Outbreak of cholera in a remote village in western India

Background & objectives: Atypical El Tor strains of Vibrio cholerae are frequently implicated in outbreaks of cholera. It is important to understand genetic variations of such strains which impact clinical and epidemiological outcomes. The present study was carried out to characterize an outbreak of cholera which occurred between July 8 and 13, 2018, in a remote settlement in Nashik district, Maharashtra. Methods: A large number of acute diarrhoea cases were reported in Rahude village, Nashik, Maharashtra since July 8, 2018. Molecular characterization of the isolated strains of V. cholerae was done. Results: 195 cases of cholera were detected from a population of 850 (attack rate 22.9%) with two deaths (Case Fatality Ratio of 1.03). A non-haemolytic polymyxin B sensitive strain of V. cholerae O1 Ogawa was isolated from 5/14 fecal samples. Molecular characterization of the isolates indicated that this strain was an altered El Tor (AET) strain. Deletion of the trinucleotide ‘GTA’ in the rstB gene, a unique feature of classical strains, was observed. Interpretation & conclusions: A cholera outbreak caused by a non-haemolytic polymixin B sensitive AET strain, occurred from July 8 to 13, 2018, in a remote settlement in western India. The molecular characterization of the outbreak strains highlighted an assortment of genetic determinants, stressing the need to monitor the genetic attributes of V. cholerae O1 in outbreaks for better understanding and mapping of clinical and epidemiological changes.

Envelope specific T cell responses & cytokine profiles in chikungunya patients hospitalized with different clinical presentations.

Background & objectives: Since the 2006 massive outbreaks, chikungunya (CHIK) is a major public health concern in India. The aim of this study was to assess envelope specific immune responses in patients with chikungunya infection. Methods: This study included 46 hospitalized patients with chikungunya virus infection (encephalitis, n=22, other systemic involvement, OSI, n=12, classical, n=12) and six controls from Ahmedabad city, Gujarat, India. T cell responses and the levels of Th1, pro/ anti-inflammatory cytokines against the CHIK virus envelope antigens were assessed by lymphocyte proliferation assay and by cytometric bead array in flow cytometry, respectively. Results: Lymphoproliferative response was uniform among the patients. Comparisons of cytokines revealed significantly higher levels of interleukin (IL)-4 and IL-5 in encephalitis, OSI and classical patients versus controls. The levels of tumour necrosis factor (TNF)-α were higher in classical patients categories compared to the controls. Interferon (IFN)-γ levels were lower in encephalitis patients versus control. Interpretation & conclusions: Our findings showed recognition of T cell epitopes on the envelope region of chikungunya virus by all patient categories. Lower level of IFN-γ may be associated with the severity of disease in these patients.

Chandipura virus encephalitis outbreak among children in Nagpur division, Maharashtra, 2007.

Background & objectives: An outbreak of acute encephalitis syndrome (AES) among children from Nagpur division, Maharashtra was investigated to confirm the aetiology and to describe clinico-epidemiological features. Methods: AES cases among children <15 yr, from Nagpur division, hospitalized between June-September 2007, were investigated. Serum and cerebrospinal fluid (CSF) were tested for IgM antibodies against Chandipura virus (CHPV) and Japanese encephalitis virus (JEV) and for CHPV RNA by RT-PCR. Partial N gene sequences were used for phylogenetic analysis. Virus isolations were attempted in rhabdomyosarcoma (RD) cell line. Sandflies were collected, pooled and tested for CHPV RNA by RT-PCR. Results: A total of 78 AES cases were recorded in children <15 yr of age. Case fatality ratio was 43.6 per cent. Male to female ratio was 1:1.2. Chandipura (CHP) was confirmed in 39 cases. CHPV RNA was detected in both CSF and serum specimens of 2 cases and in serum of 22 cases. Phylogenetic analysis showed 99.98 – 100 per cent nucleotide identity in the sequences studied. Anti-CHPV IgM antibodies were detected in CSF of 2 cases and in serum of 8 cases. Seroconversion to anti-CHPV IgM antibodies was observed in 5 cases. Clinical manifestations of CHP cases (n=38) were fever (100%), convulsion (76.3%), altered sensorium (34.2%), headache (23.7%), vomiting (44.7%) and diarrhoea (23.7%). CHPV RNA was detected in one of two pools of sandflies from affected locality. Interpretation & conclusions: Chandipura virus was confirmed as the aetiological agent of this acute encephalitis outbreak with high case-fatality among children.