Activity 9: Epidemic Investigation and Surveillance

P.I: Dr. Stephen P Luby

Nipah virus Transmission Study in Bangladesh

FPI: Dr. Jahangir Hossain

In Bangladesh, seven outbreaks of Nipah virus infection have been identified between 2001 and 2007. The case fatality rate was also high (71%). The modes of transmissions were also variable in different outbreaks. The risk factors for transmission were high among caregivers or persons living with a Nipah patient, person to person transmission and consumption of fresh date juice. Fresh date juice might potentially be contaminated with Pteropoid bat saliva.

Since 2005, we initiated a Nipah surveillance study in collaboration with Institute of Epidemiology Disease Control and Research (IEDCR), Government of Bangladesh.

The objectives of the Nipah transmission study were:

1. To identify the outbreak of Nipah virus infection
2. To characterize the conditions and risk factors for transmission of Nipah virus from person to person in Bangladesh.
3. To improve the local laboratory capacity for diagnosis of Nipah viral infection in Bangladesh.

ICDDR,B and IEDCR conducted the study with the participation of 6 Medical college Hospitals and 4 Sadar hospitals. The participating institutes were selected as Nipah cases were identified previously in those regions and the areas which were within Nipah prone zone.

We conducted a one-day seminar and training session with the Directors and Deputy Directors of Directorate General of Health Services and civil surgeons on 12th February 2006. The seminar emphasized on past outbreaks of Nipah virus infection in Bangladesh, mode of transmission of Nipah virus infection and justification for conducting Nipah surveillance study in Bangladesh. We selected a study physician from each hospital and conducted to inform and train them about the purposes of the study, methods of study, samples collection, samples transport and communication to the central level after identification of a cluster of cases i.e. two or more cases within 30 minutes walking distance and within 21 days. A Nipah laboratory was established at IEDCR in 2006 to improve local diagnostic capacity of Nipah virus.

IHP contributed to this very important study by providing training and carrying out dissemination seminars and other support to the local study physicians and coordinator. IHP also provided some supplies and contributed support to develop the laboratory at IEDCR. This surveillance is expected to continue and will be supported by IHP till December, 2007 for supplies, reagents and maintenances.

Collaborating Institutions:

• Faridpur Medical College Hospital
• Rajshahi Medical College Hospital
• Rangpur Medical College Hospital
• Shaheed Ziaur Rahman Medical Collge Hospital, Bogra
• Manikgonj Sadar Hospital
• Rajbari Sadar Hospital
• Meherpur Sadar Hospital
• Tangail Sadar Hospital
• Naogaon Sadar Hospital
• Joypurhat Sadar Hospital

Results:

Campylobacter infections and non-polio acute flaccid paralysis (NPAFP) in Bangladesh: clinical epidemiology and comparative genomic

FPI: Dr. Kaisar Ali Talukder/Dr H. P. Endtz

The incidence of GBS in developing countries remains yet to be determined. Non-polio AFP in the less than 15 year old continues to be reported in frequencies exceeding 2 per 100,000 in Bangladesh, through this study, and GBS is thought to be responsible for the majority of non-polio AFP patients. This project is the first to work on GBS in Bangladesh. Based on initial reports on the clinical symptoms, we hypothesized that Campylobacter jejuni infections were likely to be the major cause of antecedent infections and to trigger the GBS through molecular mimicry with human gangliosides.

The initial objectives are:

1. To determine the presence of campylobacter in diarrhoeal patients and appropriate controls, in food chain and water sources and in wild and farm animals in Bangladesh.
2. To describe the epidemiological, clinical and serological features of GBS in Bangladesh.
3. To identify preceding infections associated with GBS in Bangladesh, including infections by Campylobacter species.
4. To characterize the campylobacter strains from GBS and control patients, animals, food, water and environment sources using comparative genomic approaches.

Results:
In a prospective multi-centre study with Dhaka Medical Hospital and BSMMU Hospital from July 2006 and June 2007, 100 patients have been identified as GBS and 200 control patients. Strong evidence of a recent C. jejuni infection was observed in at least 55% of the patients. In Bangladesh, GBS is most frequently preceded by gastroenteritis and often affects teens and young adults and is associated with to significant morbidity and mortality. Based on these serology data, we conclude that campylobacter infections often precede GBS in Bangladesh. Our study is the first systematic analysis of GBS and preceding infections in the developing world. Follow up studies will focus on the epidemiology and host as well as microbial factors involved in the pathogenesis of GBS in Bangladesh. In view of the continuing reports of AFP in children and adults in Bangladesh and in the absence of polio, the outcome of this collaborative study is highly relevant.

Collaborating Institutions:

• Dhaka Medical College Hospital, Dhaka
• Sir Salimulla Medical College Hospital, Dhaka
• BSMMU (PG), Dhaka and,
• Erasmus University Medical Center, Rotterdam, The Netherlands

Developing trained manpower in National Laboratories for molecular surveillance and global tracking of Shigella species in Bangladesh

FPI: Dr. Kaisar Ali Talukder

This study identifies and describes new strains of Shigella species in order to develop new antimicrobial strategies, to stop or reduce the amount of horizontal transfer of antibiotic resistance markers at the intra and inter species level among the enteric pathogens, as well as to resolve health care problem. This study also guides to development an effective vaccine against the shigellosis caused by recognized, provisional serovars, and new subserotypes of Shigella species.

Specific aims:

1. To characterize the atypical and Shigella-like organisms (SLO) serologically, biochemically and molecular level by using standard serological, biochemical and molecular methods and compare these characteristics with existing serotypes of Shigella species.
2. To determine the antimicrobial resistance pattern and resistance mechanism of these atypical and SLO isolates.
3. To study the invasiveness of the strains by analyzing invasive plasmid, studying the ability to bind Congo red, and assaying the keratoconjunctivitis in the guinea pig eye.
4. To examine the presence of virulence genes of these isolates such as sen, set 1A, set1B, ial, stx1 and stx2 by PCR.
5. To investigate the pathogenicity of these Shigella-like organisms using tissue culture assay and rabbit ileal loop test.

Results:

During the period of January 1997 to June 2007, 11878 strains of Shigella had been isolated from the diarrhoeal patients attending the Dhaka treatment center of ICDDR, B. S. flexneri was found to be the most predominant (61%) followed by S. boydii (17%), S. sonnei (10%), S. dysenteriae (8%). Besides, 3% (n=356) of the strains were detected as Shigella-like organism (SLO). We found a cluster among the SLOs, which had identical plasmid pattern with large invasive plasmid and were negative in agglutination test with any available sera of Shigella. We describe this new group of Shigella with the support of biochemical tests, presence of pathogenicity genes, molecular typing using pulsed-filed gel electrophoresis (PFGE) and agglutination by a serum raised against one of these new strains. Some of these data has been published in Journal Medical Microbiology in 2007 (JMM, 2007: Vol 56, p 654-658).

Resistance to multiple antibiotics and emergence of resistance to newer antibiotics are a common phenomenon among Shigella species and has been increasing over time. Most of S. flexneri and S. dysenteriae strains are resistant to ampicillin, tetracycline, and trimethoprim-sulfomethoxazole. Among the serotypes of Shigella, S. dysenteriae type 1 and S. flexneri 2a have been found more frequently resistant to new antibiotics and has a trend of acquiring resistance to the latest choice of antibiotic for Shigella infection. Toward this trend, all strains of S. dysenteriae type 1 isolated in Bangladesh in 2003 and onwards are resistant to nalidixic acid, and ciprofloxacin. All strains of recent isolates S. flexneri 2a are also resistant to nalidixic acid, and ciprofloxacin. However, this phenomenon is not common to other serotypes of Shigella. Shigella species is still susceptible to mecillinam, azithromycin and ceftriaxone.

More precisely at the species level, 8% of S. boydii and 23% of S. dysenteriae strains isolated between January 1997 and June 2007 were identified as atypical since they reacted only with the group specific antisera but not with any of the type antigen-specific antiserum. In case of S. flexneri, we found 23.4% of the strains, which could not be typed, according to the recognized classification scheme of S. flexneri using the combination of group and type specific antisera. These strains were designated as atypical S. flexneri and were characterized phenotypically and genotypically as S. flexneri 1c, type 4 and new provisional serotype 4X. With the expansion of our interest on these atypical strains we also looked for their incidence in other countries across the boundary where Shigella infection is endemic. We found about 324 atypical strains of S. flexneri from India, Pakistan and Indonesia of which 48%, 18%, 37% were 1c, type 4 and 4x respectively. These atypical strains were previously unrecognized in these countries despite having a good prevalence in the overall Shigella burden.

Collaborating Institutions:

• Department of Microbiology, Department of Biochemistry, Department of
• Clinical Pharmacy and Pharmacology, University of Dhaka
• Department of Neurology, Dhaka Medical College.
• Department of Neurology, Sir Salimullah Medical College, Dhaka.
• Department of Microbiology and Department of Neurology, BBSMMU