Combining epidemiology and economics to assess control of a viral endemic animal disease: Porcine Reproductive and Respiratory Syndrome (PRRS).

Porcine reproductive and respiratory syndrome (PRRS) is an extremely contagious disease that causes great damage to the U.S. pork industry. PRRS is not subject to official control in the U.S., but most producers adopt control strategies, including vaccination. However, the PRRS virus mutates frequently, facilitating its ability to infect even vaccinated animals. In this paper we analyze how increased vaccination on sow farms reduces PRRS losses and when vaccination is profitable. We develop a SIR model to simulate the spread of an outbreak between and within swine farms located in a region of Minnesota. Then, we estimate economic losses due to PRRS and calculate the benefits of vaccination. We find that increased vaccination of sow farms increases the private profitability of vaccination, and also transmits positive externalities to farms that do not vaccinate. Although vaccination reduces industry losses, a low to moderate vaccine efficacy implies that large PRRS losses remain, even on vaccinated farms. Our approach provides useful insight into the dynamics of an endemic animal disease and the benefits of different vaccination regimens.

Measles.

Measles is a highly contagious, potentially fatal, but vaccine-preventable disease caused by measles virus. Symptoms include fever, maculopapular rash, and at least one of cough, coryza, or conjunctivitis, although vaccinated individuals can have milder or even no symptoms. Laboratory diagnosis relies largely on the detection of specific IgM antibodies in serum, dried blood spots, or oral fluid, or the detection of viral RNA in throat or nasopharyngeal swabs, urine, or oral fluid. Complications can affect many organs and often include otitis media, laryngotracheobronchitis, pneumonia, stomatitis, and diarrhoea. Neurological complications are uncommon but serious, and can occur during or soon after the acute disease (eg, acute disseminated encephalomyelitis) or months or even years later (eg, measles inclusion body encephalitis and subacute sclerosing panencephalitis). Patient management mainly involves supportive therapy, such as vitamin A supplementation, monitoring for and treatment of secondary bacterial infections with antibiotics, and rehydration in the case of severe diarrhoea. There is no specific antiviral therapy for the treatment of measles, and disease control largely depends on prevention. However, despite the availability of a safe and effective vaccine, measles is still endemic in many countries and causes considerable morbidity and mortality, especially among children in resource-poor settings. The low case numbers reported in 2020, after a worldwide resurgence of measles between 2017 and 2019, have to be interpreted cautiously, owing to the effect of the COVID-19 pandemic on disease surveillance. Disrupted vaccination activities during the pandemic increase the potential for another resurgence of measles in the near future, and effective, timely catch-up vaccination campaigns, strong commitment and leadership, and sufficient resources will be required to mitigate this threat.

Supporting countries to achieve their malaria elimination goals: the WHO E-2020 initiative.

BACKGROUND: Malaria causes more than 200 million cases of illness and 400,000 deaths each year across 90 countries. The World Health Organization (WHO) set a goal for 35 countries to eliminate malaria by 2030, with an intermediate milestone of 10 countries by 2020. In 2017, the WHO established the Elimination-2020 (E-2020) initiative to help countries achieve their malaria elimination goals and included 21 countries with the potential to eliminate malaria by 2020. METHODS: Across its three levels of activity (country, region and global), the WHO developed normative and implementation guidance on strategies and activities to eliminate malaria; provided technical support and subnational operational assistance; convened national malaria programme managers at three global meetings to share innovations and best practices; advised countries on strengthening their strategy to prevent re-establishment and preparing for WHO malaria certification; and contributed to maintaining momentum towards elimination through periodic evaluations, monitoring and oversight of progress in the E-2020 countries. Changes in the number of indigenous cases in E-2020 countries between 2016 and 2020 are reported, along with the number of countries that eliminated malaria and received WHO certification. RESULTS: The median number of indigenous cases in the E-2020 countries declined from 165.5 (interquartile range [IQR] 14.25-563.75) in 2016 to 78 (IQR 0-356) in 2020; 12 (57%) countries reported reductions in indigenous cases over that period, of which 7 (33%) interrupted malaria transmission and maintained a malaria-free status through 2020 and 4 (19%) were certified malaria-free by the WHO. Two countries experienced outbreaks of malaria in 2020 and 2021 attributed, in part, to the COVID-19 pandemic. CONCLUSIONS: Although the E-2020 countries contributed to the achievement of the 2020 global elimination milestone, the initiative highlights the difficulties countries face to interrupt malaria transmission, even when numbers of cases are very low. The 2025 global elimination milestone is now approaching, and the lessons learned, experience gained, and updated guidance developed during the E-2020 initiative will help serve the countries seeking to eliminate malaria by 2025.

Low pH Hypromellose (Taffix) nasal powder spray could reduce SARS-CoV-2 infection rate post mass-gathering event at a highly endemic community: an observational prospective open label user survey.

Objectives: Bney Brak city tops Israel's COVID-19 infection rate and mortality. Before the Jewish New Year (two-day gathering) SARS-CoV-2 PCR positivity rates were 17.6% and reached 28.1% two weeks later Taffix - an innovative nasal powder creates a protective gel over the nasal mucosa blocking viruses from infecting nasal cells, was tested for efficacy in preventing SARS CoV2 infection.Methods: In a prospective users survey, 243 members of an ultra-orthodox community that participated in two days prayers were followed for 14 days following this 'superspread' event. Eighty-three used Taffix throughout holiday's prayers and the following two weeks (ITT). Eighty-one used it regularly (PP). Two used it rarely if at all. The remaining 160 did not use Taffix.Results: After 14 days, 0/81 (0%) of (PP) Tafffix users, 2/83 (2.4%) of (ITT) Taffix users and 16/160 (10%) nonusers were infected. Odds ratio for infection among Taffix users was 0.22, a reduction of 78% (95%CI 1%-95%). No side effects reported.Conclusion: Taffix could be an additional tool against COVID19 spread, in addition to recommended safety measures. This is the first time that a prevention measure of SARS-CoV-2, beyond the use of masks, has proved effective.

Study design and operational framework for a community-based Malaria Elimination Demonstration Project (MEDP) in 1233 villages of district Mandla, Madhya Pradesh.

BACKGROUND: In the past decade substantial reduction in malaria morbidity and mortality has been observed through well-implemented case management and vector control strategies. India has also achieved a significant reduction in malaria burden in 2018 and has committed to eliminate malaria by 2030. The Mandla Malaria Elimination Demonstration Project (MEDP) was started in 2017 in 1233 villages of District Mandla to demonstrate malaria elimination in a tribal district with hard-to-reach areas was possible using active and passive surveillance, case management, vector control, and targeted information, education and communication campaigns. An operational plan was developed to strengthen the existing surveillance and malaria elimination systems, through fortnightly active case detection to ensure that all cases including those that are introduced into the communities are rapidly identified and treated promptly. The plan also focused on the reduction of human-mosquito contact through the use of Long-Lasting Insecticial Nets (LLINs) and Indoor Residual Spray (IRS). The operational plan was modified in view of the present COVID-19 pandemic by creating systems of assistance for the local administration for COVID-related work while ensuring the operational integrity of malaria elimination efforts. RESULTS: The use of MEDP study design and operational plan, with its built-in management control systems, has yielded significant (91%) reduction of indigenous cases of malaria during the period from June 2017 to May 2020. The malaria positivity rate was 0.33% in 2017-18, 0.13% in 2018-19, and 0.06% in 2019-20. Mass screening revealed 0.18% malaria positivity in September-October 2018, followed by 0.06% in June 2019, and 0.03% in December 2019, and these were mostly asymptomatic cases in the community. The project has been able to sustain the gains of the past three years during the ongoing COVID-19 pandemic. CONCLUSION: This paper provides the study design and the operational plan for malaria elimination in a high-burden district of Central India, which presented difficulties of hard to reach areas, forest malaria, and complex epidemiology of urban and rural malaria. The lessons learned could be used for malaria elimination efforts in rest of the country and other parts of South Asia with comparable demography and epidemiology.

Immunological characteristics govern the transition of COVID-19 to endemicity.

We are currently faced with the question of how the severity of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may change in the years ahead. Our analysis of immunological and epidemiological data on endemic human coronaviruses (HCoVs) shows that infection-blocking immunity wanes rapidly but that disease-reducing immunity is long-lived. Our model, incorporating these components of immunity, recapitulates both the current severity of SARS-CoV-2 infection and the benign nature of HCoVs, suggesting that once the endemic phase is reached and primary exposure is in childhood, SARS-CoV-2 may be no more virulent than the common cold. We predict a different outcome for an emergent coronavirus that causes severe disease in children. These results reinforce the importance of behavioral containment during pandemic vaccine rollout, while prompting us to evaluate scenarios for continuing vaccination in the endemic phase.

Addressing budget reduction and reallocation on health-related resources during COVID-19 pandemic in malaria-endemic countries.

The global COVID-19 pandemic has been affecting the maintenance of various disease control programmes, including malaria. In some malaria-endemic countries, funding and personnel reallocations were executed from malaria control programmes to support COVID-19 response efforts, resulting mainly in interruptions of disease control activities and reduced capabilities of health system. While it is principal to drive national budget rearrangements during the pandemic, the long-standing malaria control programmes should not be left behind in order to sustain the achievements from the previous years. With different levels of intensity, many countries have been struggling to improve the health system resilience and to mitigate the unavoidable stagnation of malaria control programmes. Current opinion emphasized the impacts of budget reprioritization on malaria-related resources during COVID-19 pandemic in malaria endemic countries in Africa and Southeast Asia, and feasible attempts that can be taken to lessen these impacts.

[Challenges of schistosomiasis control in China during the coronavirus disease 2019 (COVID-19) epidemic].

OBJECTIVE: To investigate the implementation of schistosomiasis control activities in China during the coronavirus disease 2019 (COVID-19) epidemic, so as to evaluate the impact of COVID-19 epidemic on the national schistosomiasis control program in China. METHODS: On April 2020, 3 counties (districts) were randomly selected from each of the 12 schistosomiasis-endemic provinces (municipality, autonomous region), and a questionnaire survey was conducted to investigate the implementation of schistosomiasis control activities in these counties (districts) from January to March 2020. Then, the impact of the COVID-19 epidemics on the national schistosomiasis control program of China was evaluated using a comparative analysis approach. RESULTS: Among the 36 counties (cities, districts) sampled from 12 provinces (municipality, autonomous region), 66.67% were at a high and medium risk of COVID-19 epidemics. The implementation of schistosomiasis control activities assignment, human schistosomiasis examination and treatment, snail control with chemical treatment and health education reduced by 44.26% to 91.56% as compared to 2019 during the same time period, and the schistosomiasis control program was more affected by COVID-19 in transmission-controlled provinces. The gross funds invested into the schistosomiasis control program reduced by 23.39% in relative to the expected, while the total expenditure increased by 41.22%. In addition, all 36 surveyed counties (districts) considered that the COVID-19 epidemic had a short-term impact on the schistosomiasis control program, with the most predominant impact on schistosomiasis control activities assignment, human resources and monitoring of endemic situation of schistosomiasis. CONCLUSIONS: The COVID-19 epidemics affect the routine schistosomiasis control program across the endemic-foci of China. Policy and financial support should be strengthened to ensure the completion of the schistosomiasis control program.

After the honeymoon, the divorce: Unexpected outcomes of disease control measures against endemic infections.

The lack of effective vaccines for many endemic diseases often forces policymakers to rely on non-immunizing control measures, such as vector control, to reduce the massive burden of these diseases. Controls can have well-known counterintuitive effects on endemic infections, including the honeymoon effect, in which partially effective controls cause not only a greater initial reduction in infection than expected, but also large outbreaks during control resulting from accumulation of susceptibles. Unfortunately, many control measures cannot be maintained indefinitely, and the results of cessation are poorly understood. Here, we examine the results of stopped or failed non-immunizing control measures in endemic settings. By using a mathematical model to compare the cumulative number of cases expected with and without control, we show that deployment of control can lead to a larger total number of infections, counting from the time that control started, than without any control-the divorce effect. This result is directly related to the population-level loss of immunity resulting from non-immunizing controls and is seen in a variety of models when non-immunizing controls are used against an infection that confers immunity. Finally, we examine three control plans for minimizing the magnitude of the divorce effect in seasonal infections and show that they are incapable of eliminating the divorce effect. While we do not suggest stopping control programs that rely on non-immunizing controls, our results strongly argue that the accumulation of susceptibility should be considered before deploying such controls against endemic infections when indefinite use of the control is unlikely. We highlight that our results are particularly germane to endemic mosquito-borne infections, such as dengue virus, both for routine management involving vector control and for field trials of novel control approaches, and in the context of non-pharmaceutical interventions aimed at COVID-19.

Mathematical modelling on COVID-19 transmission impacts with preventive measures: a case study of Tanzania.

The outbreak of COVID-19 was first experienced in Wuhan City, China, during December 2019 before it rapidly spread over globally. This paper has proposed a mathematical model for studying its transmission dynamics in the presence of face mask wearing and hospitalization services of human population in Tanzania. Disease-free and endemic equilibria were determined and subsequently their local and global stabilities were carried out. The trace-determinant approach was used in the local stability of disease-free equilibrium point while Lyapunov function technique was used to determine the global stability of both disease-free and endemic equilibrium points. Basic reproduction number, R0 , was determined in which its numerical results revealed that, in the presence of face masks wearing and medication services or hospitalization as preventive measure for its transmission, R0=0.698 while in their absence R0=3.8 . This supports its analytical solution that the disease-free equilibrium point E0 is asymptotically stable whenever R0<1 , while endemic equilibrium point E∗ is globally asymptotically stable for R0>1 . Therefore, this paper proves the necessity of face masks wearing and hospitalization services to COVID-19 patients to contain the disease spread to the population.