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.


CONCLUSIONS
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.
Centre for Population, Urbanization and Climate Change, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
Sabeena
S
Ahmed
Sean
S
Galagan
Heather
H
Scobie
Jacob
J
Khyang
Chai Shwai
CS
Prue
Wasif Ali
WA
Khan
Malathi
M
Ram
Mohammad Shafiul
MS
Alam
M Zahirul
MZ
Haq
Jasmin
J
Akter
Gregory
G
Glass
Douglas E
DE
Norris
Myaing Myaing
MM
Nyunt
Timothy
T
Shields
David J
DJ
Sullivan
David A
DA
Sack
D000293:Adolescent; D017677:Age Distribution; D001459:Bangladesh / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D002980:Climate; D003710:Demography; D019353:Endemic Diseases / Q000706:statistics & numerical data*; D062665:Epidemiological Monitoring; D005260:Female; D006798:Housing / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D016015:Logistic Models; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000635:transmission*; D008297:Male; D012621:Seasons; D062211:Spatio-Temporal Analysis