Community's knowledge and perceptions about filarial elephantiasis and hydrocele in coastal Orissa, India

This study assesses people's knowledge and perceptions on transmission, prevention and eradication of elephantiasis and hydrocele, common manifestations of chronic lymphatic filariasis (LF). The assessment was done during mass drug administration (MDA) of the programme to eliminate LF in the State of Orissa, India. A household survey with pre-tested interview questionnaire was conducted in four LF endemic districts of Orissa state, India, where the MDA has been taken place. The sampling units (clusters of households) of the household survey are taken based on (1) urban/rural and (2) type of or absence of health facility. A total of 1,448 respondents were selected randomly. Majority of the respondents heard about elephantiasis and hydrocele. About one third of them know that mosquito bite is the cause of elephantiasis but very few people know about hydrocele. Around 50% of the respondent believed that elephantiasis could be cured completely, while almost 60% said that it could be totally removed from the community. But for hydrocele, more than 80% of respondents showed a positive approach for cure and nearly about 70% said that hydrocele could totally be eradicated from community. Various causes and methods of cure and prevention were suggested. Around 55% of respondents suggested that elephantiasis can be eradicated by taking medicine, but only 40% felt that hydrocele can be cured by taking medicine. Basic knowledge on LF is poor and relatively low proportion of people knows that LF can be eliminated by taking medicine. As there are plans to undertake further rounds of MDA in Orissa, people's knowledge has to be strengthened and perception and attitudes have to be addressed to achieve positive behavioural change, which eventually lead to higher compliance of MDA.

Probability risk transmission matrix as a decision tool for assessing methods of transmission interruption of Wuchereria bancrofti infection

Lymphatic filariasis continues to cause severe morbidity and economic loss. The World Health Assembly (WHA) has passed a resolution to eliminate this disease by 2020. The major thrust of the elimination strategy is interrupting transmission by anti-parasitic treatment of entire communities. However, both vector density and community microfilaria load (CMFL) influence the intensity of transmission. Therefore, using a logistic regression approach a relationship has been established between the Risk of Infection Index (RII), vector density and CMFL. The present analysis indicates that there is no risk of transmission as long as the CMFL is maintained below 5 microfilaria (mf)/60 mm3 and the vector density per man-hour (MHD) is 25 and CMFL is <5 mf/60 mm3. In situations where CMFL is very high, parasitic control by mass administration may be cost effective in interrupting transmission. But at lower level of CMFL (<4 mf) and higher level of vector density it might be more cost effective to use vector control methods. A RII value <0.2 is considered to be the threshold for confirming interruption of transmission. Thus, the relationship has been depicted in the form of a probability matrix, which could be used for selecting an appropriate control strategy.

Larvicidal, ovicidal and repellent activities of the leaf extract of two cucurbitacious plants against filarial vector Culex quinquefasciatus (Say) (Diptera : Culicidae)

The leaf extract of two cucurbitacious plants Citrullus colocynthis and Cucurbita maxima with different solvents viz., benzene, ethylacetate, petroleum ether and methanol were tested for larvicidal, ovicidal and repellent activities against the mosquito Culex quinquefasciatus. Larval mortality was observed and recorded after 24 h exposure period. The LC50 values of C. colocynthis were 61.72, 47.58, 66.92 and 118.74 ppm respectively. C. maxima shows the LC50 values of 123.02, 75.91, 117.73 and 171.64 ppm respectively. The mean percent hatchability of the egg rafts were observed after 48 h treatment. 100% mortality was observed at 450 ppm for C. colocynthis and 600 ppm for C. maxima. Skin repellent test at 1.0, 2.5 and 5.0 mg/cm2 concentration of C. colocynthis gives the complete protection time ranges from 107 to 271 minutes. C. maxima exerted the complete protection time of 78 to 215 minutes. The leaf extract of these two plants shows the larvicidal and ovicidal properties and they can also be applied as an effective personal protection measure against mosquito bites.

Impact of 10 years of diethylcarbamazine and ivermectin mass administration on infection and transmission of lymphatic filariasis

The potential of repeated mass administration of diethylcarbamazine (DEC) and ivermectin to eliminate lymphatic filariasis has been examined in a study implemented in 10 villages with a population of 18415 in south India. During ten rounds of mass drug administration, 49-84% of the eligible population received treatment in different villages. Ten rounds of mass administration of DEC alone reduced the microfilaria (mf) prevalence and intensity by 93% and 97%, respectively, and the vector infection and infectivity rates by 91% and 89%, respectively. The corresponding figures with nine rounds of administration of ivermectin alone were 83%, 90%, 89% and 79%. Out of five villages in each treatment arm, the mf rate declined to <or=1% in four villages in the DEC arm and two villages in the ivermectin arm. No mosquitoes with infective-stage larvae were found in three of five villages in the DEC arm and two of five villages in the ivermectin arm. None of the children (n=130) were found to be positive for mf in either treatment arm. None of the 40 sampled children were found to be positive for circulating filarial antigenaemia in villages with lower endemicity in the DEC arm. The results suggest that ten rounds of DEC mass administration have the potential to interrupt transmission of infection in the majority of communities. The outcome was relatively less remarkable with ivermectin.

Persistence of Brugia malayi DNA in vector and non-vector mosquitoes: implications for xenomonitoring and transmission monitoring of lymphatic filariasis

Xenomonitoring (detection of filarial larvae or their DNA in mosquitoes) is a sensitive marker for assessing the endemicity of filariasis and a useful tool for evaluating elimination programs. To examine the fate of microfilariae (mf) and filarial DNA in vector competent and non-competent mosquito strains, we compared the detection of Brugia malayi parasites by dissection and by quantitative real-time polymerase chain reaction (PCR) in three different mosquito strains. We conclude that PCR is much more sensitive than dissection for detecting filarial larvae, especially their remnants in mosquitoes. However, parasite DNA can be detected in both vector and non-vector mosquitoes for two weeks or longer after they ingest mf-positive blood. Thus, although xenomonitoring with vector and non-vector mosquito species may be a sensitive method for indirectly detecting filarial parasites in human populations, positive test results for parasite DNA in mosquitoes do not necessarily prove that transmission is ongoing in the study area.

A role for Mansonia uniformis mosquitoes in the transmission of lymphatic filariasis in Uganda?

The possible role of Mansonia uniformis mosquitoes in the transmission of lymphatic filariasis was assessed in an endemic area of Uganda, by examining their diurnal biting cycle, host preference and ability to support the development of experimental and natural Wuchereria bancrofti infections. Anopheles gambiae s.l. served as controls. Human landing catches revealed that outdoor biting peaked early in the evening (19:00-20:00h), while indoor biting peaked around midnight (23:00-24:00h). By far the majority of indoor collected M. uniformis had derived their blood meals from humans. Both biting and feeding behaviour were therefore compatible with a potential for transmission. In experimentally fed M. uniformis (total of 1915), the microfilariae were seen to ex-sheath and to start migration, but the L1s accumulated in the thorax and only few developed further. In dissections from Day 11 onwards, 4.6% (43/932) of M. uniformis had L2 larvae and 0.7% (7/932) had L3 larvae of W. bancrofti. The corresponding figures for An. gambiae s.l. were 13.4% and 4.6%, respectively. Dissection of wild caught M. uniformis (total of 6823) did not reveal any natural infections with W. bancrofti infective larvae, whereas wild caught An. gambiae s.l. had an infective rate of 1.3%. Other filarial species, and mermithids, were common in M. uniformis. It is concluded that M. uniformis has a limited potential to support development of W. bancrofti to the infective stage, and it does not appear to play a role as a vector under natural conditions.

Prediction of 3-dimensional structure of salivary odorant-binding protein-2 of the mosquito Culex quinquefasciatus, the vector of human lymphatic filariasis

Olfaction of insects is currently recognized as the major area of research for developing novel control strategies to prevent mosquito-borne infections. A 3-dimensional model (3D) was developed for the salivary gland odorant-binding protein-2 of the mosquito Culex quinquefasciatus, a major vector of human lymphatic filariasis. A homology modeling method was used for the prediction of the structure. For the modeling, two template proteins were obtained by mGenTHERADER, namely the high-resolution X-ray crystallography structure of a pheromone-binding protein (ASP1) of Apis mellifera L., [1R5R:A] and the aristolochene synthase from Penicillium roqueforti [1DI1:B]. By comparing the template protein a rough model was constructed for the target protein using MODELLER, a program for comparative modelling. The structure of OBP of the mosquito Culex quinquefasciatus resembles the structure of pheromone-binding protein ASP1 of Apis mellifera L., [1R5R:A]. From Ramachandran plot analysis it was found that the portion of residues falling into the most favoured regions was 86.0%. The predicted 3-D model may be further used in characterizing the protein in wet laboratory.

Knowledge and perceptions about lymphatic filariasis: a study during the programme to eliminate lymphatic filariasis in an urban community of Orissa, India

This study reports the knowledge and perceptions of the people with regard to cause and transmission of chronic forms of lymphatic filariasis (LF) and its elimination programme during mass drug administration (MDA) under the programme to eliminate LF in an urban area of Orissa, India. The paper is based on both quantitative and qualitative surveys undertaken before and after the first MDA among different socio-economic strata of the urban area. The data revealed that the urban residents are aware of the chronic forms of LF and also felt that LF is a problem in their area. But most of them do not know the role of mosquitoes in the transmission of the disease. A few people explained the association between LF and hydrocele, and the role of mosquitoes. In the present study, it is observed that poor knowledge about LF is highly influenced by socioeconomic conditions. People from lower economic category were least aware of the cause of both lymphoedema and hydrocele. However, knowledge in some issues with regards to the disease and the awareness on MDA have increased significantly after MDA.

Controlling lymphatic filariasis and soil-transmitted helminthiasis together in South Asia: opportunities and challenges

Lymphatic filariasis (LF) and the major soil-transmitted helminth (STH) infections are co-endemic in many countries, particularly in Asia. Control strategies for both groups of infections have increasingly focused on the use of mass chemotherapy. With the use of albendazole, there is now a tool that is common to both. However, there are also important differences in their modes of transmission and epidemiology, and, as a result, in the overall control strategies. The Global Programme for the Elimination of Lymphatic Filariasis aims to eliminate LF through time-limited mass drug administration programmes. Control activities for STH are more diffuse, aiming to piggy-back de-worming onto existing services, such as school health activities; controlling morbidity, rather than eliminating infection, is the stated goal. In order to maximize health benefits to communities that are endemic for one or both of these infections, it is vitally important that policy makers and programme managers have a clear understanding of both commonalities and differences, and implement control strategies that allocate available resources in an optimal manner.

Transmission dynamics of lymphatic filariasis: vector-specific density dependence in the development of Wuchereria bancrofti infective larvae in mosquitoes

The principles of meta-analysis developed in a previous study were extended to investigate the process of Wuchereria bancrofti (Cobbold) (Filarioidea: Onchocercidae) infection in mosquito (Diptera: Culicidae) hosts, focusing specifically on the functional forms and strength of density dependence in the development of ingested microfilariae (mf) to infective (third instar) larvae (L3). Mathematical models describing observed mf-L3 functional responses for each of the major three parasite-transmitting vector genera, Aedes, Culex and Anopheles mosquitoes, were fitted to paired mf-L3 data collated from all available studies in the published literature. Model parameters were estimated and compared by deriving and applying a data synthetic framework, based on applying a non-linear weighted regression model for fitting mathematical models to multistudy data. The results confirm previous findings of the existence of significant between-genera differences in the mf-L3 development relationship, particularly with regard to the occurrence of limitation in Culex mosquitoes and facilitation in Aedes and Anopheles mosquitoes. New and unexpected findings regarding L3 development from ingested mf were discovered as follows: (1) for Culex, overcompensation in L3 development at higher intensities of mf (or a peaked mf-L3 functional response) was detected; (2) for Aedes mosquitoes, facilitation (with an apparent asymptotic constraint on L3 development at high mf densities) was shown to be the major process governing L3 development, and (3) for Anopheles, a stronger facilitation type of response with no apparent saturation in L3 development appears to govern L3 output from ingested mf. These results yield major new insights regarding filarial vector infection dynamics and their potential impacts on parasite control, and demonstrate the efficacy of employing a data synthetic approach to reveal and estimate parasitic infection processes in host populations.

Urban lymphatic filariasis in central Nigeria

Wuchereria bancrofti and the other mosquito-borne parasites that cause human lymphatic filariasis (LF) infect over 120 million people world-wide. Global efforts are underway to stop transmission of the parasites, using annual, single-dose mass drug administrations (MDA) to all at-risk populations. Although most MDA to date have been in rural settings, they are also recommended in urban areas of transmission. It remains unclear whether there is significant urban transmission in West Africa, however, and the need for urban MDA in this region therefore remains a matter of debate.Clinic-based surveillance, for the clinical manifestations of LF, has now been used to identify areas of urban transmission of W. bancrofti in Jos, the major urban population centre of Plateau state, Nigeria. The eight clinics investigated were all located in slum areas, close to vector breeding sites, and were therefore considered to serve at-risk populations. Over a 1-month period, selected providers in these clinics sought hydrocele, lymphoedema, elephantiasis, or acute adenolymphangitis among the patients seeking treatment. The consenting patients who were suspected clinical cases of LF, and a cohort of patients suspected to be cases of onchocerciasis, were tested for W. bancrofti antigenaemia. All the patients were asked a series of questions in an attempt to determine if those found antigenaemic could only have been infected in an urban area. During the study, 30 suspected clinical cases of LF were detected and 18 of these (including two patients who were found to be antigenaemic) lived in urban areas. Of the 98 patients with exclusively urban exposure who were tested for filarial antigenaemia, six (6.1%) were found antigenaemic. Clinic-based surveillance appears to be a useful tool for determining if there is W. bancrofti transmission in an urban setting.

Community-based study to assess the efficacy of DEC plus ALB against DEC alone on bancroftian filarial infection in endemic areas in Tamil Nadu, south India

As part of the Global Programme for Elimination of Lymphatic Filariasis (GPELF), India is implementing mass drug administration (MDA) with annual single dose of diethylcarbamazine (DEC) with and without albendazole (ALB). The impact of MDAs on filarial infections and soil-transmitted helminth (STH) infections was assessed during a 3-year period in two communities, one with DEC + ALB and the other with DEC alone. Prior to each MDA (during 2001, 2002 and 2003), filarial indices (microfilaraemia and antigenaemia) were assessed from blood samples of 450-650 persons aged 2-25 years and STH infections in stool samples (Kato-Katz method) from 325 to 500 children aged 9-10 years. Mosquitoes resting indoors were collected to determine the filarial infection status. The microfilaraemia prevalence decreased significantly (P < 0.05) in both arms, with the highest decline in the DEC + ALB arm (72%vs. 51%). Decline in micrefilaria intensity was also higher in the DEC + ALB arm (81.4%vs. 48.5%). In this arm alone, the antigenaemia prevalence was reduced significantly (62%; P < 0.001). The reduction in STH prevalence was lower in the DEC alone arm (6.5%; NS) than in the DEC + ALB arm (70.9%; P < 0.001). Also, the egg reduction in DEC alone arm was only half that of DEC + ALB arm (49%vs. 97%). Our community-based follow-up study showed higher and sustained benefits with regard to filarial and STH infections for the two-drug arm over the DEC alone arm. The trends suggest that at least 10 MDAs may be necessary to achieve the goal of elimination.

Mathematical models and lymphatic filariasis control: endpoints and optimal interventions

The current global initiative to eliminate lymphatic filariasis is a major renewed commitment to reduce or eliminate the burden of one of the major helminth infections from resource-poor communities of the world. Mathematical models of filariasis transmission can serve as an effective tool for guiding the scientific development and management of successful community-level intervention programmes by acting as analytical frameworks for integrating knowledge regarding parasite transmission dynamics with programmatic factors. However, the power of these tools for supporting control interventions will be realized fully only if researchers address the current uncertainties and gaps in data and knowledge of filarial population dynamics and the effectiveness of currently proposed filariasis intervention options.

A pilot study on the status of lymphatic filariasis in a rural community of Bihar

A pilot study of lymphatic filariasis was conducted in two contiguous villages of Patna district in Bihar situated at the side of the river Ganges, known to be endemic for lymphatic filariasis, to study present status of transmission parameters of filariasis. Of the 1872 persons examined, 8.4% were found asymptomatic but microfilaraemic. Morbidity pattern due to filarial infection showed an increase with advancement of age and significantly high in males as compared to female (p < 0.001). Acute and chronic filarial disease was observed as 0.5% and 9% respectively. Microfilaria was found in 10% of acute and 11.2% of chronic filarial cases. The Mf rate was found to be 9.9% in males and 9.0% in females respectively. The parasite species was identified as W. bancrofti. The vector fauna surveyed show highest prevalence of vector species of Cx. quinquefasciatus (43%) in both domestic as well as predomestic area in the community. Other species like Cx. vishnui and Ma. uniformis were also seen. Each household and predomestic area was searched for mosquito fauna at night. The infection rate in vectors was found to be 14% and infectivity rate (L3) was 8%. The filariasis cases detected in the study were treated with 12 days course of DEC 6 mg/kg body weight.

Lymphatic Filariasis: Treatment, Control and Elimination

Lymphatic filariasis (LF) is a disease not just treatable or controllable; it is a disease that can be eliminated. Indeed, LF is currently the target of a major global initiative to do just that; a few visionaries of the past 50 years did hypothesize that LF elimination was feasible. However, for most of the scientific and global health communities, the elimination of such a broadly disseminated, mosquito-borne disease has seemed highly unlikely. During the past decade, however, both the treatment strategies and the control strategies for LF have undergone profound paradigm shifts-all because of a rapid increase in knowledge and understanding of LF that derived directly from a series of remarkable achievements by the scientific and medical research communities. As a result, a public health dimension with a focus on affected populations, now supplements the earlier, predominantly patient-oriented clinical approach to LF. The early uncertainties, then the essential steps leading to this change in outlook are outlined below, followed by descriptions of the new strategy for LF elimination, the Global Programme created to attain this goal and the successes achieved to date.

Natural course of lymphatic filariasis: insights from epidemiology, experimental human infections, and clinical observations

Lymphatic filariasis has been described as a "spectral disease". Analysis of the natural course of infection in nonendemic individuals as well as experimental infections of "volunteers" suggests that the filarial parasites are not inherently aggressive infectious agents. Experimental infections of humans with infective larvae result in transient, low-level microfilaremia, if at all. Nonendemic individuals with limited exposure show no evidence of persistent infection or pathology. Nonendemic individuals exposed to repeated infections show accelerated pathology. It is tempting to speculate that normal, immunocompetent residents in an endemic area show either (a) no pathology (endemic normals) because they are subject to the relatively low levels of infection or (b) chronic pathology if they are repeatedly infected. It would appear that only those individuals rendered immunologically tolerant to filarial parasites become productively infected with the filarial parasites. The intensity of transmission may underlie the differences in clinical presentation seen in diverse global pockets of endemicity.

Does longevity of adult Wuchereria bancrofti increase with decreasing intensity of parasite transmission? Insights from clinical observations

To interrupt transmission of Wuchereria bancrofti, a parasite that causes lymphatic filariasis, mass treatment of at-risk populations with antifilarial drugs is recommended for 4-6 years, the minimum estimated adult worm lifespan. Factors associated with adult worm longevity are unknown. In Recife, Brazil, we conducted a retrospective cohort study of 57 men whose adult W. bancrofti were not sensitive to diethylcarbamazine and who were followed with semi-annual physical examinations (to detect intrascrotal nodules, indicative of adult worm death) and ultrasound examinations (to detect the 'filaria dance sign' (FDS), indicative of living adult worms). After 5 years, the FDS remained detectable in 10 (24.4%) of 41 adult worm nests in 25 men from areas of high filariasis transmission intensity and in 30 (90.9%) of 33 nests in 32 men from areas of low transmission (P<0.001). New nodules and adult worm nests were detected only in men from high-transmission areas. Of 30 men who were microfilaria-positive initially and whose FDS remained detectable after 5 years of follow-up, 19 (63.3%) remained microfilaria-positive in 5 ml blood (mean density, 0.4 per ml). In conclusion, survival of adult W. bancrofti is inversely associated with transmission intensity. These findings have implications for filariasis elimination and research.

Bancroftian filariasis: patterns of vector abundance and transmission in two East African communities with different levels of endemicity

Intensive monitoring of Wuchereria bancrofti vector abundance and transmission intensity was carried out in two communities, one with high-level endemicity for bancroftian filariasis (Masaika, Tanzania) and the other with low-level (Kingwede, Kenya), on the East African coast. Mosquitoes were collected in light traps, from 50 randomly selected households in each community, once weekly for 1 year. They were identified, dissected and checked for parity and filarial larvae. Anopheles gambiae s. l., An. funestus and Culex quinquefasciatus transmitted W. bancrofti in the two communities but the importance of each of these taxa differed between the communities and by season. The overall vector densities and transmission intensities were significantly higher in Masaika than in Kingwede (the annual biting rate by 3.7 times and the annual transmission potential by 14.6 times), primarily because of differences in the available breeding sites for the vectors and in the vectorial capacity of the predominant vector species. A marked seasonal variation in vector abundance and transmission potential contributed to the complex transmission pattern in the communities. Generally, these indices were higher during and shortly after the rainy seasons than at other times of the year. Considerable differences in W. bancrofti transmission were thus observed between communities within a relatively small geographical area (mainly because of environmentally-determined differences in vector habitats), and these were reflected in the marked differences in infection level in the human populations. The variation in vector abundance, vector composition and transmission intensity in the two communities is discussed in respect to its cause, its effects, and its significance to those attempting to control bancroftian filariasis.

Significant decrease in the prevalence of Wuchereria bancrofti infection in anopheline mosquitoes following the addition of albendazole to annual, ivermectin-based, mass treatments in Nigeria

A prospective entomological survey was conducted in four sentinel villages in central Nigeria from 1999-2002, to assess the impact of annual, single-dose, mass drug administrations (MDA), with a combination of ivermectin and albendazole, on the transmission of Wuchereria bancrofti. As they were also endemic for human onchocerciasis, the four villages had received annual MDA based on ivermectin alone for 7 years prior to the addition of albendazole. Resting Anophelines gambiae s. l., An. funestus and Culex species were collected from 92 sequentially sampled households and dissected. Mosquitoes harbouring any larval stage of W. bancrofti were classified as 'infected', and those containing the third-stage larvae of the parasite were classified as 'infective'. Over the 41-month observation period, 4407 mosquitoes were captured and dissected, of which 64% were An. gambiae s. l., 34% An. funestus, and 1% Culex species. The baseline data, from dissections performed before the addition of albendazole to the MDA, showed high prevalences of mosquito infection (8.9%) and infectivity (2.9%), despite apparently good treatment coverages during the years of annual ivermectin monotherapy. Only the anopheline mosquitoes were found to harbour W. bancrofti larvae. After the third round of MDA with the ivermectin-albendazole combination, statistically significant decreases in the prevalences of mosquito infection (down to 0.6%) and infectivity (down to 0.4%) were observed (P<0.0001 for each). The combination of albendazole and ivermectin appears to be superior to ivermectin alone for reducing the frequency of W. bancrofti infection in mosquitoes.

Lymphatic filariasis in Ghana: establishing the potential for an urban cycle of transmission

Lymphatic filariasis is a significant public health and economic problem in many tropical and sub-tropical regions. Unplanned urbanization leading to a lack of proper sanitary conditions has resulted in an increase in the urban-based transmission of a number of vector-borne diseases, including lymphatic filariasis. It has been well established that lymphatic filariasis is endemic in rural areas of Ghana. The goal of this study was to determine if there is a potential of establishing urban transmission cycles in Ghana's major cities. We clinically and immunologically assessed 625 individuals from the three major urban areas (Bawku, Bolgatanga and Secondi/Takoradi), finding that the prevalence of infection with Wuchereria bancrofti ranged from 0 to 12.5%. The results of a polymerase chain reaction based analysis of mosquitoes collected from these areas suggested that there is a low but detectable prevalence of mosquitoes infected with W. bancrofti. We conclude that there may be a potential for an established urban transmission of lymphatic filariasis in Ghana.

Factors associated with participation in a campaign of mass treatment against lymphatic filariasis, in Leogane, Haiti

In October 2000, to interrupt transmission of Wuchereria bancrofti, an intense health-education campaign followed by a mass drug administration (MDA) with diethylcarbamazine and albendazole was undertaken in Leogane, Haiti. Three months after the MDA, which was the first in the study area, a knowledge-attitude-practice (KAP) survey, with a cluster-sample design and probability sampling, was undertaken, to determine the existing knowledge of the local residents, their attitudes toward the MDA, and the possible reasons for non-compliance. Questionnaire-based interviews were used to explore the KAP of 304 subjects (one randomly chosen resident aged > 14 years from each selected household) in 33 communities. Most (93%) of the interviewees were aware of filariasis and 72% knew at least one clinical sign of the disease. Awareness of the MDA was high (91%). The most frequently mentioned sources of information were other people (56%) and radio announcements (33%). More than 80% of the respondents encouraged other people to take the drugs distributed in the MDA and 63% had been treated. The primary reasons given for failing to take the drugs were absenteeism during the distribution (17%), use of contraceptive drugs (12%) and pregnancy (11%). In a multivariate analysis, being male [odds ratio (OR) = 3.3; 95% confidence interval (CI) = 1.5-7.4], knowing that a mosquito transmits the disease (OR = 2.6; CI = 1.2-5.4), and having learned about the MDA through posters and banners (OR = 2.9; CI = 1.2-7.5) were found to be positively associated with taking the drugs. Information from such post-treatment surveys should be useful in developing better health communication for subsequent MDA.

Susceptibility of Mansonia uniformis to Brugia malayi microfilariae from infected domestic cat

Microfilariae of Brugia malayi is transmitted to man and other susceptible hosts via mosquito. The transmission of B. malayi from cat to man by Ma. uniformis bite has never been reported. The Ma. uniformis mosquito is the normal vector for Wuchereria bancrofti but has never been reported as a vector for B. malayi, or a susceptible host for the growth and development of the microfilariae of B. malayi. The purpose of this study was to examine the development of B. malayi in Mansonia uniformis after feeding on the blood of an infected cat in the laboratory. The B. malayi infected cat was identified using PCR with the primers Bm-1/Bm-2 on DNA (at 10 ng/50 microl) extracted from the WBC of the cat. W. bancrofti was employed as a negative control. The sensitivity of the B. malayi DNA detection by PCR was 0.0001 ng. Adult Ma. uniformis mosquitos at the ages of 5, 10, and 15 days, 100 mosquitos in each group, were fed on the infected cat blood. Recovery of third stage microfilariae was found to be the highest in the 5-day old mosquito group (48%), followed by the 10- and 15-day old mosquito groups (32% and 18%, respectively). The mean number of B. malayi microfilariae found in thorax, head, and abdomen of the mosquitos were composed. The 5-day old (40.3%) and 10-day old (41.9%) mosquitos were significantly more susceptible to microfilariae than the 15-day old mosquitos (17.8%) (p-values using the Scheffe method: 0.027 and 0.039, respectively). There was no significant difference in the mean number of microfilariae in the thorax (p = 0.482) by age, but the mean numbers of microfilariae in the heads, and abdomens were significantly different by age between the 5- and10-, and the 15-day old mosquitos (p < 0.001 and p = 0.004, respectively).