Nipah virus infection of pigs in peninsular Malaysia

Between late 1998 and 1999, the spread of a new disease of pigs, characterized by a pronounced respiratory and neurological syndrome, sometimes accompanied by the sudden death of sows and boars, was recorded in pig farms in peninsular Malaysia. The disease appeared to have a close association with an epidemic of viral encephalitis among workers on pig farms. A previously unrecognised paramyxovirus was later identified from this outbreak; this virus was related to, but distinct from, the Hendra virus discovered in Australia in 1994. The new virus was named 'Nipah' and was confirmed by molecular characterization to be the agent responsible for the disease in both humans and pigs. The name proposed for the new pig disease was 'porcine respiratory and neurological syndrome' (also known as 'porcine respiratory and encephalitis syndrome'), or, in peninsular Malaysia, 'barking pig syndrome'. The authors describe the new disease and provide the epidemiological findings recorded among infected pigs. In addition, the control programmes which were instituted to contain the virus in the national swine herd are outlined.     

Nipah virus infection among abattoir workers in Malaysia, 1998-1999.

BACKGROUND: An outbreak of encephalitis primarily affecting pig farmers occurred during 1998-1999 in Malaysia and was linked to a new paramyxovirus, Nipah virus, which infected pigs, humans, dogs, and cats. Because five abattoir workers were also affected, a survey was conducted to assess the risk of Nipah infection among abattoir workers. METHODS: Workers from all 143 registered abattoirs in 11 of 13 states in Malaysia were invited to participate in this cross-sectional study. Participants were interviewed to ascertain information on illness and activities performed at the abattoir. A serum sample was obtained to test for Nipah virus antibody. RESULTS: Seven (1.6 %) of 435 abattoir workers who slaughtered pigs versus zero (0%) of 233 workers who slaughtered ruminants showed antibody to Nipah virus (P = 0.05). All antibody-positive workers were from abattoirs in the three states that reported outbreak cases among pig farmers. Workers in these three states were more likely than those in other states to have Nipah antibody (7/144 [4.86%] versus 0/291 [0%], P < 0.001) and report symptoms suggestive of Nipah disease in pigs admitted to the abattoirs (P = 0.001). CONCLUSIONS: Nipah infection was not widespread among abattoir workers in Malaysia and was linked to exposure to pigs. Since it may be difficult to identify Nipah-infected pigs capable of transmitting virus by clinical symptoms, using personal protective equipment, conducting surveillance for Nipah infection on pig farms which supply abattoirs, and avoiding handling and processing of potentially infected pigs are presently the best strategies to prevent transmission of Nipah virus in abattoirs.     

Proximate determinants of fertility in peninsular Malaysia

The continuing decline in fertility despite a contraction in contraceptive use in Peninsular Malaysia since the mid-1980s has triggered considerable interest in the reasons behind this phenomenon, such as increase in abortion, sterility, and out-of-wedlock pregnancy. Fertility decline has been attributed to rapid socioeconomic development, which can only influence fertility through the intermediate variables. Application of vital statistics, population census, and survey data of Peninsular Malaysia on Bongaarts's model vindicates that marriage postponement and contraceptive use are the 2 most important proximate determinants of fertility, but the effects are not uniform across the ethnic groups. For instance, the predicted total fertility rate for Chinese and Malays are 2.9 and 1.6, respectively, compared with the observed level of 3.0 and 1.9. Postpartum infecundability and abortion also play a part in explaining ethnic fertility differentials. The fertility inhibiting effects of these proximate determinants have significant implications on reproductive health and future population growth.     

Mammals and scrub typhus ecology in peninsular Malaysia

The overall comparisons of habitats are given in (Table III). The habitats are arranged in order of extent of alterations by man, with the least disturbed at the top. The highest average blood isolation rates came from the least disturbed areas. The highest monthly maximal rickettsial isolation rates from blood and maximal prevalence rates of antibody per month were also obtained at Bukit Lanjan, the habitat least altered by activities of man. The lowest average blood isolation rate (6%) and the lowest monthly maximal rickettsial isolation and antibody prevalence rates were obtained at Bukit Mandol, the habitat most extensively and intensively altered by man. The intermediate habitats had intermediate rates.We caution anyone interpreting these observations, however, in terms of human disease, which seems to be associated with hyperendemic foci. Here we are not dealing with hyperendemicity from the standpoint of human disease, but present evidence of widespread endemicity from which hyperendemic foci may derive. Also, we have not yet identified the prevalent strains and do not know their infectivity to man.     

Nipah Virus Infection in Dogs, Malaysia, 1999

The 1999 outbreak of Nipah virus encephalitis in humans and pigs in Peninsular Malaysia ended with the evacuation of humans and culling of pigs in the epidemic area. Serologic screening showed that, in the absence of infected pigs, dogs were not a secondary reservoir for Nipah virus.     

A survey of Nipah virus infection among various risk groups in Singapore

Following the Nipah virus (NV) outbreak in March 1999 in Singapore, a serological survey was undertaken to screen individuals potentially exposed to NV. Blood samples were tested for NV IgM, IgG and neutralizing antibodies. Twenty-two (1.5%) of 1469 people tested had antibodies suggesting NV infection. Although 12 of the 22 infected people (54.6%) were symptomatic, the remaining 10 (45.4%) were clinically well and had no past history of compatible pulmonary or neurological disease. Clinical and serological findings suggested three people had been infected with NV before the outbreak was recognized. All those who were infected were male abattoir workers. None of the people who had contact with horses, and no healthcare workers exposed to infected patients and their specimens had detectable antibodies. This study provides evidence that NV causes asymptomatic infection. All of the antibody positive individuals had direct contact with pigs and there was no evidence of human to human transmission.     

Bacterial pathogens isolated from cockroaches trapped from paediatric wards in peninsular Malaysia

A survey was conducted in 4 paediatric wards in Malaysia to determine the distribution of various species of cockroaches and to examine their gut contents for bacteria. Cockroaches were trapped from food dispensing areas (kitchens), store rooms, cupboards and open wards. 104 cockroaches were caught, consisting of Periplaneta americana (67.3%), Blattella germanica (26%), P. brunnea (4.8%), and Supella longipalpa (1.9%). Bacteria were isolated from all cockroaches except 3 P. americana. Many bacterial species were identified, including the pathogenic and potentially pathogenic species Shigella boydii, S. dysenteriae, Salmonella typhimurium, Klebseilla oxytoca, K. ozaena and Serratia marcescens.     

Dengue virus in Mexican bats

Individuals belonging to five families, 12 genera, and 19 different species of bats from dengue endemic areas in the Gulf and Pacific coasts of Mexico were examined by ELISA, RT-PCR, and for the presence of dengue virus (DV) NS1 protein. Nine individuals from four species were seropositive by ELISA: three insectivorous, Myotis nigricans (four positives/12 examined), Pteronotus parnellii (3/19), and Natalus stramineus (1/4), and one frugivorous Artibeus jamaicensis (1/35) (12.86% seroprevalence in positive species). DV serotype 2 was detected by RT-PCR in four samples from three species (all from the Gulf coast - rainy season): two frugivorous, A. jamaicensis (2/9), and Carollia brevicauda (1/2), and one insectivorous, M. nigricans (1/11). The latter was simultaneously positive for NS1 protein. DV RT-PCR positive animals were all antibody seronegative. M. nigricans showed positive individuals for all three tests. This is the first evidence suggesting the presence of DV in bats from Mexico.     

Nipah virus in Lyle's flying foxes, Cambodia

We conducted a survey in Cambodia in 2000 on henipavirus infection among several bat species, including flying foxes, and persons exposed to these animals. Among 1,072 bat serum samples tested by enzyme-linked immunosorbent assay, antibodies reactive to Nipah virus (NiV) antigen were detected only in Pteropus lylei species; Cynopterus sphinx, Hipposideros larvatus, Scotophilus kuhlii, Chaerephon plicata, Taphozous melanopogon, and T. theobaldi species were negative. Seroneutralization applied on a subset of 156 serum samples confirmed these results. None of the 8 human serum samples was NiV seropositive with the seroneutralization test. One virus isolate exhibiting cytopathic effect with syncytia was obtained from 769 urine samples collected at roosts of P. lylei specimens. Partial molecular characterization of this isolate demonstrated that it was closely related to NiV. These results strengthen the hypothesis that flying foxes could be the natural host of NiV. Surveillance of human cases should be implemented.     

Risk factors for Nipah virus encephalitis in Bangladesh

Nipah virus (NiV) is a paramyxovirus that causes severe encephalitis in humans. During January 2004, twelve patients with NiV encephalitis (NiVE) were identified in west-central Bangladesh. A case-control study was conducted to identify factors associated with NiV infection. NiVE patients from the outbreak were enrolled in a matched case-control study. Exact odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by using a matched analysis. Climbing trees (83% of cases vs. 51% of controls, OR 8.2, 95% CI 1.25-infinity) and contact with another NiVE patient (67% of cases vs. 9% of controls, OR 21.4, 95% CI 2.78-966.1) were associated with infection. We did not identify an increased risk for NiV infection among persons who had contact with a potential intermediate host. Although we cannot rule out person-to-person transmission, case-patients were likely infected from contact with fruit bats or their secretions.     

Henipavirus infection in fruit bats (Pteropus giganteus), India

We tested 41 bats for antibodies against Nipah and Hendra viruses to determine whether henipaviruses circulate in pteropid fruit bats (Pteropus giganteus) in northern India. Twenty bats were seropositive for Nipah virus, which suggests circulation in this species, thereby extending the known distribution of henipaviruses in Asia westward by >1,000 km.     

Assessing socioeconomic correlates of birthweight in peninsular Malaysia: ethnic differences and changes over time

This paper presents evidence from the Malaysian Family Life Survey that mothers' reports of their babies' birthweights, including reports of unweighed babies' approximate size at birth, can be used to examine many biological and socioeconomic correlates of birthweight. The study uses a sample of 5583 singleton births that occurred between 1945 and 1976. In these data, the frequency distribution of birthweights and their bivariate and multivariate relationships with the biological correlates of mother's age, baby's sex, first parity and infant mortality are consistent with those found in prospective studies. A new biological correlate, mother's age at menarche, is introduced as a proxy for the mother's nutrition during childhood. Late age at menarche is associated with lower birthweight. Other results show mothers younger than 20 years and older than 35 appear to be at greater risk of bearing small babies, but the former effect is no longer important when parity is controlled. Short interbirth intervals are associated with small babies. We attempt to distinguish whether this is due to prematurity or to maternal nutritional depletion; both effects appear to be operating. Higher income appears to mitigate the pernicious effect of short interbirth intervals. Indian babies weigh significantly less than those of other ethnic groups. Furthermore, birthweights have increased since the 1950s for Malays and Chinese, but not for Indians. The lower birthweights and lack of improvement over time for Indians appear to be due to close birthspacing, lack of access to medical care and falling incomes.     

Antibodies to Nipah-like virus in bats (Pteropus lylei), Cambodia

Serum specimens from fruit bats were obtained at restaurants in Cambodia. We detected antibodies cross-reactive to Nipah virus by enzyme immunoassay in 11 (11.5%) of 96 Lyle's flying foxes (Pteropus lylei). Our study suggests that viruses closely related to Nipah or Hendra viruses are more widespread in Southeast Asia than previously documented.     

Coccidioides posadasii infection in bats, Brazil

To analyze the eco-epidemiologic aspects of Histoplasma capsulatum in Brazil, we tested 83 bats for this fungus. Although H. capsulatum was not isolated, Coccidioides posadasii was recovered from Carollia perspicillata bat lungs. Immunologic studies detected coccidioidal antibodies and antigens in Glossophaga soricina and Desmodus rotundus bats.