Preliminary in vitro antiplasmodial activity of Aristolochia griffithii and Thalictrum foliolosum DC extracts against malaria parasite Plasmodium falciparum.

BACKGROUND: Resistance development in human malaria parasites against commonly used antimalarial drugs has necessitated the scientific exploration of traditionally used antimalarial plants. Plant derivatives have been used for curing malaria historically. The present study involves in vitro evaluation of two medicinally important plants Aristolochia griffithii and Thalictrum foliolosum DC used in antimalarial chemotherapy by the tribes of northeast India. METHOD: Chloroform, ethyl acetate and n-butanol extracts of Aristolochia griffithii and Thalictrum foliolosum DC were evaluated in vitro against chloroquine sensitive (SS) and chloroquine resistance strains (RS) of P. falciparum. The tests were conducted following WHO standard method and the inhibition of parasite (IC50) was calculated. RESULTS: In A. griffithii, the IC50 value for ethyl acetate extracts against SS was 6.2 ± 0.02 µg/ml and found to be lower than chloroform extracts, which exhibited an IC50 value of 14.1 ± 0.1 µg/ml (t = 191.1; p < 0.0001). The IC50 values of both chloroform and ethyl acetate extracts for RS were higher as compared to the SS (p < 0.0001). In T. foliolosum DC the IC50 concentration of chloroform extracts for SS and RS were 0.5 ± 0.0 and 1.1 ± 0.0 µg/ml respectively (t = 54.2; p < 0.0001). CONCLUSION: The present findings, although preliminary, but scientifically demonstrate that identification and isolation of active compounds of these two plant materials and testing against different Plasmodium species could lead to the development of potential antimalarial drugs for future.

Synergistic mosquito-repellent activity of Curcuma longa, Pogostemon heyneanus and Zanthoxylum limonella essential oils.

Mosquito repellents play an important role in preventing man-mosquito contact. In the present study, we evaluated the synergistic mosquito-repellent activity of Curcuma longa, Pogostemon heyneanus and Zanthoxylum limonella essential oils. The mosquito repellent efficacies of three essential oils were evaluated separately and in combination under laboratory and field conditions. N,N-Diethylphenylacetamide (DEPA) and dimethylphthalate (DMP) were used for comparison of the protection time of the mixture of essential oils. At an optimum concentration of 20%, the essential oils of C. longa, Z. limonella and P. heyneanus provided complete protection times (CPTs) of 96.2, 91.4 and 123.4 min, respectively, against Aedes albopictus mosquitoes in the laboratory. The 1:1:2 mixture of the essential oils provided 329.4 and 391.0 min of CPT in the laboratory and field trials, respectively. The percent increases in CPTs for the essential oil mixture were 30 for DMP and 55 for N,N-diethylphenylacetamide (DEPA). The synergistic repellent activity of the essential oils used in the present study might be useful for developing safer alternatives to synthetic repellents for personal protection against mosquitoes.

Prioritizing areas for malaria control using geographical information system in Sonitpur district, Assam, India.

OBJECTIVE: To identify the malaria hot spots at health subcentre level in an endemic district using a geographical information system (GIS). The results will be useful for rapid retrieval of malaria information, and to prioritize malaria control efforts in identified hot spots. STUDY DESIGN: Extraction, analysis and synthesis of relevant data. METHODS: Malaria epidemiological data from 2006 to 2009 were analysed to determine the annual parasitic index, slide positivity rate, annual blood examination rate and Plasmodium falciparum percentage for each health subcentre in the district. Maps were produced using GIS, and integrated to identify the malaria hotspots. RESULTS: Out of 288 health subcentres, GIS identified 10 hot spots at extremely high risk of malaria and 14 hot spots at high risk of malaria. Malaria may flare up in these hot spots whenever favourable transmission conditions arise. Health authorities have been advised to establish control measures in these selected hot spots for timely prevention. CONCLUSION: There is a need for adequate monitoring and allocation of available resources for better interventions in the malaria hotspots. The GIS model used in this study can be used, even at village or cluster level, to pin point the malaria hot spots, and information can be updated and retrieved easily.

DDT & deltamethrin resistance status of known Japanese encephalitis vectors in Assam, India.

BACKGROUND & OBJECTIVE: Japanese encephalitis (JE) outbreaks are common in Assam, northeastern State of India. Information on resistance in known JE vectors in the affected area is important for effective control measures. This study was undertaken to determine the species abundance of JE vectors endemic to Sibsagar district of Assam, and their susceptibility against DDT and deltamethrin. METHODS: Adult mosquitoes were collected using CDC light trap and aspirators from human dwellings from 13 endemic villages falling under three Primary Health Centres. Collected mosquitoes were identified and unfed female mosquitoes were used for DDT and deltamethrin sensitivity bioassay. The bioassay was performed following WHO protocol using standard susceptibility test kit. Knockdown time (KDT) was monitored at every 10 minutes intervals, whereas mortalities were recorded 24 h post-exposure. Vector density and resistance status were mapped using geographic information system (GIS) technique. RESULTS: A total of 7655 mosquitoes were sampled under three genera, i.e. Anopheles, Culex and Mansonia, and nine species, the JE vector Cx. vishnui group (31.78%) was the most predominant species, followed by Ma. uniformis (16.81%) and Ma. indiana (16.45%). All vector species were suspected to be resistant to DDT and sensitive to deltamethrin, except Ma. indiana, which was suspected to deltamethrin resistant. The KDT50 and KDT95 values of vector mosquitoes for DDT were significantly higher as compared to deltamethrin. The probit model used to estimate KDT50 and KDT95 values did not display normal distribution of percentage knockdown with time for all the vectors tested for DDT and deltamethrin, except for Ma. indiana for deltamethrin assay and Cx. gelidus for the DDT assay. INTERPRETATION & CONCLUSION: Differences in insecticide resistance status were observed between insecticides and vector species. The results of this study provided baseline data on insecticide resistance in known JE vectors of Sibsagar, Assam. The maps generated may allow better communication in control operations and comparison of changes in susceptibility status of these vectors over time.

Emergence of multidrug-resistant NDM-1-producing Gram-negative bacteria in Bangladesh.

The main objective of this study was to investigate the prevalence of bla (NDM-1) in Gram-negative bacteria in Bangladesh. In October 2010 at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) laboratories, 1,816 consecutive clinical samples were tested for imipenem-resistant Gram-negative organisms. Imipenem-resistant isolates were tested for the bla (NDM-1) gene. Among 403 isolates, 14 (3.5 %) were positive for bla (NDM-1), and the predominant species were Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli. All bla (NDM-1)-positive isolates were resistant to multiple antibiotics. Among ß-lactamase genes, bla (CTX-M-1-group) was detected in ten isolates (eight bla (CTX-M-15)), bla (OXA-1-group) in six, bla (TEM) in nine, bla (SHV) in seven, and bla (VIM) and bla (CMY) in two isolates each. The 16S rRNA methylase gene, armA, was detected in five K. pneumoniae isolates and in one E. coli isolate. rmtB and rmtC were detected in a Citrobacter freundii and two K. pneumoniae isolates, respectively. qnr genes were detected in two K. pneumoniae isolates (one qnrB and one qnrS) and in an E. coli isolate (qnrA). Transferable plasmids (60-100 MDa) carrying bla (NDM-1) were detected in 7 of the 11 plasmid-containing isolates. Pulsed-field gel electrophoresis (PFGE) analysis grouped K. pneumoniae isolates into three clusters, while E. coli isolates differed significantly from each other. This study reports that approximately 3.5 % of Gram-negative clinical isolates in Bangladesh are NDM-1-producing.

A cross sectional investigation of malaria epidemiology among seven tea estates in Assam, India.

In the present investigation, the epidemiology of malaria among seven tea estates of Nagaon and Udalguri districts of Assam, India has been described. A cross-sectional open study was carried out to understand the malaria epidemiology and associated risk factors among the tea tribes during March to September 2009. Out of 1,182 peripheral blood smears examined, 506 found positive for malaria (slide positivity rate, SPR = 42.8) with Plasmodium falciparum as predominant species. Dimakuchi tea estate was having highest SPR (P = 0.0275) and contributed more number of P. falciparum cases (P < 0.00001). Tea estates studied in both Udalguri and Nagaon districts were equally affected and the SPR recorded were 41.75 and 43.32% respectively. 154 malaria cases detected were having 'O' blood group but each blood group was found to have similar susceptibility of acquiring malaria infection (χ(2 ) = 3.603; P = 0.3076) and P. falciparum infection (χ(2 ) = 1.818; P = 0.6110). The SPR was highest among children more than 2 years of age group and variation in SPR among the age groups was statistically significant (χ(2 ) = 17.186; P = 0.0018). No gender biasing was observed in malaria distribution. Anemia was found associated with the infection among both the sexes. The findings suggest that tea estates are endemic for stable malaria transmission primarily due to P. falciparum and the prevalence rate decline with age, suggesting the development of protective immunity. Promising intervention measures could be able to reduce the malaria prevalence effectively in the study areas.

Diversity and seasonal densities of vector anophelines in relation to forest fringe malaria in district Sonitpur, Assam (India).

The prevalence and bionomics of known Indian malaria vector anophelines was studied in three forest fringe villages in Sonitpur district of Assam, India. Anopheles philippinensis/nivipes (36.8%) and An. annularis (25.6%) were the most abundant of the seven vector anopheline species recorded. Densities of vector anophelines in general were high during monsoon season and low during winter months. An. dirus s.l. was the most anthropophagic (91.6%) of all the species collected whereas, An. annularis, An. fluviatilis s.l. and An. varuna were predominantly zoophagic. The highest and the lowest slide positivity rates (SPR) was recorded during monsoon (36%) and winter (12.5%) seasons, respectively. SPR was positively correlated with vector anopheline densities (r = 0.902), which itself was found to be correlated with mean minimum temperature and relative humidity (RH).

Malaria situation in forest-fringed villages of Sonitpur district (Assam), India bordering Arunachal Pradesh during an outbreak.

BACKGROUND & OBJECTIVES: Epidemiological and entomological studies were undertaken in forest-fringed villages in Sonitpur district (Assam) bordering Arunachal Pradesh, India to assess the malaria situation. Blood smears (thick and thin) were collected from the fever cases through door-to-door survey. Both the blood smears stained with Giemsa were used for malaria parasite detection. Slide positivity rate (SPR) was recorded as 39.1% with predominance of Plasmodium falciparum (97.1%) infections. Children between 5 and 14 yr showed higher rates of infection. METHODS & RESULTS: Over all malaria prevalence was higher among the males (SPR 43.2%) than in females (SPR 34.5%). Adult mosquito collection was made using CDC miniature light-traps from dusk-to-dawn. Per-trap night density of mosquitoes in human dwellings and cattlesheds were 289 and 925, respectively. Anopheles minimus and An. dirus, the major vectors of malaria in Northeastern region of India formed 33.2% of the total vectors recorded. An. dirus could be recorded only from human dwellings. The results showed high malaria risk in the study villages. INTERPRETATION & CONCLUSION: High vector density with high parity rate, poor socio-economic conditions, lack of awareness, poor sanitation and congenial atmosphere for mosquito proliferation are aggravating the malaria situation in the study area.

The drug sensitivities of Plasmodium falciparum in the Sonitpur district, Assam, India.

Falciparum malaria is an ongoing problem in the foothills of Northeast India. Evaluation of the drug sensitivities of P. falciparum was carried out in four endemic villages of the Sonitpur District of Assam, involving 218 cases who were tested in vivo over 35 days. Chloroquine resistance was detected at the RI level in 29 cases (13%) and RII level in 8 cases (4%). No RIII chloroquine resistant cases were detected in the study. RI resistance was observed in the age groups 6-10 years, 11-14 years, and 15 years and above in 16%, 17%, and 13%, respectively. RII level resistance was observed in 4% of all those groups combined. All the RI and RII resistant cases responded well to a single dosage of Metakelfin (sulfamethoxypyrazine I.P 1,500 mg and pyrimethamine I.P 75 mg).

Epidemiological and entomological aspects of malaria in forest-fringed villages of Sonitpur district, Assam.

BACKGROUND & OBJECTIVES: Detailed epidemiological and entomological studies were undertaken in forest-fringed villages and a Tea Estate in Sonitpur, Assam to assess the malaria situation. METHODS: Door-to-door active surveillance was carried out to collect blood samples. Thick and thin blood smears stained with Giemsa were used for malaria parasite detection. Mosquito collections were made using CDC miniature light-traps and hand catch methods from dusk-to-dawn. RESULTS: 48% SPR, 49.1 Pf% was recorded from the study villages. Children between 10 and 14 years were most sufferers. Per trap night density of mosquitoes in human dwellings was 204.3 and in cattlesheds--908.7, An. minimus accounted for 20.7% of total malaria vectors. INTERPRETATION & CONCLUSION: The results showed high malaria risk in the study villages. High vector density with high parity rate, poor socio-economic conditions, lack of awareness, poor sanitation and congenial atmosphere for mosquito proliferation are aggravating the malaria situation more complex in the study area.

Evaluation of botanicals as repellents against mosquitoes.

Repellent properties of three plant extracts--essential oil (steam distillate) of Zanthoxylum limonella (fruits), Citrus aurantifolia (leaf) and petroleum ether extract of Z. limonella (fruits) were evaluated as repellent against Aedes (S.) albopictus mosquitoes in mustard (Dhara) and coconut (Parachute) oil base under laboratory conditions. Three concentrations--10, 20 and 30% of the repellents were evaluated. Repellents in mustard oil afforded longer protection time against the bites of Aedes (S.) albopictus mosquitoes than those in coconut oil. At 30% concentration, 296-304 min protection time was achieved by the test repellents in mustard oil base while repellents in coconut oil exhibited 223.5-245 min protection time at the same concentration. Oil of Z. limonella gave the highest protection time against the bites of Aedes (S.) albopictus mosquitoes at all the concentrations than other herbal repellents tested both in mustard and coconut oil.

Field evaluation of herbal mosquito repellents.

Repellent properties of Zanthoxylum armatum DC. Syn. Z. alatum Roxb. (Timur), Curcuma aromatica (Jungli haldi) and Azadirachta indica (Neem) oils were evaluated against mosquitoes in mustard (Brassica sp.) and coconut (Cocos sp.) oil base and compared with synthetic repellent. Dimethyl phthalate (DMP) as standard. Timur and jungli haldi afforded better protection in the both the base at all the concentrations. Tepellents in mustard oil gave longer protection time than those in coconut oil. At 0.57 mg/cm2 concentration timur oil gave significantly higher protection both in mustard (445 min) as well as coconut oil (404 min) than the other repellents and DMP.

Role of Anopheles culicifacies during an outbreak of malaria in Gorubandha P.H.C., Assam.

Entomological investigation during an outbreak of malaria in Gorubandha PHC in Sonitpur district revealed unusually high density of Anopheles culicifacies followed by An.minimus. Parity rates of both the species were very high, 65% and 62.2% respectively. An. culicifacies was incriminated as malaria vector. Sporozoite rate recorded was 0.63%. Both the species were found susceptible to DDT. This substantiates the epidemiological observation which yielded 98% Plasmodium falciparum malaria out of 35.2% malaria positive cases. Incrimination of An. culicifacies means adding one more malaria vector to this region.

Age of marriage and length of the first birth interval in a traditional Indian society: life table and hazards model analysis.

The length of the first birth interval is one of the strongest and most persistent factors affecting fertility in noncontracepting populations, with longer intervals usually associated with lower fertility. Compared to Western society, the average length of the first birth interval is much longer in traditional Indian society. Yet Indian fertility rates are higher because of either ineffective family planning procedures or deliberate nonuse of birth control and because of the high proportion of the population that is married. Here, we examine the effects of various sociodemographic covariates (with an emphasis on the role of age at marriage) on the length of the first birth interval for two states of India: Assam and Uttar Pradesh. Life table and multivariate hazards modeling techniques are applied to the data. Covariates such as age at marriage, present age of mother, female's occupation, family income, and place of residence have strong effects on the variation of the length of the first birth interval. For each subgroup of females (classified according to different levels of the covariates), the median length of the first birth interval for the Assam (Bengali-speaking) sample is shorter than that of the Uttar Pradesh (Hindi-speaking) sample.

PIP: Indian marriage customs vary by religion, caste, geographic location, and educational background. This study examined the effects of age at marriage and socioeconomic factors on the interval to first birth in Assam and Uttar Pradesh (UP) states. Data were obtained on Bengali-speaking scheduled castes (the lowest castes) in Assam and Hindu-speaking scheduled castes in UP from a 1988-89 survey in Assam and a 1987-88 survey in UP. The Assam survey included 1805 scheduled caste households and the UP survey included 3931 households (1143 scheduled castes). Income is grouped as very poor (under 50 rupees), poor, middle, and rich (over 100 rupees). Cox's proportional hazard models expressed the relative risks of time to first birth. Marriage age underwent a change, with the greatest differences occurring among younger, illiterate, working class Manasudra subclass women in the highest income and middle status groups living in Ghazipur district. The life table methods of Namboordiri and Suchindran were used to calculate median lengths of birth intervals and revealed that Assam women have shorter intervals. The shortest intervals were among Assam working mothers, and the longest intervals were among Assam females of other subcastes. In UP, the shortest birth interval was among literate mothers, and the longest interval (49 months) was among younger mothers. Nearly 7% of women did not give birth within 97 months. As marriage age increased, the birth interval shortened. In Assam, the birth interval was significantly related to marriage ages under 13 years, 14 years, and 15-16 years; the present age of the mother, mother's occupation, other subcaste group; and the very poor and middle income group. In UP, the significant factors explaining birth interval were marriage ages of under 13 years and 14 years, present age of the mother, and mothers living in Ghazipur district. The relative risks of first birth for mothers in marriage age groups under 13 years, 14 years, and 15-16 years was 0.58, 0.77, and 0.88 respectively. Mothers in UP had similar risks in the first two age groups.

Breastfeeding and postpartum amenorrhea in a traditional society: a hazards model analysis.

There is considerable variation in the length of the postpartum amenorrhea during which breastfeeding suppresses fertility, both within and between societies. In this paper, we investigate the association between breastfeeding and the resumption of menses and the impact of various biological and social covariates thereon, using data from two retrospective surveys in India. We use both univariate life table and multivariate time-dependent hazards techniques to analyze the data. Most prior investigations related the impact of breastfeeding to postpartum amenorrhea by taking duration of breastfeeding as a fixed covariate. However, breastfeeding beyond the resumption of menstruation cannot affect the duration of menses. Accordingly, the present study has a methodological focus in the sense that breastfeeding is treated as a time-dependent covariate. We found that breastfeeding, age of mother at child's birth, social status, level of income, religion and caste (subcaste), and residential status have significant effects on return of menses in Indian traditional society.

PIP: Breastfeeding is thought to be the major determinant of prolonged postpartum amenorrhea (PPA) and anovulation in societies where nursing is virtually universal, prolonged, and of high intensity. Considerable variation, however, exists within and between societies in the length of PPA during which breastfeeding suppresses fertility. The authors investigate the association between breastfeeding and the resumption of menses and the impact of various biological and social covariates thereon. Findings are based upon data drawn from 2 retrospective surveys conducted in India over the period 1987-89 and analyzed with both univariate life table and multivariate time-dependent hazards techniques. Since breastfeeding beyond the resumption of menstruation cannot affect the duration of menses, this study treats breastfeeding as a time-dependent covariate. Analysis revealed that breastfeeding, age of mother at child's birth, social status, level of income, religion and caste, and residential status have significant effects on the return of menses in Indian traditional society.

A model that fits female age at first marriage in a traditional society.

"The female age at marriage is an important variable in the human reproduction process--especially in traditional societies in which almost all births occur within the marital context. This paper uses the Type I extreme value distribution to describe the female age at marriage pattern of a traditional society in India. A procedure to obtain maximum likelihood estimation of the parameters of the model is discussed. The model is found to be suitable for estimation of the observed proportion of ever married females, mean, median and model age at marriage."

Household structure and family pattern of a traditional society.

"In this paper, [the] main aim is to examine the household structure and family units of a scheduled caste population--a traditional society of India--with the help of survey data. Data [are] from a socio-demographic survey [of a] scheduled caste population residing in the rural areas of Assam." Information is provided on types of households and family units; residence pattern and household structure; and household size.

Mosquito survey in Tripura.

Vector survey carried out in Tripura revealed the presence of 17 species of anophelines with a density of 92.39 per trap night. Major malaria vector encountered was Anopheles philippinensis which formed 30% of the total collection and is exophagic in nature. Another efficient malaria vector An. minimus which formed 5% of the total collection prevails equally both indoors and outdoors. The high parity rate of An. philippinensis (59%) and An. minimus (63.9%) gives a strong indication about their vectorial status in Tripura.

Studies on malaria and filariasis vectors in Kamorta and Great Nicobar Islands.

A total of 1401 adult mosquitoes mainly dominated by Anopheles sundaicus (40.18%) and Culex quinquefasciatus (57.31%) were collected from Kamorta and Great Nicobar Islands. It was revealed from human bait collection that both species prevailed almost all through the night (density 8.1/man hour) with a peak around midnight. Mixed breeding of A. sundaicus with A. vagus, Cx. quinquefasciatus, Cx. bitaeniorhynchus and Cx. tritaeniorhynchus was observed at many places. Adult A. sundaicus were found highly susceptible to DDT and larvae to Temephos (Abate). Cx. quinquefasciatus was resistant to DDT (31% mortality). High parity of A. sundaicus (40.42%) is an indication of the vectorial potential of this species to sustain malaria transmission in these islands.