Miguel Angel Descalzo

Emerging trends in the seroprevalence of canine leishmaniosis in the Madrid region (central Spain)

This report describes a cross-sectional serological survey of the epidemiology of canine leishmaniasis (CanL) performed in 2006 and 2007 in the Madrid region (central Spain) where the disease is endemic. The work presented here is one of the several studies conducted in different Spanish regions under the Integrated Project of the European Commission entitled Emerging Diseases in a changing European eNvironment (EDEN). The aim of this project is to identify and catalogue European ecosystems and environmental conditions that determine the spatial and temporal distributions and dynamics of several pathogenic agents including Leishmania infantum (EDEN-LEI). The study area (Madrid Autonomous Region) was selected on the grounds of its wide altitude range. This area was surveyed from NE to SW across its mountain range (Sistema Central) and plateau area. One thousand and seventy-six dogs from 32 villages were examined for clinical signs of CanL, and serum samples were obtained to determine several haematological and biochemical variables. Leishmaniasis-specific antibodies were identified using an indirect immunofluorescence antibody test (IFAT). 87 of the 1076 dogs were seropositive for the protozoan (IFAT: cut-off>or=1/80) indicating a seroprevalence of 8.1% (0-16.1% depending on the village). On the basis of a physical examination and the biochemical/haematological status of each dog, 32 of the 87 infected dogs were described as clinically healthy (37%). Seroprevalence showed a peak in young dogs (1-2 years) and a second larger peak among the older dogs (7-8 years). Factors correlated with a higher infection risk were age (OR=1.15 [95% CI: 1.07-1.22]), weight (OR=1.10 [95% CI: 1.04-1.16]), and living outdoors as opposed to in a home (OR=3.38 [95% CI: 1.42-8.05]). According to data from studies performed in 1992 in the same area, the seroprevalence of CanL has increased 1.54-fold [95% CI: 1.04-2.29]. Given that this increasing trend cannot be attributed to differences in the sociodemographic characteristics of the dog populations, it is proposed that environmental changes could have had an impact on vector and reservoir densities and their geographical distributions. Further studies designed to explain this trend should attempt to correlate sand fly densities and CanL seroprevalences with climate, land use and human changes.

Mapping the Current Distribution and Predicted Spread of the Leishmaniosis Sand Fly Vector in the Madrid Region (Spain) Based on Environmental Variables and Expected Climate Change

Leishmaniosis caused by Leishmania infantum is a widespread zoonotic disease that is endemic in the Mediterranean basin. Based on prior point abundance data for the two sand fly vectors of leishmaniosis in the Madrid region (Phlebotomus perniciosus and Phlebotomus ariasi), models were constructed to predict the spatial distribution patterns of these vectors. The models were obtained by negative binomial regression of several environmental variables and then used to map vector distributions. To validate the maps, we used serological prevalence data of Leishmania infection in dogs and incidence data were obtained through questionnaires completed by veterinarians in the region. Seropositive dogs and veterinary clinics registering a higher incidence of canine leishmaniosis appeared closer to our modeled vector foci. In the face of climate change, we simulated the future distributions of the sand flies for each third of the 21st century and predicted their spread in the region.

Nutritional and socio-economic factors associated with Plasmodium falciparum infection in children from Equatorial Guinea: results from a nationally representative survey

BackgroundMalaria has traditionally been a major endemic disease in Equatorial Guinea. Although parasitaemia prevalence on the insular region has been substantially reduced by vector control in the past few years, the prevalence in the mainland remains over 50% in children younger than five years. The aim of this study is to investigate the risk factors for parasitaemia and treatment seeking behaviour for febrile illness at country level, in order to provide evidence that will reinforce the EG National Malaria Control Programme.MethodsThe study was a cross-sectional survey of children 0 to 5 years old, using a multistaged, stratified, cluster-selected sample at the national level. It included a socio-demographic, health and dietary questionnaires, anthropometric measurements, and thick and thin blood smears to determine the Plasmodium infection. A multivariate logistic regression model was used to determine risk factors for parasitaemia, taking into account the cluster design.ResultsThe overall prevalence of parasitemia was 50.9%; it was higher in rural (58.8%) compared to urban areas (44.0%, p = 0.06). Age was positively associated with parasitemia (p < 0.0001). In rural areas, risk factors included longer distance to health facilities (p = 0.01) and a low proportion of households with access to protected water in the community (p = 0.02). Having had an episode of cough in the 15 days prior to the survey was inversely related to parasitemia (p = 0.04). In urban areas, the risk factors were stunting (p = 0.005), not having taken colostrum (p = 0.01), and that someone in the household slept under a bed net (p = 0.002); maternal antimalarial medication intake during pregnancy (p = 0.003) and the household socio-economic status (p = 0.0002) were negatively associated with parasitemia. Only 55% of children with fever were taken outside their homes for care, and treatment seeking behaviour differed substantially between rural and urban populations.ConclusionResults suggest that a national programme to fight malaria in Equatorial Guinea should take into account the differences between rural and urban communities in relation to risk factors for parasitaemia and treatment seeking behaviour, integrate nutrition programmes, incorporate campaigns on the importance of early treatment, and target appropriately for bed nets to reach the under-fives.

Infectivity to Phlebotomus perniciosus of dogs naturally parasitized with Leishmania infantum after different treatments

BackgroundIn Europe most dogs with clinical leishmaniosis are treated with leishmanicides, typically antimonials combined with allopurinol and good clinical recovery is observed in a high number of these dogs. Through xenodiagnosis, the capacity of a treated animal to infect the vector of the disease under treatment is assessed as a measure of the chemotherapeutic efficacy of the drug used. The objective of the present study was to evaluate through direct xenodiagnosis the infectivity to Phlebotomus perniciosus of dogs naturally parasitized with Leishmania infantum after treatment, and to follow the clinical and parasite course of disease. Thirty two dogs with clinical leishmaniosis were assigned to one of three treatment groups: meglumine antimoniate plus allopurinol (Group A), meglumine antimoniate (Group B) or allopurinol (Group C). During the study, the dogs were examined before treatment (Day 0) and bimonthly thereafter until Day 180 (six months post-treatment onset).ResultsThe three groups were scored over time according to the effects of treatment on clinical signs and clinical-pathological variables. Significant differences in clinical scores were observed between Group A and the other two groups, indicating the combined treatment was the most effective. After treatment, bone marrow cultures were positive for the parasite in 30.8% of dogs in some of the check ups (3 or 25% in Group A, 1 or 11.1% in Group B, and 4 or 80% in Group C). Our xenodiagnosis experiments revealed that 15.4% of treated dogs were still able to infect sand flies at some point after treatment (2 dogs or 16.6% in Group A, 2 or 22.2% in Group B and none in Group C). Only 7.7% of the entire study population could infect sand flies as from the second month post-treatment onset.ConclusionThe three treatment regimens tested significantly reduced the infectivity of dogs towards sand flies, thus diminishing the epidemiological risks of treated dogs both for human beings and other healthy dogs. Despite its low cure rate, the use of allopurinol after a course of leishmanicide treatment is proposed to keep dogs non-infectious during the disease transmission season (4-6 months in southern Europe).

Spatial variability in the density, distribution and vectorial capacity of anopheline species in a high transmission village (Equatorial Guinea)

BackgroundMalaria transmission varies from one country to another and there are also local differences in time and space. An important variable when explaining the variability in transmission is the breeding behaviour of the different vector species and the availability of breeding sites. The aim of this study was to determine the geographical variability of certain entomological parameters: human biting rate (HBR), sporozoitic index (SI) for Plasmodium falciparum and entomological inoculation rate (EIR).MethodsThe study was carried out in a small village in the mainland region of Equatorial Guinea. Adult mosquitoes were collected by CDC light traps. Polymerase Chain Reaction was employed to identify the species within the Anopheles gambiae complex and to detect P. falciparum sporozoites. The geographical position of all the dwellings in the village were taken using a global positioning system receiver unit. Data relating to the dwelling, occupants, use of bednets and the mosquitoes collection data were used to generate a geographical information system (GIS). This GIS allowed the minimum distance of the dwellings to the closest water point (potential breeding sites) to be determined.ResultsA total of 1,173 anophelines were caught: 279 A. gambiae s.l. (217 A. gambiae s.s. and one Anopheles melas), 777 Anopheles moucheti and 117 Anopheles carnevalei. A. moucheti proved to be the main vector species and was responsible for 52.38 [95% IC: 33.7–71] night infective bites during this period. The highest SI was found in A. carnevalei (24%), even though the HBR was the lowest for this species. A significant association was found between the distance from the dwellings to the closest water point (River Ntem or secondary streams) and the total HBR.ConclusionA clear association has been observed between the distance to potential breeding sites and the variability in the anopheline density, while the other parameters measured do not seem to condition this spatial variability. The application of GIS to the study of vector-transmitted diseases considerably improves the management of the information obtained from field surveys and facilitates the study of the distribution patterns of the vector species.

Impact of different strategies to control Plasmodium infection and anaemia on the island of Bioko (Equatorial Guinea).

BackgroundOn the island of Bioko (Equatorial Guinea), insecticide-treated nets (ITNs) have been the main tool used to control malaria over the last 13 years. In 2004, started an indoor residual spraying (IRS) campaign to control malaria. The purpose of this study is to asses the impact of the two control strategies on the island of Bioko (Equatorial Guinea), with regards to Plasmodium infection and anaemia in the children under five years of age.MethodsTwo transversal studies, the first one prior to the start of the IRS campaign and the second one year later. Sampling was carried out by stratified clusters. Malaria infection was measured by means of thick and thin film, and the packed cell volume (PCV) percentage. Data related to ITN use and information regarding IRS were collected. The Pearsons chi-square and logistic regression statistical tests were used to calculate odds ratios (OR)ResultsIn the first survey, 168 children were sampled and 433 children in the second one. The prevalence of infection was 40% in 2004, and significantly lower at 21.7% in 2005. PCV was 41% and 39%, respectively. 58% of the children surveyed in 2004 and 44.3% in 2005 had slept under an ITN. 78% of the dwellings studied in 2005 had been sprayed. In the 2005 survey, sleeping without a mosquito net meant a risk of infection 3 times greater than sleeping protected with a net hanged correctly and with no holes (p < 0.05).ConclusionIRS and ITNs have proven to be effective control strategies on the island of Bioko. The choice of one or other strategy is, above all, a question of operational feasibility and availability of local resources.

Evaluation of a spray of permethrin and pyriproxyfen for the protection of dogs against Phlebotomus perniciosus

Dogs are the main domestic reservoir of Leishmania infantum in the Old World (Leishmania chagasi in the New World) a parasite responsible for many cases of human visceral leishmaniasis in both endemic and non-endemic regions. One strategy for the control of leishmaniasis would be to prevent dogs from being bitten by sandflies, the vector of leishmaniasis. This study was designed to assess the efficacy of spraying a combination of permethrin and pyriproxyfen on to dogs artificially exposed to sandflies. Two groups of four male dogs, one of them treated and the other left untreated as controls, were exposed for one hour to 100 female sandflies seven days before the treatment, on the day of treatment and seven, 14, 21, and 28 days later. After each exposure, sandflies were collected, counted and scored. The prevention of sandfly bite was calculated by measuring the number of fed sandflies (dead and alive) after treatment. In this experimental assay, the repellent effect of the treatment against sandfly bites after 21 days was 71·4 per cent, but the insecticidal effect was only 7·2 per cent.

Efficacy of 65% permethrin applied to dogs as a spot-on against Phlebotomus perniciosus

Leishmania infantum is a protozoan parasite causing leishmaniosis, a visceral disease transmitted by the bites of sand flies. As the main reservoir of the parasite, dogs are the principal targets of control measures against this disease, which affects both humans and dogs. Several studies have revealed the usefulness of topical insecticide treatment (collars, spot-ons and sprays) in reducing the incidence and prevalence of L. infantum. The present study was designed to test the efficacy of 65% permethrin applied to dogs as a spot-on against the sand fly vector Phlebotomus perniciosus. The duration of the desired effects was also estimated to help design an optimal treatment regimen. Twelve dogs assigned to treatment (n=6) and control (n=6) groups were exposed to sand flies once a week over a seven-week period. Repellent and insecticidal efficacies were estimated and compared amongst the groups. Our findings indicate satisfactory repellent, or anti-feeding, effects lasting 3 weeks and short-term insecticidal effects lasting 2 weeks after initial application. Accordingly, we recommend the use of this product every 2-3 weeks during the active phlebotomine sand fly period to protect dogs against the bites of P. perniciosus.

Nutritional status and its correlates in Equatorial Guinean preschool children: results from a nationally representative survey.

Background In Equatorial Guinea, as a result of the recent growth of the oil industry, there is an opportunity to address important public health problems through public and private initiatives. To propose effective nutrition and public health strategies, it is important first to have reliable information on the nutritional status of the population and the underlying factors affecting it. Objective To assess the nutritional status and the prevalence of anemia among Equatoguinean children in a nationally representative sample and to identify the risk factors associated with the nutritional problems detected. Methods The study was a cross-sectional survey using a multistaged, stratified, cluster-selected sample. The survey included a sociodemographic, health, and dietary questionnaire and measurement of hematocrit and anthropometric features, from which nutritional indicators based on the National Center for Health Statistics (NCHS) reference and the World Health Organization (WHO) standards were calculated. Logistic regression models were used for the multivariate analysis. A total of 552 children aged 0 to 60 months were surveyed. Results The overall prevalence of stunting (< −2 height-for-age z-scores [HAZ]) was 29.7% based on the NCHS reference and 35.2% based on WHO standards; the risk factors associated with stunting were age (p < .0001), low socioeconomic status (p = .01), and fishing by a member of the household (p = .003) The prevalence of mild anemia (hemoglobin < 110 g/L) was 69.3%, and that of moderate or severe anemia (hemoglobin < 80 g/L) was 8.3%. The only significant risk factor associated with moderate to severe anemia was low household socioeducational level (p = .01). Conclusions Stunting and anemia are public health problems in Equatorial Guinea. Integrated strategies, including fighting poverty and improving maternal education, should be undertaken.

The economic and nutrition transition in Equatorial Guinea coincided with a double burden of over- and under nutrition

We assess trends in childrens nutritional status in Equatorial Guinea, a country in socioeconomic transition. Nationally representative samples were conducted in 1997, at the start of the economic take off, and again in 2004. Children aged 0-60 months were included in the surveys (N=436, 552). Both surveys included a sociodemographic, dietary and health questionnaire, and anthropometric measurements from which height-for-age (HAZ); weight-for-age (WAZ) and weight-for-height (WHZ) Z-scores were calculated. Between 1997 and 2004, the prevalence of child overweight for all children increased from 21.8% to 31.7%, especially in urban areas (from 18.2% to 29.4%, p=0.01). Stunting prevalence among children >or=2 years old decreased (from 57.9% to 45.3%, p<0.02), but for all age groups remained very high (34.7% overall, 46.5% rural and 28.5% urban in 2004). The economic take off in Equatorial Guinea appeared to coincide with substantial increases in the prevalence of child overweight whereas the prevalence of stunting decreased even if it remained high. The results suggest that the country is undergoing a nutrition transition and acquiring the concomitant double burden of under and over nutrition.