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We report the effect of a rodent control program on the incidence of zoonotic cutaneous leishmaniasis in an endemic region of Iran. A 1-year interruption in rodent control led to 2 years of increased incidence of zoonotic cutaneous leishmaniasis. Restarting rodent control led to a decline of zoonotic cutaneous leishmaniasis.

Despite the periodic mouse plague outbreaks in Australia which largely occur due to favourable climatic conditions, their economic impacts remain understudied. To bridge this knowledge gap, the present study analysed the economic impacts of the 2021 mouse plague in New South Wales (Australia) among households, farms, and businesses/facilities. We further analysed the influence of selected cost parameters on mouse bait rebate claims by the farmers as well as the relative efficiency of the chemical mouse control options used by farmers to minimize avoidable crop yield losses. Our study found that the total direct cost of the 2021 mouse plague was A$ 100.62 million, with farmers bearing 67.10% of the total cost. It was also revealed that the type of farming influenced the likelihood of a farmer claiming or not claiming mouse bait rebate. The most efficient chemical mouse control option was the combination of anticoagulants used around buildings and zinc phosphide used in pastures and crops as it reduced avoidable crop yield losses more than each rodenticide when used independently. However, more research is required on how other variables may influence the efficiency of mouse control methods to forestall future outbreaks of mouse plagues and their associated economic impacts.

Lassa fever is a viral haemorrhagic fever caused by an arenavirus. The disease is endemic in West African countries, including Guinea. The rodents Mastomys natalensis and Mastomys erythroleucus have been identified as Lassa virus reservoirs in Guinea. In the absence of a vaccine, rodent control and human behavioural changes are the only options to prevent Lassa fever in highly endemic areas. We performed a 4 year intervention based on chemical rodent control, utilizing anticoagulant rodenticides in 3 villages and evaluating the rodent abundance before and after treatment. Three additional villages were investigated as controls. Analyses to assess the effectiveness of the intervention, bait consumption and rodent dynamics were performed. Anthropological investigations accompanied the intervention to integrate local understandings of human-rodent cohabitation and rodent control intervention. Patterns of bait consumption showed a peak at days 5-7 and no consumption at days 28-30. There was no difference between Bromadiolone and Difenacoum bait consumption. The main rodent species found in the houses was M. natalensis. The abundance of M. natalensis, as measured by the trapping success, varied between 3.6 and 16.7% before treatment and decreased significantly to 1-2% after treatment. Individuals in treated villages welcomed the intervention and trapping because mice are generally regarded as a nuisance. Immediate benefits from controlling rodents included protection of food and belongings. Before the intervention, local awareness of Lassa fever was non-existent. Despite their appreciation for the intervention, local individuals noted its limits and the need for complementary actions. Our results demonstrate that chemical treatment provides an effective tool to control local rodent populations and can serve as part of an effective, holistic approach combining rodent trapping, use of local rodenticides, environmental hygiene, house repairs and rodent-proof storage. These actions should be developed in collaboration with local stakeholders and communities.

Lassa fever (LF), caused by the Lassa virus and transmitted primarily by Mastomys natalensis rodents, is a severe hemorrhagic disease endemic to West Africa, particularly Nigeria, with significant morbidity and mortality rates. This study develops dynamic models for LF, incorporating crucial but often overlooked factors such as vertical transmission (i.e., transmission from parents to their offsprings) in rodents, surface contamination, and asymptomatic human carriers. The persistence of the disease is shown analytically. Using data from Nigeria to train the models, the impact of various control and mitigation measures is assessed. The results of the study reveal that asymptomatic individuals are key drivers of LF and that including additional LF virus transmission pathways, e.g., vertical transmission and environmental contamination, increases the estimated reproduction number threefold compared to previous studies. Models incorporating rodent dynamics show the highest disease prevalence, highlighting the critical role of rodent control. Specifically, effective interventions using only rodent control measures require maintaining rodent populations below a specific threshold. In addition, a multifaceted approach, combining antiviral treatment, environmental disinfection, and personal protective equipment, significantly enhances disease control, while the introduction of a competitor rodent species can drastically reduce human and rodent infections. Ultimately, the study underscores the need for integrated, multifaceted strategies, including targeting rodents, asymptomatic cases, and comprehensive treatment and disinfection protocols, for effective LF management.

The use of rodenticides is a primary method for eradicating rodents from islands for conservation purposes. Rodenticide residue monitoring is often incorporated into rodent eradication project planning to understand the potential effects on nontarget species, but robust long-term sampling is often challenging due to logistical and financial constraints. We documented more than two years of rodenticide residues at fine-scale intervals with over 570 samples associated with a rodent eradication attempt. Brodifacoum-25D Conservation was applied in an attempt to eradicate house mice ( Mus musculus ) from Midway Atoll National Wildlife Refuge in the Northwestern Hawaiian Islands. As a cooperating agency, USDA National Wildlife Research Center collected and tested environmental samples for brodifacoum residues, targeting compartments (invertebrates, vertebrates, water, soil, and plants) that may affect the health of humans and wildlife. Brodifacoum residues in invertebrates peaked immediately after bait application and persisted in low levels until becoming undetectable nine months after bait application. Brodifacoum residues decreased over time but persisted in some vertebrate species (geckos, fish, birds) throughout the one-year sampling period after bait applications. All soil and water environmental samples had either no detectable residues or were under method limit of quantitation. No detectable residues were found in drinking water systems or food plant samples. The adaptive environmental monitoring, which included rapid turnaround of analytical chemistry results, enabled real-time management decisions for nontarget species, mitigation approaches, and community action.

Rodent infestation on poultry farms incurs heavy economic losses to this industry by causing feed loss and disease introduction. Development and continuous improvement of rodents control techniques are vital to minimize and control the damages caused by rodents. Here, we test the feed preference of rodents for locally available and palatable food grains viz. millet (whole), wheat (cracked) and rice (broken) and taste additives namely whole egg (5%), eggshell (5%), peanut cracked (5%) and yeast (2%) that were offered mixed in millet-wheat (50:50 by wt.) bait. We tested the preferences of different food additives through a process of feed choice mechanism. We applied two different techniques to compare the preference of mixed feed baits, these techniques included no-choice with multiple choice feeding tests and paired choice with multiple choices feeding tests. The results indicated that consumption of bait with added whole egg was significantly higher (p > 0.05). Further test for its effectiveness as a carrier for rodenticides revealed 56%, 82% and 92%, reduction in rodent activities with zinc phosphide (2%), coumatetralyl (0.0375%) and Brodifacoum (0.005%) respectively. Our results point to a need on continuous improvement of feed baits by using different combinations to effectively control the rodent infestation.

Synanthropic rodents are ubiquitous in low-income communities and pose risks for human health, as they are generally resistant to control programs. However, few or no studies have evaluated the long-term effect of chemical and infrastructural interventions on rodent population dynamics, especially in urban low-income communities, or evaluated the potential recovery of their population following interventions. We conducted a longitudinal study in a low-income community in the city of Salvador (BA, Brazil) to characterize the effect of interventions (chemical and infrastructural) on the dynamics of rodent population, and documented the post-intervention recovery of their population. We evaluated the degree of rodent infestation in 117 households/sampling points over three years (2014–2017), using tracking plates, a proxy for rodent abundance/activity. We reported a significant lower rodent activity/abundance after the chemical and infrastructural interventions (Z = −4.691 (p < 0.001)), with track plate positivity decreasing to 28% from 70% after and before interventions respectively. Therefore, the combination of chemical and infrastructural interventions significantly decreased the degree of rodent infestation in the study area. In addition, no rodent population rebound was recorded until almost a year post-intervention, and the post-intervention infestation level did not attain the pre-intervention level all through the study. Moreover, among pre-treatment conditions, access to sewer rather than the availability of food was the variable most closely associated with household rodent infestation. Our study indicates that Integrated Pest Management (IPM)-approaches are more effective in reducing rodent infestation than the use of a single method. Our findings will be useful in providing guidance for long-term rodent control programs, especially in urban low-income communities.

The Natal multimammate mouse (Mastomys natalensis) is the reservoir host of Lassa virus, an arenavirus that causes Lassa haemorrhagic fever in humans in West Africa. Because no vaccine exists and therapeutic options are limited, preventing infection through rodent control and human behavioural measures is currently considered to be the only option. In order to assess the efficacy of rodent control, we performed a 4-year field experiment in rural Upper Guinea and developed a mathematical model to simulate different control strategies (annual density control, continuous density control, and rodent vaccination). For the field study, rodenticide baits were placed each year in three rural villages, while three other villages were used as controls. Rodents were trapped before and after every treatment and their antibody status and age were determined. Data from the field study were used to parameterize the mathematical model. In the field study, we found a significant negative effect of rodent control on seroprevalence, but this effect was small especially given the effort. Furthermore, the rodent populations recovered rapidly after rodenticide application, leading us to conclude that an annual control strategy is unlikely to significantly reduce Lassa virus spillover to humans. In agreement with this finding, the mathematical model suggests that the use of continuous control or rodent vaccination is the only strategy that could lead to Lassa virus elimination. These field and model results can serve as a guide for determining how long and frequent rodent control should be done in order to eliminate Lassa virus in rural villages.

Leptospirosis is a re-emergent worldwide zoonosis. It is endemic in Martinique where transmission conditions are favourable. Humans are usually infected through contact with water contaminated with urine of rodents. Recent human leptospirosis outbreaks in Martinique require today effective rodent management to prevent leptospirosis transmission. Nowadays, use of anticoagulant rodenticides (AR) is the main method implemented to control rodent populations. Nevertheless, intensive use of these AR has selected worldwide many VKORC1-based resistant rodent strains to AR. Our aim was to characterize the sensitivity of Martinique commensal rodents to AR to better prevent leptospirosis transmission. Resistance of house mice to first-generation and in rare cases even to second-generation ARs were clearly demonstrated in Martinique with the detection of the Y139C mutation with a very high allelic frequency of 40% and the A26T/Y139C double-mutation with an allelic frequency of 0.9%. In black rat, the most prevalent rodent in Martinique, 3 new Vkorc1 coding mutations were detected, the H68N, A115T and S149N mutations associated with moderate resistance to first generation AR. Therefore, rodent management in Martinique must be carried carefully to avoid resistance diffusion and maintain long-term effective rodent management, to be able to efficiently prevent leptospirosis transmission.

Rodents infest urban environments, causing damage and acting as vectors for disease transmission. Currently, anticoagulants are the most widely used chemical rodenticides, and their extensive and widespread use can contaminate the environment. To ensure effectiveness and avoid accumulation of rodent baits in the environment, it is important to evaluate how long rodent baits maintain their palatability and efficacy. In rodent control programs, rodent baits are placed in locations such as sewers, but after a few days, baits appear altered, causing doubts about the control efficacy. For this reason, baits are replaced periodically, which increases costs and generation of chemical waste. The objective of this study was to evaluate the palatability and efficacy of commercial paraffin-type rodent bait blocks placed in sewers in São Paulo City over a period of 90 days. Bait blocks were placed in sewers and collected after 30, 60, and 90 days. Additionally, in a laboratory two-choice test, wild-caught urban Norway rats were offered 40–60 g of bait and an equal volume of standard rat pellets. The amount of bait and rat pellet consumed was registered, the palatability was calculated, and the efficacy was measured as the percentage mortality over 14 days. The results showed that, even when they had an altered appearance, bait blocks remained palatable to the rats and were effective after at least 90 days. Leaving bait blocks for longer periods could be an effective strategy for reducing costs and could help to ensure the control of urban rodents in an environmentally sustainable way.