Epidemiology of meningococcal disease in Latin America: current situation and opportunities for prevention

Objective: Meningococcal disease continues to be a serious public health concern, being associated with high morbidity and mortality rates in many countries from Latin America. In addition to discussing recent changes in the epidemiology of meningococcal disease in the region, we also analyse the development and potential impact of new vaccines on the prevention of meningococcal disease. Methods: MEDLINE, SciELO, LILACS and websites of the national Ministries of Health databases were searched using the terms meningococcal disease, meningococcal epidemiology, Neisseria meningitidis, meningococcal vaccines and the name of Latin America countries, from 1998 to 2008, with emphasis on review articles, clinical trials and epidemiological studies. Results: Epidemiology of meningococcal disease in Latin America is characterized by marked differences from country to country. The overall incidence of meningococcal disease per year varied from less than 0.1 cases per 100,000 inhabitants in countries like Mexico to two cases per 100,000 inhabitants in Brazil. The highest age-specific incidence of meningococcal disease occurred in infants less than 1 year of age. Serogroups B and C were responsible for the majority of cases reported, but the emergence of serogroups W135 and Y was reported in some countries. Serogroup A disease is now rare in Latin America. Discussion: Although a few countries have established meningitis surveillance programs, the information is not uniform, and the quality of the reported data is poor in the majority of the region. The availability of new effective meningococcal conjugate vaccines and promising protein-based vaccine candidates against meningococcus B highlights the importance of a better understanding of the true burden of meningococcal disease in Latin America and also the need for cost-effectiveness studies before incorporating the new meningococcal vaccines to national immunization programs.

Genetic analysis of ticks belonging to the Rhipicephalus sanguineus group in Latin America

Phylogenetic analyses based on mitochondrial 16S rDNA sequences were generated from Rhipicephalus sanguineus group specimens collected in 29 localities among 9 Latin-American countries, plus ticks collected in South Africa, Spain, and Italy. Sequences from Latin America generated six different haplotypes (A, B, C, D, E, and F). Phylogenetic analyses generated trees that segregated our tick sequences into two distinct clades: one is represented by haplotypes A-C, and South African R. sanguineus and Rhipicephalus turanicus ticks; the second clade is represented by haplotypes D-F, and European R. sanguineus and R. turanicus ticks. When haplotypes A-Fare plotted in the Latin America map according to their geographical coordinates, it is clearly seen that haplotypes D-F are restricted to the southern portion of this continent, whereas haplotypes A-C are distributed in areas between northern Mexico and Brazil (except for the extreme south of this last country, where haplotype E was present). Hence, our phylogenetic analyses separated New World specimens of R. sanguineus into two distinct clades, one represented by tropical and subtropical populations (haplotypes A-C), here designated as the `tropical` species. On the other hand, haplotypes D-F are here designated as the `temperate` species because of their distribution in the southern portion of South America. Until recently, it was assumed that the R. sanguineus group was represented by a single species in the New World, namely R. sanguineus. While the present results coupled with recent studies support the presence of at least two species under the taxon R. sanguineus in the New World, they also show that even in the Old World, the taxon R. sanguineus might be represented by more than one species, since our phylogenetic analysis segregated European and South African R. sanguineus ticks into two distinct clades. The same can be applied for Spanish and South African R. turanicus. (C) 2010 Elsevier B.V. All rights reserved.

Smallest weak and smallest totally weak critical sets in the latin squares of order at most seven

A critical set in a latin square of order n is a set of entries in a latin square which can be embedded in precisely one latin square of order n. Also, if any element of the critical set is deleted, the remaining set can be embedded in more than one latin square of order n. In this paper we find smallest weak and smallest totally weak critical sets for all the latin squares of orders six and seven. Moreover, we computationally prove that there is no (totally) weak critical set in the back circulant latin square of order five and we find a totally weak critical set of size seven in the other main class of latin squares of order five.

On the direct product of two weak uniquely completable partial latin squares

In this note we show by counter-example that the direct product of two weak uniquely completable partial latin squares is not necessarily a uniquely completable partial latin square. This counter-example rejects a conjecture by Gower (see [3]) on the direct product of two uniquely completable partial latin squares.

'Homescapes' and identity reformations in Australian multicultural drama

A consideration of identity formation in contemporary Australian multicultural theatre is offered through a re-assessment of the unsettled (and unsettling) constructions of Australia as 'home' in the work of three playwrights. William Yang's Sadness disrupts a localized perception of home, space, and cultural communities to amalgamate two disparate communities (the queer/homosexual community in Sydney and the Asian-Australian, or 'Austasian' community) into a reconfigured Australian identity. Janis Balodis's The Ghosts Trilogy uses many actors who play across the unsettled lines of history, amid numerous voices, homes, and homelands that indicate the enormity of what 'Australia' comes to signify. Noelle Janaczewska's The History of Water constructs a way of locating the self by means of a metaphoric home as each character establishes herself on a psychic plane rather than choosing the strictly physical locations to which she has access. In their interrogations of home and homeland, these plays challenge assumptions regarding identity, disrupt notions of the ultimate ownership of land/culture by anyone, and problematize the idea of settlement as it is currently articulated in Australia.

Steiner trades that give rise to completely decomposable latin interchanges

In this paper we focus on the representation of Steiner trades of volume less than or equal to nine and identify those for which the associated partial latin square can be decomposed into six disjoint latin interchanges.

The three-way intersection problem for latin squares

The set of integers k for which there exist three latin squares of order n having precisely k cells identical, with their remaining n(2) - k cells different in all three latin squares, denoted by I-3[n], is determined here for all orders n. In particular, it is shown that I-3[n] = {0,...,n(2) - 15} {n(2) - 12,n(2) - 9,n(2)} for n greater than or equal to 8. (C) 2002 Elsevier Science B.V. All rights reserved.

Latin interchanges and direct products

In this paper we focus on the identification of latin interchanges in latin squares which are the direct product of latin squares of smaller orders. The results we obtain on latin interchanges will be used to identify critical sets in direct products. This work is an extension of research carried out by Stinson and van Rees in 1982.