Domestic vectors of Chagas' disease in three rural communities of Nicaragua

A triatomine survey was conducted in three rural settlements of Nicaragua (Santa Rosa, Quebrada Honda and Poneloya) where Chagas' disease is endemic, to determine rates of house infestation, evaluate the housing condition and to asess the performance of the María sensor box in detection of domestic vectors. A total of 184 households were selected and vectors were sought by the methods of timed manual capture and by sensor boxes. The sole vectors species found in this study was Triatoma dimidiata. Of the examined bugs 50, 60 and 33%, in the respective communities, were infected with T. cruzi. The rates of house infestation as determined by manual capture and sensor boxes were respectively, 48.3% and 54.2% in Santa Rosa, 29.8% and 51.2% in Quebrada Honda and in Poneloya 3.8 and 5.9% with significant difference between the methods in Quebrada Honda. When compared with the manual capture, the Maria sensor box detected vectors in 71.4% of positive houses in two of the communities but also was able to detect bugs in 39.3% and 41.1% of houses where manual capture had been negative. Housing condition was evaluated according to three structural parameters, in this way, in the first community 79.2% of houses were classified as bad, 20.8% as regular; in the second one 42.5% were bad and 57.5% regular, whereas in the third 62.5% of the houses were regular. Rates of infestation did not differ greatly between the different housing conditions. Our results show that the sensor box is as efficient as manual capture and could be implemented in our country.

Toxoplasma gondii infection in Brazilian domestic outpatient cats

The occurrence of Toxoplasma antibodies in domestic outpatient cats in the city of São Paulo was evaluated using the indirect immunofluorescence assay. A total of 248 blood samples obtained from male and female cats seen at the Veterinary Teaching Hospital at the University of São Paulo between February 1996 and January 1997 were tested. Of these, 17.7% were positive, with a 64 titer being detected in most animals. The frequence of Toxoplasma antibodies was significantly higher in older cats, those fed raw meat and those with free access to the outdoor environment. There was no significant difference in reactivity between males and females. We conclude that diet and free access to the outdoor environment were equally important as predisposing factors to the risk of Toxoplasma infection.

Experimental infection and horizontal transmission of Bartonella henselae in domestic cats

In order to study B. henselae transmission among cats, five young cats were kept in confinement for two years, one of them being inoculated by SC route with B. henselae (10(5) UFC). Only occasional contact among cats occurred but the presence of fleas was observed in all animals throughout the period. Blood culture for isolation of bacteria, PCR-HSP and FTSZ (gender specific), and BH-PCR (species-specific), as well as indirect immunofluorescence method for anti-B. henselae antibodies were performed to confirm the infection of the inoculated cat as well as the other naive cats. Considering the inoculated animal, B. henselae was first isolated by blood culture two months after inoculation, bacteremia last for four months, the specific antibodies being detected by IFI during the entire period. All contacting animals presented with bacteremia 6 months after experimental inoculation but IFI did not detect seroconversion in these animals. All the isolates from these cats were characterized as Bartonella (HSP and FTSZ-PCR), henselae (BH-PCR). However, DNA of B. henselae could not be amplified directly from peripheral blood by the PCR protocols used. Isolation of bacteria by blood culture was the most efficient method to diagnose infection compared to PCR or IFI. The role of fleas in the epidemiology of B. henselae infection in cats is discussed.

Microwave treatment of human milk to prevent transmission of Chagas disease

It is recognized that breast feeding is an alternative means of transmission of Chagas disease. However, thermal treatment of milk can prevent this occurrence. As domestic microwave ovens are becoming commonplace, the efficacy of microwave thermal treatment in inactivating Trypanosoma cruzi trypomastigotes in human milk was tested. Human milk samples infected with T. cruzi trypomastigotes (Y strain) from laboratory-infected mice, were heated to 63 °C in a domestic microwave oven (2 450 MHz, 700 W). Microscopical and serological examinations demonstrated that none of the animals inoculated orally or intraperitoneally with infected milk which had been treated, got the infection, while those inoculated with untreated, infected milk, became infected. It was concluded that the simple treatment prescribed, which can easily be done at home, was effective in inactivating T. cruzi trypomastigotes contained in human milk.

Domestic Rhodnius ecuadoriensis (Hemiptera, Reduviidae) infestation in Northern Peru: a comparative trial of detection methods during a six-month follow-up

Two passive methods in the assessment of intradomiciliary infestation by Rhodnius ecuadoriensis were tested: (i) the Gomes Nuñez sensor box (GN), (ii) sheets of white typing paper and (iii) one active timed manual method. The study was carried out in the Alto Chicama River Valley, Province of Gran Chimú, Department of La Libertad. The study design consisted of an initial searching of triatomines inside of the domestic environment by the manual capture active procedure (man/hour) covering all the studied houses. Then, matched pairs of GN boxes and paper sheets were simultaneously installed in the bedrooms of 207 households distributed in 19 localities. A comparative prospective trial of these passive detection devices were monitored at 2, 4 and, finally 6 months follow-up. Parasitological Trypanosoma rangeli and/or T. cruzi infections were investigated in two houses with high level of infestation by R. ecuadoriensis. 16.9% of the 207 households investigated by an initial active manual method were infested with R. ecuadoriensis. The proportion of infested houses fluctuated from 6.2 to 55.5% amongst the 19 localities investigated. T. rangeli natural infection was detected in R. ecuadoriensis specimens collected in two households. Parasite rates in the bugs ranged from 16.6 to 21.7% respectively. The most striking fact was an average rate of salivary gland infection ranging from 7.4 to 8.3%. At the end of the sixth month period, a cumulative incidence of 31.4% of positive GN boxes against 15.9% for paper sheets was recorded. All three methods combined detected domestic infestation in 129 (62.3%) of the 207 houses studied in the 19 localities. The range of houses infested varies from 6.7% to 92.9%. In areas with low bug density infestation rates, the methodology experienced in our studies, seems to be the best choice for investigations on domestic R. ecuadoriensis populations.

Lutzomyia longipalpis behavior and control at an urban visceral leishmaniasis focus in Argentina

During the earlier stages of visceral leishmaniasis transmission in Posadas City, Misiones, both the night activity and attraction to humans of Lutzomyia longipalpis were assessed, in order to provide preliminary recommendations. The impact of peridomestic deltamethrin spraying performed by local officials was also evaluated. Although Lu. longipalpis were found in traps located over a dog the entire night, 90% of the females were captured from 20.30h to 1.30h, and only landed on a human when he was at a distance of 1.5 m from the dog. Peridomestic spraying of deltamethrin (25 mg/m²) reduced the sand fly capture up to seven days post-intervention without dispersion in the border of the sprayed areas. These results support the recommendations about time-space focus of the protection measures: first half of the night, in the backyard, with pets and domestic animals kept at least 5 m from humans. The deltamethrin as it was used did not seem very effective in this scenario; neither did the eventual use of bed nets, at least in adults, due to the place/hour of sand fly higher activity. This study strengthens the need for a multidisciplinary approach to develop prevention strategies based both on biological and anthropological studies.

Thermoterapy effective and safer than miltefosine in the treatment of cutaneous leishmaniasis in Colombia

In Colombia, pentavalent antimonials and miltefosine are the drugs of choice for the treatment of cutaneous leishmaniasis; however, their toxicity, treatment duration, (treatment adherence problems), cost, and decreased parasite sensitivity make the search for alternative treatments of American cutaneous leishmaniasis necessary. Based on the results found in a controlled, open, randomized, phase III clinical trial, the efficacy and safety of miltefosine was compared to that of thermotherapy for the treatment of cutaneous leishmaniasis in Colombia. Adult patients from the Colombian army participated in the study; they received either 50 mg of miltefosine three times per day for 28 days by the oral route (n = 145) or a thermotherapy (Thermomed®) application of 50 °C for 30 seconds over the lesion and surrounding area (n = 149). Both groups were comparable with respect to their sociodemographic, clinical, and parasitological characteristics. The efficacy of miltefosine by protocol and by intention to treat was 70% (85/122 patients) and 69% (85/145 patients), respectively. The adverse effects were primarily gastrointestinal for miltefosine and pain at the lesion site after treatment for thermotherapy. No statistically significant difference was found in the efficacy analysis (intention to treat and protocol) between the two treatments. ClinicalTrials.gov: NCT00471705.

In vitro PHYTOTHERAPY OF VECTOR SNAILS BY BINARY COMBINATIONS OF LARVICIDAL ACTIVE COMPONENTS IN EFFECTIVE CONTROL OF FASCIOLIASIS

SUMMARY A food-borne trematode infection fascioliasis is one among common public health problems worldwide. It caused a great economic loss for the human race. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. The life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria inside of the snail Lymnaea acuminata. In vitro toxicity of different binary combinations (1:1 ratio) of plant-derived larvicidal active components such as citral, ferulic acid, umbelliferone, azadirachtin and allicin against Fasciola redia and cercaria were tested. The mortality of larvae was observed at 2h, 4h, 6h and 8h of treatment. In in vitro condition azadirachtin + allicin (1:1 ratio) was highly toxic against redia and cercaria (8h LC50 0.006 and 0.005 mg/L). Toxicity of citral + ferulic acid was lowest against redia and cercaria larvae.

Echinococcus granulosus sensu lato GENOTYPES IN DOMESTIC LIVESTOCK AND HUMANS IN GOLESTAN PROVINCE, IRAN

Cystic echinococcosis (CE) is a globally parasitic zoonosis caused by larval stages of Echinococcus granulosus. This study investigated E. granulosus genotypes isolated from livestock and humans in the Golestan province, northern Iran, southeast of the Caspian sea, using partial sequencing data of the cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase 1 (nad1) mitochondrial genes. Seventy E. granulosus isolates were collected from animals in slaughterhouses: 18 isolates from sheep, 40 from cattle, nine from camels, two from buffaloes and one from a goat, along with four human isolates (formalin-fixed, paraffin-embedded tissues) from CE patients of provincial hospitals. All isolates were successfully analysed by PCR amplification and sequencing. The sequence analysis found four E. granulosus genotypes among the 74 CE isolates: G1 (78.3%), G2 (2.7%), G3 (15%) and G6 (4%). The G1-G3 complex genotype was found in all of the sheep, goat, cattle and buffalo isolates. Among the nine camel isolates, the frequency of G1-G3 and G6 genotypes were 66.7% and 33.3%, respectively. All four human CE isolates belonged to E. granulosus sensu stricto. This study reports the first occurrence of the G2 genotype in cattle from Iran and confirms the previously reported G3 genotype in camels in the same country.

Sensitivity of Gomez-Nuñez boxes for the detection of household infestation with Panstrongylus megistus

Four methods for detecting household infestations with Panstrongylus megistus were compared: 1) manual collection; 2) collection after pyrethrum application; 3) search viable eggs; and 4) Gomez-Nuñez boxes. Manual collection was the most sensitive method (23% infested), followed by pyrethrum (21%), Gomez-Nuñez boxes (15%) and viable eggs (12%). About 10% of infested houses were positive exclusively on the Gomez-Nuñez box test. More over, 6 out of the 7 houses positive exclusively on the Gomez-Nuñez method were located in a recently sprayed area, where P. megistus density was low. Inspection of Gomez-Nuñez boxes at 12 weekspost-application was twice as effective as inspection at 6 weekspost-application. Triatomine feces was the most common evidencefor thepresence of P. megistus found within Gomez-Nuñez boxes. Gomez-Nuñez boxes area a useful adjunct to manual collection in detecting domestic infestations with P. megistus, especially in areas where bug densities are low. However, the utility of Gomez-Nuhez boxes must be weighed against the time and labor they require.

A key for identifying faecal smears to detect domestic infestations of triatomine bugs

Early detection of residual populations of domestic triatomine bugs that survive insecticide treatment is a key component of successful evaluation and vigilance for Chagas disease control. We have recently demonstrated that sheets of paper, tacked on to the walls of infested houses, can become streaked with the faeces of triatomine bugs and thus reveal thepresence of an infestation. In thispaper, wepresent a simple key to differentiate the faecal streaks of triatomine bugs from those of other domestic arthropods such as cockroaches, ticks and cimicid bedbugs.

How effective is dog culling in controlling zoonotic visceral leishmaniasis? a critical evaluation of the science, politics and ethics behind this public health policy

INTRODUCTION: Zoonotic kala-azar, a lethal disease caused by protozoa of the genus Leishmania is considered out of control in parts of the world, particularly in Brazil, where transmission has spread to cities throughout most of the territory and mortality presents an increasing trend. Although a highly debatable measure, the Brazilian government regularly culls seropositive dogs to control the disease. Since control is failing, critical analysis concerning the actions focused on the canine reservoir was conducted. METHODS: In a review of the literature, a historical perspective focusing mainly on comparisons between the successful Chinese and Soviet strategies and the Brazilian approach is presented. In addition, analyses of the principal studies regarding the role of dogs as risk factors to humans and of the main intervention studies regarding the efficacy of the dog killing strategy were undertaken. Brazilian political reaction to a recently published systematic review that concluded that the dog culling program lacked efficiency and its effect on public policy were also reviewed. RESULTS: No firm evidence of the risk conferred by the presence of dogs to humans was verified; on the contrary, a lack of scientific support for the policy of killing dogs was confirmed. A bias for distorting scientific data towards maintaining the policy of culling animals was observed. CONCLUSIONS: Since there is no evidence that dog culling diminishes visceral leishmaniasis transmission, it should be abandoned as a control measure. Ethical considerations have been raised regarding distorting scientific results and the killing of animals despite minimal or absent scientific evidence

Factors associated with Leishmania chagasi infection in domestic dogs from Teresina, State of Piauí, Brazil

INTRODUCTION: Many studies have evaluated risk factors for human visceral leishmaniasis, but few have focused on the infection among dogs. The objective of this study was to assess the association between peridomestic socioeconomic and environmental factors and the presence of dogs seropositive for Leishmania chagasi in the City of Teresina, Brazil. METHODS: This case-control study was based on the results of a routine seroepidemiological survey among domestic dogs carried out in 2007. Serological tests were performed by means of indirect immunofluorescence antibody test. All dwellings in which at least one seropositive dog was detected were considered cases, and controls were a random sample of dwellings in which only seronegative dogs were identified. Associations between variables were expressed as odds ratios (OR) and their respective 95% confidence intervals (95%CI) estimated using multivariate logistic regression. RESULTS: Dwellings with a history of dogs removed by the visceral leishmaniasis control program in the last 12 months had five-fold higher odds of having at least one seropositive dog as compared with dwellings having no history of dog removal (OR = 5.19; 95%CI = 3.20-8.42). Dwellings with cats had 58% increased odds of dog infection as compared with those having no cats (OR = 1.58; 95%CI = 1.01-2.47). CONCLUSIONS: Identification of factors associated with canine visceral leishmaniasis might be used for the delimitation of areas of higher risk for human visceral leishmaniasis, since infection in dogs generally precedes the appearance of human cases.

Approaches towards tick and tick-borne diseases control

Ticks are obligate haematophagous ectoparasites of wild and domestic animals as well as humans, considered to be second worldwide to mosquitoes as vectors of human diseases. Tick-borne diseases are responsible worldwide for great economic losses in terms of mortality and morbidity of livestock animals. This review concerns to the different tick and tick-parasites control methods having a major focus on vaccines. Control of tick infestations has been mainly based on the use of acaricides, a control measure with serious drawbacks, as responsible for the contamination of milk and meat products, as a selective factor for acaricide-resistant ticks and as an environmental contaminant. Research on alternatives to the use of acaricides is strongly represented by tick vaccines considered a more cost-effective and environmentally safe strategy. Vaccines based on the Bm86 tick antigen were used in the first commercially available cattle tick vaccines and showed good results in reducing tick numbers, affecting weight and reproductive performance of female ticks which resulted in reduction of cattle tick populations over time and consequently lower reduction of the pathogen agents they carry.