Chikungunya fever: a re-emerging viral infection.
ABSTRACT Chikungunya (CHIK) fever is a re-emerging viral disease characterized by abrupt onset of fever with severe arthralgia followed by constitutional symptoms and rash lasting for 1-7 days. The disease is almost self-limiting and rarely fatal. Chikungunya virus (CHIKV) is a RNA virus belonging to family Togaviridae, genus Alphavirus. Molecular characterization has demonstrated two distinct lineages of strains which cause epidemics in Africa and Asia. These geographical genotypes exhibit differences in the transmission cycles. In contrast to Africa where sylvatic cycle is maintained between monkeys and wild mosquitoes, in Asia the cycle continues between humans and the Aedes aegypti mosquito. CHIKV is known to cause epidemics after a period of quiescence. The first recorded epidemic occurred in Tanzania in 1952-1953. In Asia, CHIK activity was documented since its isolation in Bangkok, Thailand in 1958. Virus transmission continued till 1964. After hiatus, the virus activity re-appeared in the mid-1970s and declined by 1976. In India, well-documented outbreaks occurred in 1963 and 1964 in Kolkata and southern India, respectively. Thereafter, a small outbreak of CHIK was reported from Sholapur district, Maharashtra in 1973. CHIKV emerged in the islands of South West Indian Ocean viz. French island of La Reunion, Mayotee, Mauritius and Seychelles which are reporting the outbreak since February, 2005. After quiescence of about three decades, CHIKV re-emerged in India in the states of Andhra Pradesh, Karnataka, Maharashtra, Madhya Pradesh and Tamil Nadu since December, 2005. Cases have also been reported from Rajasthan, Gujarat and Kerala. The outbreak is still continuing. National Institute of Communicable Diseases has conducted epidemiological, entomological and laboratory investigations for confirmation of the outbreak. These have been discussed in detail along with the major challenges that the country faced during the current outbreak.
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ABSTRACT: Aedes albopictus is a vector of dengue and chikungunya viruses in the field, along with around 24 additional arboviruses under laboratory conditions. As an invasive mosquito species, Ae. albopictus has been expanding in geographical range over the past 20 years, although the poleward extent of mosquito populations is limited by winter temperatures. Nonetheless, population densities depend on environmental conditions and since global climate change projections indicate increasing temperatures and altered patterns of rainfall, geographic distributions of previously tropical mosquito species may change. Although mathematical models can provide explanatory insight into observed patterns of disease prevalence in terms of epidemiological and entomological processes, understanding how environmental variables affect transmission is possible only with reliable model parameterisation, which, in turn, is obtained only through a thorough understanding of the relationship between mosquito biology and environmental variables. Thus, in order to assess the impact of climate change on mosquito population distribution and regions threatened by vector-borne disease, a detailed understanding (through a synthesis of current knowledge) of the relationship between climate, mosquito biology, and disease transmission is required, but this process has not yet been undertaken for Ae. albopictus. In this review, the impact of temperature, rainfall, and relative humidity on Ae. albopictus development and survival are considered. Existing Ae. albopictus populations across Europe are mapped with current climatic conditions, considering whether estimates of climatic cutoffs for Ae. albopictus are accurate, and suggesting that environmental thresholds must be calibrated according to the scale and resolution of climate model outputs and mosquito presence data.Pathogens and global health. 07/2013; 107(5):224-41.
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ABSTRACT: The Indian Ocean chikungunya epidemic re-emerged in Thailand in August 2008. Forty-five adults with laboratory-confirmed chikungunya in Songkhla province, Thailand were clinically assessed and serially bled throughout the acute and convalescent phase of the disease. Patient symptoms, antibody responses, and viral kinetics were evaluated using observational assessments, polymerase chain reaction (PCR), and serological assays. All subjects experienced joint pain with 42 (93%) involving multiple joints; the interphalangeal most commonly affected in 91% of the subjects. The mean duration of joint pain was 5.8 days, 11 (25%) experiencing discomfort through the duration of the study. Rash was observed in 37 (82%) subjects a mean 3.5 days post onset of symptoms. Patents were positive by PCR for a mean of 5.9 days with sustained peak viral load through Day 5. The IgM antibodies appeared on Day 4 and peaked at Day 7 and IgG antibodies first appeared at Day 5 and rose steadily through Day 24.The American journal of tropical medicine and hygiene 02/2014; · 2.53 Impact Factor
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ABSTRACT: After a gap of three decades, from 2005 onwards, a series of Chikungunya virus (CHIKV) outbreaks occurred worldwide. This study was performed to detect CHIKV infection, its genotype among symptomatic Eastern Indian patients and to analyze any association between the presence of CHIKV genome in patient body with appearance of disease symptoms (n = 199). Plasma-extracted viral RNA was reverse transcribed to cDNA and PCR-amplified followed by agarose gel electrophoresis. Viral load among CHIKV-positive patients was determined by real time RT-PCR. CHIKV-IgM in sera was detected by ELISA. Sequencing and phylogenetic analysis of plasma-extracted PCR products was done. CHIKV genome and IgM were detected among 65.3% (n = 130) and 41.2% (n = 82) patients respectively. Joint swelling was significantly associated with CHIKV infection (P-value: 0.0003). CHIKV PCR positive patients were grouped in two categories: Group-I: viral load <10(4) copies/ml and Group-II: viral load ≥10(4) copies/ml. Higher number of acute stage patients clustered in Group-II. Fever and joint swelling were significantly more prevalent among Group-II patients, whereas rash and diarrhoea among Group-I patients (P-value <0.05). Patient-isolated CHIKV sequences clustered with CHIKV ECSA genotypes in the phylogenetic tree, with two types of CHIKV strains found to circulate among them-as indicated by their different nucleotide sequences. This is the first study detecting the presence of CHIKV ECSA genotype among Eastern Indian patients. Fever and joint swelling might have appeared first followed by rash, diarrhea during disease progression-as indicated by CHIK viral load in patients. Thus, viral load can be used as unique diagnostic and prognostic marker of Chikungunya disease pathogenesis. J. Med. Virol. © 2013 Wiley Periodicals, Inc.Journal of Medical Virology 10/2013; · 2.37 Impact Factor