The potential impact of Anopheles stephensi establishment on the transmission of Plasmodium falciparum in Ethiopia and prospective control measures.

BACKGROUND: Sub-Saharan Africa has seen substantial reductions in cases and deaths due to malaria over the past two decades. While this reduction is primarily due to an increasing expansion of interventions, urbanisation has played its part as urban areas typically experience substantially less malaria transmission than rural areas. However, this may be partially lost with the invasion and establishment of Anopheles stephensi. A. stephensi, the primary urban malaria vector in Asia, was first detected in Africa in 2012 in Djibouti and was subsequently identified in Ethiopia in 2016, and later in Sudan and Somalia. In Djibouti, malaria cases have increased 30-fold from 2012 to 2019 though the impact in the wider region remains unclear. METHODS: Here, we have adapted an existing model of mechanistic malaria transmission to estimate the increase in vector density required to explain the trends in malaria cases seen in Djibouti. To account for the observed plasticity in An. stephensi behaviour, and the unknowns of how it will establish in a novel environment, we sample behavioural parameters in order to account for a wide range of uncertainty. This quantification is then applied to Ethiopia, considering temperature-dependent extrinsic incubation periods, pre-existing vector-control interventions and Plasmodium falciparum prevalence in order to assess the potential impact of An. stephensi establishment on P. falciparum transmission. Following this, we estimate the potential impact of scaling up ITN (insecticide-treated nets)/IRS (indoor residual spraying) and implementing piperonyl butoxide (PBO) ITNs and larval source management, as well as their economic costs. RESULTS: We estimate that annual P. falciparum malaria cases could increase by 50% (95% CI 14-90) if no additional interventions are implemented. The implementation of sufficient control measures to reduce malaria transmission to pre-stephensi levels will cost hundreds of millions of USD. CONCLUSIONS: Substantial heterogeneity across the country is predicted and large increases in vector control interventions could be needed to prevent a major public health emergency.

Injury Prevention Practices as Depicted in G- and PG-Rated Movies, 2008-2012.

Unintentional injuries are the leading cause of death among children in the United States. The use of recommended safety practices can reduce injuries. Children often learn behaviors from media exposure. Children's movies released in 1995-2007 infrequently depicted appropriate injury prevention practices. The aim of this study was to determine if injury prevention practices in children's movies have improved. The top grossing 25 G- and PG-rated movies in the United States per year for 2008-2012 were eligible for inclusion in the study. Movies or scenes were excluded if they were animated, not set in the present day, fantasy, documentary, or not in English. Injury prevention practices involving riding in a motor vehicle, walking, boating, bicycling, and four other activities were recorded for characters with speaking roles. Fifty-six (45%) of the 125 movies met the inclusion criteria. A total of 603 person-scenes were examined involving 175 (29%) children and 428 (71%) adults. Thirty-eight person-scenes involved crashes or falls, resulting in four injuries and no deaths. Overall, 59% (353/603) of person-scenes showed appropriate injury prevention practices. This included 313 (70%) of 445 motor-vehicle passengers who were belted; 15 (30%) of 50 pedestrians who used a crosswalk, 2 (7%) of 30 boaters who wore personal flotation devices, and 8 (29%) of 28 bicyclists who wore helmets. In comparison with previous studies, there were significant increases in usage of seat belts, crosswalks, personal flotation devices, and bicycle helmets. However, 41% of person-scenes still showed unsafe practices and the consequences of those behaviors were infrequently depicted.

Target antigen, age, and duration of antigen exposure independently regulate immunoglobulin G subclass switching in malaria.

The isotype/subclass of immunoglobulin determines antibody function, but rather little is known about factors that direct class switching in vivo. To evaluate factors that might influence the maturation of the antibody response during infection, we conducted a seroepidemiological study of the immunoglobulin G (IgG) subclass response to four merozoite-associated antigens of Plasmodium falciparum in a mountainous region of northeastern Tanzania, where malaria endemicity declines with increasing altitudes. We found that IgG1/IgG3 class switching is independently affected by the nature of the antigen, cumulative exposure to the antigen, and the maturity of the immune system (i.e., the age of the individual). These observations provide insights into the effects of immune system maturity, the duration and intensity of antigen exposure, and inherent characteristics of individual antigens on the process of class switching in human B cells. Our data also throw light on the consequences of class switch decisions on the gradual acquisition of antimalarial immunity.