Kala-azar in Varanasi (UP)--preliminary observations

An epidemiological and entomological survey was conducted in Badohi town of Varanasi district of Uttar Pradesh (India) from where an outbreak of kala-azar was reported. Serological and clinical results showed 83 cases who responded to sodium antimony gluconate. Phlebotomus argentipes and P. papatasi could be detected in area of outbreak. An active transmission of kala-azar is strongly indicated.     

Sandfly survey in Nainital and Almora districts of Uttaranchal with particular reference to Phlebotomus argentipes, vector of kala-azar

Kala-azar continues to pose a major public health problem in Bihar, West Bengal and parts of eastern Uttar Pradesh in India causing great deal of morbidity and mortality. During 1998, several kala-azar cases from Sub-Himalayan region were treated in Delhi hospitals. And a suspected focus of kala-azar was subsequently reported from this area. Therefore a preliminary sandfly survey was carried out during October, 1999 in 18 randomly selected villages at different altitudes in Nainital & Almora districts of Kumaon region Uttaranchal. The surveys revealed relative preponderance of vector sandfly Ph. argentipes as 77%; mainly confined to cattlesheds and mixed dwellings in the villages at an altitude ranging from 350-960 metres main sea level. The other sandfly species encountered were: Ph. papatasi 6.9%, Ph. major 2.9% and 13.2% Sergentomyia spp. 17.4% Ph. argentipes reacted positive with human antisera and 82.6% with bovine but none reacted with goat, pig dog and bird antisera indicating that Ph. argentipes in the area is mainly zoophilic. Ph. argentipes was found to be highly susceptible to DDT; mortality ranging from 98-100%.     

Impact of Olyset nets on malaria transmission in India

BACKGROUND & OBJECTIVES: Efficacy of Olyset nets, long-lasting insecticidal nets were tested from August 2003 to August 2006 against Anopheles culicifacies, the vector which transmits 60% of all malaria cases in rural India. METHODS: Three villages in District Gautam Budh Nagar (Uttar Pradesh), India were selected for the trial and Olyset nets were distributed in one village, in another village untreated nets were distributed and the third village was kept as control where nets were not used. Entomological, and epidemiological data were collected using standard methods. RESULTS: The use of Olyset nets reduced the indoor resting density of An. culicifacies and also reduced mosquito entry into the structures where Olyset nets were used. No mosquitoes were caught landing on the Olyset nets. There was a reduction in the parity rate of An. culicifacies in the Olyset net village as compared with untreated net and no net villages. The impact of Olyset nets was observed on malaria incidence and only one case of Plasmodiumfalciparum malaria was reported in the Olyset net village but these continued to be found in the village with untreated nets and the control. CONCLUSION: Results of the present study confirmed that Olyset nets are highly effective in reducing the indoor resting density of mosquitoes, man-vector contact and malaria incidence.     

Virgin soil: the spread of visceral leishmaniasis into Uttar Pradesh, India

We conducted a cross-sectional study to determine the incidence of visceral leishmaniasis (VL) and risk factors in two villages in Uttar Pradesh, India reported to have had a recent outbreak. In 245 households with 2,203 people, we detected 3 current VL cases, 32 past cases, and 8 VL deaths since 2001 (annual incidence = 6 per 1,000). Risk factors included living in the same household as a VL case (odds ratio [OR] = 76, P < 0.0005 in one village and OR = 22, P < 0.0005 in the other village), sleeping downstairs and outside in the summer (OR = 4.7, P = 0.004), and an age > or = 15 years old (OR = 2.9, P = 0.024). Increasing cattle density was a risk factor in one village but not the other. We were not able to determine the route by which VL entered the villages. Our data demonstrate a new spread of VL in previously unaffected areas. We recommend carefully supervised spraying with DDT, surveillance to pinpoint other affected villages, and efforts to increase availability of diagnostic and treatment facilities.     

Mapping of risk prone areas of kala-azar (Visceral leishmaniasis) in parts of Bihar State, India: an RS and GIS approach

BACKGROUND & OBJECTIVES: The kala-azar fever (Visceral leishmaniasis) is continuing unabated in India for over a century, now being largely confined to the eastern part of India mainly in Bihar state and to some extent in its bordering states like West Bengal and Uttar Pradesh. Two study sites namely Patepur block in Vaishali district with high endemicity in northern part and Lohardagga block in Lohardagga district with absolute non-endemicity in southern part of Bihar were selected for the study with the following objectives : (i) to study the macro-ecosystem in relation to distribution of vector -Phlebotomus argentipes; (ii) to identify/map the risk prone areas or villages in a block for quick remedial measures; and (iii) to make use of satellite remote sensing and GIS to demonstrate the utility for rapid assessment of landuse/landcover and their relation with the incidence of kalaazar leading to the mapping of risk prone areas. METHODS: Indian Remote Sensing (IRS)-1D LISS III satellite data for the periods of March and November 2000 were analysed in Silicon graphic image processing system using ERDAS software. False color composites (FCC) were generated and landuse/landcover was assessed using Maximum likelihood supervised classification techniques based on ground truth training sets. During the study the GIS functions are used to quantify the remotely sensed landscape proportions of 5 km2 buffer surrounding each known group of villages of high occurrence of sandflies in endemic and nonendemic study sites. Instead of traditional ground based survey methods to vector surveillance, the present study used a combination of remote sensing (RS) and geographical information system (GIS) approach to develop landscape predictors of sandfly abundance-an indicator of human vector contact and as a measure of risk prone areas. RESULTS: Statistical analysis using the remotely sensed landscape variables showed that rural villages surrounded by higher proportion of transitional swamps with soft stemmed edible plants and banana, sugarcane plantations had higher sandfly abundance and would, therefore, be at higher risk prone areas for man-vector contact. INTERPRETATION & CONCLUSION: The present study clearly brought out the usefulness of satellite remote sensing technology in generating the crucial information on spatial distribution of landuse/landcover classes with special emphasis on indicator landcover classes thereby helping in prioritising the area to identify risk prone areas of kala-azar through GIS application tools.     

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.     

Quick control of bubonic plague outbreak in Uttar Kashi, India

A localized outbreak of bubonic plague occurred in village Dangud (population 332), district Uttar Kashi, Uttaranchal, India in the second week of October 2004. 8 cases were considered outbreak associated based on their clinical and epidemiological characteristics; 3 (27.3%) of them died within 48 hours of developing illness. All the 3 fatal cases and five surviving cases had enlargement of inguinal lymph nodes. None of them had pneumonia. The age of the cases ranged from 23-70 years and both sexes were affected. No such illness was reported from adjoining villages. The outbreak was fully contained within two weeks of its onset by supervised comprehensive chemoprophylaxis using tetracycline. A total of approximately 1250 persons were given chemoprophylaxis in three villages. There was no clear history of rat fall in the village. No flea was found on rodents or animals. 16 animal serum samples were found to be negative for antibodies against F-1 antigen of Y. pestis. However, Y. pestis was isolated from two rodents (Rattus rattus and Mus musculus) trapped in the village. One case and three animal sera showed borderline sero-positivity against rickettsial infection. The diagnosis of plague was confirmed by detection of four fold rise of antibody titre against F-1 antigen of Yersinia pestis in paired sera of three cases (one of the WHO approved criteria of diagnosis of confirmed plague). This outbreak and the occurrence of earlier outbreaks of plague in Surat (Gujarat) and Beed (Maharashtra) in 1994 and in district Shimla (Himachal Pradesh) in 2002 confirm that plague infection continue to exist in sylvatic foci in many parts of India which is transmitted to humans occasionally. Thus, there is a strong need for the States to monitor the plague activity in known sylvatic foci regularly and have a system of surveillance to facilitate prompt diagnosis and treatment of cases to control the disease. This investigation highlights that with high index of suspicion the disease can be diagnosed early and mounting of supervised comprehensive response can prevent the disease to proceed to pneumonic stage where man to man transmission gets established and outbreak assumes larger dimensions.     

四川省汶川县黑热病流行病学调查研究

本文报道四川省汶川县黑热病流行情况的调查结果。1987年以来共确诊患者141例,分布在两区一镇六个乡,发病年龄以5岁以下儿童为主,发病季节以春夏季为多。对5个村寨的调查,凡病犬多的村寨都有黑热病人发生,证实汶川黑热病流行与犬内脏利什曼病的感染有着密切关系。此外,间有病人相距很近或一家中有数例患者先后发病的现象。在调查的125只家犬中,以1～3龄的家犬发病较高。中华白蛉为当地唯一媒介。     

Japanese Encephalitis epidemic in Anantapur district, Andhra Pradesh (October-November, 1999).

Epidemic of Japanese Encephalitis has occurred in Andhra Pradesh during October-November, 1999 affecting 15 out of 23 districts. In total, 873 cases with 178 deaths have been recorded up to the day 29.11.99. The epidemiological investigation has been done in Anantapur district in western Andhra Pradesh, where the outbreak has started in the third week of October. In the district 47 PHC have been affected. On an average 4.5 per cent of 3175 villages have been affected. Average number of cases per affected village have been 1.5. Rural population has been primarily affected. Age groups 1-14 years including infants have been affected but nearly 86.8% of cases have been among 1-9 year age group. The overall case fatality rate has been 18.4 per cent. Clinical features have been high fever, headache, altered sensorium, convulsions and coma. A marked seasonal onset of a few cases per village and 93.75 per cent of human serum samples collected from hospitalised cases showed the evidence of J.E. virus infection indicating that the present outbreak was due to JE virus. High density of Culex vishnui complex mosquitoes has been observed in the area. All the environmental and ecological conditions, temperature, rainfall and relative humidity have been in favour of JE transmission. Analysis of the data for the last 10 years showed that the human JE cases occurred in Anantapur in September-October months, which shifted to October-November, 99. Prolonged draught conditions were observed till October. Possibly the delayed monsoon and congenial atmospheric conditions after monsoon were favourable to the vector species for extra-human cycle of transmission in 1999. Low level transmission leading to small number of cases continued during the succeeding years every September-October till the present epidemic. In all 24 PHCs and urban towns were identified with 212 cases and 39 deaths till 29.11.99.     

Building small dams can decrease malaria: a comparative study from Sundargarh District, Orissa, India

The adverse health effect of environmental changes brought about with the construction of large and small dams has often been reported. Here, we present results of a 5-year (2001-2005) study documenting the positive effect of such developmental projects in reducing malaria in an area where malaria transmission is mainly due to the highly efficient anthropophagic vector Anopheles fluviatilis with some contribution from Anopheles culicifacies. The former breeds exclusively in the slow-flowing streams and the latter breeds in a variety of habitats. The study was conducted in San Dulakudar village and comparisons were made with two control villages situated near the stream with similar topography and malaria transmission pattern. Epidemiological data was collected through longitudinal weekly surveillance and cross-sectional surveys in all the study villages. The mean annual malaria incidence rates due to Plasmodium falciparum in children of 1-5 years age group during 2001 before construction of dam was 1304.3 and 785.7 cases/1000 population in dam site village and control villages, respectively. However, after construction of dam, there was gradual reduction in the malaria cases in dam site village and during 2005 the incidence was significantly reduced to 181.8 (P<0.01) whereas it was increased to 1000 in control villages without any significant change in comparison to baseline year (P>0.05). A significant reduction in malaria incidence and parasite rate was also recorded in all the age groups in dam site village without registering any significant change in control villages. The construction of a small dam in the study village altered the water flow above and below the dam thereby making it unfavourable for the breeding of A. fluviatilis which in turn brought about significant impact on malaria transmission.     

Seroepidemiology of malaria in northern Thailand: II. Focal and temporal variations in endemicity

Four population groups from regions of Northern Thailand were surveyed for the presence of antibodies to Plasmodium falciparum using the indirect immunofluorescent antibody (IFA) test. Each of the four populations was selected from areas known to represent different patterns of malaria transmission. Group 1 was from an area where there had been no malaria transmission for approximately 30 years. Individuals in this group below age 40 showed an extremely low prevalence of malaria antibodies. Group 2 was chosen from an area where low levels of transmission have continued despite more than 30 years of DDT spraying. In this group the age related pattern of malaria antibodies varied from village to village but in all villages there was a sharp increase in the prevalence of IFA positive tests in individuals over 30. The third group has had continuously high levels of transmission. Although there are differences in the age related prevalence of IFA positives when individual villages are compared, there is a greater prevalence at all ages than in the first two groups. The fourth group was selected from an area where transmission had recently resumed after freedom from indigenous cases for approximately six years. There was little difference in the prevalence of IFA positive individuals below the age of 25 but above that there was a steady increase in prevalence with age. The correlation of IFA antibody positives with known patterns of malaria transmission in these four areas demonstrates the usefulness of this serological technique in assessing malaria endemicity and the effectiveness of control measures as well as in the interpretation of other malaria statistics.     

Malaria transmission and major malaria vectors in different geographical areas of Southeast Asia

During the last decade, major progress in malaria control has been achieved in Vietnam, Laos and Cambodia. However, malaria is still a potentially fatal disease in some hilly-forested areas and continues to be endemic in a few coastal foci. To estimate the risk that stems from the major vectors after a decade of intensive malaria control, an entomological study based on human landing collections was conducted between April 1998 and November 2000 in six study villages (four in Vietnam, one in Cambodia and one in Laos) located in different physio-geographical areas. Five villages were selected in places where new cases of malaria still occurred. In the sixth village, in the northern hilly area of Vietnam, no case of malaria was detected during the past 3 years. In three study villages of the hilly forested areas of Cambodia and central Vietnam, Anopheles dirus A still played an important role in malaria transmission and maintain perennial transmission inside the villages despite its low density. Anopheles minimus A was found in all study villages except in the southern coastal village of Vietnam. Its role in malaria transmission, however, varied between localities and surveys. In one study village of central Vietnam it was almost absent (one specimen collected over 480 man nights), and in another village sporozoite positive specimens (2.8%) were only observed during the first two surveys whereas this species disappeared from the collections from November 1998 onwards (six surveys: 360 man nights). In the northern study site An. minimus A and C were found in all collections, but no local malaria transmission occurred. However, the constant presence of these two species associated with a high longevity (parous rate up around 80% and 65%, respectively), suggests that transmission can occur at almost any time if parasite reservoirs are reintroduced in the area. The proper management of malaria cases and population movement is, therefore, important to prevent outbreaks and the reintroduction of malaria in northern Vietnam. In the study site of the Mekong delta, An. sundaicus occurred at high densities (up to 190 bites/man/night). The recent changes in land use from rice cultivation to shrimp farming probably explains the increase of this brackish water breeding species during the study period. However, none of the 11,002 specimens was positive for Plasmodium circumsporozoite protein (CSP). The relative low survival rate as estimated by the parous rate (around 47%) may reflect its low vectorial status that could explain the very low malaria incidence (1.9 case/100 persons/year) in this study site. A calculated sporozoite rate of maximum 1/300,000 is enough to explain this low malaria incidence. Despite the successes in malaria control, the vector An. dirus A continues to play an important role in malaria transmission, whereas An. minimus A showed temporal and spatial variation in its role as vector. The role of An. sundaicus as vector could not be confirmed because of the low incidence in the coastal study village. Other Anopheles species may be locally involved, but in the five study villages where malaria is still present they probably do not contribute significantly to malaria transmission. The study also points towards the fact that in Southeast Asia it will become increasingly difficult to incriminate Anopheles species in malaria transmission while the risk for malaria transmission still persist.     

Studies on bionomics of Anopheles fluviatilis and its sibling species in Nainital district, U.P.

A study on the bionomics of Anopheles fluviatilis sensu lato was carried out in two physiographic regions, viz. Bhabar and Terai of District Nainital, Uttar Pradesh. In both areas, An. fluviatilis was found resting indoors predominantly in cattlesheds. Cytological examination of An. fluviatilis revealed that species T and U were sympatric in Bhabar and Terai villages with predominance of species T. These two sibling species appear to be poor vectors of malaria.     

Epidemiological profile of Japanese encephalitis in Gorakhpur district, Uttar Pradesh, 1982-1988.

An in-depth study of Japanese Encephalitis (JE) situation in Gorakhpur district of Uttar Pradesh from 1982-1988 showed increasing trend in the incidence of JE. Total number of annual cases and case fatality rate (CFR) rose from 118 and 23.7 per cent in 1982 to 772 and 32.2 per cent in 1988 respectively. A definite increase was noticed in the number of cases per block following lull years in 1984 and 1987. Among the total affected 1201 villages, 1083 were affected only once. All age groups were affected and the disease showed marked seasonality during August to November. JE, which came in epidemic form in earlier years has established in the area in endemic form.     

Lymphatic filariasis in two distinct communities of upper Assam

Current status of bancroftian filariasis among two distinct communities of Upper Assam was evaluated. High prevalence (10.3% mf rate) in tea workers descendents of tribals migrated from endemic states such as Orissa, Bengal, Uttar Pradesh and southern states of India, were recorded. Among non tea workers (indigenous population) significantly low mf rate was found in spite of the fact that both the communities are living in close vicinity and in similar ecological and mosquitogenic conditions. Culex quinquefasciatus was incriminated as vector in the areas of both the communities. A group of recent migrants of Bihar and Bengal living in the locality of non tea worker population were also found microfilaraemic. Significantly lower infection rate in non tea worker population appears to be associated with host susceptibility to the infection. Familial clustering in microfilaraemic subjects noticed in tea workers group also suggests involvement of racial susceptibility to infection.     

溴氰菊酯和三氯杀虫酯现场灭蛉效果观察

用2.5％可湿性溴氰菊酯和国产三氯杀虫酯(7504)进行现场喷洒灭蛉结果表明,每平方米墙面使用溴氰菊酯37.5mg、25mg和12.5mg剂量,可使白蛉数量比对照区降低13—19倍,削平季节高峰。当年的灭蛉效果超过50％的可湿性DDT。在模拟土墙和泸纸药膜上,残效至少可达50天以上。建议以每平方米12.5mg作为灭蛉喷洒剂量推广使用;7504每平方米1g的剂量可使白蛉数量降低8.9倍,值得进一步试用,但其剂型应研究改进。连续观察证明,在当地条件下,于喷洒后第三年白蛉密度可恢复到具有流行病学意义的程度。     

Genetic markers in refractory and susceptible malaria patients in village Bhanera, Distt. Ghaziabad, U.P.

Malaria 'susceptible' and 'refractory' subjects from village Bhanera in District Ghaziabad (Uttar Pradesh) were examined for various genetic markers, viz., ABO, haptoglobin, haemoglobin and glucose-6-phosphate dehydrogenase polymorphism. One hundred and nine susceptible and 36 refractory subjects were studied. No significant differences with respect to distribution patterns of the genetic markers were observed in the two groups except for AB blood group. In general, a high incidence of ahaptoglobinaemia was observed in this population and incidence increased with the increase in malaria attacks, suggesting that repeated malaria attacks cause ahaptoglobinaemia.     

Bionomics of Anopheles culicifacies giles in riverine tract rural areas of district Shahjahanpur, Uttar Pradesh

Studies on seasonal prevalence, resting behaviour, gonotropic conditions and breeding habits of Anopheles culicifacies were carried out from January 1987 to December 1989 in riverine villages of Dadraul PHC in Shahjahanpur district, Uttar Pradesh. Man hour densities of An. culicifacies varied from 11.3 to 125.1 during the study period. The species showed two peaks of high prevalence: one during March to June and the other during October to December. The first peak was higher than the second. The collection revealed a higher proportion of freshly fed to semi-gravid females thus indicating the outdoor resting behaviour of the species. From the immatures collected from riverbed pools, 7 anopheline species were identified. Of the 955 specimens identified, An. culicifacies constituted the highest number (62.1%). The study indicates that low rainfall and drought did not affect An. culicifacies densities or malaria transmission in riverine areas.     

Patterns of house infestation dynamics by non-domiciliated Triatoma dimidiata reveal a spatial gradient of infestation in rural villages and potential insect manipulation by Trypanosoma cruzi

Objective  Chagas disease is a major vector-borne parasitic disease in Latin America, primarily transmitted to humans by triatomine vectors. Non-domiciliated triatomine species such as Triatoma dimidiata in the Yucatan peninsula, Mexico, can transiently invade houses and are emerging as a major challenge to control Trypanosoma cruzi transmission to humans. We analyzed the spatio-temporal spreading of house infestation by T. dimidiata in four rural villages.
Methods  Triatomines were collected in four rural villages over a 2 years period, and the spatio-temporal patterns of infestation were analyzed.
Results  Triatomines were consistently more abundant at the periphery of villages than in centers, indicating a much higher risk of T. cruzi transmission at the periphery. Male T. dimidiata were found further in the center of the village, while females remained closer to the periphery, suggesting differential dispersal capabilities between sexes, although the timing of dispersal appeared identical. Surprisingly, infected females were consistently collected in houses much further from the surrounding bushes than non-infected females, while the distribution of males was unaffected by their T. cruzi infection status, suggesting an increased dispersal capability in infected females.
Conclusion  The spatial structure of infestation should be taken into account for the prioritization of vector control activities within villages, and spatially targeted interventions may be explored. A potential vector manipulation by T. cruzi, observed for the first time in triatomines, may favor parasite transmission to new hosts.     

Effect of rice cultivation on malaria transmission in central Kenya

A 12-month field study was conducted between April 2004 and March 2005 to determine the association between irrigated rice cultivation and malaria transmission in Mwea, Kenya. Adult mosquitoes were collected indoors twice per month in three villages representing non-irrigated, planned, and unplanned rice agro-ecosystems and screened for blood meal sources and Plasmodium falciparum circumsporozoite proteins. Anopheles arabiensis Patton and An. funestus Giles comprised 98.0% and 1.9%, respectively, of the 39,609 female anophelines collected. Other species including An. pharoensis Theobald, An. maculipalpis Giles, An. pretoriensis Theobald, An. coustani Laveran, and An. rufipes Gough comprised the remaining 0.1%. The density of An. arabiensis was highest in the planned rice village and lowest in the non-irrigated village and that of An. funestus was significantly higher in the non-irrigated village than in irrigated ones. The human blood index (HBI) for An. arabiensis was significantly higher in the non-irrigated village compared with irrigated villages. For An. funestus, the HBI for each village differed significantly from the others, being highest in the non-irrigated village and lowest in the planned rice village. The sporozoite rate and annual entomologic inoculation rate (EIR) for An. arabiensis was 1.1% and 3.0 infective bites per person, respectively with no significant difference among villages. Sporozoite positive An. funestus were detected only in planned rice and non-irrigated villages. Overall, 3.0% of An. funestus samples tested positive for Plasmodium falciparum sporozoites. The annual EIR of 2.21 for this species in the non-irrigated village was significantly higher than 0.08 for the planned rice village. We conclude that at least in Mwea Kenya, irrigated rice cultivation may reduce the risk of malaria transmission by An. funestus but has no effect on malaria transmission by An. arabiensis. The zoophilic tendency of malaria vectors in irrigated areas accounts partly for low malaria transmission rates despite the presence of higher vector densities, highlighting the potential of zooprophylaxis in malaria control.