Typing of Plasmodium falciparum DNA from 2 years old Giemsa‑stained dried blood spots using nested polymerase chain reaction assay.

A panel of 129 Giemsa‑stained thick blood spots (TBS) confirmed for Plasmodium falciparum infection having different levels of parasite density were collected from a malaria endemic area. DNA was extracted and nested polymerase chain reaction (PCR) assay was performed to amplify P. falciparum DNA. Nested PCR assay successfully amplified P. falciparum DNA at a very low parasitaemia of ~10 parasites/μl of blood. Current PCR assay is very simple and can be used retrospectively to monitor the invasion and prevalence of different Plasmodium species in endemic areas.

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).

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.

Laboratory and field evaluation of Bacillus thuringiensis and B. sphaericus against mosquito larvae.

Laboratory and field trials were carried out with two formulations of Bacillus thuringiensis and four strains of Bacillus sphaericus (B 42, B 64, B 87 and B 33) against mosquito larvae in different breeding habitats of Tezpur, Assam. LC90 of B. thuringiensis var israelensis (formulation Teknar) against Ae. albopictus, Cx. quinquefasciatus and Cx. gelidus were recorded as 0.443, 0.453 and 2.15 ppm respectively and LC90 of B. thuringiensis (Deltox: VCRC B-17) against Ae. albopictus, Cx. quinquefasciatus, Cx. gelidus and Cx. malayi were 8.414, 11.22, 5.24 and 6.761 ppm respectively. LC90 of B. sphaericus strains B 42, B 64, B 87 and B 33 against Cx. quinquefasciatus were 0.055, 0.115, 0.046 and 0.257 ppm respectively. At the dosage of 1 l/ha 87 per cent mortality was achieved after 24 hrs with Bti and it increased to 90-95 per cent at 1.5 l/ha. In polluted cemented drains 93-97 per cent kill of Cx. quinquefasciatus was observed at 2.5 l/ha. Out of four strains of B. sphaericus evaluated, strain B 87 was found to be the most effective as 87-96 per cent kill was achieved with only 0.1 kg/ha for Cx. quinquefasciatus, Cx. vishnui and A. vagus. For others 0.2 kg/ha dosage, eliminated 96-100 per cent Cx. vishnui gr. for B 42, 92-93 per cent for B 64 and 90-93 per cent for B 33 strain.