Temporal and Spatial Epidemiological Analysis of Peste Des Petits Ruminants Outbreaks from the Past 25 Years in Sheep and Goats and Its Control in India.

This study was aimed to understand the temporal and spatial epidemiology of peste des petits ruminants (PPR) in India using national surveillance data available in the National Animal Diseases Referral Expert System (NADRES) along with its control plan undertaken. On analysis of the outbreaks/cases reports in sheep and goats in NADRES database from 1995 to 2019, it was observed that PPR features among the top ten diseases and stands first among viral diseases, and among reported deaths, PPR accounts for 36% of mortality in sheep and goats. PPR outbreaks occur round the year in all the seasons but are encountered most frequently during the lean period especially, in the winter season (January to February) in different regions/zones. The reported outbreaks have been progressively declined in most of the states in India due to the implementation of a mass vaccination strategic program since 2011. On state-wise analysis, the PPR risk-areas showed wide variations with different levels of endemicity. Andhra Pradesh, West Bengal, and Karnataka were the top three outbreaks reported states during 1995-2010, whereas Jharkhand and West Bengal states reported more outbreaks during 2011-2015 and 2016-2019 periods. The temporal and spatial distribution of PPR in India provides valuable information on the hotspot areas/zones to take appropriate policy decisions towards its prevention and control in different regions/zones of India. The study also identifies when and where intensive surveillance and vaccination along with biosecurity measures need to be implemented for the control and eradication of the disease from India in consonance with the PPR Global Control and Eradication Strategy.

Coaggregation and biofilm formation of Leptospira with Staphylococcus aureus.

It is not known how Leptospira react to wound or a cut infected with microbes, such as pathogenic Staphylococcus, or their common habitat on oral or nasal mucosal membranes. In the present study, Staphylococcus aureus MTCC-737 showed strong co-aggregation with leptospiral strains (>75%, visual score of + 4) in vitro. All tested strains of Leptospira were able to form biofilm with S. aureus. Scanning electron microscopy analysis revealed intertwined networks of attached cells of L. interrogans and S. aureus, thus providing evidence of a matrix-like structure. This phenomenon may have implications in Leptospira infection, which occurs via cuts and wounds of the skin.

Correlation Between Physicochemical Properties of Soil and Presence of Leptospira.

Leptospirosis is an important global public health problem. Favourable environmental factors are influencing the survival of leptospires in soil, which is an important link in the transmission cycle. The present study was designed to understand the correlation between various soil nutrients and presence of Leptospira in soil samples of different regions of Andaman and Nicobar Islands. The study revealed a significant positive relationship between presence of Leptospira and concentration of iron, manganese and copper in soil. Presence of iron, manganese and copper in the soil may influence the survival and transmission of leptospirosis.

Changing trend in the seroprevalence and risk factors of human leptospirosis in the South Andaman Island, India.

Seroprevalence of leptospirosis among a healthy population of the South Andaman Island was assessed through random sampling. Previous studies have high seroprevalences of up to 55% in general population and 65% in agricultural labourers. The study subjects (1,181 in total, 781 rural and 400 urban) were interviewed and tested for antibodies against Leptospira. Multivariate models were developed to determine the risk factors in the rural and the urban population. The overall seroprevalence was 10.9%, with rural (12.9%) being higher than the urban subjects (7.0%). The commonest infecting serogroup was Icterohaemorrhagiae (53.5%), followed by Grippotyphosa (13.2%). Compared to the earlier observation, seroprevalence was lower and an apparent shift in the infecting serogroup was found. This shift was in concordance with the changing trend in animal population. Significant difference in risk factors, both in rural and urban areas, was also observed. Similar trends in seroprevalence are being observed around the world. Therefore, time to time prevalence studies are needed for the development of effective control measure.

Can Subminimal Inhibitory Concentrations of Antibiotics Induce the Formation of Biofilm in Leptospira?

Antibiotics at subminimal inhibitory concentrations (sub-MICs) are known to induce biofilm formation in numerous bacteria in vitro. In this report, the effect of sub-MIC levels of antibiotics (doxycycline and tetracycline) on biofilm formation by leptospiral reference strains and isolates was investigated. The sub-MIC levels of both tetracycline and doxycycline were able to induce biofilm in some of the leptospiral strains. This is the first report demonstrating the effect of sub-MIC level of antibiotics in inducing biofilm formation in Leptospira. The induction of biofilm may solely be a response to the amount of threshold stress enforced by low levels of antibiotics. The mechanism of biofilm induction by subinhibitory antibiotic concentrations needs to be explored further. Studies are required to understand the clinical relevance of the phenomenon and its contribution to biofilm formation in the host, resulting in the failure of antimicrobial therapy during the treatment of chronic leptospirosis.

In Vitro Antimicrobial Susceptibility of Pathogenic Leptospira Biofilm.

Pathogenic Leptospira spp. are the causative agent of leptospirosis. Biofilm formation in leptospires is a new area of study, and its role in pathogenesis is not fully explored. As in other biofilm-forming bacteria, Leptospira biofilm may play a significant role in antibiotic resistance. In this study, the antimicrobial susceptibility of Leptospira biofilm was investigated by 96-well plate assay using Alamar Blue. Leptospira biofilm showed five to sixfold increase in resistance in all the strains used. The range of minimal bactericidal concentrations for penicillin G, ampicillin, tetracycline, and doxycycline was 1,600 U/ml, 800-1,600 µg/ml, 800-1,600 µg/ml, and 800-1,600 µg/ml, respectively. In agar substrate, the biofilm showed six- to sevenfold increase in resistance to antibiotics compared to planktonic cell. The present study emphasizes the importance of biofilm formation and its antibiotic susceptibility patterns. This could pave the way for devising appropriate strategy to prevent the occurrence of potential chronic leptospirosis in endemic areas and also during an outbreak situation.