Genetic Variability and Host Specialization in the Latin American Clade of Ceratocystis fimbriata.

The Ceratocystis fimbriata complex includes many undescribed species that cause wilt and canker diseases of many economically important plants. Phylogenetic analyses of DNA sequences have delineated three geographic clades within Ceratocystis fimbriata. This study examined host specialization in the Latin American clade, in which a number of lineages were identified using sequences of the internal transcribed spacer (ITS) region of the rDNA. Three host-associated lineages were identified from cacao (Theobroma cacao), sweet potato (Ipomoea batatas), and sycamore (Platanus spp.), respectively. Isolates from these three lineages showed strong host specialization in reciprocal inoculation experiments on these three hosts. Six cacao isolates from Ecuador, Trinidad, and Columbia differed genetically from other cacao isolates and were not pathogenic to cacao in inoculation tests. Further evidence of host specialization within the Latin American clade of Ceratocystis fimbriata was demonstrated in inoculation experiments in growth chambers using sweet potato, sycamore, Colocasia esculenta, coffee (Coffea arabica), and mango (Mangifera indica) plants; inoculation experiments in Brazil using Brazilian isolates from cacao, Eucalyptus spp., mango, and Gmelina arborea; and inoculation experiments in Costa Rica using Costa Rican isolates from cacao, coffee, and Xantho-soma sp. Hosts native to the Americas appeared to be colonized by only select pathogen genotypes, whereas nonnative hosts were colonized by several genotypes. We hypothesize that local populations of Ceratocystis fimbriata have specialized to different hosts; some of these populations are nascent species, and some host-specialized genotypes have been moved to new areas by humans.

Seimatoantlerium tepuiense gen. nov., a unique epiphytic fungus promoting taxol from the Venezuelan Guyana

Seimatoantlerium gen. nov., type species, S.tepuiense sp. nov. is proposed for an acervular fungus producing 4-septate, holobastic conidia with 6-8 unbranched, apical appendages that dehisce as an appendage apparatus and also commonly possessing one or two exogenous basal appendages as well as a pedicel. It is compared with Seimatosporium, Seimatosporiopsis, and other genera. It is epiphytic on Maguireothamnus speciosus, a rubiaceous plant endemic to the tepuis of southeastern Venezuela. It produces the anti-oomycetous anticancer compound, taxol, as shown by immunological and spectroscopic methods. Taxol production is discussed relative to the ability of this fungus to exist in an extremely moist ecosystem, as well as to its relationship to other plant associated fungi. (AU)

From "forest malaria" to "bromeliad malaria": a case-study of scientific controversy and malaria control

The article analyses the evolution of knowledge and rationale of control of a special case of malaria transmission based on Bromelia-Kerteszia complex. Since bromeliaceae function as a 'host of the carrier' and were previously associated with natural forests, the elucidation of bromeliad malaria historically elicited controversies concerning the imputation of Kerteszaie as transmitters as well as over control strategies directed to bromelia eradication (manual removal, herbicides and deforestation), use of insecticides and chemoprophylaxis. Established authority, disciplinary traditions, conceptual premises and contemporary criteria for validating knowledge in the field partly explain the long time gap since Adolpho Lutz announced as the beginning of the century the existence of a new mosquito and breeding site as responsible for a 'forest malaria' epidemic occurring at a high altitude. The article brings attention to how economic, political and institutional determinants played an important role in redefining studies that led both in Trinidad and Brazil to the recognition of the importance of kerteszia transmission, including urban areas, and establishing new approaches to its study, most relevant of all the concurrence of broad ecological research. The article then describes the Brazilian campaign strategies which showed significant short-term results but had to wait four decades to achieve the goal of eradication due to the peculiar characteristics of this pathogenic complex. Finally, it brings attention to the importance of encompassing social values and discourses, in this case, environmental preservation, to understanding historical trends of malaria control programs(AU)

Ecotourism and health tourism in the Caribbean

Sees the region as having a great potential for ecotourism, however the environment must be preserved and concept of sustainable development must be central to the success of such ventures. Acknowledges that the region has particular advantages in health and tourism and this should be part of the ecotourism investment package. (AU)

Seasonal incidence and vertical distribution patterns of oviposition by Aedes aegypti in an urban environment in Trinidad, W. I

The oviposition patterns of Aedes aegypti were investigated using modified ovitraps placed along 4 vertical transects and monitored weekly for 52 wk in St. Augustine, Trinidad, W. I. From the 832 ovitraps exposed at ground level, 1.2, 3.0 and 4.6-m elevations, 43 percent(361) were found containing 20,114 Ae.aegpti eggs. During the wet season, 52.7 percent of the eggs were collected whereas during the dry season only 47.3 percent were collected. Egg populations were highest at the 1.2-m elevation. The implications of these results are discussed. (AU)

Aedes aegypti infestation characteristics in several Caribbean countries and implications for integrated community-based control

Periodic larval surveys for Aedes aegypti were conducted in 11 Caribbean countries between 1983 and 1989. On average, there were 24 potential larval habitats per house including 4.9 which held water at the time of examination. Breteau indices for the various islands ranged from 34.7 to 121.6. In descending order of importance, water storage drums, house plants, buckets, used tires and miscellaneous small discarded containers accounted for 84 percent of all foci. Highest rates of infestation were found in tires (38.4 percent) and drums (33.8 percent). For the development of integrated community-based vector control programs, not only should consideration be given to the larval ecology of Ae. aegypti, but also to the sociological significance of the various container habitats and the selection of control strategies most appropriate for their management. (AU)

Human T-lymphotropic virus type I (HTLV-I) seroprevalence in Jamaica - II geographic and ecological determinants

An island-wide cohort of 13,260 Jamaicans who applied for food-handling licenses during 1985 and 1986 were tested for antibodies to human T-cell lymphotropic virus type I (HTLV-I). Demographic and residence history data were linked to geographic measures of elevation, rainfall, crop-growing areas, population density, and additional measures of urbanization and correlated with HTLV-I antibody status. By logistic regression analysis (performed separately for men and women), men and women who currently resided at low elevation (ó1,000 ft (305 m)) were more likely to be HTLV-infected than were those residing at high elevation. Men, but not women, who were born in citrus-growing areas were more likely to be HTLV-I infected than were men who were born in other areas. By univariate analysis, there was a significant positive trend of increasing HTLV-I seroprevalence with increasing amount of annual rainfall associated with birthplace and primary residence areas. However, these associations did not remain in significance after adjusting for age and sex. These environmental associations raise the possibility of new modes of viral transmission or host response to infection, although they may simply be surrogates for socioeconomic status, breast-feeding habits, or sexual behaviour, which are known determinants of HTLV-I zero prevalence. (AU)

Aedes aegypti surveillance in Tobago, West Indies (1983-1988)

During 1983-88 Aedes aegypti were collected using larval surveys and ovitraps in Tobago, WI. The main artificial containers used by Ae. aegypti were drums (35.4 percent) and small miscellaneous containers (23.4 percent). From a total of 15,600 ovitraps exposed, 183 (1.3 percent) were positive, with 25 containing Ae. aegypti eggs and 158 with Haemagogus equinus eggs. No Aedes albopictus eggs were detected in Tobago during this study. (AU)

Serological and ecological study of the genus Leptospira in Jamaica

In a serological and ecological study of the genus Leptospira in Jamaica, 535 sera from three species of livestock animals, bovine, porcine and caprine were serologically tested by the microscopic agglutination technique using live leptospiral antigens. Of the number tested, 316 (59.06 percent) were reactive with titers equalling or greater than 1:100. A total of six serotypes were identified and representative serovars were as follows:- jules (serogroup Hebdomadis) 257 (51.92 percent); icterohemorrhagiae (serogroup Ictero-hemorrhagiae) 140 (28.07 percent); autumnalis (serogroup Autumnalis) 41 (8.3 percent); canicola (serogroup Canicola) 30 (6.06 percent); pomona (serogroup Pomona) 25 (5.19 percent) and abramis (serogroup Pyrogenes) 2 (0.4 percent). The porcine species recorded the highest percentage of reactive sera (65.5 percent) and the caprine the lowest (38.9 percent). The widest distribution of serotypes occurred in pigs. A comparison of the parishes showed that the positive sera from Portland (80.9 percent) and Westmoreland (71.6 percent) topped others and St. Andrew had the lowest 11.0 percent. For the ecological study, 22 soil and 25 water samples collected from five selected livestock farms in the island were cultured initially in enrichment artificial medium (Ellinghausen and McCullough semi-solid), ESS, incorporating 5-fluorouracil, for the isolation of leptospires. A total of 23 (48.9 percent) isolates were obtained:- 16 (72.7 percent) from the soil samples and 7 (28 percent) from the water samples. One water isolate was lost and the 22 parent isolates were subsequently inoculated into weanling hamsters. The kidney tissues and heartblood of the inoculated hamsters on culture yielded 8 leptospiral isolates and the microscopic agglutination test of the sera of inoculated hamsters gave 9 reactive results. There was no positive results either from culture or serological test of the control (uninoculated) hamsters. The investigations revealed that the constituents of Jamaican soil, the heavy rainfall and the various environmental factors are ideal for the survival and distribution of leptospires in the island. Flooding helps to spark off epizootic outbreaks and the leptospiral serotypes mentioned earlier are enzootic and endemic in Jamaica. The predominant serotypes are jules and icterohemorrhagiae. People at high risk are the livestock attendants and milkers. The epidemiological importance of the serotypes identified and suggested means of dealing with their adverse effects are discussed (AU)

The influence of rainfall on the dynamics of some mosquito populations in savanna area of Surinam

Weekly collections of adult female mosquitos were made near Powaka, an Amerindian village, located in the savanna belt of northern Surinam. Culex portesi Senevet and Abbonnenc, C. spissipes (Theobald) and C. mollis Dyar and Knab were the most abundant mosquito species. In order to better understand the population dynamics of these species, correlation coefficients were calculated between population density and rainfall in consecutive weeks prior to the week of the "index catch". Also the relationships between parous rate and population density were analysed. It is concluded that the duration from egg hatching to first adult blood meal of Culex mollis, C. spissipes and C. portesi may take approximately 1 week, 3 to 4 weeks and 5 weeks, respectively. The length of the gonotrophic cycle is estimated to be about 3 weeks for Culex mollis and 2 weeks for C. spissipes as well for C. portesi. (AU)

Some aspects of the ecology and lifecycle of Amblyomma cajennense (Fabricius 1787) in Trinidad and their influence on tick control measures

The distribution in Trinidad of the tick Amblyomma cajennense is defined, and the methods used to determine the boundaries of the infested areas are outlined. The relationships between the climate, vegetation and husbandry methods and the distribution of the tick are described. Monthly tick collections from specific animals to determine exact seasonal variations were not possible but a study was made of the normal life cycle under laboratory conditions, the results being used to assist in interpreting the field picture and formulating methods of control. Possible systems of control are outlined and mention is made of the feasibility of eradication of the species in Trinidad (Summary)

Distribution of the snail Biomphalaria glabrata, intermediate host of Schistosoma mansoni, within a St. Lucian field habitat

A total of 6360 mud samples were obtained, in 62 collections made with an exhaustive sampling device, from banana drains of the West Indian island of St. Lucia during fortnightly samplings over a 2«-year period. Analysis of counts of the snail Biomphalaria glabrata from these samples showed that this species had a contagious distribution. This finding is consistent with other evidence that banana drains from a rigorous habitat for B. glabrata. Its distribution was more contagious than that of Oncomelania quadrasi in certain Philippine habitats and several species of aquatic snail counts for standard statistical techniques was z=x0.287 but the more convenient cube root transformation is probably adequate. However, if too few snails are collected (15 or fewer per 100 samples) or if the frequency distribution of snail counts is discontinuous, with too many widely separated high frequency counts, neither transformation will be entirely satisfactory.(AU)

Dispersion of St. Lucian Schistosoma mansoni cercariae in natural standing and running waters determined by cercaria counts and mouse exposure

Experiments were carried out to investigate the dispersion of Schistosoma mansoni cercariae in natural standing waters on St. Lucia using Sandt's method and mouse exposure. In standing-water habitats, cercariae located and infected mice as far as 3.1m. The worm burdens in mice increased in direct proportion to the numbers of cercariae, from 300 worms at the 200 cercariae per mouse level to 942 worms at the 800 cercariae per mouse level. At each cercarial level, more male than female worms were recovered. The sex ratios (male to female) of the worms were 1.8 at the 200 cercariae per mouse level, 1.5 at the 400 cercariae per mouse level and 1.1 at the 800 cercariae per mouse level. Between 1.2 and 6.9 percent of the cercariae succesfully infected mice. In running-water habitits, cercariae were carried down-stream as far as 195.1m, but they infected mice only as far as 97.5m. The mice exposed in water with an average water velocity of39.9cm/sec yielded the highest number of worms, followed by those exposed at 10.4cm/sec and 74.4cm/sec. In each case, more male than female worms were recovered. The sex ratios of the worms were 2.5 at 10.4cm/sec, 9.6 at 39.9cm/sec and 18.0 at 74.4cm/sec. Between 0.100 and 0.185 percent of the cercariae succesfully infected mice. On St. Lucia, cercariae shed by infected snails in standing-water habitats such as marshes and banana drains, probably play little role in transmission owing to the limited ability of cercariae to move very far. These habitats might, however, assume greater importance where they border streams because cercariae could be swept into them. On the other hand, running waters extend significantly the dispersion of cercariae and increase the risk of people becoming infected while washing their clothes and bathing in the streams (Summary)

Enzootic rodent leishmaniasis in Trinidad, West Indies

Human cutaneous leishmaniasis is a zoonotic disease widely distributed in Central and South America. Small mammals play important roles in the natural history of the disease. This article attempts to define more precisely the roles that these mammals play in the ecology of the parasite.(AU)