Infectious diseases & vaccine sciences

Infectious diseases continue to be the major cause of morbidity and mortality worldwide. Bangladesh is unfortunately home to many infectious diseases and these occur at high rates in our field sites.

Over the last several decades Bangladesh has made remarkable progress in reducing the human health burden of infectious disease, especially in children, largely due to reduction in mortality from infectious diseases.

Despite substantial progress, vaccine preventable diseases remain important causes of ill health and premature death in Bangladesh. In the most recent national demographic and health survey 62% of deaths among children under the age of 5 years in Bangladesh were ascribed to infectious diseases. This accounts for 55 deaths per 1000 live births. If we expect communicable disease reduction to account for its proportionate share of improvement in child mortality, then childhood infectious disease mortality needs to be reduced by 34 deaths per 1000 live births, or a 38% reduction between 2000 and 2015.

There is further need for enhanced prevention, diagnosis and management of a wide array of diseases with infectious aetiologies. These include pneumonia, diarrhoeal diseases, tuberculosis, measles, and vector-borne diseases, like dengue, malaria, visceral leishmaniasis (kala azar) and filariasis.

ICDDR,B has unique epidemiological strength to conduct studies on disease incidence and burden, as well as prospective interventions to control disease. Our various field sites, epidemiologic expertise, and state-of-the-art laboratories give ICDDR,B a distinct advantage in conducting all phases of vaccine evaluations for enteric and respiratory infections, as well as new vaccines for tuberculosis and dengue.

At a glance

• Overall an infectious disease, as a cause of mortality, has declined substantially since 1990.
• Diarrhoeal disease mortality has declined by 90%, but still needs to decrease further
• Pneumonia mortality has not improved substantially, and needs zinc and vaccine programmes to bring these rates down
• Tuberculosis needs to be controlled before HIV/AIDS becomes prevalent

Drug-resistant infectious diseases will continue to strain resources and threaten existing methods for effective therapy. Of added concern are serious diseases for which effective prevention strategies already exist but remain a problem for much of Bangladesh, such as measles (for which existing affordable vaccines are under-utilized) and Haemophilus influenzae type B (Hib), hepatitis B, typhoid, and pneumococcal diseases (for which safe and effective vaccines exist, but cost is a barrier to their introduction, acceptance, and use).

In 1992, ICDDR,B scientists identified a new strain of cholera, V. cholerae O139 (Bengal), and traced its evolution. This is the first time that scientists have been able to watch a new pathogen emerge and evolve prospectively. We expect that this strain will be the next (8th) pandemic strain. ICDDR,B is in a position to prepare the world for how to deal with this new pandemic strain, and potentially develop a vaccine that would decrease the number of deaths caused by past cholera pandemics.

Childhood and adult mortality can be reduced dramatically through improved management of infectious diseases and prevention via introduction of vaccines and behaviour modification. New technologies are providing opportunities for rapid, practical diagnostic tests which will improve management; vaccines which can provide prevention opportunities; options for treatment including an enhanced ‘super’ ORS; and novel antimicrobial therapies.

ICDDR,B scientists have already shown how vaccines given during childhood and pregnancy save lives and reduce illness. Our work will now be to assist in the development and evaluation of a package of new vaccines for diarrhoea and pneumonia.

ICDDR,B scientists have been conducting surveillance for other emerging infections and in cooperation with the Government of Bangladesh and the World Health Organization, are prepared to respond to these new threats. These include, but are not limited to, influenza, leishmaniasis, and Nipah virus.

ICDDR,B scientists have initiated studies on tuberculosis to understand its antibiotic resistance and epidemiology in a defined rural area. Work continues through monitoring spread in urban areas, improving the effectiveness of DOTS therapy, early detection, and improving diagnosis and treatment of children. This is also building the capacity for conducting field trials of new therapies and improved vaccines.

ICDDR,B scientists have conducted research on dengue fever and documented the serotypes and the epidemiology of the infection in the country. More advanced research is planned to improve case management, reduce incidence through innovative mosquito reduction strategies and evaluation of new vaccines.

The burden of disease of multi-resistant P. falciparum malaria in Bangladesh is currently being documented. This infection threatens 10 to 15 million Bangladeshis - more than most African countries. ICDDR,B will develop community-based strategies for controlling malaria and using a rural field site, develop models that will be useful for all of south-east Asia. Within the malaria research arena, it seems that Asian malaria has been relatively neglected, and our field area is ideal for evaluating community-based interventions.

The control of infectious diseases requires an understanding of basic mechanisms and ICDDR,B scientists have undertaken studies of how certain bacteria survive in the environment, how they spread to people, what genetic properties they possess that allows them to be pathogenic, and the immune responses that protect people. ICDDR,B will continue to conduct this type of basic research that is vital to a complete understanding of host-infection interaction and eventual control of diseases. This is especially true for cholera, amoebiasis, and other enteric infections.