Population structure of the primary malaria vector in South America, Anopheles darlingi, using isozyme, random amplified polymorphic DNA, internal transcribed spacer 2, and morphologic markers.
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A genetic and morphologic survey of Anopheles darlingi populations collected from seven countries in Central and South America was performed to clarify the taxonomic status of this major malaria vector species in the Americas. Population genetics was based on three techniques including isozyme, random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR), and internal transcribed spacer 2 (ITS2) markers. The results of the isozyme analysis indicated moderate differences in the allele frequencies of three putative loci (glutamate oxalaoacetate transaminase-1, isocitrate dehydrogenase-1, and phosphoglucomutase) of the 31 analyzed. No fixed electromorphic differences separated the populations of An. darlingi, which showed little genetic divergence (Nei distances = 0.976-0.995). Fragments produced by RAPD-PCR demonstrated evidence of geographic partitioning and showed that all populations were separated by small genetic distances as measured with the 1 - S distance matrix. The ITS2 sequences for all samples were identical except for four individuals from Belize that differed by a three-base deletion (CCC). The morphologic study demonstrated that the Euclidean distances ranged from 0.02 to 0.14, with the highest value observed between populations from Belize and Bolivia. Based on these analyses, all the An. darlingi populations examined demonstrated a genetic similarity that is consistent with the existence of a single species and suggest that gene flow is occurring throughout the species' geographic range. (+info)
Helminth parasites in six species of shorebirds (Charadrii) from the coast of Belize.
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Thirteen species of helminth parasites were recovered from six species of charadriid shorebirds (Aves: Charadriiformes) from Belize: the ruddy turnstone, Arenaria interpres, the snowy plover, Charadrius alexandrinus, the semipalmated plover, C. semipalmatus, the killdeer, C. vociferus, the white-rumped sandpiper, Calidris fuscicollis, and the black-bellied plover, Pluvialis squatarola. Cestode species were predominant (N = 8), followed by trematode species (N = 3) and acanthocephala (N = 2). The trematode, Paramaritremopsis solielangi infected four of the six species of hosts. The cestodes, Nadejdolepis litoralis and N. paranitidulans infected three and two host species respectively. Helminth parasite species were contagious (clumped) and not evenly distributed among hosts. Twelve of the 13 species were generalists. The one specialist Microphallus kinsellae was recovered from one C. fuscicollis. Three of the four types of feeding guilds were present and in approximately the same number. All but M. kinsellae have been reported from other species of hosts, mostly from Eurasia and North America. (+info)
Epidemiology of acute hepatitis in the Stann Creek District of Belize, Central America.
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Hepatitis is common in the Stann Creek District of southern Belize. To determine the etiologies, incidence, and potential risk factors for acute jaundice, we conducted active surveillance for cases. Cases of jaundice diagnosed by a physician within the previous 6 weeks were enrolled. Evaluation included a questionnaire and laboratory tests for hepatitis A, B, C, D, and E, a blood film for malaria, and a serologic test for syphilis. Etiologies of jaundice among 62 evaluable patients included acute hepatitis A, 6 (9.7%), acute hepatitis B, 49 (79.0%), hepatitis non-A-E, 2 (3.2%), and malaria, 5 (8.1%). There were no cases of acute hepatitis E. One patient each with antibody to hepatitis C and D were detected. The annualized incidence of hepatitis A was 0.26 per 1,000. All cases of hepatitis A were in children 4-16 years of age. The annualized incidence of hepatitis B, 2.17 per 1,000, was highest in adults aged 15-44 years (4.4 per 1,000) and was higher in men (36 cases; 3.09 per 1,000) than women (13 cases; 1.19 per 1,000). Four (31%) of the women with hepatitis B were pregnant. The annualized incidence was significantly higher in Mestizo (6.18 per 1000) and Maya (6.79 per 1,000) than Garifuna (0.38 per 1,000) or Creole (0.36 per 1,000). Persons with hepatitis B were significantly more likely to be born outside of Belize (82%), had been in Belize < 5 years (73%), and lived and worked in rural areas (96%) than was the general population. Of those > or = 14 years of age with hepatitis B, only 36% were married. Few persons admitted to transfusions, tattoos, IV drug use, multiple sexual partners, visiting prostitutes, or sexually transmitted diseases. Only 1 of 49 had a reactive test for syphilis. Six patients were hospitalized (including 3 with acute hepatitis B and one with hepatitis A), and none to our knowledge died. Acute hepatitis B is the most common cause of viral hepatitis in the Stann Creek District, but the modes of transmission remain obscure. Infants, women attending prenatal clinics, and new workers are potential targets for immunization with hepatitis B vaccine. (+info)
A sebaceous cyst with a difference: Dermatobia hominis.
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Dermatobia hominis causes furuncular myiasis and is endemic to South America. This report describes a case in a young woman who had recently visited Belize, highlighting the importance of clinical history (including travel history) and close liaison between pathologist and surgeon. (+info)
Persistence of Mhc heterozygosity in homozygous clonal killifish, Rivulus marmoratus: implications for the origin of hermaphroditism.
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The mangrove killifish Rivulus marmoratus, a neotropical fish in the order Cyprinodontiformes, is the only known obligatorily selfing, synchronous hermaphroditic vertebrate. To shed light on its population structure and the origin of hermaphroditism, major histocompatibility complex (Mhc) class I genes of the killifish from seven different localities in Florida, Belize, and the Bahamas were cloned and sequenced. Thirteen loci and their alleles were identified and classified into eight groups. The loci apparently arose approximately 20 million years ago (MYA) by gene duplications from a single common progenitor in the ancestors of R. marmoratus and its closest relatives. Distinct loci were found to be restricted to different populations and different individuals in the same population. Up to 44% of the fish were heterozygotes at Mhc loci, as compared to near homozygosity at non-Mhc loci. Large genetic distances between some of the Mhc alleles revealed the presence of ancestral allelic lineages. Computer simulation designed to explain these findings indicated that selfing is incomplete in R. marmoratus populations, that Mhc allelic lineages must have diverged before the onset of selfing, and that the hermaphroditism arose in a population containing multiple ancestral Mhc lineages. A model is proposed in which hermaphroditism arose stage-wise by mutations, each of which spread through the entire population and was fixed independently in the emerging clones. (+info)
A cluster randomized trial of a sex education programme in Belize, Central America.
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BACKGROUND: Concerns about adverse consequences of early childbearing and risk of sexually transmitted diseases (STD) have renewed interest in the sexual behaviour of adolescents in developing countries, where they represent a large proportion of the population and are at highest risk. To date, little is known about the sexual knowledge of adolescents in developing countries. This study's primary objective was to evaluate the effectiveness of a responsible sexuality education programme (RSP) in changing knowledge associated with sex and sexuality; secondary objectives were to evaluate changes in attitudes and behavioural intent. METHODS: A cluster randomized design randomizing high school classes in Belize City. Subjects were 13-19 years old. RESULTS: Seven schools in Belize City were selected; 8 classrooms were randomized to the intervention arm and 11 classrooms to the control arm (N = 399). The intervention was associated with two more correct answers on the post-test (difference score was 2.22 points, 95% CI = 0.53, 3.91) after adjusting for gender and previous sexual experience. After controlling for gender and previous sexual experience, the intervention was associated with no change in the attitudes (0.06, 95% CI: -2.89, 2.82) or behavioural intent domains (0.84, 95% CI: -1.12, 2.46). CONCLUSIONS: Greater changes in knowledge were observed in the intervention group than in the control group following the intervention. Changes were not observed for the attitude or behavioural intent domains. These results and the results of similar studies may be used to further improve sex education programmes as it is imperative that students have access to the information necessary to make informed decisions regarding their sexual health. (+info)
Evaluation of a school-based intervention for HIV/AIDS prevention among Belizean adolescents.
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The purpose of this study was to evaluate the impact of a cognitive-behavioral peer-facilitated school-based HIV/AIDS education program on knowledge, attitudes and behavior among primary and secondary students in Belize. Students (N = 150) were recruited from six schools in Belize City. A quasi-experimental research design was used to assess the impact of a 3-month intervention. Seventy-five students received the intervention and 75 students served as controls. The intervention was guided by constructs from the Theory of Reasoned Action and Social Cognitive Theory. At the follow-up assessment, the intervention group showed higher HIV knowledge, were more likely to report condom use, had more positive attitudes toward condoms and were more likely to report future intentions to use condoms than the students in the control group. Overall, the findings indicate that the intervention had a positive impact on participants. Given the increasing rate of HIV/AIDS in Belize, especially among adolescents, this study has important implications for the country of Belize. (+info)
The effect of health education interventions on child malaria treatment-seeking practices among mothers in rural refugee villages in Belize, Central America.
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This paper reports on a study conducted to examine the effect of health education interventions on mothers' treatment-seeking behaviors for their children's malaria fevers. The study used a quasi-experimental post-test community-based design with an intervention and control group. A post-intervention survey was conducted to assess knowledge, attitudes and child fever and malaria treatment-seeking behaviors and access and exposure to health messages. Survey results indicated that some health education interventions, especially interpersonal communication, appeared to have a positive impact on fever and malaria beliefs and attitudes and on positive treatment-seeking behaviors. While some interventions appeared to have a positive impact on fever and malaria beliefs and attitudes and on positive treatment-seeking behaviors, limitations in the study design made assigning specific effects to the interventions difficult. However, health education interventions remain a valuable tool in addressing malaria in children. (+info)