Distribution of Two Subgroups of Human T-Lymphotropic Virus Type 1 (HTLV-1) in Endemic Japan

Endemic areas of human T-lymphotropic virus type 1 (HTLV-1) have been reported in Japan as well as tropical Africa, Central and South America and Melanesia. The existence of two subgroups, i.e., the transcontinental and Japanese subgroups, was reported in Japan. In the present study, we provide data on the ratio of the two subgroups in each endemic area and infection foci and examine the distribution of HTLV-1 in Japan and neighboring areas. A 657 bp fragment of env region of HTLV-1 proviral genome was successfully amplified for 183 HTLV-1 positive DNA samples. The subgroup determination was done by RFLP reactions using endonucleases <i>HpaI</i> and <i>HinfI</i>. The northern part of mainland Kyushu, represented by Hirado and Kumamoto, was monopolized by the Japanese subgroup, while the transcontinental subgroup ranged from 20 to 35% in the Pacific coast areas of Shikoku (Kochi), the Ryukyu Archipelago (Kakeroma and Okinawa) and Taiwan. An interesting finding in the present study is the presence of the transcontinental subgroup in Kochi, suggesting the endemicity of the transcontinental subgroup along the Kuroshio Current.

Phylogeography of Human T-lymphotropic Virus Type 1 (HTLV-1) Lineages Endemic to Japan

We conducted phylogenetic analyses and an estimation of coalescence times for East Asian strains of HTLV-1. Phylogenetic analyses showed that the following three lineages exist in Japan: “JPN”, primarily comprising Japanese isolates; “EAS”, comprising Japanese and two Chinese isolates, of which one originated from Chengdu and the other from Fujian; and “GLB1”, comprising isolates from various locations worldwide, including a few Japanese isolates. It was estimated that the JPN and EAS lineages originated as independent lineages approximately 3,900 and 6,000 years ago, respectively. Based on archaeological findings, the “Out of Sunda” hypothesis was recently proposed to clarify the source of the Jomon (early neolithic) cultures of Japan. According to this hypothesis, it is suggested that the arrival of neolithic people in Japan began approximately 10,000 years ago, with a second wave of immigrants arriving between 6,000 and 4,000 years ago, peaking at around 4,000 years ago. Estimated coalescence times of the EAS and JPN lineages place the origins of these lineages within this 6,000–4,000 year period, suggesting that HTLV-1 was introduced to Japan by neolithic immigrants, not Paleo-Mongoloids. Moreover, our data suggest that the other minor lineage, GLB1, may have been introduced to Japan by Africans accompanying European traders several centuries ago, during or after “The Age of Discovery.” Thus, the results of this study greatly increase our understanding of the origins and current distribution of HTLV-1 lineages in Japan and provide further insights into the ethno-epidemiology of HTLV-1.

Anemia and Related Factors in Preschool Children in the Southern Rural Lao People's Democratic Republic

Anemia is a severe public health problem in the Lao People’s Democratic Republic (PDR). Consequently, a new control strategy to reduce the burden of anemia has been introduced for preschool children (aged 6–52 months). The objective of this study was to assess the current prevalence of anemia and related factors in preschool children in southern rural Lao PDR. A population-based cross-sectional study was carried out in six communities in Songkhone district, Savannakheth province, in February 2009. As a result, the prevalence of anemia was found to be 48.9% (95% confidence interval (CI), 43.5–54.3), although most cases were mild. A multiple logistic regression analysis indicated that there was no protective effect of breastfeeding against anemia. The anemia prevalence was higher in 1) children aged 6–23 months (Odds Ratio (OR) = 1.73, 95% CI, 1.02–2.90) than in older children, 2) children in large families (6 or more members) (OR = 1.96, 95% CI, 1.17–3.29), and 3) children in three remote villages with relatively difficult access to markets (OR = 3.01, 95% CI, 1.25–7.47).<br />In Lao PDR, improvement of food practices and home-fortified food supplementation interventions are essential. High-risk groups should be targeted and a long-term health education program that aims to modify food habits implemented. Furthermore, in settings where iron deficiency is not the only cause of anemia, combining an iron supplement with other measures is necessary.

Effect of communal piped water supply on pattern of water use and transmission of schistosomiasis haematobia in an endemic area of Kenya

An attempt was made to examine the long-term impact of the introduction of communal piped water supply on pattern of water use and transmission of schistosomiasis haematobia in an endemic area of Kenya. In the study area, Mtsangatamu, a control program based on repeated selective mass-chemotherapy had been carried out for 6 years from 1987 to 1993. The pre-treatment overall prevalence and intensity of infection in 1987 were 59.2% and 10.9 eggs⁄10 ml of urine (Muhoho <I>et al</I>., 1997). During the control program, the prevalence was kept at a low range of 20 to 40% (Muhoho <I>et al</I>., 1994). At the end of the program, in 1994, gravity-fed water supply was provided to the village. Although the water facilities were damaged by flooding in 1998, new and further expanded gravity-fed water supply facilities consisting of 7 standpipes were introduced in 2000. The follow-up survey done in 1999 revealed reduced prevalence and intensity of infection, I.e. 23.0% and 1.2 eggs⁄ 10 ml of urine (unpublished data). The present study was carried out in 2006, 6 years after the last mass-chemotherapy. Urine examination showed that the prevalence and intensity of infection had return to 52.2% and 7.4 eggs⁄10 ml, nearly the same level as the pre-treatment level. The results of our study demonstrated that, over the long-term, the gravity-fed water supply facilities had little impact on the overall prevalence and intensity of infection in this village. However, analysis of the spatial pattern of infection, observation of human water contact at the river and a questionnaire on water use shed light on the possible impact of water supply on human water contact. The younger people (5-19 years old) with easy access to the standpipes showed a lower prevalence and intensity of infection, while the relationship was not clear in other age groups.<br>The result of the questionnaire indicated that the long distance from household to standpipe was the major factor limiting the use of the communal tap water. Most of the villagers who used piped water as the main source of water lived within 800 m of the nearest standpipe, and villagers who used river water exclusively lived beyond that distance. Observation of water-related activities at the communal water facilities also indicated that the residents who lived near standpipes used the piped water more frequently.<br>The frequency of total visits to river water sites did not differ between residents who lived near and far from the standpipe. However, water contact in the form of playing, the highest risk behavior, was observed exclusively among children who lived far (>250m) from standpipes, although the number of observations was small.<br>The present study demonstrated that the water facilities had little effect on the dispersed population but might have a beneficial effect on some villagers given easy access to standpipes.

A SIMULATION SHEDS A LIGHT ON THE PRESENT HIV EPIDEMIC

A hypothetical community of one million people where birth rate and death rate are equal was applied to the modified deferential equations Lipsitch and Nowak published in 1995 in order to examine the impact of partner acquisition change on the HIV epidemic over a relatively short term. The results showed that if the partner exchange rate increases from two to three per year in the population, the epidemic caused by a more virulent strain would overweigh that caused by a less virulent strain within a century. This result reveals that an increase in the rate of partner acquisition gives the more virulent strain an advantage in terms of propagating the virus in a given population, at least over a relatively short term of several decades. The partner acquisition rate also exerts an influence on the magnitude of the HIV epidemic and the time it needs to reach a peak in the hypothetical community.<BR>These results indicate that increased sexual contact may be even more important than expected and thus shed a new light on the present HIV epidemic.