Moazzem Hossain

Human rabies in rural Bangladesh.

Rabies is a major public health problem in Bangladesh, where most of the population live in rural areas. However, there is little epidemiological information on rabies in rural Bangladesh. This study was conducted in 30 upazilas (subdistricts) covering all six divisions of the country, to determine the levels of rabies and animal bites in Bangladesh. The total population of these upazilas was 6 992 302. A pretested questionnaire was used and data were collected by interviewing the adult members of families. We estimated that in Bangladesh, 166 590 [95% confidence interval (CI) 163 350-170 550] people per year are bitten by an animal. The annual incidence of rabies deaths in Bangladesh was estimated to be 1·40 (95% CI 1·05-1·78)/100 000 population. By extrapolating this, we estimated that 2100 (95% CI 1575-2670) people die annually from rabies in Bangladesh. More than three-quarters of rabies patients died at home. This community-based study provides new information on rabies epidemiology in Bangladesh.

Five-year (January 2004-December 2008) surveillance on animal bite and rabies vaccine utilization in the Infectious Disease Hospital, Dhaka, Bangladesh.

The magnitude of animal bite and utilization of rabies vaccine was determined at the Infectious Disease Hospital, Dhaka, Bangladesh. From January 2004 to December 2008, 150,068 patients with animal bite visited the hospital, 86.2% and 13.8% of them received nerve tissue and tissue culture vaccine (TCV), respectively. Dog bite was most frequent, found in 90.7% cases. In 794 rabies cases only 24.4% had a history of post-exposure vaccination. Only a negligible number of patients received rabies immunoglobulin (RIG). To prevent further human deaths and economic losses intra-dermal TCV regime and equine RIG should be immediately introduced in Bangladesh.

A survey of the dog population in rural Bangladesh.

Globally, Bangladesh ranks third in the number of human deaths from rabies. Although dogs are the principal known transmitters of rabies and knowledge of dog populations is essential for effective national control and proper planning, dog control programs are scarce in Bangladesh. Our objective was to count dogs in a rural area to understand the dog population of the country. For this purpose we selected six unions of Raipura upazila in Narsingdi district. Dog counting was done by direct observation following accepted guidelines. We determined the mean density of the dog population in Bangladesh to be 14 dog/km(2) (95% CI 3.7, 24) and the human:dog ratio to be 120 (95% CI 55, 184). Our paper contribute to the literature which shows great variation in the human:dog ratio across regions of the developing world. The human:dog ratio depends on the areas human (as well as dog) population, whereas dog density per unit area indicates the true number of dogs. We propose that extrapolating from the human:dog ratios of other regions not be relied upon for estimating dog populations, unless the ratios can be supplemented by actual counts of dogs within the target area.

Arctic-like Rabies Virus, Bangladesh

Arctic/Arctic-like rabies virus group 2 spread into Bangladesh ≈32 years ago. Because rabies is endemic to and a major public health problem in this country, we characterized this virus group. Its glycoprotein has 3 potential N-glycosylation sites that affect viral pathogenesis. Diversity of rabies virus might have public health implications in Bangladesh.

Enzyme-linked immunosorbent assay for the diagnosis of Wuchereria bancrofti infection using urine samples and its application in Bangladesh.

In Sri Lanka, urine ELISA showed high sensitivity and specificity in detecting filaria-specific IgG4. It also produced much higher positive rates than antigen tests in prevalence studies with young children. In this study, we have confirmed the usefulness of urine ELISA in the field of Bangladesh. The ELISA detected 89 of 105 (85%) ICT antigen test positive subjects in endemic areas. With both ICT and microfilaria positives, the sensitivity was 97% (30/31). All of 104 ICT negative people in a non-endemic area were ELISA negative (100% specificity). In a prevalence study with 319 young children (5-10 years) from a low endemic area after five rounds of MDA, seven (2.2%) were detected by the present urine test, but only one (0.3%) by ICT (P=0.075). The satisfactorily high sensitivity, 100% specificity and effective case detection among young ages along with scope for analyzing the titers will indicate urine ELISA to be an effective tool in the post-MDA surveys to confirm elimination or to detect resurgence in Bangladesh.

Visual detection of filaria-specific IgG4 in urine using red-colored high density latex beads

The use of urine for the immunodiagnosis of lymphatic filariasis has a definite advantage: the sample collection is not invasive and thus well accepted by people. Urine-based ELISA to detect filaria-specific IgG4 has been used successfully. However, ELISA requires equipment such as a microplate reader, which is often not available in most endemic areas. We have developed a new visual immunodiagnosis that detects urinary IgG4 using red-colored latex beads (bead test). The sensitivity was 87.2% when ICT antigen test positive people were regarded as the standard (136/156), and the specificity was 97.2% with the non-endemic people in Japan and Bangladesh, and the urine ELISA negatives in Sri Lanka (1264/1300). In a prevalence study, the bead test could detect filarial infection more effectively than ICT test among young children in Sri Lanka, indicating the usefulness of the visual test in epidemiological studies.

Geographical Distribution of Kala-Azar in South Asia

Kala-azar or visceral leishmaniasis (VL) is a parasitic disease caused by the trypanosomatid parasite Leishmania donovani on the Indian subcontinent, where it is transmitted by the sandfly Phlebotomus argentipes. Leishmaniasis is found in about 88 countries, where 350 million people are believed to be at risk. About 500,000 cases of VL occur annually, mostly affecting countries in the tropics and subtropics. More than 90% of the world’s cases of VL occur in India, Bangladesh, Nepal, Sudan, and Brazil, affecting largely the socially marginalized and the poorest communities. In South Asia, kala-azar occurs in India, Bangladesh, and Nepal, with a small focus reported from Bhutan. Nearly 200 million people are considered to be at risk of contracting kala–azar in this region. In May 2005, the health ministers of these three countries signed a memorandum of understanding in Geneva during the World Health Assembly, making a commitment to eliminate kala-azar from their respective countries by 2015. The target of the elimination program is to reduce the incidence of kala-azar to less than one case of kala-azar or post-kala-azar dermal leishmaniasis per 10,000 population at the district (in Nepal) or subdistrict/upazila level (in Bangladesh and India). As of 2008, kala-azar was endemic in 52 districts in India, 12 districts in Nepal, and 45 districts in Bangladesh.

Short Communication: Evaluation of a New Rapid Diagnostic Test for Quality Assurance by Kala Azar Elimination Programme in Bangladesh

In Bangladesh, serological tests have been widely used for the primary screening of visceral leishmaniasis (VL). Several serologic tests are available for the diagnosis of VL. Selection of the best test is important to permit diagnostic differentiation between symptomatic and asymptomatic patients and to reduce cross-reactivity. We evaluated the effectiveness of a new serological test “Onsite Leishmania Ab Rapid Test” as a part of “quality assurance” activities for the kala azar elimination programme of the Government of Bangladesh. Plasma samples of 100 parasitologically confirmed cases of VL along with 101 healthy controls were tested, and “Onsite Leishmania Ab Rapid Test” strip tests were positive in 94 out of 100 confirmed VL cases, whereas four out of 51 healthy subjects from the VL endemic areas also tested positive. All the 50 healthy volunteers tested negative. Thus, the sensitivity and specificity of “Onsite Leishmania Ab Rapid Test” strip test were found to be 94% (95% CI: 87–98) and 96% (95% CI: 90–99), respectively. This study showed that the performance of the “Onsite Leishmania Ab Rapid Test” strip tests was up to the recommended level.

Climate Change and Kala-Azar

Kala-azar or visceral leishmaniasis (VL) is a parasitic disease caused by Leishmania donovani. On the Indian subcontinent, it is transmitted by the sand fly, Phlebotomus argentipes. Kala-azar is found in about 88 tropical and sub-tropical countries with approximately 350 million people living in affected areas and at risk of infection. About 500,000 cases occur annually. More than 90% of the world’s VL cases are in India, Bangladesh, Nepal, Sudan, and Brazil, affecting largely the socially marginalized and the poorest communities. In the South-East Asian Region, kala-azar occurs in India, Bangladesh, and Nepal with a small focus reported in Bhutan. In this region about 200 million people are “at risk.” Fifty-two districts in India, 12 in Nepal, and 45 in Bangladesh are endemic. Most of the SEAR countries are vulnerable to the consequences of climate change. The ultimate effects of climate change are increased flooding, the breakdown of sanitation systems, increased salinity, more vector growth, and more water- and food-borne diseases, which ultimately impact human health. Environmental changes often modify the transmission patterns of vector-borne diseases. Increases in temperature due to climate change provide a better breeding environment for vectors, including the sand fly, in places where temperatures were previously below optimum, and so, a higher rate of human VL infection may result. Further research in this area is needed.

Diagnosis and Treatment of Kala-Azar and Post-kala-azar Dermal Leishmaniasis

In South Asia, the diagnosis of kala-azar is based on a history of fever and a positive serological test for the presence of antibody against a 39 kDa recombinant antigen, the rK39 dipstick test. The clinical symptoms are characterized by prolonged and irregular fever often associated with chills and rigor, splenomegaly, lymphadenopathy, hepatomegaly, pancytopenia, progressive anemia, and weight loss. Kala-azar is almost always fatal if left untreated. Laboratory confirmation of the diagnosis requires demonstration of Leishman-Donovan bodies in smears of patients’ splenic tissue, bone marrow, or lymph nodes. The serological test may remain positive for 2 years after completion of kala-azar treatment, and therefore is not useful to detect relapse or treatment failure. Diagnosis of post-kala-azar dermal leishmaniasis (PKDL) is typically based on previous history of kala-azar in a patient who presents with skin manifestations of macules, papules, or nodules without loss of sensation over these lesions. In India, PKDL develops within 2–3 years after treatment of kala-azar in 5–10% of cases. Many drugs are effective against kala-azar, including miltefosine, paromomycin, sodium stibogluconate (SSG), amphotericin B, and liposomal amphotericin B (AmBisome). Although monotherapy with one of these drugs has commonly been used for the treatment of kala-azar, a combination of these drugs is likely to be used in the near future when the results of ongoing clinical trials become available. Treatment options for PKDL are more limited, and long courses of treatment with SSG are still used.