Effects of bovine leukemia virus infection on production and reproduction in dairy cattle.

The purpose of this study was to determine the effects of bovine leukemia virus (BLV) infection on production, reproduction and longevity in dairy cattle. The study population was a commercial Holstein dairy herd of approximately 400 milking cows. Cattle were tested for antibodies to BLV at least annually for three years and when culled. Four groups of culled cows were compared: seronegative cows (n = 79), seropositive cows without lymphocytosis (n = 176), seropositive cows with lymphocytosis (> or = 9,000 lymphocytes/microliter) (n = 74), and seropositive cows with lymphosarcoma (n = 29). Seropositive groups of cows were bred more times and had longer calving intervals than seronegative cows. The seropositive groups had greater 305-day ME (mature equivalent) FCM (3.5% fat-corrected milk) per lactation and were older when culled than seronegative cows. However, the percent fat per lactation was greater in seronegative cows. In the last complete lactation, differences in 305-day ME FCM, days open and cull age between groups were reduced and none were significant (p > 0.05). In the cull lactation, only cows with lymphocytosis had reduced milk production relative to seronegative cows, although this difference was not significant. After adjustment for initial production and reproductive values, only seropositive nonlymphocytotic cows were culled at a significantly older age than seronegative cattle. Lymphocytotic cows were culled four months younger on average than nonlymphocytotic seropositive cows. Hence, BLV infected cows had greater milk production on average than uninfected cows. Adverse effects of BLV infection were primarily limited to lymphocytotic cows which were culled earlier and had reduced milk production in the cull lactation.

Prolonged QT interval and risk of sudden death in South-East Asian men.

Sudden death in sleep occurs in substantial numbers among young men in South-East Asia. The frequencies of electrocardiographic abnormalities were measured in groups with varying risks of such sudden death. The mean heart-rate-corrected QT interval (QTc) was significantly (p less than 0.05) greater among 123 Laotian refugees in Thailand at high risk (405 [95% confidence interval 397-413] ms) than in 77 Laotian refugees in the United States at lower risk (364 [359-369] ms) and 199 non-Asian US residents at negligible risk (358 [354-362] ms). Among refugees in Thailand, prolonged QTc interval was associated with poor thiamine status and a history of seizure-like episodes in sleep. Thiamine deficiency may be a cause of prolonged QT interval and sudden death in this region.

Risk factors for invasive cervical cancer and reduction of risk by 'Pap' smears in Thai women.

A case-control study of invasive cervical cancer was conducted in Siriraj Hospital, Thailand, as part of a WHO-sponsored collaborative study of neoplasia and steroid contraceptives. Data from 189 histologically confirmed cases and 1023 randomly selected hospitalized controls who were recruited from October 1979 through March 1983 were analysed to identify risk factors for cervical cancer in Thai women, and to assess the effectiveness of Papanicolaou smears (Pap smears) in preventing invasive cervical cancer in Thailand. Variables that distinguish women at significantly increased risk of invasive cervical cancer, to whom preventive programmes should be directed, include a history of treatment for abnormal vaginal discharge (an indicator of vaginal or cervical infection), a history of venereal disease, and little or no education (an indicator of low socioeconomic status). Risk of invasive cervical cancer decreased significantly as the frequency of Pap smears increased, and was reduced by 75% in women who had at least one Pap smear per year.