluesadee S, Lumlertdacha B, Boongird K, Wanghongsa S, Chanhome L, Rollin P, et al. (2005). Beats Nipah virus, Thailand. Emerging Infectious Diseases. 11 (12) (in)
• Wang, L., Harcourt, B.H., Yu, Mr., Tamin, A., Rota, P.A., Bellini, W.J., Eaton, B.T. (2001). Molecular biology off Hendra and Nipah viruses. Microbes and Infection 3, 279-287.

External bonds

• Hendra virus CSIRO FAQ (in)
• Nipah virus CSIRO FAQ (in)

Category: Zoonose

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