Field evaluation of the establishment potential of wMelPop Wolbachia in Australia and Vietnam for dengue control.

BACKGROUND: Introduced Wolbachia bacteria can influence the susceptibility of Aedes aegypti mosquitoes to arboviral infections as well as having detrimental effects on host fitness. Previous field trials demonstrated that the wMel strain of Wolbachia effectively and durably invades Ae. aegypti populations. Here we report on trials of a second strain, wMelPop-PGYP Wolbachia, in field sites in northern Australia (Machans Beach and Babinda) and central Vietnam (Tri Nguyen, Hon Mieu Island), each with contrasting natural Ae. aegypti densities. METHODS: Mosquitoes were released at the adult or pupal stages for different lengths of time at the sites depending on changes in Wolbachia frequency as assessed through PCR assays of material collected through Biogents-Sentinel (BG-S) traps and ovitraps. Adult numbers were also monitored through BG-S traps. Changes in Wolbachia frequency were compared across hamlets or house blocks. RESULTS: Releases of adult wMelPop-Ae. aegypti resulted in the transient invasion of wMelPop in all three field sites. Invasion at the Australian sites was heterogeneous, reflecting a slower rate of invasion in locations where background mosquito numbers were high. In contrast, invasion across Tri Nguyen was relatively uniform. After cessation of releases, the frequency of wMelPop declined in all sites, most rapidly in Babinda and Tri Nguyen. Within Machans Beach the rate of decrease varied among areas, and wMelPop was detected for several months in an area with a relatively low mosquito density. CONCLUSIONS: These findings highlight challenges associated with releasing Wolbachia-Ae. aegypti combinations with low fitness, albeit strong virus interference properties, as a means of sustainable control of dengue virus transmission.

Living arrangements, patrilineality and sources of support among elderly Vietnamese.

PIP: This study examined social support for the elderly in Ho Chi Minh (HCM) City and Hanoi, Viet Nam, in 1996. The sample included the main towns and provinces surrounding the cities. Two major findings were that the family was the main source of social security for the elderly. Almost 75% of the elderly in Hanoi, and 80% in HCM City, lived with at least 1 adult child. Parents were more likely to live with a married son. Most of the remaining elderly lived in close proximity to adult children. Over 50% of the elderly lived in households with at least 3 generations, regardless of their location in the north or the south. Older elderly were more likely to live in 3-generation households. 5-6% of the elderly lived alone or with a spouse and did not live near an adult child. Living alone was more prevalent in rural areas and among women. In both regions, almost 60% were female and over 50% were aged under 70 years. 56.6-61.8% were currently married; 37.3-38.1% were widowed. The elderly functioned within a strong patrilineal system. The proportion of male children who lived with a parent divided by the proportion of female children living with a parent (patrilineal ratio) was at least 3 times higher in Hanoi, urban towns, and rural areas in the Red River Delta, than in HCM City and its environs. There was substantial variation in non-family support. A higher proportion of elderly in Hanoi received pensions and social welfare benefits. The elderly in the south were less likely to name themselves or their spouses as the main sources of family income.^ieng

Protective effect opf lodoxamide tromethamine on allergen inhalation challenge.

Lodoxamide tromethamine (U-42,585E) is a new drug intended for prophylaxis of mast cell-mediated allergic disease. It is a water-soluble, cromolyn-like agent with demonstrated activity in rat peritoneal mast cell assay, rat percutaneous anaphylaxis (rat PCA) and sensitized rhesus monkey airway system. Ten allergen-sensitive asthmatics were pretreated with lodoxamide (0.01, 0.1, or 1.0 mg) or placebo, then challenged with serial dilutions of allergen extract. Analysis of allergen dose-response curve parameters shows that pretreatment with lodoxamide offers significant protection against experimental allergen-induced bronchoconstriction. At 0.01 mg, lodoxamide was effective in over half the subjects tested. Administration of lodoxamide by inhalation at doses of 0.1 and 1.0 mg uniformly allowed subjects to tolerate significantly larger doses of inhaled allergen. Side effects observed at these doses were minimal.