The role of private drug vendors as malaria treatment providers in selected malaria endemic areas of Sri Lanka.

BACKGROUND AND OBJECTIVES: The involvement of private drug vendors in malaria treatment is particularly high in developing countries and understanding their practices and knowledge about antimalarials and malaria treatment will aid in devising strategies to increase the correct use of antimalarials and improve adherence to the government's malaria drug policy. Results of a study on the knowledge and practices of the private drug vendors conducted in seven districts in Sri Lanka, mostly in malarious areas are presented. METHODS: Data on awareness of government's malaria drug policy, practice of issuing antimalarials, knowledge about malaria and antimalarial drugs were collected from the drug vendors using pre-tested questionnaire in vernacular language. Data were statistically analysed using Stata 8.2. Chi-square test was carried out for individual explanatory variables and a logistic regression model was applied taking all response variables as binary outcome. RESULTS: Vendors' knowledge on antimalarials was poor with 58% of the vendors being unaware of the government malaria drug policy in the country. Also, the advice provided to customers buying antimalarials was limited. However, the majority of the private vendors emphasised that they were aware of the importance of case confirmation before treatment as stressed in the national policy. Although, the vendors did not have a high awareness of national drug policies they were only found selling chloroquine and primaquine as recommended by the Ministry of Health. INTERPRETATION AND CONCLUSION: In recent years Sri Lanka, as a whole, has experienced very little malaria. The reduction in demand for antimalarials due to low incidence levels may have influenced the knowledge and awareness on antimalarials and government drug policies. However, since low levels of malaria do not guarantee that epidemics will not occur, attempts to educate private drug vendors as a part of an organised control programmes are of major importance.

Food of larval Anopheles culicifacies and Anopheles varuna in a stream habitat in Sri Lanka.

No previous studies have been conducted on the natural food of larval Anopheles culicifacies s.l. (the major malaria vector) and An. varuna (a secondary vector) in Sri Lanka. The present study analyzed the contents of guts dissected from larvae collected from pools in a natural stream-cum-irrigation conveyance channel in the Upper Yan Oya watershed in the North Central Province of the country during August-September 1997 and July 1998. Determinations of physicochemical and biological parameters of the pools and their water were done at the same time. A fluorochromatic stain, 4',6-diamidino-2-phenylindole, was used to stain larval gut contents. Quantitative estimates of different categories of food types were made by analyzing the gut contents of 95 An. culicifacies (26 second instars and 69 fourth instars) and 52 An. varuna (21 second instars and 31 fourth instars). Detritus was the most frequent food type, comprising >74% of the gut contents in both species. Other food types included bacteria (cocci and rods), filamentous algae, diatoms, and desmids. Overall, bacteria constituted a significantly higher proportion of the gut contents in An. culicifacies than in An varuna. Significantly more detritus, bacteria, and total particulate matter occurred in 4th instars of An. culicifacies than in An. varuna, indicating a greater food intake in the former species. Second instars of An. culicifacies and An. varuna did not differ significantly in any parameter. A significant increase in food intake between 2nd and 4th instars was seen for An. culicifacies, but not An. varuna. Food indices were lower in An. varuna than in An. culicifacies when the 2 species co-occurred, indicating competition for food, and the implications of this to adult body size, survival, and fecundity are discussed.

Physico-chemical characteristics of Anopheles culicifacies and Anopheles varuna breeding water in a dry zone stream in Sri Lanka.

BACKGROUND & OBJECTIVES: Selected physico-chemical characteristics of flowing and pooled water in a stream that generated two malaria vectors, Anopheles culicifacies s.l. Giles and Anopheles varuna Iyengar, were investigated during August-September 1997 and July 1998 at the Upper Yan Oya watershed in north-central Sri Lanka. METHODS: The physico-chemical parameters measured were: temperature, dissolved oxygen, pH, conductivity, total dissolved solids, alkalinity, ammonia nitrogen, nitrate nitrogen, calcium, magnesium, carbondioxide, ferrous iron, phosphate, colour and turbidity. In total, 75.5% of 151 samples analysed were mosquito-positive. Logistic regression was used for statistical analysis. RESULTS: Among physico-chemical parameters, An. culicifacies (the major malaria vector in the country) was positively related only to temperature, and An. varuna (a secondary malaria vector) to calcium. Among habitat characteristics, An. culicifacies was associated with light and vegetation, and negatively associated with the presence of potential predators. An. varuna was positively associated with other aquatic fauna. INTERPRETATION & CONCLUSION: Surprisingly this detailed study did not find an association between An. culicifacies and dissolved oxygen as previously found in the few studies that have looked at physico-chemical characteristics of malaria vector breeding habitats in south Asia. This study, along with existing information from other studies indicate that most of the physico-chemical parameters measured under natural conditions within the same habitat type is insufficient to explain the distribution of vectors within such habitats. However, it seems likely that both An. culicifacies and An. varuna follow a strategy whereby ovipositing females scatter their eggs over most of or all of a highly temporary and only transiently available stream bed pool habitat, in order to optimise breeding success.

Anopheline ecology and malaria infection during the irrigation development of an area of the Mahaweli Project, Sri Lanka.

A study on adult anopheline ecology and malaria vector incrimination was carried out from 1986 to 1989 during irrigation development in an area of the Mahaweli Project in eastern Sri Lanka. Eleven potential vector species were collected resting indoors or by using human or bovid bait, and from light trap catches. Overall, Anopheles vagus (Donitz), An. annularis (van der Wulp), and An. subpictus (Grassi) were the most prevalent, and An. culicifacies (Giles) and An. barbirostris (van der Wulp) were the least prevalent species. The abundance of An. aconitus (Donitz), An. jamesii (Theobald), An. pallidus (Theobald), and An. subpictus increased after irrigation development, while An. annularis, An. barbirostris, An. culicifacies and An. varuna (Iyengar) decreased. Populations of An. nigerrimus (Giles), An. tessellatus (Theobald), and An. vagus did not change substantially. Seven species were infected with malaria parasites, as determined by enzyme-linked immunosorbent assays (ELISA) done on mosquito head-thorax triturates. The main species involved were An. annularis, at peak abundance during the 1986-1987 period of development leading to the onset of irrigation, and An. subpictus, during times of seasonal abundance in the post-irrigation period of 1988 to 1989. Although occurring at low abundance, An. culicifacies was involved in malaria transmission irregularly throughout the study period. While there was strong ELISA-based evidence implicating An. subpictus as a major post-irrigation vector, confirmation of its vector status must await dissection and ELISA-based evidence of P. vivax and P. falciparum sporozoite infection rates in salivary glands.

Measuring the economic cost of malaria to households in Sri Lanka.

The economic cost at the household level of labor days lost due to malaria and other illnesses was estimated in a rural community in Sri Lanka. Over a one-year period, 223 episodes of malaria were recorded from the 298 inhabitants of the village. Based on daily activity records, the economically active age group was defined as 14-60 years. In this age group, 1.8% of working days were lost due to malaria and 5.2% due to all other illnesses. The value of a labor day lost was based on the actual rural wage rate for children, women, and men, with weeks during periods of high labor demand weighting more than weeks during lean agricultural periods. In this way the annual economic loss per household amounted to US $15.56 for malaria and US $47.46 for all other illnesses. This corresponded to a loss of 6% and 18% of annual household net income, respectively. Although the overall economic impact was limited, malaria cases were concentrated in an important agricultural season. During this season, 5.6% of working days were lost due to malaria. In addition, children, who were not part of the economically active population, lost 10% of school days due to malaria during the high transmission season. In estimating the socioeconomic impact of malaria and in measuring cost-benefits of malaria control interventions, these costs have to be considered together with direct expenditures incurred by households such as on treatment and travel and with costs for the service providers.

Malaria vectors in a traditional dry zone village in Sri Lanka.

Malaria transmission by anopheline mosquitoes was studied in a traditional tank-irrigation-based rice-producing village in the malaria-endemic low country dry zone of northcentral Sri Lanka during the period August 1994-February 1997. Adult mosquitoes were collected from human and bovid bait catches, bovid-baited trap huts, indoor catches, and pit traps. Mosquito head-thoraces were tested for the presence of Plasmodium falciparum and P. vivax, and blood-engorged abdomens for the presence of human blood by ELISAs. House surveys were done at two-day intervals to record cases of blood film-confirmed malaria among the villagers. A total of 7,823 female anophelines representing 14 species were collected. Trends in anopheline abundance were significantly correlated with rainfall of the preceding month in An. annularis, An. barbirostris, An. subpictus, An. vagus, and An. varuna, but were not significant in An. culicifacies and An. peditaeniatus. Malaria parasite infections were seen in seven mosquito species, with 75% of the positive mosquitoes containing P. falciparum and 25% P. vivax. Polymorph PV247 was recorded from a vector (i.e., An. varuna) for the first time in Sri Lanka. Computations of mean number of infective vector (MIV) rates using abundance, circumsporozoite (CS) protein rate, and human blood index (HBI) showed the highest rate in An. culicifacies. A malaria outbreak occurred from October 1994 to January 1995 in which 45.5% of village residents experienced at least a single disease episode. Thereafter, malaria incidence remained low. Anopheles culicifacies abundance lagged by one month correlated positively with monthly malaria incidence during the outbreak period, and although this species ranked fifth in terms of abundance, infection was associated with a high MIV rate due to a high CS protein rate and HBI. Abundance trends in other species did not correlate significantly with malaria. It was concluded that An. culicifacies was epidemiologically the most important vector in the study area.

Serologic evidence for an epizootic dengue virus infecting toque macaques (Macaca sinica) at Polonnaruwa, Sri Lanka.

Dengue is one of the most rapidly emerging diseases in the tropics. Humans are the principal reservoir of dengue viruses. It is unclear if nonhuman primates also serve as a reservoir of human dengue viruses under certain conditions. In this study, a cross-sectional serologic survey was carried out to characterize the pattern of transmission of a recently identified dengue virus among toque macaques in Sri Lanka. The results indicated that an epizootic dengue virus was active among the macaques. A single epizootic had taken place between October 1986 and February 1987 during which 94% of the macaques within the 3 km2 study site were exposed to the virus. The epizootic was highly focal in nature because macaques living 5 km from the study population were not exposed to the virus. The transmission of dengue viruses among macaques in the wild may have important public health implications.

Viruses isolated from mosquitoes collected in Sri Lanka.

Attempts to isolate viruses from 178,181 unengorged female mosquitoes collected from different ecologic areas of Sri Lanka yielded 31 isolates: 17 of Japanese encephalitis (JE) virus, nine of Getah virus, three of a Batai-related bunyavirus, and two of Arkonam virus. Culex tritaeniorhynchus and Mansonia uniformis mosquitoes were found to carry JE virus in a dry zone nonepidemic area, and Cx. pseudovishnui was found to carry it in a wet zone nonepidemic area. Japanese encephalitis virus was isolated from Cx. tritaeniorhynchus, Cx. gelidus, Cx. fuscocephala, and Cx. whitmorei during a human epidemic in the dry zone. Getah virus was isolated from Cx. tritaeniorhynchus, Cx. gelidus, and Cx. fuscocephala collected in the vicinity of swine. Isolations of Getah, Arkonam, and Batai-related viruses from Sri Lanka are reported for the first time.

Household responses to malaria and their costs: a study from rural Sri Lanka.

A study of the cost of malaria at the household level, community perceptions, preventive measures and illness behaviour linked to the disease was undertaken in 5 villages in the dry zone of Sri Lanka. The surveyed community had a high knowledge of malaria, although side effects of antimalarial drugs were often confused with symptoms of the disease. The community sought prompt diagnosis and treatment at 'western-type' facilities, with 84% making use of government facilities as their first choice and 16% preferring private facilities. The preventive measures used were burning coils (54% of families) and special leaves (69% of families), and 93% of the families had their houses sprayed with insecticides. Average direct expenditure on a single malaria episode was $3 US, with some families spending more than 10% of the annual household net income per episode. The highest expenditure was on special diets for the sick person, to neutralize the perceived heating effect of the disease and its treatment.

PIP: Knowledge of community perceptions of malaria, treatment-seeking behaviors, and the household costs of illness is essential to the planning of sustainable malaria control interventions. These factors were investigated in household surveys conducted in 5 villages in Sri Lanka's dry zone in February 1995. 95% of the 216 families interviewed regarded malaria as their main health problem, followed by diarrhea and eye diseases. Malaria was ranked as the third most important community concern, following lack of water for cultivation and poverty. Overall knowledge of malaria's causes, symptoms, and treatment was high, although the side effects of antimalarial drugs were often confused with symptoms of the disease. Reported for the 3-month period preceding the survey were 178 episodes of malaria involving 160 families. Home treatment with paracetamol was the first step taken in 85% of cases; however, all families sought prompt treatment from Western-type facilities, especially government hospitals (48%) and mobile clinics (30%). No families consulted indigenous or ayurvedic physicians, despite their availability in the area. This utilization of prompt, effective treatment is presumed to reflect high knowledge about malaria, the perceived seriousness of the disease, and good transport facilities in the area. The total direct expenditure on a single episode of malaria averaged US $3; the median net annual income was $258. Special foods for malaria patients aimed at neutralizing the perceived heating effect of malaria and antimalarial drugs (e.g., sodas, oranges) were the most costly item. Adults lost an average of 7.8 days of work per episode and those accompanying them to health facilities lost 2.9 days. Preventive measures used by families included bed nets (23%), mosquito coils (54%), and insecticides (93%).

Risk factors for malaria: a microepidemiological study in a village in Sri Lanka.

Environmental and socioeconomic risk factors for malaria were studied in a village in Sri Lanka. Over a period of one year, all 49 households in the village were visited every alternate day to obtain information on malaria episodes. Information on risk factors was obtained through questionnaires and direct observations. Age below 17 years (relative risk [RR] = 1.66, 95% confidence interval [95% CI] 1.18-2.35), use of bed nets (RR = 0.16, 95% CI 0.05-0.45) and traditional fumigants (RR = 0.58, 95% CI 0.37-0.93) were independent predictors of malaria. People using anti-mosquito pyrethrum coils had a higher risk for malaria than people living in houses where they were not used (RR = 1.46, 95% CI 1.03-2.07). The build-up of Anopheles culicifacies populations before the start of the transmission season had taken place in a stream near the village. Living close to the stream was a risk factor for malaria early in the transmission season, although this did not reach statistical significance (comparing < 250 m with > 500 m, RR = 2.13, 95% CI 0.96-4.71).

Human otoacariasis: a retrospective study from an area of Sri Lanka.

Intra-aural ticks were present in 870 (15.2%) of 5714 patients who reported with ear-related complaints to the ear, nose and throat ward at Ratnapura Hospital, Sabaragamuwa Province, Sri Lanka, from January 2000 to December 2001. A retrospective study of 383 of these otoacariasis cases showed that the majority (70.8%) of surgically-removed ticks were nymphal Amblyomma integrum, together with nymphal and adult Rhipicephalus haemaphysaloides, R. sanguineus, Hyalomma brevipunctata, H. marginatum, and unidentified (damaged) ticks (collectively, 29.2%). Tick infestations peaked during the period November-February. More female than male patients reported with otoacariasis, and more children (aged 0-10 years) and adults (aged >/=21 years) than adolescents. There was no evidence of age-dependent differences in infestation among male and female patients. The tick-infested cases were widespread, spanning 75 km on a north-south axis and 55 km on an east-west axis within Sabaragamuwa Province. The present report represents the largest episode of human otoacariasis recorded in the literature, and may be indicative of a wider, but little-reported, human tick problem in Sri Lanka.

Japanese encephalitis in Sri Lanka--the study of an epidemic: vector incrimination, porcine infection and human disease.

A prospective study of mosquito vectors, porcine infection and human disease was carried out during a Japanese encephalitis (JE) epidemic in the North Central province of Sri Lanka (November-December 1987) and a subsequent non-epidemic year (1988). The epidemic involved 361 cases of human encephalitis, virologically confirmed by immunoglobulin M enzyme-linked immunosorbent assay (ELISA), and was preceded 2-3 weeks earlier by sentinel porcine seroconversion. Virus isolation and viral antigen detection (ELISA) in field-caught mosquitoes incriminated Culex tritaeniorhynchus (Giles) and Cx gelidus Theobald as the major vectors of virus transmission during the porcine amplification and human 'spill-over' phases of the epidemic. Virus was also demonstrated in Cx fuscocephala Theobald, Cx whitmorei (Giles) and Mansonia uniformis (Theobald) during the epidemic. The major difference between the epidemic (1987) and non-epidemic (1988) years was a lower vector biomass and lower rates of virus carriage in the mosquito population.

Anopheles culicifacies breeding in Sri Lanka and options for control through water management.

This paper assesses the options for control of malaria vectors through different water management practices in a natural stream in Sri Lanka. The association between water level in the stream and breeding of the immature stages of the primary vector Anopheles culicifacies was investigated and the feasibility of using existing irrigation infrastructure to reduce the breeding potential discussed. The most feasible option would be to implement a management routine where water is released periodically from an upstream reservoir to reduce the number of breeding sites downstream. This study indicates that by regulating the water level above 20 cm in the stream throughout the dry season the breeding of A. culicifacies could be significantly reduced. The intervention would have only limited impact on the water lost for agriculture and the management input would be minimal. However, for the intervention to work a high degree of support from the local community is essential and consultation between government departments needed.

A village treatment center for malaria: community response in Sri Lanka.

Early diagnosis and treatment of malaria cases is one of the basic elements of the current global malaria control strategy. In order to provide this service to people in rural areas there is a need for new cost-effective approaches. To ensure that such new approaches are acceptable to the target communities, it is important to know the rationale for people's malaria treatment-seeking behavior. The present study provides insights into the reasons for people's preferences for different types of healthcare facilities and describes variation of these preferences within a rural community in Sri Lanka. The study reports on the experiences with the establishment of a village health facility and its effect on the treatment-seeking behavior of the population. After the introduction of the village treatment center it quickly took over the role of main provider for diagnosis and treatment of malaria from the government facilities. The treatment center did not improve the response time in seeking treatment for young children, but the delay for adults was reduced by 1-2 days. Mothers with small children often preferred the government facilities since they wanted a more qualified opinion than available from the locally recruited staff of the village treatment center. The treatment center significantly reduced the stress and discomfort experienced by the elderly and handicapped segment of the community. The study indicated that the effective catchment area of a village treatment center will be influenced by the degree of initial support from key individuals in the communities, the selection procedure and training of assistants, and the history of the relationships between different villages to be served by the center. The government health services and communities across the dry zone of Sri Lanka could benefit substantially from the establishment of more village treatment centers. To ensure the long-term sustainability of these type of facilities it is necessary to assess the feasibility of charging a user fee and establishing multi-purpose clinics. Government policies and administrative procedures will need to be adjusted to make the successful operation of village treatment centers possible.

Anopheline (Diptera:Culicidae) breeding in a traditional tank-based village ecosystem in north central Sri Lanka.

A 13-mo survey of immature anopheline mosquitoes breeding in surface water habitats was done at Mahameegaswewa village within the Huruluwewa watershed in north central Sri Lanka as part of a multidisciplinary study on malaria epidemiology. The watershed is representative of the ancient small tank-based irrigation network that still forms an important component of the rice production system in the low elevation dry zone. In total, 3,818 immatures representing 12 species were obtained from 2,940 samples taken from 5 larval habitats within the village ecosystem. Anopheles varuna Iyengar and An. culicifacies Giles were the most abundant species collected. Peak abundance in both species occurred in August-October. Anopheles barbirostris Van der Wulp and An. peditaeniatus Leicester also were abundant, but neither these nor the other anophelines attained comparable abundance to An. varuna and An. culicifacies. A clear progression in breeding habitat use from stream bed to tank bed and drainage area pools was seen in An. culicifacies during the premonsoon period. Environmental management measures to reduce or modify these habitats could potentially decrease malaria. transmission.

Longitudinal studies of Aedes aegypti (Diptera: Culicidae) in Thailand and Puerto Rico: blood feeding frequency.

We used a histologic technique to study multiple blood feeding in a single gonotrophic cycle by engorged Aedes aegypti (L.) that were collected weekly for 2 yr from houses in a rural village in Thailand (n = 1,891) and a residential section of San Juan, Puerto Rico (n = 1,675). Overall, mosquitoes from Thailand contained significantly more multiple meals (n = 1,300, 42% double meals, 5% triple meals) than mosquitoes collected in Puerto Rico (n = 1,156, 32% double meals, 2% triple meals). The portion of specimens for which frequency of feeding could not be determined was 31% at both sites. We estimated that on average Ae. aegypti take 0.76 and 0.63 human blood meals per day in Thailand and Puerto Rico, respectively. However, frequency of multiple feeding varied among houses and, in Puerto Rico, the neighborhoods from which mosquitoes were collected. In Thailand 65% of the mosquitoes fed twice on the same day, whereas in Puerto Rico 57% took multiple meals separated by > or = 1 d. At both sites, the majority of engorged specimens were collected inside houses (Thailand 86%, Puerto Rico 95%). The number of blood meals detected was independent of where mosquitoes were collected (inside versus outside of the house) at both sites and the time of day collections were made in Puerto Rico. Feeding rates were slightly higher for mosquitoes collected in the afternoon in Thailand. Temperatures were significantly higher and mosquitoes significantly smaller in Thailand than in Puerto Rico. At both sites female size was negatively associated with temperature. Rates of multiple feeding were associated positively with temperature and negatively with mosquito size in Thailand, but not in Puerto Rico. Multiple feeding during a single gonotrophic cycle is a regular part of Ae. aegypti biology, can vary geographically and under different climate conditions, and may be associated with variation in patterns of dengue virus transmission.

Malaria transmission by Anopheles subpictus (Diptera: Culicidae) in a new irrigation project in Sri Lanka.

Indoor resting Anopheles subpictus in a new irrigation scheme in Sri Lanka were investigated during 1989-1990 for malaria infection by dissection and ELISA, and human feeding rates by ELISA analysis of blood meals. Indoor resting abundance was 22.3 females per house per 15-min catch in April-June 1989, 2.2 in November-December 1989, and 7.5 in April-June 1990. ELISA-based malaria infection rates (Plasmodium vivax and P. falciparum combined) were 1.4% during April-June and 3.2% during November-December 1989, and 12.5% during April-June 1990. Dissection and ELISA confirmed the presence of oocysts and sporozoites of P. falciparum in 1990. Human blood was detected in 4.3, 0.8, and 5.2% of analyzed meals, respectively, during the three sampling periods. Estimates of the entomological inoculation rate (EIR) ranged from 0.00006 to 0.005 in different samples and vectorial capacity (VC) was 0.0005 for the 1990 sample. Thus, An. subpictus is incriminated as a vector of human malaria in Sri Lanka.

Detection of multiple blood feeding in Aedes aegypti (Diptera: Culicidae) during a single gonotrophic cycle using a histologic technique.

We evaluated a histologic technique for its usefulness in detecting multiple blood feeding by Aedes aegypti (L.) in a single gonotrophic cycle. To standardize the procedure, we carried out a laboratory study in which 166 mosquitoes imbibed two blood meals at known intervals. Eighty percent (78/98) of the multiple meals were detected when the interval between meals was from 1 to < to = 24 h and the time from the second meal to fixation ranged from 0 to 12 hr. At intervals outside this range, only 34% (23/68) of the multiple meals were detected. Overall, 61% (101/166) of the double meals were detected. Examination of 96 engorged Ae. aegypti collected by aspiration from inside houses in San Juan, Puerto Rico, indicated that 50% had imbibed multiple meals. Most wild-caught mosquitoes took their last meal the day before capture, and most multiple feeders fed twice on consecutive days. A dark line of digested blood, or heme, around the first meal and a physical separation between meals were the most useful histologic parameters for detecting multiple feeding in wild Ae. aegypti. An association of multiple feeding with advanced stages of oocyte development suggests that, at the time of collection, most Ae. aegypti from the study site had fed twice in each gonotrophic cycle. We conclude that, although it is labor intensive, histologic examination is an appropriate technique for a longitudinal, community-wide survey of multiple feeding by Ae. aegypti.

Characteristics of malaria vector breeding habitats in Sri Lanka: relevance for environmental management.

In and around a village in the Anuradhapura District of Sri Lanka anopheline larvae were sampled from July 1994 to April 1996 in all surface water bodies. Samples positive for Anopheles culicifacies, the established vector of malaria in Sri Lanka, and for An. barbirostris, An. vagus, and An. varuna, potential secondary vectors, were characterized by site, exposure to sunlight, substratum, turbidity of the water, presence of vegetation, and presence of fauna. Availability of pools of stagnant water in the stream near the village and along the edge of the village tank was highly predictive for presence of An. culicifacies larvae, independent from the other characteristics that were included in the study. The biological and physical characteristics could not very well explain the preference for certain habitats, but it was of interest that An. culicifacies, generally considered to bread in sun exposed clear water pools, was able to exploit habitats that were shaded and contained turbid water. Environmental management interventions to control An. culicifacies breeding have to take into account that the secondary vectors of malaria exploit other habitats and would not be affected by the interventions.