Jasmin Akter

Association between Cryptosporidium infection and human leukocyte antigen class I and class II alleles.

BACKGROUND Cryptosporidium species are a common cause of diarrhea, which can be severe and protracted in young children and immunocompromised individuals. METHODS A cohort of 226 Bangladeshi children aged 2-5 years was prospectively followed for >3 years to study the role of host genetics in susceptibility to infection, as well as the community impact of cryptosporidiosis on this population. RESULTS Ninety-six children (42.5%) received a diagnosis of Cryptosporidium infection. A total of 51 (22.6%) had asymptomatic infection. Fifty-eight (25.7%) had cryptosporidiosis, of whom 17 (29.3%) had recurrent disease. Children with cryptosporidiosis presented early, and most had abdominal pain and a short course of diarrhea. Infected children were more likely to carry the human leukocyte antigen (HLA) class II DQB1*0301 allele, particularly those with both asymptomatic and symptomatic infection (P = .009); a strong association was found between carriage of the DQB1*0301/DRB1*1101 haplotype and development of both asymptomatic and symptomatic infection (P = .009). Infected children were also more likely to carry the B*15 HLA class I allele. CONCLUSIONS This is the first study to describe a possible genetic component of the immune response to Cryptosporidium infection, which includes HLA class I and II alleles. Cryptosporidiosis in Bangladeshi children aged 2-5 year is common and often recurrent, but the duration is shorter and the abdominal pain greater than that described in children aged <2 years.

Azithromycin Combination Therapy for the Treatment of Uncomplicated Falciparum Malaria in Bangladesh: An Open-Label Randomized, Controlled Clinical Trial

BACKGROUND In recent studies, the combination of azithromycin and artesunate has proven to be a promising alternative for the treatment of uncomplicated falciparum malaria. METHODS We conducted a randomized, controlled clinical trial assessing the efficacy of azithromycin-artesunate combination therapy. The study was conducted involving 228 patients aged 8-65 years. Patients were randomized to 1 of 2 cohorts at a ratio of 2:1, receiving either azithromycin-artesunate once daily for 3 days (30 mg/kg per day of azithromycin plus 4 mg/kg per day of artesunate) or an adult dose of 80 mg of artemether plus 960 mg of lumefantrine (4 tablets Coartem or the equivalent for children weighing <35 kg) twice daily for 3 days. RESULTS The 42-day cure rate by Kaplan-Meier analysis was 94.6% (95% confidence interval [CI], 89.38%-97.44%) in the azithromycin-artesunate arm and 97.0% (95% CI, 89.45%-99.40%) in the control arm. Fever clearance times and parasite clearance times did not show any differences between the 2 arms (P=.59 and .95, respectively). No serious adverse events were seen, but the percentage of patients who developed any adverse event was higher in the control group (P=.03). CONCLUSIONS Our data suggest that azithromycin-artesunate is an efficacious and well-tolerated treatment for patients with uncomplicated falciparum malaria in Bangladesh.

Mapping hypoendemic, seasonal malaria in rural Bandarban, Bangladesh: a prospective surveillance.

BackgroundUntil recently the Chittagong Hill tracts have been hyperendemic for malaria. A past cross-sectional RDT based survey in 2007 recorded rates of approximately 15%. This study was designed to understand the present epidemiology of malaria in this region, to monitor and facilitate the uptake of malaria intervention activities of the national malaria programme and to serve as an area for developing new and innovative control strategies for malaria.MethodsThis research field area was established in two rural unions of Bandarban District of Bangladesh north of Bandarban city, which are known to be endemic for malaria due to Plasmodium falciparum. The project included the following elements: a) a demographic surveillance system including an initial census with updates every four months, b) periodic surveys of knowledge attitude and practice, c) a geographic information system, d) weekly active and continuous passive surveillance for malaria infections using smears, rapid tests and PCR, f) monthly mosquito surveillance, and e) daily weather measures. The programme included both traditional and molecular methods for detecting malaria as well as lab methods for speciating mosquitoes and detecting mosquitoes infected with sporozoites.ResultsThe demographic surveillance enumerated and mapped 20,563 people, 75% of which were tribal non-Bengali. The monthly mosquito surveys identified 22 Anopheles species, eight of which were positive by circumsporozoite ELISA. The annual rate of malaria was close to 1% with 85% of cases in the rainy months of May-October. Definitive clustering identified in the low transmission season persisted during the high transmission season.ConclusionThis demographically and geographically defined area, near to the Myanmar border, which is also hypoendemic for malaria, will be useful for future studies of the epidemiology of malaria and for evaluation of strategies for malaria control including new drugs and vaccines.

Malaria hotspots drive hypoendemic transmission in the Chittagong Hill Districts of Bangladesh.

Background Malaria is endemic in 13 of 64 districts of Bangladesh, representing a population at risk of about 27 million people. The highest rates of malaria in Bangladesh occur in the Chittagong Hill Districts, and Plasmodium falciparum (predominately chloroquine resistant) is the most prevalent species. Methods The objective of this research was to describe the epidemiology of symptomatic P. falciparum malaria in an area of Bangladesh following the introduction of a national malaria control program. We carried out surveillance for symptomatic malaria due to P. falciparum in two demographically defined unions of the Chittagong Hill Districts in Bangladesh, bordering western Myanmar, between October 2009 and May 2012. The association between sociodemographics and temporal and climate factors with symptomatic P. falciparum infection over two years of surveillance data was assessed. Risk factors for infection were determined using a multivariate regression model. Results 472 cases of symptomatic P. falciparum malaria cases were identified among 23,372 residents during the study period. Greater than 85% of cases occurred during the rainy season from May to October, and cases were highly clustered geographically within these two unions with more than 80% of infections occurring in areas that contain approximately one-third of the total population. Risk factors statistically associated with infection in a multivariate logistic regression model were living in the areas of high incidence, young age, and having an occupation including jhum cultivation and/or daily labor. Use of long lasting insecticide-treated bed nets was high (89.3%), but its use was not associated with decreased incidence of infection. Conclusion Here we show that P. falciparum malaria continues to be hypoendemic in the Chittagong Hill Districts of Bangladesh, is highly seasonal, and is much more common in certain geographically limited hot spots and among certain occupations.

Hemoglobin E and Glucose-6-Phosphate Dehydrogenase Deficiency and Plasmodium falciparum Malaria in the Chittagong Hill Districts of Bangladesh

Hemoglobin E is largely confined to south and southeast Asia. The association between hemoglobin E (HbE) and malaria is less clear than that of hemoglobin S and C. As part of a malaria study in the Chittagong Hill Districts of Bangladesh, an initial random sample of 202 individuals showed that 39% and 49% of Marma and Khyang ethnic groups, respectively, were positive for either heterozygous or homozygous hemoglobin E. In this group, 6.4% were also found to be severely deficient and 35% mildly deficient for glucose-6-phosphate dehydrogenase (G6PD). In a separate Plasmodium falciparum malaria case-uninfected control study, the odds of having homozygous hemoglobin E (HbEE) compared with normal hemoglobin (HbAA) were higher among malaria cases detected by passive surveillance than age and location matched uninfected controls (odds ratio [OR] = 5.0, 95% confidence interval [CI] = 1.07-46.93). The odds of heterozygous hemoglobin E (HbAE) compared with HbAA were similar between malaria cases and uninfected controls (OR = 0.71, 95% CI = 0.42-1.19). No association by hemoglobin type was found in the initial parasite density or the proportion parasite negative after 2 days of artemether/lumefantrine treatment. HbEE, but not HbAE status was associated with increased passive case detection of malaria.

Asymptomatic Plasmodium falciparum Malaria in Pregnant Women in the Chittagong Hill Districts of Bangladesh

Background Pregnancy is a known risk factor for malaria which is associated with increased maternal and infant mortality and morbidity in areas of moderate-high malaria transmission intensity where Plasmodium falciparum predominates. The nature and impact of malaria, however, is not well understood in pregnant women residing in areas of low, unstable malaria transmission where P. falciparum and P. vivax co-exist. Methods A large longitudinal active surveillance study of malaria was conducted in the Chittagong Hill Districts of Bangladesh. Over 32 months in 2010–2013, the period prevalence of asymptomatic P. falciparum infections was assessed by rapid diagnostic test and blood smear and compared among men, non-pregnant women and pregnant women. A subset of samples was tested for infection by PCR. Hemoglobin was assessed. Independent risk factors for malaria infection were determined using a multivariate logistic regression model. Results Total of 34 asymptomatic P. falciparum infections were detected by RDT/smear from 3,110 tests. The period prevalence of asymptomatic P. falciparum infection in pregnant women was 2.3%, compared to 0.5% in non-pregnant women and 0.9% in men. All RDT/smear positive samples that were tested by PCR were PCR-positive, and PCR detected additional 35 infections that were RDT/smear negative. In a multivariate logistic regression analysis, pregnant women had 5.4-fold higher odds of infection as compared to non-pregnant women. Malaria-positive pregnant women, though asymptomatic, had statistically lower hemoglobin than those without malaria or pregnancy. Asymptomatic malaria was found to be evenly distributed across space and time, in contrast to symptomatic infections which tend to cluster. Conclusion Pregnancy is a risk factor for asymptomatic P. falciparum infection in the Chittagong Hill Districts of Bangladesh, and pregnancy and malaria interact to heighten the effect of each on hemoglobin. The even distribution of asymptomatic malaria, without temporal and spatial clustering, may have critical implications for malaria elimination strategies.

Genotyping of Plasmodium falciparum using antigenic polymorphic markers and to study anti-malarial drug resistance markers in malaria endemic areas of Bangladesh

BackgroundIn the past many regions of Bangladesh were hyperendemic for malaria. Malaria control in the 1960s to 1970s eliminated malaria from the plains but in the Chittagong Hill Tracts remained a difficult to control reservoir. The Chittagong Hill Tracts have areas with between 1 and 10% annual malaria rates, predominately 90-95% Plasmodium falciparum. In Southeast Asia, multiplicity of infection for hypo-endemic regions has been approximately 1.5. Few studies on the genetic diversity of P. falciparum have been performed in Bangladesh. Anderson et al. performed a study in Khagrachari, northern Chittagong Hill Tracts in 2002 on 203 patients and found that parasites had a multiplicity of infection of 1.3 by MSP-1, MSP-2 and GLURP genotyping. A total of 94% of the isolates had the K76T Pfcrt chloroquine resistant genotype, and 70% showed the N86Y Pfmdr1 genotype. Antifolate drug resistant genotypes were high with 99% and 73% of parasites having two or more mutations at the dhfr or dhps loci.MethodsNested and real-time polymerase chain reaction (PCR) methods were used to genotype P. falciparum using antigenic polymorphic markers and to study anti-malarial drug resistance markers in malaria endemic areas of Bangladesh.ResultsThe analysis of polymorphic and drug resistant genotype on 33 paired recrudescent infections after drug treatment in the period 2004 to 2008 in the Chittagong Hill Tracts, which is just prior to countrywide provision of artemisinin combination therapy. Overall the multiplicity of infection for MSP-1 was 2.7 with a slightly smaller parasite diversity post-treatment. The 13 monoclonal infections by both GLURP and MSP-1 were evenly divided between pre- and post-treatment. The MSP-1 MAD block was most frequent in 66 of the samples. The prevalence of the K76T PfCRT chloroquine resistant allele was approximately 82% of the samples, while the resistant Pfmdr1 N86Y was present in 33% of the samples. Interestingly, the post-treatment samples had a small but significantly higher frequency of the sensitive PfCRT alleles by RT-PCR.ConclusionThe parasite population retains high population diversity despite hypo-endemic transmission with retention, but decrease in the chloroquine-resistant allele and Pfmdr1 resistant alleles in the Chittagong Hill Tracts of Bangladesh.

The practice of Jhum cultivation and its relationship to plasmodium falciparum infection in the Chittagong Hill Districts of Bangladesh

Malaria is endemic in the Chittagong Hill Districts of southeastern Bangladesh. Previous epidemiological analyses identified the agricultural practice of jhum cultivation as a potential risk factor for malaria infection. We conducted qualitative interviews with jhum cultivators and surveillance workers to describe jhum cultivation and used demographic and malaria surveillance in two study unions from May of 2010 to August of 2012 to better understand the relationship between jhum cultivation and malaria infection. Qualitative interviews revealed that jhum cultivation is conducted on remote, steep hillsides by ethnic tribal groups. Quantitative analyses found that adult jhum cultivators and individuals who live in the same residence had significantly higher incidence rates of symptomatic Plasmodium falciparum infection compared with non-cultivators. These results confirm that jhum cultivation is an independent risk factor for malaria infection and underscore the need for malaria testing and treatment services to reach remote populations in the Chittagong Hill Districts.

Plasmodium falciparum, vivax and malariae detection during the low transmission season in the hill tracts of Bangladesh

A recent active cross sectional survey by a rapid diagnostic test (RDT) in 2007 showed crude malaria prevalence is 11% among the 1.5 million people most at risk for malaria in Bangladesh. An active randomized population malaria surveillance was initiated by JHMRI and ICDDR,B in Kuhalong union near hypoendemic Bandabarn in the Chittagong hill tracts of Bangladesh. The population of Kuhalong is 11,000 with approximately 2,000 households which were enumerated in a baseline census with a GIS mapping component. A demographic surveillance system and knowledge attitude and practice surveys have been obtained as part of the project to follow mosquito vectors by monthly trapping, host susceptibility factors and malariometrics. Here we present results from weekly malariometrics during the October to March low transmission season in the age groups of less than 5, 5 to 15 and greater than 15 years. Microscopy, RDT and real-time PCR was performed on active surveillance showing approximately 2% positive rates by microscopy or RDT in close to 500 individuals. A real-time PCR assay detected 6% prevalence. The sensitivity of the RT-PCR in the 96-well format was increased to 10-100 parasites per microliter with a glycogen/ acetate DNA precipitation at low speed tabletop centrifugation after column extraction. We detected P. vivax and P. malariae in less than 5% of the malaria positive patient samples by RT-PCR. All the P. falciparum isolates were chloroquine resistant PfCRT K76T genotype and atovaquone sensitive PfCYTb 268Y by fluorescent TAQman probe analysis. A reverse transcriptase real-time PCR assay from dried blood on filter papers was able to detect gametocytes. Studies on malaria seropositivity rates are in progress. In summary, a significant asymptomatic malaria PCR positive population exists. The role of this subpopulation in contributing to continuing transmission is being evaluated. Chloroquine resistance is fixed in this geographic area still responsive to artemisinin combination therapy.

Subclinical Plasmodium falciparum infections act as year-round reservoir for malaria in the hypoendemic Chittagong Hill districts of Bangladesh

OBJECTIVES An analysis of the risk factors and seasonal and spatial distribution of individuals with subclinical malaria in hypoendemic Bangladesh was performed. METHODS From 2009 to 2012, active malaria surveillance without regard to symptoms was conducted on a random sample (n=3971) and pregnant women (n=589) during a cohort malaria study in a population of 24000. RESULTS The overall subclinical Plasmodium falciparum malaria point prevalence was 1.0% (n=35), but was 3.2% (n=18) for pregnant women. The estimated incidence was 39.9 per 1000 person-years for the overall population. Unlike symptomatic malaria, with a marked seasonal pattern, subclinical infections did not show a seasonal increase during the rainy season. Sixty-nine percent of those with subclinical P. falciparum infections reported symptoms commonly associated with malaria compared to 18% without infection. Males, pregnant women, jhum cultivators, and those living closer to forests and at higher elevations had a higher prevalence of subclinical infection. CONCLUSIONS Hypoendemic subclinical malaria infections were associated with a number of household and demographic factors, similar to symptomatic cases. Unlike clinical symptomatic malaria, which is highly seasonal, these actively detected infections were present year-round, made up the vast majority of infections at any given time, and likely acted as reservoirs for continued transmission.