Epidemiology of malaria in Rohingya refugee camps in Bangladesh within 2017-2020.

BACKGROUND: Malaria causes significant morbidity and mortality in tropical and sub-tropical regions, particularly in humanitarian emergencies including refugee camps in malaria endemic areas. An epidemiological investigation was conducted on malaria disease distribution and risk factors in the world's largest refugee settlement, the Rohingya refugee camps on the south-eastern border area of Bangladesh, within 2017-2020. METHODS: From February 2017 to March 2020, 30,460 febrile patients were tested for malaria using light microscopy and rapid diagnostic tests. Most were self-presenting symptomatic patients and a minority were from door-to-door malaria screening. Diagnostic tests were done by trained medical technologists upon the advice of the concerned physicians in the camps. Test positivity rate (%) and annual parasite incidence were calculated and compared using chi-squared (χ 2) test or odds ratios. RESULTS: The overall average annual test positivity rate (TPR) was 0.05%. TPR was highest in people who had travelled to the forest in the previous 2 months, at 13.60%. Cases were clustered among male adults aged 15-60 years. There were no cases among children under five years or pregnant women and no deaths from malaria. CONCLUSION: This study found very few malaria cases among Rohingya refugees with the majority of cases being imported from hilly forested areas, which were thus assumed to act as the reservoir for transmission.

Anti-malarial investigation of Acorus calamus, Dichapetalum gelonioides, and Leucas aspera on Plasmodium falciparum strains.

INTRODUCTION: Malaria is a significant global health concern and adversely affects people in developing countries including Bangladesh. The causative agent Plasmodium falciparum is resistant to several currently available anti-malarial drugs, such as mefloquine, chloroquine, and artemisinin-based combination therapy (ACT), and this has been a major global challenge towards the control of the disease. There is urgent need for novel anti-malarial chemotherapeutic agents. METHODOLOGY: The present study aimed to evaluate antimalarial activity of methanolic extracts of three Bangladeshi medicinal plants- Acorus calamus, Dichapetalum gelonioides and Leucas aspera - against both chloroquine sensitive (3D7) and resistant (Dd2) strains of P. falciparum. Histidine-rich protein 2 (HRP2) based ELISA was used to evaluate the in vitro inhibitory activity of the extracts. RESULTS: D. gelonioides extract showed moderate (IC50 = 19.15 µg/mL) and promising activity (IC50 = 10.43 µg/mL) against 3D7 and Dd2 strains respectively. A. calamus remained inactive against both 3D7 (IC50 = 72.29 µg/mL) and Dd2 strain (IC50 = 67.81 µg/mL). L. aspera initially remained inactive against 3D7 strain (IC50 = 60.51 µg/mL), but displayed promising activity (IC50 = 7.693) against Dd2 strain. CONCLUSIONS: This is the first time these plant materials have been assessed for their in vitro antimalarial properties. It is pivotal to conduct further phytochemical analysis of D. gelonioides and L. aspera to evaluate the presence of potential novel antimalarial drug compounds.

An update of intestinal helminth infections among urban slum communities in Bangladesh.

Aim: To assess the prevalence of intestinal helminth infections and associated risk factors among people living in urban slums in Bangladesh. Methods: A cross-sectional study was conducted across three clusters: Dhaka, Sylhet and Chattogram. In total, 360 individuals divided into two groups (school-aged children and adults) provided stool samples and completed a semi-structured questionnaire. Parasitological assessment was performed using the formol-ether concentration technique. Results: Overall, 31.7% (114/360) of participants had helminthiasis, with 13.3% (48/360) having mixed infections. Among the infected participants, school-aged children had a higher rate of infection (41.7%, 75/180) compared with adults (21.7%, 39/180). Ascaris lumbricoides was the predominant parasite, followed by hookworms, Trichuris trichiura, Hymenolepis nana, Enterobius vermicularis and Rhabditis sp. Parasitic infections were significantly associated with type of latrine used, direct exposure to soil, open defaecation, and presence of free-roaming animals. Conclusion: Despite continuous efforts to control helminthiasis, a substantial proportion of the study participants were infected with intestinal helminths. Ignorance of the roles of the environment and animals was influential, and had a negative impact on existing control interventions. An integrated public health and veterinary public health approach is required for sustainable control of intestinal helminthiasis.

Real-time PCR assay and rapid diagnostic tests for the diagnosis of clinically suspected malaria patients in Bangladesh.

BACKGROUND: More than 95% of total malaria cases in Bangladesh are reported from the 13 high endemic districts. Plasmodium falciparum and Plasmodium vivax are the two most abundant malaria parasites in the country. To improve the detection and management of malaria patients, the National Malaria Control Programme (NMCP) has been using rapid diagnostic test (RDT) in the endemic areas. A study was conducted to establish a SYBR Green-based modified real-time PCR assay as a gold standard to evaluate the performance of four commercially-available malaria RDTs, along with the classical gold standard- microscopy. METHODS: Blood samples were collected from 338 febrile patients referred for the diagnosis of malaria by the attending physician at MatirangaUpazila Health Complex (UHC) from May 2009 to August 2010. Paracheck RDT and microscopy were performed at the UHC. The blood samples were preserved in EDTA tubes. A SYBR Green-based real-time PCR assay was performed and evaluated. The performances of the remaining three RDTs (Falcivax, Onsite Pf and Onsite Pf/Pv) were also evaluated against microscopy and real-time PCR using the stored blood samples. RESULT: In total, 338 febrile patients were enrolled in the study. Malaria parasites were detected in 189 (55.9%) and 188 (55.6%) patients by microscopy and real-time PCR respectively. Among the RDTs, the highest sensitivity for the detection of P. falciparum (including mixed infection) was obtained by Paracheck [98.8%, 95% confidence interval (CI) 95.8-99.9] and Falcivax (97.6%, 95% CI 94.1-99.4) compared to microscopy and real-time PCR respectively. Paracheck and Onsite Pf/Pv gave the highest specificity (98.8%, 95% CI 95.7-99.9) compared to microscopy and Onsite Pf/Pv (98.8, 95% CI 95.8-99.9) compared to real-time PCR respectively for the detection of P. falciparum. On the other hand Falcivax and Onsite Pf/Pv had equal sensitivity (90.5%, 95% CI 69.6-98.8) and almost 100% specificity compared to microscopy for the detection of P. vivax. However, compared to real-time PCR assay RDTs and microscopy gave low sensitivity (76.9%, 95% CI 56.4-91) in detecting of P. vivax although a very high specificity was obtained (99-100%). CONCLUSION: The results of this study suggest that the SYBR Green-based real-time PCR assay could be used as an alternative gold standard method in a reference setting. Commercially-available RDTs used in the study are quite sensitive and specific in detecting P. falciparum, although their sensitivity in detecting P. vivax was not satisfactory compared to the real-time PCR assay.

Plasmodium falciparum Genetic Diversity in Bangladesh Does Not Suggest a Hypoendemic Population Structure.

Despite the recommendation for the use of merozoite surface protein 1 (msp1), merozoite surface protein 2 (msp2), and glutamate-rich protein (glurp) genes as markers in drug efficacy studies by World Health Organization and their limited use in Bangladesh, the circulating Plasmodium falciparum population genetic structure has not yet been assessed in Bangladesh. This study presents a comprehensive report on the circulating P. falciparum population structure based on msp1, msp2, and glurp polymorphic gene markers in Bangladesh. Among the 130 pretreatment (day 0) P. falciparum samples from seven malaria-endemic districts, 14 distinct genotypes were observed for msp1, 20 for msp2, and 13 for glurp Polyclonal infection was reported in 94.6% (N = 123) of the samples. Multiplicity of infection (MOI) for msp1 was the highest (1.5) among the MOIs of the markers. The heterozygosity for msp1, msp2, and glurp was 0.89, 0.93, and 0.83, respectively. Data according to different malaria-endemic areas are also presented and discussed. Bangladesh is considered as a malaria-hypoendemic country. However, the prevalence of polyclonal infection and the genetic diversity of P. falciparum do not represent hypoendemicity.

Relationship between sand fly fauna and kala-azar endemicity in Bangladesh.

An entomological survey was carried out in Mymensingh district which contributes the highest incidence of visceral leishmaniasis (kala-azar) in Bangladesh. For the first time in Bangladesh CDC miniature light trap was used for indoor collection of sand flies. A total of 726 sand fly specimens belonging to nine species, one species of the genus Phlebotomus and eight species Sergentomyia genus were collected. Phlebotomus argentipes Annaandale Brunetti made up 59.2% of the total collection. Among Sergentomyia species Sergentomyia shorttii Adler & Theodor contributed 14.4% of the total collection. Density of sand flies both vector and non-vector species were significantly higher in endemic areas than non-endemic areas.