Chikungunya virus: A general overview

Chikungunya virus (CHIKV) is a re-emerging mosquito borne alphavirus responsible for the recent outbreak in the Americas. Immunologically naïve population in the Americas favors the spread of epidemics. Chikungunya fever is characterized by an abrupt febrile illness, polyarthralgia and maculopapular rash. In chikungunya fever, shock or severe hemorrhage is very rarely observed; the onset is more acute and the duration of fever is shorter than dengue disease. The pain is much more pronounced and localized to the joints and tendons in chikungunya fever, in comparison to dengue fever. There is no specific and effective antiviral therapy and vaccines are still in trails. The only effective preventive measures consist of individual protection against mosquito bites and vector control. Disease prevention is important due to the economic burden it entails. Clinicians need to distinguish chikungunya fever between dengue fever and other diseases to give a successful treatment and prevent disease spreading

Universal primers for the amplification and sequence analysis pf actin-1 from diverse mosquito species

We report the development of universal primers for the reverse-transcription polymerase chain reaction (RT-PCR) amplification and nucleotide sequence analysis of actin cDNAs from taxonomically diverse mosquito species. Primers specific to conserved regions of the invertebrate actin-1 gene were designed after actin cDNA sequences of Anopheles gambiae, Bombyx mori, Drosophila melanogaster, and Caenorhabditis elegans. The efficacy of these primers was determined by RT-PCR with the use of total RNA from mosquitoes belonging to 30 species and 8 genera (Aedes, Anopheles, Culex, Deinocerites, Mansonia, Psorophora, Toxorhynchites, and Wyeomyia). The RT-PCR products were sequenced, and sequence data were used to design additional primers. One primer pair, denoted as Act-2F (5′-ATGGTCGGYATGGGNCAGAAGGACTC-3′) and Act-8R (5′-GATTCCATACCCAGGAAG-GADGG-3′), successfully amplified an RT-PCR product of the expected size (683-nt) in all mosquito spp. tested. We propose that this primer pair can be used as an internal control to test the quality of RNA from mosquitoes collected in vector surveillance studies. These primers can also be used in molecular experiments in which the detection, amplification or silencing of a ubiquitously expressed mosquito housekeeping gene is necessary. Sequence and phylogenetic data are also presented in this report

Epidemiological Trends of Dengue Disease in Mexico (2000–2011): A Systematic Literature Search and Analysis

<div><p>This systematic literature review describes the epidemiology of dengue disease in Mexico (2000–2011). The annual number of uncomplicated dengue cases reported increased from 1,714 in 2000 to 15,424 in 2011 (incidence rates of 1.72 and 14.12 per 100,000 population, respectively). Peaks were observed in 2002, 2007, and 2009. Coastal states were most affected by dengue disease. The age distribution pattern showed an increasing number of cases during childhood, a peak at 10–20 years, and a gradual decline during adulthood. All four dengue virus serotypes were detected. Although national surveillance is in place, there are knowledge gaps relating to asymptomatic cases, primary/secondary infections, and seroprevalence rates of infection in all age strata. Under-reporting of the clinical spectrum of the disease is also problematic. Dengue disease remains a serious public health problem in Mexico.</p></div

Dengue disease in Mexico: regional data from public health databases [20].

<p>Data shown are number of uncomplicated dengue fever cases (incidence per 100,000 population).</p><p>*Cases in Distrito Federal are imported from other Mexican states (no dengue disease transmission occurs).</p><p>Dengue disease in Mexico: regional data from public health databases <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003158#pntd.0003158-Mexican1" target="_blank">[20]</a>.</p

Incidence of dengue disease (per 100,000 population) in Mexico and associated hospitalization and mortality: national data [15], [16], [20]–[25].

<p>*Mexican public health data <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003158#pntd.0003158-Mexican1" target="_blank">[20]</a>.</p>†<p>Social security sector excluded.</p>‡<p>10 additional deaths classified as dengue fever (A90X) occurred in 2010.</p><p>Incidence of dengue disease (per 100,000 population) in Mexico and associated hospitalization and mortality: national data <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003158#pntd.0003158-Diaz1" target="_blank">[15]</a>, <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003158#pntd.0003158-FalcnLezama1" target="_blank">[16]</a>, <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003158#pntd.0003158-Mexican1" target="_blank">[20]</a>–<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003158#pntd.0003158-Torres1" target="_blank">[25]</a>.</p

Circulation of dengue virus serotypes in Mexico, 2000–2011 [16], [20], [26].

<p>Data shown are number cases (incidence per 100,000 population). All four DENV serotypes were in circulation during the review period, although the predominant serotype varied between years: at the beginning of the review period, DENV-2 was the predominant serotype (2000–2005). DENV-1 became predominant in 2006–2010, after which DENV-1 and -2 isolates were present in similar proportions. DENV-3 isolates were more common before 2007. DENV-4 isolates were present at low levels in most years after 2003.</p

Reported number and incidence of dengue fever and dengue haemorrhagic fever cases, Mexico, 2000–2011 [20].

<p>Over the period of the literature survey (2000–2011), the overall annual number of confirmed cases of (A) dengue fever (DF) and (B) dengue haemorrhagic fever (DHF) increased considerably in Mexico. The increase in number of cases and population incidence over time was not linear and peaks were observed in 2002, 2007, and 2009.</p

Geographical distribution of dengue disease and dengue haemorrhagic fever cases in Mexico, 2000–2012 [19], [20].

<p>Regional populations in Mexico are exposed to differing magnitudes of dengue disease risk due to the mix of epidemic, endemic, and hyperendemic areas. Mexico is divided into 31 states and one federal district that contains the capital, Mexico City (A). These dispersion maps of dengue disease and DHF throughout Mexico highlights the regional pattern of the occurrence of (B) dengue disease and (C) dengue haemorrhagic fever with high concentrations of cases in the important tourist and commercial centres on the coast and in tropical areas.</p