Influence of relative humidity in Vibrio cholerae infection: A time series model.

Background & objectives : Spread of cholera in West Bengal is known to be related to its ecosystem which favours Vibrio cholerae. Incidence of cholera has not been correlated with temperature, relative humidity and rainfall, which may act as favourable factors. The aim of this study was to investigate the relational impact of climate changes on cholera. Methods : Monthly V. cholerae infection data for of the past 13 years (1996-2008), average relative humidity (RH), temperature and rainfall in Kolkata were considered for the time series analysis of Seasonal Auto-Regressive Integrated Moving Average (SARIMA) model to investigate relational impact of climatic association of V. cholerae infection and General Linear Model (GLM) for point estimation. Results : The SARIMA (1,0,0)(0,1,1) model revealed that monthly average RH was consistently linear related to V. cholerae infection during monsoon season as well as temperature and rainfall were non-stationary, AR(1), SMA(1) and SI(1) (P<0.001) were highly significant with seasonal difference. The GLM has identified that consistent (<10%) range of RH (86.78 ± 4.13, CV=5.0, P <0.001) with moderate to highest (>7 cm) rainfall (10.1 ± 5.1, CV=50.1, P <0.001) and wide (>5-10°C) range of temperature (29.00 ± 1.64, CV=5.6, P <0.001) collectively acted as an ideal climatic condition for V. cholerae infection. Increase of RH to 21 per cent influenced an unusual V. cholerae infection in December 2008 compared to previous years. Interpretation & conclusions : V. cholerae infection was associated higher RH (>80%) with 29°C temperature with intermittent average (10 cm) rainfall. This model also identified periodicity and seasonal patterns of cholera in Kolkata. Heavy rainfall indirectly influenced the V. cholerae infection, whereas no correlation was found with high temperature.

The outcome of a pilot study on the epidemiology of rotavirus in three District Hospitals in Kenya-March 1990

This pilot study was done in preparation to assist in chosing the appropriat site for a 5-year main study. The study aim was to find the differences in epidemiology of rotavirus (RV) and other viral agents causing gastroenteritits in children in Kenya between an urban hospital; in this case Kenyatta National Hospital; and a rural hospital to be chosen from Narok; Nanyuki or Kitui district hospitals. Stool specimens were collected for two weeks during the same period from children aged 0 to 14 years attending outpatient clinics and those admitted with diarrhoea at the hospitals. Stool specimens were subsequently analysed by the ELISA method. The presence of RV was confirmed by the sodium dodecyl sulphate polyacrylamide gel electrophoresis method which demonstrates the electrophoretic pattern of the RNA genome. The RV positive rates were 35 (21 in 60) in Nanyuki; 13.8 (4 in 29) in Narok and 1.8 (1 in 56) in Kitui. From these 26 RV strains; 8 (7 long and one short) electropherotype patterns were demonstrated. Subgrupingand serotyping was also done by ELISA method on the 26 isolates yielding 2 subgroup I and 24 subgroup II. The major serotypes were 1(30.8) and 4(26.9) while serotypes were undeterminable in 10 positive specimens. Tissue culture using MA104 cells yielded 5 strains from these positive specimens

Preparation of a neutralizing monoclonal antibody specific to serotype 8 rotavirus strains with a super-short RNA pattern.

Extensive cross-neutralization tests have identified seven serotypes of rotavirus. Recently, it has been reported that several human strains (69M, B37 and B38) with a super-short RNA pattern carry new serotype specificity (serotype 8). By using the strain 69M as an immunizing antigen, we prepared a neutralizing monoclonal antibody (designated 69M-2D). In neutralization tests using 18 human and two animal rotavirus strains with different serotype specificities, the 69M-2D antibody was found to neutralize only serotype 8 strains. Also, in an enzyme-linked immunosorbent assay (ELISA), the antibody reacted exclusively with the serotype 8 strains. Thus, the reactivity pattern of the 69M-2D antibody was serotype 8-specific. This antibody should be useful as another reagent for serotyping rotaviruses by ELISA.

Determination of subgroup, serotype and electropherotype of human rotaviruses obtained from diarrheic patients in the Philippines.

A total of 40 rotavirus specimens obtained from infants with acute gastroenteritis in Metro Manila, Philippines, were analyzed for their subgroup and serotype specificities and RNA electropherotype. A half (50%) of the specimens contained subgroup I human rotaviruses (HRVs), while 45% of them contained subgroup II HRVs. All subgroup II HRVs were determined to be serotype 1, except one specimen belonging to serotype 3, by an enzyme-linked immunosorbent assay with serotype specific monoclonal antibodies. However, serotype specificity of all subgroup I specimens failed to be determined. In polyacrylamide gel electrophoresis, RNAs extracted from HRVs of either subgroup showed long electropherotype. At least two electropherotypes were distinguished in subgroup I viruses, while five different patterns of viral RNA were found in subgroup II viruses.