Incorporating Queueing Theory into a Spatial Optimization Framework to Improve Mass Vaccination Programs.

Background: Mass vaccination is a cornerstone of public health emergency preparedness and response. However, injudicious placement of vaccination sites can lead to the formation of long waiting lines or queues, which discourages individuals from waiting to be vaccinated and may thus jeopardize the achievement of public health targets. Queueing theory offers a framework for modeling queue formation at vaccination sites and its effect on vaccine uptake. Methods: We developed an algorithm that integrates queueing theory within a spatial optimization framework to optimize the placement of mass vaccination sites. The algorithm was built and tested using data from a mass canine rabies vaccination campaign in Arequipa, Peru. We compared expected vaccination coverage and losses from queueing (i.e., attrition) for sites optimized with our queue-conscious algorithm to those obtained from a queue-naive version of the same algorithm. Results: Sites placed by the queue-conscious algorithm resulted in 9-19% less attrition and 1-2% higher vaccination coverage compared to sites placed by the queue-naive algorithm. Compared to the queue-naive algorithm, the queue-conscious algorithm favored placing more sites in densely populated areas to offset high arrival volumes, thereby reducing losses due to excessive queueing. These results were not sensitive to misspecification of queueing parameters or relaxation of the constant arrival rate assumption. Conclusion: One should consider losses from queueing to optimally place mass vaccination sites, even when empirically derived queueing parameters are not available. Due to the negative impacts of excessive wait times on participant satisfaction, reducing queueing attrition is also expected to yield downstream benefits and improve vaccination coverage in subsequent mass vaccination campaigns.

Perceptions of Problems with Household Insects: Qualitative and Quantitative Findings from Peri-Urban Communities in Arequipa, Peru.

Vector-borne diseases continue to impose a major health burden on Peru and neighboring countries. The challenge of addressing vector-borne disease is compounded by changing social, economic, and climatic conditions. Peri-urban Arequipa is an important region to study insect infestations because of ongoing challenges with disease vectors such as triatomines and a variety of other insects. We conducted surveys (N = 1,182) and seven focus groups (average seven participants) in peri-urban Arequipa to explore knowledge of and perception toward various insects that infest the region. Focus group participants reported the presence of a wide variety of insects in and around the home, including disease vectors such as triatomines (also identified by 27.2% of survey households), mosquitoes, spiders, and bed bugs, as well as nuisance insects. Health concerns related to insects included vector-borne diseases, spider bites, allergies, and sequelae from bed bug bites, and hygiene concerns. A majority of participants in the quantitative surveys identified triatomines as the insect they were most worried about (69.9%) and could identify Chagas disease as a health risk associated with triatomines (54.9%). Insect infestations in peri-urban Arequipa present multiple burdens to residents, including injury and illness from triatomines and other insects, as well as potential mental and economic concerns related to insects such as bed bugs. Future initiatives should continue to address triatomine infestations through educational outreach and implement a more holistic approach to address the burden of both disease and nuisance insects.

A critical analysis of national plans for climate adaptation for health in South America.

Climate adaptation measures are critical for protecting human health. National Adaptation Plans (NAPs), Nationally Determined Contributions (NDCs), and National Communications (NCs) play a crucial role in helping countries identify, analyze, and address their vulnerabilities to climate change impacts, while also assessing available resources and capacities. This study aimed to assess the comprehensiveness of South American countries' NAPs, NDCs, and NCs in addressing the effects of climate change on health. A total of 38 NAPs, NDCs, and NCs of 12 South American countries were analysed. Ad hoc scores were developed to assess baseline information, adaptation proposals, identification of involved institutions, funding needs and allocation, measurable progress indicators, and coherence. Overall, all South American countries have NDCs and NCs, and seven have NAPs. In most countries, the intersectoral health analysis revealed a lack of linkage to health issues related to that sector. Additionally, most planning documents lack detailed information to guide policymakers in taking practical actions; areas with low scores include allocation of funds, involvement of health-related institutions, and measurable indicators. While South American countries acknowledge the health impacts of climate change in their plans, enhancing public health protection requires maximizing climate policy benefits and including health-related issues across all relevant sectors. Funding: This study was not funded. However, three co-authors received funding for some of their time: AV and KC were supported by the Wellcome Trust (209734/Z/17/Z); RCN was funded by K01AI139284 (NIH-NIAID). Funding for the publication was provided by Universidad Peruana Cayetano Heredia.

An effective internet-based system for surveillance and elimination of triatomine insects: AlertaChirimacha.

Vector-borne diseases remain a significant public health threat in many regions of the world. Traditional vector surveillance and control methods have relied on active and passive surveillance programs, which are often costly and time-consuming. New internet-based vector surveillance systems have shown promise in removing some of the cost and labor burden from health authorities. We developed and evaluated the effectiveness of a new internet-based surveillance system, "AlertaChirimacha", for detecting Triatoma infestans (known locally by its Quechua name, Chirimacha), the Chagas disease vector, in the city of Arequipa, Peru. In the first 26 months post-implementation, AlertaChirimacha received 206 reports of residents suspecting or fearing triatomines in their homes or neighborhoods, of which we confirmed, through pictures or inspections, 11 (5.3%) to be Triatoma infestans. After microscopic examination, none of the specimens collected were infected with Trypanosoma cruzi. AlertaChirimacha received 57% more confirmed reports than the traditional surveillance system and detected 10% more infested houses than active and passive surveillance approaches combined. Through in-depth interviews we evaluate the reach, bilateral engagement, and response promptness and efficiency of AlertaChirimacha. Our study highlights the potential of internet-based vector surveillance systems, such as AlertaChirimacha, to improve vector surveillance and control efforts in resource-limited settings. This approach could decrease the cost and time horizon for the elimination of vector-mediated Chagas disease in the region.

Dog Population Rabies Immunity before a Mass Vaccination Campaign in Lima, Peru: Vulnerabilities for Virus Reestablishment.

Lima, Peru, has not had a case of canine rabies since 1999. However, Lima remains at risk of rabies reintroduction due to the free movement of dogs from nearby rabies-endemic areas. In Latin America, rabies vaccination campaigns must reach 80% of dogs to halt transmission, but estimates of vaccine coverage are often unavailable, unreliable, or inaccurate. Quantifying virus neutralizing antibodies (VNA) allows monitoring of the immunological status of the canine population, evaluation of the degree of humoral protection to the virus, and assessing, partially, the population response to vaccination. We evaluated the dog population's immunity level against the rabies virus before a mass vaccination campaign in Lima. We collected 141 canine blood samples in the district of Surquillo and quantified rabies virus neutralizing antibody titers using the fluorescent antibody virus neutralization test). We surveyed dogs owners to reconstruct canine vaccination histories. Among dogs previously vaccinated, 73.9% exceeded the seroconversion threshold of > 0.5 IU/mL. Among all dogs, only 58.2% reached the titer limit for seroconversion. Dogs ≤ 1 year old constituted 26.2% of the total canine population and had lower levels of VNA than dogs > 1 year old (χ2 = 9.071; P = 0.028). Importantly, dogs vaccinated with single-pathogen vaccines had higher levels of VNA than those who received combined-pathogen vaccines (χ2 = 7.721; P = 0.005). We provide an important and timely glimpse to the immunity status of the dog population in urban areas of Lima, a metropolis near a dog rabies-endemic region.

Association between seroprevalence of measles virus in monkeys and degree of human-monkey contact in Bangladesh.

Measles infections can cause significant morbidity and mortality in human and monkey populations. The endemicity of measles in human populations and viral circulation within populations of free-living monkeys may have important repercussions for potential zoonotic transmission events and for the long-term health of monkey populations. Yet, there has not yet been a rigorous investigation of the dynamics of measles transmission where human and monkey populations coexist. In this study, to determine the difference in seroprevalence of the measles virus across different contexts of human-monkey contact, we analyzed serum samples collected from 56 apparently healthy Macaca mulatta monkeys who occupied diverse contexts, with different degrees of human-monkey contact, in Bangladesh. This is the first report of measles virus seroprevalence in monkeys in Bangladesh. We found a clear association between measles virus seropositivity in monkeys and the context in which they interact with humans. Seroprevalence was the lowest in wild areas (0.0%) and increased in shrines (4.8%), urban areas (5.9%), and was highest among monkeys who are used as performance animals (50.0%). This work suggests that a One Health approach informed by local interspecies transmission dynamics is necessary to develop strategies that both improve measles vaccination coverage, achieve long-term surveillance in monkey populations, and prevent measles spillback to monkeys. This approach aims to inform conservation efforts and protect the long-term health of human and monkey populations.

Modeling the impact of xenointoxication in dogs to halt Trypanosoma cruzi transmission.

BACKGROUND: Chagas disease, a vector-borne parasitic disease caused by Trypanosoma cruzi, affects millions in the Americas. Dogs are important reservoirs of the parasite. Under laboratory conditions, canine treatment with the systemic insecticide fluralaner demonstrated efficacy in killing Triatoma infestans and T. brasiliensis, T. cruzi vectors, when they feed on dogs. This form of pest control is called xenointoxication. However, T. cruzi can also be transmitted orally when mammals ingest infected bugs, so there is potential for dogs to become infected upon consuming infected bugs killed by the treatment. Xenointoxication thereby has two contrasting effects on dogs: decreasing the number of insects feeding on the dogs but increasing opportunities for exposure to T. cruzi via oral transmission to dogs ingesting infected insects. OBJECTIVE: Examine the potential for increased infection rates of T. cruzi in dogs following xenointoxication. DESIGN/METHODS: We built a deterministic mathematical model, based on the Ross-MacDonald malaria model, to investigate the net effect of fluralaner treatment on the prevalence of T. cruzi infection in dogs in different epidemiologic scenarios. We drew upon published data on the change in percentage of bugs killed that fed on treated dogs over days post treatment. Parameters were adjusted to mimic three scenarios of T. cruzi transmission: high and low disease prevalence and domestic vectors, and low disease prevalence and sylvatic vectors. RESULTS: In regions with high endemic disease prevalence in dogs and domestic vectors, prevalence of infected dogs initially increases but subsequently declines before eventually rising back to the initial equilibrium following one fluralaner treatment. In regions of low prevalence and domestic or sylvatic vectors, however, treatment seems to be detrimental. In these regions our models suggest a potential for a rise in dog prevalence, due to oral transmission from dead infected bugs. CONCLUSION: Xenointoxication could be a beneficial and novel One Health intervention in regions with high prevalence of T. cruzi and domestic vectors. In regions with low prevalence and domestic or sylvatic vectors, there is potential harm. Field trials should be carefully designed to closely follow treated dogs and include early stopping rules if incidence among treated dogs exceeds that of controls.

Modeling the impact of xenointoxication in dogs to halt Trypanosoma cruzi transmission.

Background: Chagas disease, a vector-borne parasitic disease caused by Trypanosoma cruzi , affects millions in the Americas. Dogs are important reservoirs of the parasite. Under laboratory conditions, canine treatment with the systemic insecticide fluralaner demonstrated efficacy in killing Triatoma infestans and T. brasiliensis, T. cruzi vectors, when they feed on dogs. This form of pest control is called xenointoxication. However, T. cruzi can also be transmitted orally when mammals ingest infected bugs, so there is potential for dogs to become infected upon consuming infected bugs killed by the treatment. Xenointoxication thereby has two contrasting effects on dogs: decreasing the number of insects feeding on the dogs but increasing opportunities for exposure to T. cruzi via oral transmission to dogs ingesting infected insects. Objective: Examine the potential for increased infection rates of T. cruzi in dogs following xenointoxication. Design/Methods: We built a deterministic mathematical model, based on the Ross-MacDonald malaria model, to investigate the net effect of fluralaner treatment on the prevalence of T. cruzi infection in dogs in different epidemiologic scenarios. We drew upon published data on the change in percentage of bugs killed that fed on treated dogs over days post treatment. Parameters were adjusted to mimic three scenarios of T. cruzi transmission: high and low disease prevalence and domestic vectors, and low disease prevalence and sylvatic vectors. Results: In regions with high endemic disease prevalence in dogs and domestic vectors, prevalence of infected dogs initially increases but subsequently declines before eventually rising back to the initial equilibrium following one fluralaner treatment. In regions of low prevalence and domestic or sylvatic vectors, however, treatment seems to be detrimental. In these regions our models suggest a potential for a rise in dog prevalence, due to oral transmission from dead infected bugs. Conclusion: Xenointoxication could be a beneficial and novel One Health intervention in regions with high prevalence of T. cruzi and domestic vectors. In regions with low prevalence and domestic or sylvatic vectors, there is potential harm. Field trials should be carefully designed to closely follow treated dogs and include early stopping rules if incidence among treated dogs exceeds that of controls. Author summary: Chagas disease, caused by the parasite Trypanosoma cruzi , is transmitted via triatomine insect vectors. In Latin America, dogs are a common feeding source for triatomine vectors and subsequently an important reservoir of T. cruzi . One proposed intervention to reduce T. cruzi transmission is xenointoxication: treating dogs with oral insecticide to kill triatomine vectors in order to decrease overall T. cruzi transmission. Fluralaner, commonly administered to prevent ectoparasites such as fleas and ticks, is effective under laboratory conditions against the triatomine vectors. One concern with fluralaner treatment is that rapid death of the insect vectors may make the insects more available to oral ingestion by dogs; a more effective transmission pathway than stercorarian, the usual route for T. cruzi transmission. Using a mathematical model, we explored 3 different epidemiologic scenarios: high prevalence endemic disease within a domestic T. cruzi cycle, low prevalence endemic disease within a domestic T. cruzi cycle, and low prevalence endemic disease within a semi-sylvatic T. cruzi cycle. We found a range of beneficial to detrimental effects of fluralaner xenointoxication depending on the epidemiologic scenario. Our results suggest that careful field trials should be designed and carried out before wide scale implementation of fluralaner xenointoxication to reduce T. cruzi transmission.

Do Incentives Crowd Out Motivation? A Feasibility Study of a Community Vector-Control Campaign in Peru.

Incentives are a useful tool in encouraging healthy behavior as part of public health initiatives. However, there remains concern about motivation crowd out-a decline in levels of motivation to undertake a behavior to below baseline levels after incentives have been removed-and few public health studies have assessed for motivation crowd out. Here, we assess the feasibility of identifying motivation crowd out following a lottery to promote participation in a Chagas disease vector control campaign. We look for evidence of crowd out in subsequent participation in the same behavior, a related behavior, and an unrelated behavior. We identified potential motivation crowd out for the same behavior, but not for related behavior or unrelated behaviors after lottery incentives are removed. Despite some limitations, we conclude that motivation crowd out is feasible to assess in large-scale trials of incentives.

The Amazonian Tropical Bites Research Initiative, a hope for resolving zoonotic neglected tropical diseases in the One Health era.

BACKGROUND: Neglected tropical diseases (NTDs) disproportionately affect populations living in resource-limited settings. In the Amazon basin, substantial numbers of NTDs are zoonotic, transmitted by vertebrate (dogs, bats, snakes) and invertebrate species (sand flies and triatomine insects). However, no dedicated consortia exist to find commonalities in the risk factors for or mitigations against bite-associated NTDs such as rabies, snake envenoming, Chagas disease and leishmaniasis in the region. The rapid expansion of COVID-19 has further reduced resources for NTDs, exacerbated health inequality and reiterated the need to raise awareness of NTDs related to bites. METHODS: The nine countries that make up the Amazon basin have been considered (Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Surinam and Venezuela) in the formation of a new network. RESULTS: The Amazonian Tropical Bites Research Initiative (ATBRI) has been created, with the aim of creating transdisciplinary solutions to the problem of animal bites leading to disease in Amazonian communities. The ATBRI seeks to unify the currently disjointed approach to the control of bite-related neglected zoonoses across Latin America. CONCLUSIONS: The coordination of different sectors and inclusion of all stakeholders will advance this field and generate evidence for policy-making, promoting governance and linkage across a One Health arena.

Incentivizing optimal risk map use for Triatoma infestans surveillance in urban environments.

In Arequipa, Peru, a large-scale vector control campaign has successfully reduced urban infestations of the Chagas disease vector, Triatoma infestans. In addition to preventing new infections with Trypanosoma cruzi (etiological agent of Chagas disease), the campaign produced a wealth of information about the distribution and density of vector infestations. We used these data to create vector infestation risk maps for the city in order to target the last few remaining infestations, which are unevenly distributed and difficult to pinpoint. Our maps, which are provided on a mobile app, display color-coded, individual house-level estimates of T. infestans infestation risk. Entomologic surveillance personnel can use the maps to select homes to inspect based on estimated risk of infestation, as well as keep track of which parts of a given neighborhood they have inspected to ensure even surveillance throughout the zone. However, the question then becomes, how do we encourage surveillance personnel to actually use these two functionalities of the risk map? As such, we carried out a series of rolling trials to test different incentive schemes designed to encourage the following two behaviors by entomologic surveillance personnel in Arequipa: (i) preferential inspections of homes shown as high risk on the maps, and (ii) even surveillance across the geographical distribution of a given area, which we term, 'spatial coverage.' These two behaviors together constituted what we termed, 'optimal map use.' We found that several incentives resulted in one of the two target behaviors, but just one incentive scheme based on the game of poker resulted in optimal map use. This poker-based incentive structure may be well-suited to improve entomological surveillance activities and other complex multi-objective tasks.

Misuse, perceived risk, and safety issues of household insecticides: Qualitative findings from focus groups in Arequipa, Peru.

BACKGROUND: The current body of research on insecticide use in Peru deals primarily with application of insecticides offered through Ministry of Health-led campaigns against vector-borne disease. However, there is a gap in the literature regarding the individual use, choice and perceptions of insecticides which may influence uptake of public health-based vector control initiatives and contribute to the thousands of deaths annually from acute pesticide poisoning in Peru. METHODS: Residents (n = 49) of the Alto Selva Alegre and CC districts of peri-urban Arequipa participated in seven focus group discussions (FGD). Using a FGD guide, two facilitators led the discussion and conducted a role-playing activity. this activity, participants insecticides (represented by printed photos of insecticides available locally) and pretended to "sell" the insecticides to other participants, including describing their qualities as though they were advertising the insecticide. The exercise was designed to elicit perceptions of currently available insecticides. The focus groups also included questions about participants' preferences, use and experiences related to insecticides outside the context of this activity. Focus group content was transcribed, and qualitative data were analyzed with Atlas.ti and coded using an inductive process to generate major themes related to use and choice of insecticides, and perceived risks associated with insecticide use. RESULTS: The perceived risks associated with insecticides included both short- and long-term health impacts, and safety for children emerged as a priority. However, in some cases insecticides were reportedly applied in high-risk ways including application of insecticides directly to children and bedding. Some participants attempted to reduce the risk of insecticide use with informal, potentially ineffective personal protective equipment and by timing application when household members were away. Valued insecticide characteristics, such as strength and effectiveness, were often associated with negative characteristics such as odor and health impacts. "Agropecuarios" (agricultural supply stores) were considered a trusted source of information about insecticides and their health risks. CONCLUSIONS: It is crucial to characterize misuse and perceptions of health impacts and risks of insecticides at the local level, as well as to find common themes and patterns across populations to inform national and regional programs to prevent acute insecticide poisoning and increase community participation in insecticide-based vector control campaigns. We detected risky practices and beliefs about personal protective equipment, risk indicators, and safety levels that could inform such preventive campaigns, as well as trusted information sources such as agricultural stores for partnerships in disseminating information.

The impact of the COVID-19 pandemic on rabies reemergence in Latin America: The case of Arequipa, Peru.

In Latin America, there has been tremendous progress towards eliminating canine rabies. Major components of rabies elimination programs leading to these successes have been constant and regular surveillance for rabid dogs and uninterrupted yearly mass dog vaccination campaigns. Unfortunately, vital measures to control COVID-19 have had the negative trade-off of jeopardizing these rabies elimination and prevention activities. We aimed to assess the effect of interrupting canine rabies surveillance and mass dog vaccination campaigns on rabies trends. We built a deterministic compartment model of dog rabies dynamics to create a conceptual framework for how different disruptions may affect rabies virus transmission. We parameterized the model for conditions found in Arequipa, Peru, a city with active rabies virus transmission. We examined our results over a range of plausible values for R0 (1.36-2.0). Also, we prospectively evaluated surveillance data during the pandemic to detect temporal changes. Our model suggests that a decrease in canine vaccination coverage as well as decreased surveillance could lead to a sharp rise in canine rabies within months. These results were consistent over all plausible values of R0. Surveillance data from late 2020 and early 2021 confirms that in Arequipa, Peru, rabies cases are on an increasing trajectory. The rising rabies trends in Arequipa, if indicative to the region as whole, suggest that the achievements made in Latin America towards the elimination of dog-mediated human rabies may be in jeopardy.

Relative Frequency of Blastocystis Subtypes 1, 2, and 3 in Urban and Periurban Human Populations of Arequipa, Peru.

Blastocystis is one of the most common protozoa found in the human gut and are genetically diverse and widely distributed around the world. Nonspecific and inconsistent symptoms have been associated with this protozoon; thus, its clinical importance remains controversial. Our aim was to estimate the relative frequency of Blastocystis subtypes 1, 2, and 3, which are the predominant subtypes reported in South America, based on conserved regions of SSU rDNA sequences and determine the factors associated with them. A total of 116 Blastocystis-positive stool samples were processed using conventional PCR with Blastocystis-specific primers. We identified subtype 1 (10.3%), subtype 2 (7.8%), subtype 3 (25.0%), and mixed subtype infections (8.7%). However, we could not identify any Blastocystis subtypes in 48.3% of the samples; therefore, it is likely that other subtypes were present in the area. No association was found between any gastrointestinal symptom and single or mixed Blastocystis subtypes. We found a statistically significant association between Blastocystis subtype 2 and irritable bowel syndrome (OR = 17.8, 95% CI = 1.5-408.4, p = 0.039); however, the number of samples with IBS was small (n= 4). There was no association between the Blastocystis subtypes and any epidemiological variable studied. In rural populations, we only identified subtype 1, while in urban and periurban populations, we identified subtypes 1, 2, and 3.

Socio-Demographic Determinants Associated with Blastocystis Infection in Arequipa, Peru.

Blastocystis is one of the most common protozoa in the human gut and a zoonotic organism related to unsanitary living conditions. This protozoon shows a broad distribution, unclear symptomatology, and undefined pathogenicity. In Peru, studies report the presence of Blastocystis in many regions, but the highest prevalence levels are reported in Arequipa. The aim of this study was to link Blastocystis infection with social determinants of health. We recruited and surveyed 232 infected and uninfected participants from houses with at least one Blastocystis-infected person. All samples were concentrated by spin concentration method in saline solution, examined by wet mount under light microscopy and confirmed with methylene-stained stool smear. We found a human Blastocystis prevalence of 51.3% in the study sample. We also found statistical associations between Blastocystis infection and peri-urban location in the city as well as the use of alternative non-domiciliary water supplies, suggesting these are risk factors for human Blastocystis infection.

Clinical and epidemiological aspects of chronic Chagas disease from Southern Brazil.

INTRODUCTION: Patients with Chagas disease (CD), caused by Trypanosoma cruzi, present a higher risk of developing other chronic diseases, which may contribute to CD severity. Since CD is underreported in the southern state of Paraná, Brazil, we aimed to characterize clinical and epidemiological aspects of individuals chronically infected with T. cruzi in Southern Brazil. METHODS: A community hospital-based study was performed, recording clinical/demographic characteristics of 237 patients with CD from Southern Brazil. To estimate the association between different forms of CD and sociodemographic and clinical variables, multiple logistic regression models were built using the Akaike information criterion. RESULTS: Mean age was 57.5 years and 59% were females. Most patients' (60%) place of origin/birth was within Paraná and they were admitted to the CD outpatient clinic after presenting with cardiac/digestive symptoms (64%). The predominant form of CD was cardiac (53%), followed by indeterminate (36%), and digestive (11%). The main electrocardiographic changes were in the right bundle branch block (39%) and left anterior fascicular block (32%). The average number of comorbidities per patient was 3.9±2.3; systemic arterial hypertension was most common (64%), followed by dyslipidemia (34%) and diabetes (19%); overlapping comorbidities were counted separately. Male sex was associated with symptomatic cardiac CD (OR=2.92; 95%CI: 1.05-8.12; p=0.040). CONCLUSIONS: This study provided greater understanding of the distribution and clinical profile of CD patients in Southern Brazil, indicating a high prevalence of comorbidities among these patients who are a vulnerable group due to advanced age and substantial risk of morbidity.

The impact of the COVID-19 pandemic on rabies reemergence in Latin America: the case of Arequipa, Peru.

Over the past decades, there has been tremendous progress towards eliminating canine rabies in Latin America. Major components of rabies prevention programs in Latin America leading to these successes have been constant and intense surveillance for rabid dogs and uninterrupted yearly mass dog vaccination campaigns. However, vital measures to control COVID-19 in Latin America have had the negative trade-off of jeopardizing these rabies elimination and prevention activities. In this paper, we aimed to assess the effect of interrupting canine rabies surveillance and mass dog vaccination campaigns on rabies trends. We built a deterministic compartment model of dog rabies dynamics parameterized for conditions found in Arequipa, Peru, where there is an ongoing dog rabies epidemic. Our model suggests that a decrease in canine vaccination coverage as well as decreased surveillance leading to an increased length of survival of infected dogs could lead to a sharp rise in canine rabies and, subsequently, human rabies risk. We examined our results over the best estimate of the basic reproductive number in Arequipa (R0 = 1.44) and a range of plausible values for R0 (1.36 - 2). The rising trend was consistent. It is very possible that COVID-19 will continue to challenge our public health departments in the short- and medium-term. Innovative strategies to conduct dog vaccination and rabies surveillance during these trying times should be considered to safeguard the achievements made in Latin America towards the elimination of dog-mediated human rabies.

En las últimas décadas ha habido un tremendo progreso hacia la eliminación de la rabia canina en América Latina. Los principales componentes de los programas de prevención de la rabia en América Latina que condujeron a estos éxitos han sido la vigilancia constante e intensa de los perros con rabia y las campañas anuales de vacunación masiva ininterrumpida. Sin embargo, las medidas esenciales para controlar el COVID-19 en América Latina han tenido el balance negativo de poner en peligro estas actividades de prevención y eliminación de rabia. En este artículo, nuestro objetivo fue evaluar el efecto que la interrupción de la vigilancia de la rabia canina y las campañas de vacunación masiva de perros tendría en las tendencias de la rabia. Modelamos la dinámica de la rabia canina mediante un modelo determinístico de comportamientos parametrizado para las condiciones que se encuentran en Arequipa, Perú, donde hay una epidemia de rabia canina en curso. Nuestro modelo sugiere que una disminución en la cobertura de vacunación canina, así como una disminución en la vigilancia (que llevaría a una mayor supervivencia de los perros infectados), podría llevar a un aumento súbito de rabia canina y, seguidamente, del riesgo de rabia humana. Examinamos nuestros resultados sobre la mejor estimación del número reproductivo básico en Arequipa (R0 = 1.44) y un rango de valores plausibles para R0 (1.36 ­ 2). La tendencia al alza fue consistente. Es muy posible que el COVID-19 continúe desafiando a nuestros departamentos de salud pública a corto y mediano plazo. Por lo tanto, deben considerarse estrategias innovadoras para llevar a cabo la vacunación de perros y la vigilancia de la rabia durante estos tiempos difíciles para salvaguardar los logros alcanzados en América Latina hacia la eliminación de la rabia humana mediada por perros.

Behavioral and structural barriers to accessing human post-exposure prophylaxis and other preventive practices in Arequipa, Peru, during a canine rabies epidemic.

A canine rabies epidemic started in early 2015 in Arequipa, Peru and the rabies virus continues to circulate in the dog population. Some city residents who suffer dog bites do not seek care or do not complete indicated post-exposure prophylaxis (PEP) regimens, increasing the risk of human rabies. The objectives of our study are to qualitatively assess knowledge about rabies, and preventive practices, such as rabies vaccine administration, following a dog bite. We conduct eight focus group discussions in peri-urban and urban communities with 70 total participants. In our results, we observe low awareness of rabies severity and fatality, and different practices following a dog bite, depending on the community type: for example, whereas participants in the urban communities report cleaning the wound with hydrogen peroxide rather than soap and water, participants in peri-urban areas cover the wound with herbs and hair from the dog that bit them. Misconceptions about rabies vaccines and mistreatment at health centers also commonly prevent initiating or completing PEP. We identify important behavioral and structural barriers and knowledge gaps that limit evidence-based preventive strategies against rabies and may threaten successful prevention of dog-mediated human rabies in this setting.

Spatial Inequality Hides the Burden of Dog Bites and the Risk of Dog-Mediated Human Rabies.

Since its reintroduction in 2015, rabies has been established as an enzootic disease among the dog population of Arequipa, Peru. Given the unknown rate of dog bites, the risk of human rabies transmission is concerning. Our objective was to estimate the rate of dog bites in the city and to identify factors associated with seeking health care in a medical facility for wound care and rabies prevention follow-up. To this end, we conducted a door-to-door survey with 4,370 adults in 21 urban and 21 peri-urban communities. We then analyzed associations between seeking health care following dog bites and various socioeconomic factors, stratifying by urban and peri-urban localities. We found a high annual rate of dog bites in peri-urban communities (12.4%), which was 2.6 times higher than that in urban areas (4.8%). Among those who were bitten, the percentage of people who sought medical treatment was almost twice as high in urban areas (39.1%) as in peri-urban areas (21.4%).

Elucidating the Mechanism of Trypanosoma cruzi Acquisition by Triatomine Insects: Evidence from a Large Field Survey of Triatoma infestans.

Blood-sucking triatomine bugs transmit the protozoan parasite Trypanosoma cruzi, the etiologic agent of Chagas disease. We measured the prevalence of T. cruzi infection in 58,519 Triatoma infestans captured in residences in and near Arequipa, Peru. Among bugs from infected colonies, T. cruzi prevalence increased with stage from 12% in second instars to 36% in adults. Regression models demonstrated that the probability of parasite acquisition was roughly the same for each developmental stage. Prevalence increased by 5.9% with each additional stage. We postulate that the probability of acquiring the parasite may be related to the number of feeding events. Transmission of the parasite does not appear to be correlated with the amount of blood ingested during feeding. Similarly, other hypothesized transmission routes such as coprophagy fail to explain the observed pattern of prevalence. Our results could have implications for the feasibility of late-acting control strategies that preferentially kill older insects.