Entomological indices of Aedes aegypti at some international airports and seaports of southern India--a report.

Entomological surveys were undertaken at some of the international airports/seaports (Bangalore, Calicut, Chennai, Cochin, Thiruvanathapuram and Vishakapatnam) to find out the breeding prevalence of dengue vector mosquito in diverse breeding containers from 1998 to 2004. Three vector indices (House index, Container index and Breateu index) were used to assess the breeding potential at each airport/seaport. International Health Regulations urged national governments to keep all the international airports/seaports and peripheral areas up to 400 meters free from Aedes aegypti mosquitoes. However, surveys revealed high vector indices at all the airports and seaports. Health authorities of airports/seaports need to take cognizance of these facts and develop action plan for appropriate control measures with emphasis on vector surveillance.

Impact of DDT spraying on malaria transmission in Bareilly District, Uttar Pradesh, India.

BACKGROUND & OBJECTIVES: Impact of indoor residual spraying of DDT on malaria transmission and vector density was evaluated in six villages of Shergarh PHC, Bareilly district, Uttar Pradesh under the operational condition of National Vector Borne Disease Control Programme (NVBDCP) from July 2001 to March 2002 (one transmission season only). METHODS: Two rounds of DDT (50% WDP) spraying @ 1 g/m2 were done both in the experimental and control villages by the state health authorities. The spraying in experimental villages was supervised by Malaria Research Centre (MRC) whereas the district health authorities supervised the operation in control villages. Mass blood surveys were made three times--before the first round, in between the first and second rounds and after the second round of spraying. The blood smears were examined by the trained microscopists of MRC, Haldwani. From the above examinations epidemiological indicators such as slide positivity rate (SPR), slide falciparum rate (SFR) and infant parasite rate (IPR) were calculated. All malaria positive cases were given radical treatment as per NVBDCP schedule. Entomological parameters such as per man hour mosquito density, parity rate, gonotrophic condition and adult susceptibility status of Anopheles culicifacies to diagnostic dosages of DDT (4%) were monitored as per the standard techniques. RESULTS: A total of 988.5 kg of DDT was consumed during two rounds of spray. The house coverage varied from 87 to 95.3%. Parasitological evaluation revealed significant reduction in malaria cases (p < 0.0005) and infant parasite rate declined from 2.9 to 0%. Entomological observations revealed considerable reduction in the density of malaria vector An. culicifacies despite of its 21.4% mortality against DDT test papers. INTERPRETATION & CONCLUSION: The overall results of the study revealed that DDT is still a viable insecticide in indoor residual spraying owing to its effectivity in well supervised spray operation and high excito-repellency factor.

First time detection of Japanese encephalitis virus antigen in dry and unpreserved mosquito Culex tritaeniorhynchus Giles, 1901, from Karnal district of Haryana state of India.

Japanese encephalitis virus (JEV) antigen has been detected by antigen capture enzyme linked immunosorbentassay (ELISA) in dry specimens of the mosquito Culex tritaeniorhynchus Giles, 1901, collected from Karnal district of Haryana state in northern India. These mosquitoes were stored in dry condition for 20 months, at room temperature, before processing. The procedure of detecting JEV infection in long time stored, dry vector mosquitoes, has important application in the surveillance of Japanese encephalitis.

Study on susceptibility status in aquatic and adult stages of Aedes aegypti and Ae. albopictus against insecticides at international airports of south India.

A study on susceptibility status in aquatic and adult stages of Aedes aegypti and Ae. albopictus was undertaken at International Airports of Thiruvananthapuram and Cochin located in southern India. WHO standard test kits were used to conduct insecticide susceptibility tests against various organophosphates, organochlorines, carbamates and synthetic pyrethroids. The results indicate that adult Aedes aegypti and Ae. albopictus were resistant to DDT and dieldrin, but susceptible to propoxur, fenitrothion, malathion, deltamethrin, permethrin and lambdacyhalothrin. The susceptibility test conducted on immature stages of Ae. aegypti and Ae. albopictus revealed that they are susceptible to the larvicides commonly used under the National Vector Borne Diseases Control Programme viz. Temephos (0.02 ppm), Fenthion (0.05 ppm) Malathion (1.0 ppm) and Fenitrothion (0.06 ppm).

Surveillance of dengue vector at thiruvananthapuram (Kerala) International Airport.

A survey of Aedes (Stegomyia) mosquitoes was undertaken in and around the International airport at Thiruvananthapuram during premonsoon season. An attempt has been made in this paper to elaborate on the presence of risk potential for Dengue /yellow fever at the airport with the detection of Aedes breeding. The entomological indices have also been discussed with regard to presence of potential wet containers and rate of infestation by Aedes mosquitoes. The airport area was searched for Aedes (Stegomyia) breeding where 20% of the premises were found positive for Aedes aegypti breeding and one premise (6.6%) was found positive with Aedes albopictus breeding. In the 400 meters (perimeter) of airport, four municipal wards namely Chakka, Sankumugam, Valiyathura and Vettucadu were surveyed. The house index ranged from 5.8% to 11.7% for Aedes aegypti while, it was between 9.8% to 19.2% with regard to Aedes albopictus. The container index ranged between 4.4% to 9.9% for Aedes aegypti and 7.1% to 15.3% for Aedes albopictus. Breteau index was found to be between 23.5% to 51.9% for both the species. The susceptibility test conducted against different insecticides showed that the immature stages of Ae. aegypti and Ae. albopictus were found to be susceptible to the commonly used larvicides in public health viz. Temephos (0.02 ppm), Fenthion (0.05 ppm), Malathion (1.0 ppm) and Fenitrothion (0.06 ppm).

Efficacy of a new formulation of Bacillus thuringiensis var israelensis (Bti) in laboratory and field conditions of Kumaun foothills of Uttaranchal, India.

Efficacy of a new Bti formulation was tested in the laboratory and small scale field trials against mosquito larvae were carried out from March to June, 2001 in different breeding habitats of Kumaun foothill region of Nainital and Udham Singh Nagar districts, Uttaranchal state, India. Laboratory tests revealed increased efficacy against Culex quinquefasciatus (LC50 = 0.035 mg/L) followed by Aedes aegypti (LC50 = 0.0628 mg/L), An. culicifacies sp A (LC50 = 0.184mg/L) and An. stephensi (LC50 - 0.2216mg/L). Results of field trials revealed 100% mortality of mosquito larvae after treatment with Bti @ 0.5 gm/m2 surface area. The impact was similar on different mosquito species breeding in different habitats. However, repeated treatments were required due to reappearance of larvae in the breeding habitats within a week. No side effects of Bti was observed during field trial on non- target organisms (NTOs). Environmental disturbances and man made problems affected the spray impact of Bti.

Susceptibility status of Japanese encephalitis vectors in Kurnool and Mehboobnagar districts of Andhra Pradesh, India.

An entomological survey in Kurnool and Mahboobnagar districts of Andhra Pradesh state, India was undertaken in January, 2002 to find out vector population of Japanese Encephalitis and their susceptibility status to different insecticides. Five Culicine species viz. of Cx. tritaeniorhynchus, Cx. vishnui, Cx. pseudovishnui, Cx. bitaeniorhynchus, Cx. gelidus were captured during the survey. Another suspected vectors Anopheles subpictus and An. hyrcanus were also prevalent in the study villages. The larval population showed a high degree of resistance to Fenthion and Temephos. The test mortality to DDT ranged between 75% and 90%. The mortality of Cx. tritaeniorhynchus, Cx vishnui and An. subpictus ranged from 85% to 95%. Cx. tritaeniorhynchus is susceptible to Deltamethrin and Cyfluthrin. Cx. vishnui showed 80 % and 85% mortality to DDT and Malathion respectively.

Malaria outbreak in Bhojpur PHC of district Moradabad, Uttar Pradesh, India.

Based on the reports of 18 fever related deaths in Bhojpur Primary Health Centre (PHC) of Moradabad District (UP), a study was undertaken during September and October, 2000 to explore the possibility of outbreak of malaria in the area and the reasons of the outbreak. The slide positivity rate (SPR) and slide falciparum rate (SFR) in active fever surveys were found to be 84.7% and 82.2% respectively. Among children the average enlarged spleen and spleen rate were 1.9 and 27.4 per cent respectively. The mortality rate of Anopheles culicifacies in DDT, Malathion and Deltamethrin was 42.5, 86.7 and cent per cent respectively. The results of the study revealed that the outbreak was of malaria with predominance of Plasmodium falciparum causing several deaths in the affected villages. The investigation revealed that there was disruption of surveillance and supervision of malaria activities.

Dengue/DHF: an emerging disease in India.

Dengue/DHF is an emergent disease in India and some parts of country are endemic and periodically contributing annual outbreaks of dengue/DHF. Dengue infection manifests as undifferentiated fever, dengue haemorrhagic fever (DHF) which leads to hospitalization large number of people in a localized area. There is high mortality and morbidity associated with the onset of each dengue outbreak leading to great socio-economic impact. The prevention and control of dengue outbreak depends upon the proper monitoring of the disease case through disease surveillance so as to ensure timely management of cases. Vector surveillance helps in the proper and timely implementation of emergency control measures against dengue vector i.e. Aedes aegypti. There is an urgent need for an effective diagnostic strategy for early diagnosis to shorten the illness duration, hospitalization time and the associated complications.

Efficacy of chloroquine in febrile Plasmodium falciparum infected children in Mewat region of Haryana.

During 1996, Mewat region of Gurgaon district in Haryana experienced high incidence of Plasmodium falciparum malaria, assuming epidemic proportion in large number of villages affected by floods. Mortality due to fever was also high. In vivo 7 days study amongst 32 febrile P. falciparum infected children of 1 to 14 years age group in flood affected villages of Ferozpur Jhirka Community Health Centre of Mewat region was carried out. All the 32 cases showed good response to chloroquine suggesting that drug was effective and useful as first line of treatment, reducing severity of P. falciparum infection and resolving fever due to infection of the species. The study also indicated that chloroquine was an effective drug in controlling epidemic situation and mortality in areas of high incidence of P. falciparum. Pyrogenic stimulus was variable among different developmental stages of P. falciparum and suggestive of the need of earliest possible initiation of anti-malaria treatment, community based fever survey and blood smear examination. Increase in incidence of fever in an endemic community, particularly in children, should be considered as an indicator of impending outbreak of P. falciparum malaria. Effectiveness of diagnostic and control measures taken can be evaluated on the basis of incidence of malaria particularly due to P. falciparum infection and also incidence of fever in an endemic community.

Anthropophily of Anophelines in Duars of West Bengal and other regions of India.

Attempts have been made to identify the source of blood meals of twenty three anopheline species from various areas of high malaria endemicity in India. Anopheles minimus, Anopheles fluviatilis and Anopheles dirus showed a high propensity for human blood in North-Eastern parts of the country while Anopheles sundicus was found to be anthropophilic in Andaman & Nicobar Islands. Anopheles culicifacies, Anopheles maculatus and Anopheles philippinensis were found primarily zoophilic in north-eastern areas. High anthropophily has been closely related to sporozoite infection in anophelines specially in Anopheles minimus and is of great epidemiological significance.

Impact assessment of IEC campaign during anti-malaria month, June 1998 through KABP study.

To assess the IEC Campaign during anti malaria month (June, 98), a base line KABP study through pre-assessment and post-assessment was conducted in the State of Gujarat (four districts namely Ahmedabad, Dang, Panchmahal and Baroda). The study was carried out based on questionnaire (open and closed) developed by NAMP in the randomly selected population. A rapid assessment of the current level of KABP among a sample of population before and after the observance of anti-malaria month. The results of the KABP study revealed that there is definite impact (between 2.18 to 30%) and change in the KABP of the local people, where intensive and continuous I.E.C. activities are being undertaken. In order to achieve the desired change in knowledge, attitude, behaviour and practice of the respondents, it requires continuous I.E.C. campaign throughout the year. The attitude, behaviour and practice in the hard core areas need special efforts, where maximum efforts are required to bring a change in. It should be taken more intensively in the problematic and hardcore areas on priority basis.

Response to wing-web challenge of Rous sarcoma virus subgroups in some chicken breeds.

Response to wing-web challenge (WWC) of Rous sarcoma virus (RSV) subgroups was studied in 4-8 weeks old chicks of a light breed, a heavy breed and a cross between an indigenous black plumage Bantam fowl and Australorp breed. Wing-web tumor (WWT) began to develop within one week in response to virus subgroups A (BS-RSV) and C [RSV (RAV-49)] challenge. In chicks challenged with subgroup D [RSV (RAV-50)] virus it took a minimum of 4 weeks for development of WWT. Positive response to WWC by subgroups A, C and D virus was 84%, 100% and 52%, respectively. The duration of exhibition of positive response was maximum for subgroup A virus, followed by subgroup D and minimum for subgroup C virus.

Some aspects of changing behaviour of malaria vectors in tribal areas of India.

The field entomological studies and surveys carried out in 72 tribal districts out of 100 in seven penninsular States namely, Andhra Pradesh, Bihar, Gujarat, Madhya Pradesh, Maharashtra, Orissa and Rajasthan indicated that in most of the areas the vector mosquitoes encountered during the present study were almost the same as recorded by the earlier workers except that Anopheles fluviatilis James, 1902 was recorded in the areas of district Raipur, Durg, Bilaspur, Raigarh, Shahdol, Rajnandgaon, Barwani and Janjgir of Madhya Pradesh, and Sundergarh of Orissa during the present survey. This vector was not recorded in earlier studies by other workers. An. culicifacies Giles, 1901 was not found in present survey in East Godavari and Vishakhapatnam of Andhra Pradesh and Ganjam and Koraput of Orissa where this mosquito was found in collections earlier. Similarly, An. fluviatilis was not encountered during the present field study in Bhilwara of Rajasthan, Phulbani and Kalahandi of Orissa, Thane, Nanded and Nasik of Maharashtra and Bharuch of Gujarat state. During this study An. fluviatilis was noted to be mostly endophilic whereas earlier workers noted this mosquito to be exophilic in a large number of districts. The majority of the tribal districts seem to be under the influence of two malaria vectors, An. culicifacies and An. fluviatilis and these tribal districts are maintaining a high malaria endemicity with predominance of Plasmodium falciparum infection. In the present study, the transmission seasons were noted to be longer than recorded earlier in the districts of Andhra Pradesh, Gujarat, Rajasthan and Orissa. In the remaining states it is almost similar as recorded earlier.

Blood meal identification by using Microdot ELISA in vector mosquitoes.

The blood meals of five mosquito species which are vectors for malaria, J.E. and Filaria were determined by using Microdot ELISA technique, which is a rapid and sensitive method. A total of 4354 freshly fed mosquitoes comprising of Anopheles culicifacies, An stephensi, Culex quinquefasciatus, Cx. vishnui gp. and Cx. tritaeniorhynchus were tested. Results of the study reveal that highest proportion of An. culicifacies between 76-100% fed on bovine host followed by 0.3 to 24.2% on human. Cx. vishnui showed 1.9% feeding on human, 49-87.7% on bovine and 7.4-12.3% on the pigs. It has been observed that malaria vectors namely An. culicifacies and An. stephensi are still zoophilic in nature. Similarly, the vector of J.E. namely Culex vishnui gp. and Cx. tritaeniorhynchus also fed on cattle but some samples have indicated feeding of blood meal from pigs.

Preventing dengue/dengue haemorrhagic fever outbreaks in the National Capital Territory of Delhi--the role of entomological surveillance.

Outbreaks of Dengue/Dengue Haemorrhagic Fever have been occurring in the National Capital Territory (NCT) Delhi from time to time. A massive outbreak of Dengue/DHF causing considerable mortality occurred in 1996 in the NCT, Delhi. Since this outbreak regular entomological surveillance has been instituted, for timely preventive action against Dengue/DHF. The Central Cross Checking Organisation (CCO) of the National Malaria Eradication Programme cross-checks Aedes surveillance activities in Delhi. In this paper we present our experiences in entomological surveillance in relation Dengue, to share them with other workers in this field.

'Anti-malaria month'--a step forward in multisectoral collaboration and community involvement in malaria control.

For a long time malaria control in India has largely been a government responsibility with little involvement of the community at large, and other sectors of the economy in the control efforts. There is now increasing realisation that involvement of the community and a multi-sectoral approach should be essential components of the malaria control strategy. The National Malaria Eradication Programme is accordingly laying greater emphasis on coordination with other sectors of the economy, and changing community perceptions and health-related behaviour. A massive programme of community mobilisation with this objective in view has been taken up since 1997. A major component of this community mobilisation programme is the observance of an 'Anti-Malaria Month', during which, country wide awareness campaigns are undertaken at all levels of implementation, to promote inter-sectoral collaboration and community action for malaria control. The present paper summarises the rationale and messages of the 'Anti-Malaria month'.