Development of improved analytical methods for use in animal health and in foodborne disease surveillance for source attribution

Considering the 'One Health' principles, the links between animal and human health are very strong. Both domestic and wild animals are sources of infectious agents that cause diseases in humans. Poor animal health may also indirectly affect human health, through reduced access to food. A large number of infectious diseases of animals, the transboundary animal diseases, spread rapidly across borders. Robust and accurate diagnostic assays are needed to detect the infectious agents rapidly and to limit their spread. A large arsenal of novel assays has been developed during the last three decades, with a tremendous impact on the detection of infectious agents. The new diagnostic methods are mostly laboratory-based and expensive, requiring sophisticated equipment and special skills. However, rapid and cheap field-based assays have also been developed. Herein, the authors give several examples of the development of novel assays, with special focus on the 'One Health' principles.

Molecular characterization of peste des petits ruminants viruses from outbreaks caused by unrestricted movements of small ruminants in pakistan

Peste des petits ruminants (PPR) is an endemic disease of small ruminants, and vaccination has been the method of control but outbreaks are continuously occurring in Pakistan. The following study presents a detailed investigation of an outbreak, suspected to be PPR, probably introduced by PPRV-infected sheep and goats from Sindh Province (north-west) to Punjab Province (central) of Pakistan during the flood relief campaign in 2011. A total of 70 serum samples from 28 different flocks were tested with competitive ELISA (H antibodies), which detected 24 (34.2%) samples positive for PPRV antibodies. Nasal swabs and faeces were tested with immunocapture ELISA (N antigen), which detected 18 (25.7%) samples positive for PPRV antigen. The RNA detected positive (n = 28, 40%) using real-time PCR was subjected to conventional PCR for the amplification of the fusion and nucleoprotein genes. Sequencing of both genes and subsequent phylogenetic analysis indicated the grouping of all the sequences to be in lineage IV along with other Asian isolates of PPRV. However, sequences of both genes were divided into two groups within lineage IV. One group of viruses clustered with previously characterized Pakistani isolates, whereas the other group was distinctly clustered with isolates from the Middle East or India. The sequence identity indicated the introduction of at least one population of PPRV from a different source and circulation in the local flocks of small ruminants, which emphasized the need to obtain health clearance certificate before movement of animals. The results of this study provide baseline data for the genetic characterization of different PPRV populations in Pakistan.

Newcastle disease virus in pakistan: genetic characterization and implication in molecular diagnosis

Newcastle disease (ND) is a fatal and contagious disease that poses a constant threat to the poultry industry around the globe. Due to the complex clinico-pathological picture and high genetic variability, the efficient diagnosis of NDV strains is a challenge. In an emerging wave of ND in the north of Pakistan, samples from six outbreaks in commercial poultry and two from healthy backyard poultry flocks were screened for NDV. A real-time PCR based on the fusion and polymerase genes of NDV detected all six isolates whereas a validated real-time PCR based on the matrix gene failed to detect any of these isolates, most likely due to substantial mismatches in the probe-binding site. All isolates have shown ICPI and MDT values similar to the velogenic form of NDV strains. The cleavage site in the F protein was found to be (112)RRQKR↓F(117), typical of virulent NDV. Phylogenetic reconstruction, based on fusion and matrix genes, provided enough evidences to consider these isolates as a new subgenotype within genotype VII. This study raised concerns about the genetic variability of NDV circulating in Pakistan, and sensitivity of the assays for the detection of the NDV isolates in clinical samples.

Detection and phylogenetic analysis of peste des petits ruminants virus isolated from outbreaks in Punjab, Pakistan

Peste des Petits Ruminants (PPR) is an important viral disease of small ruminants and is endemic in Pakistan. In the following study, samples from two outbreaks of PPR in goats have been subjected to laboratory investigations. The Peste des Petits Ruminants virus (PPRV) genome was detected using both conventional and real-time PCR. Genetic characterization of the local PPRV field isolates was conducted by sequencing 322 bp of the fusion (F) gene and 255 bp of the nucleoprotein (N) gene. The phylogenetic tree based on the F gene clustered samples from both outbreaks into lineage 4 along with other Asian isolates, specifically into subcluster 1 along with isolates from Middle East. Analysis of N gene revealed a different pattern. In this case, the Pakistani samples clustered with Chinese, Tajikistani and Iranian isolates, which probably represents the true geographical pattern of virus circulation. This is the first report presenting the phylogenetic tree based on N gene as well as performing a parallel comparison of the trees of F and N gene together from Pakistani isolates. The results of this study shed light on the PPRV population in Pakistan and emphasize the importance of using molecular methods to understand the epidemiology. Such understanding is essential in any efforts to control the number and impact of outbreaks that are occurring in endemic countries such as Pakistan, especially in the current scenario where OIE and FAO are eager to control and subsequently eradicate PPR from the globe, as has been achieved for Rinderpest.

Prevalence and chemo-therapeutical investigations of gastrointestinal nematodes in domestic pigeons in Lahore, Pakistan

The prevalence of gastrointestinal nematodes was studied in 143 (80 male and 63 female) domestic pigeons. Faecal samples were collected to determine the gastrointestinal nematodes of domestic pigeons through qualitative and quantitative faecal examinations. A total of 48 (male 33 and 25 female) naturally infected domestic pigeons were divided into G1 (albendzdole) and G2 (fenbendazole) treatment-groups along with one control group (C). The overall prevalence of gastrointestinal nematodes was 40.5% (58/143) in domestic pigeons. Likewise, the prevalence of gastrointestinal nematodes in males and females was found 41.3% (33/58) and 39.7% (25/58) respectively. The overall prevalence of Capillaria obsignata and Ascaridia columbae was found to be 67.2% and 32.8%, respectively. The prevalence of C. obsignata and A. columbae in males was 72.7% (24/33) and 27.8% (9/33) and in females was 60% (15/25) and 40% (10/25), respectively. There was no significant sex related difference seen in the prevalence of C. obsignata (p>0.56) and A. columbae (p>0.40) in domestic pigeons, respectively. The overall efficacy of albendazole and fenbendazole was calculated to be 66% and 71%. A remarkable significant difference (p<0.05) was observed in eggs per gram before and after treatment in both G1 and G2 treated-groups. The efficacy of fenbendazole was found to be more significant (p<0.02) than albendazole.

Occupational exposure from external radiation used in medical practices in Pakistan by film badge dosimetry

Occupational exposure data of workers due to external sources of radiation in various medical practices such as nuclear medicine (NM), radiotherapy and diagnostic radiology (DR) in Pakistan were collected and analysed. Whole-body doses of workers were measured by film badge dosimetry technique during 2003-2007. Annual average effective dose in NM, radiotherapy and DR varied in the range of 1.39-1.80, 1.05-1.45 and 1.22-1.71 mSv, respectively, during 2003-2007. These values are quite low and well below the annual limit of 20 mSv averaged over a period of 5 consecutive years. Nobody received the radiation dose >50 mSv in any single year over a period of 5 consecutive years; therefore, no overexposure case has been detected. Decreasing trend of annual average dose values in aforementioned categories of work during 2003-2007 indicates the improvement of radiation protection status in medical field in Pakistan.

The impact of the disease early warning system in responding to natural disasters and conflict crises in Pakistan

The disease early warning system (DEWS) was introduced in the immediate aftermath of the 2005 earthquake in Pakistan, with the objective to undertake prompt investigation and mitigation of disease outbreaks. The DEWS network was replicated successfully during subsequent flood and earthquake disasters as well as during the 2008-09 internally displaced persons' crisis. DEWS-generated alerts, prompt investigations and timely responses had an effective contribution to the control of epidemics. Through DEWS, 1360 reported alerts during 2005-09 averted the risk of disease outbreaks through pre-emptive necessary measures, while the 187 confirmed outbreaks were effectively controlled. In the aftermath of the disasters, DEWS technology also facilitated the development of a disease-surveillance system that became an integral part of the district health system. This study aims to report the DEWS success and substantiate its lead role as a priority emergency health response intervention.

Design and development of a portable gamma radiation monitor

A portable gamma radiation monitor has been designed and developed. The monitor can be used effectively in the dose range from 0.07 to 500 mGy/h due to gamma rays of energy greater than 65 keV. The monitor overestimated radiation doses and the uncertainty in the measured dose rate has been found to be < or = 30%. The response of the monitor can be considered isotropic within an acceptable error of +/-30%. Provision has also been added to use the monitor as an installed radiation monitor. In installed mode, it can be operated from a remote location up to 1 km and the timing history can be stored on a personal computer.

Risk to household contacts of tuberculous patients based on Mantoux test and antibody titre

BACKGROUND

Tuberculosis, being an infectious disease, carries a risk of infection to contacts attending tuberculous patients. This study was conducted to evaluate the risk for household contacts of tuberculous patients as compared to non-contacts. The study was conducted at PGMI, Gulab Devi Hospital and Defence Housing Authority Lahore. The study included 120 household contacts and 80 non-contacts.

METHODS

A Cross sectional study for evaluation of antituberculous antibodies levels by ELISA method in two groups; Mantoux positive household contacts 49, Mantoux negative household contacts 71 and normal healthy persons 'non contacts' 80. Routine Haematological investigations like HB, TLC and ESR were done by conventional methods and all the sera of 200 subjects included in the study were tested for IgM, IgG and IgA anti tuberculous antibodies by enzyme linked immunosorbant assay (ELISA). Purified protein derivative 0.1 ml containing 5 TU was injected intradermally. The test was read after 72 hours by measuring the induration around injection site of forearm.

RESULTS

There was no difference in the average age of the household contacts and non-contacts. The complaints of pyrexia, night sweats and weight loss were more in house hold contacts as compared to non-contacts. The awareness about BCG vaccination was equal in both. There were 49 contacts with positive Mantoux test while negative Mantoux test was found in 71 contacts. There were only three Mantoux positive among eighty non-contacts. There was no significant difference in the presence of IgM among household contacts as compared to non-contacts. However both IgG and IgA were present in significantly higher number of household contacts compared to non-contacts.

CONCLUSION

Household contacts of patients suffering from active pulmonary tuberculosis have more chances of being infected with Mycobacterium tuberculosis as compared to the healthy non-contact, as shown by the higher levels of antituberculous antibodies & positivity of Mantoux test.

Using flowering times and leaf numbers to model the phases of photoperiod sensitivity in Antirrhinum majus L

A model has been developed that can be used to determine the phases of sensitivity to photoperiod for seedlings subjected to reciprocal transfers at regular intervals between long (LD) and short day (SD) conditions. The novel feature of this approach is that it enables the simultaneous analysis of the time to flower and number of leaves below the inflorescence. A range of antirrhinum cultivars were grown, all of which were shown to be quantitative long-day plants. Seedlings were effectively insensitive to photoperiod when very young (juvenile). However, after the end of the juvenile phase, SD delayed flowering and increased the number of leaves below the inflorescence. Plants transferred from LD to SD showed a sudden hastening of flowering and a decrease in leaf number once sufficient LD had been received for flower commitment. Photoperiod had little effect on the rate of flower development. The analysis clearly identified major cultivar differences in the length of the juvenile phase and the photoperiod-sensitive inductive phase in both LD and SD.

Rational prescription of medicines--a study of indoor patients at a tertiary care hospital

BACKGROUND

A study was conducted at Ayub Teaching Hospital, Abbottabad, a tertiary hospital, to know whether drugs are prescribed rationally keeping in mind indications, interactions, contraindications, proper dosage and economy of the patient.

METHODS

The study was a descriptive case study. Records of 200 patients admitted in various units of the hospital were analysed by a panel of pharmacologists and conclusions drawn.

RESULTS

It was found that only 52% of patients receive prescriptions that were rationale in all aspects. Where as in rest of the patients the rationale could be challenged.

CONCLUSION

This study stresses the need for more concentrated and dedicated effort towards prescription of medicines.

Substrate-induced up-regulation of Na(+)-dependent glutamate transport activity

Sodium-dependent transporters regulate extracellular glutamate in the CNS. Recent studies suggest that the activity of several different neurotransmitter transporters can be rapidly regulated by a variety of mechanisms. In the present study, we report that pre-incubation of primary 'astrocyte-poor' neuronal cultures with glutamate (100 microM) for 30 min nearly doubled the V(max) for Na(+)-dependent accumulation of L-[(3)H]-glutamate, but had no effect on Na(+)-dependent [(3)H]-glycine transport. Pre-incubation with glutamate also increased the net uptake of non-radioactive glutamate, providing evidence that the increase in accumulation of L-[(3)H]-glutamate was not related to an increase in intracellular glutamate and a subsequent increase in exchange of intracellular non-radioactive glutamate for extracellular radioactive glutamate. The glutamate receptor agonists, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate, quisqualate, and (1 S, 3R)-1-aminocyclopentane-1,3-dicarboxylic acid did not mimic the effect of pre-incubation with glutamate and the glutamate-induced increase was not blocked by receptor antagonists. However, compounds known to interact with the transporters, including L-aspartate, D-aspartate, L-(-)-threo-3-hydroxyaspartate (L-THA) and L-trans-pyrrolidine-2,4-dicarboxylate (L-trans-PDC), caused variable increases in transport activity and attenuated the increase induced by glutamate, suggesting that the increase is related to the interaction of glutamate with the transporters. Several studies were attempted to define the mechanism of this regulation. We found no evidence for increases in transporter synthesis or cell surface expression. Inhibitors of signaling molecules known to regulate other neurotransmitter transporters had no effect on this stimulation. Using a variety of cultures, evidence is provided to suggest that this substrate-induced up-regulation of glutamate transport is specific for the GLT-1 and GLAST subtypes and does not influence transport mediated by EAAC1. These studies suggest that the interaction of glutamate with some of the subtypes of glutamate transporters causes an increase in transport activity. Conceivably, this phenomenon provides an endogenous mechanism to increase the clearance of glutamate during periods of prolonged elevations in extracellular glutamate.

Diagnosis of Clostridium difficile antibiotic associated diarrhoea culture versus toxin assay

OBJECTIVE

To compare the results of Clostridium Difficile (CD) on culture with detection of C. difficile toxin by Enzyme Immunoassay (EIA) in the stool specimens of hospitalized patients with antibiotic associated diarrhoea (AAD).

PATIENTS AND METHODS

The study included 80 adult patients with AAD and 20 adult patients with non-AAD. Stool specimens of all these subjects were inoculated on cycloserine cefoxitin fructose agar and incubated anaerobically to isolate C. difficile. At the same time, all the stool specimens were tested for C. difficile toxin by EIA technique using cytoclone A and B kit manufactured by Cambridge Biotech Corporation, Worcester, Massachusette.

RESULTS

Out of 80 adult patients with AAD, thirty were females and fifty males. C. difficile was isolated on culture from stool specimen of 16 patients, while twenty-three stool specimens were positive for C. difficile toxin. From 20 control subjects, C. difficile was isolated from stool specimen of only one subject. No stool specimen from the controls was positive for toxin.

CONCLUSION

Diagnosis of CDAAD by culture is difficult and time consuming because of strict anaerobic nature of organism. Moreover, mere isolation of C. difficile on culture is not sufficient to establish the pathogenic role of these isolates. C. difficile toxin detection by EIA technique is a highly sensitive and specific method for diagnosis of CDAAD. Using this method, results are available in three hours time. Therefore, EIA is recommended for rapid diagnosis of CDAAD.

Ameloblastoma of the jaws

Ameloblastoma is a histologically benign tumor derived from odontogenic apparatus. The tumor can infiltrate into surrounding tissues. Although it is benign, it presents symptoms of a malignant tumor, such as infiltration into the lungs, pleura, regional and distant metastases, orbit, base of skull, brain and has resulted in death. It also has a high incidence of recurrences, the existence of regional or distant metastasis, showing a microscopic pattern of ameloblastic carcinoma with cytologic features of an increasing nuclear/cytoplastic ratio, nuclear hyperchromatism, and the presence of mitosis. We report a study of 12 patients of ameloblastoma of the jaws between January 1992 and December 1996 consisting of 8 affected in the mandible and 4 in the maxilla. One patient with a tumor in the maxilla was excluded from this study, due to a different histological and clinical behaviour of the ameloblastoma.

The glutamate transporter, GLT-1, is expressed in cultured hippocampal neurons

There are multiple subtypes of Na+-dependent glutamate transporters. Several studies suggest that EAAC1 and EAAT4 are expressed in neurons, while GLT-1 and GLAST expression is thought to be restricted to glia. In the present study, expression of GLT-1 and EAAC1 was examined in cultured rat hippocampal neurons using single cell mRNA amplification and immunocytochemistry with subtype specific antibodies. GLT-1 and EAAC1 mRNAs were observed in all neurons examined. Neuronal phenotype was confirmed in these cells by expression of neurofilament (NF-L) mRNA and absence of glial fibrillary acidic protein (GFAP) mRNA. EAAC1 immunoreactivity was observed in essentially all cells which expressed neuron specific enolase (NSE) and GLT-1 immunoreactivity was detected in the majority (approximately 90%) of NSE-positive cells. Consistent with the glial expression of GLT-1, GLT-1 immunoreactivity was also observed in NSE-negative cells. These studies provide evidence that GLT-1 expression is not intrinsically restricted to glial cells, but can occur in neurons under certain circumstances.