Posts or Comments 15 June 2024

Archive for "Vector Control"



Climate &Mosquitoes &Vector Control Bill Brieger | 02 Dec 2023

Changing Vector Behavior, one of the threats to malaria elimination

A new study from Kenya addresses one of the major challenges to malaria elimination. The authors note changing vector behaviour towards early morning biting has been established. Children are observed to come to school early, as do mosquitoes that have “peak landing between 06:00 and 07:00.” They also found that mosquitoes continue their activity until 11:00. The An. funestus mosquitoes they collected “were either fed or gravid, potentially indicative of multiple bloodmeals within each gonotrophic cycle, and had a sporozoite rate of 2.05%.” this is of particular concern because school aged children are not always prioritized in various malaria control interventions.

In Cambodia researchers found that “20% of collected Anopheles were active during the day, with increased day biting during the dry season.” Ellie Sherrard-Smith and colleagues explain that bednets and indoor residual spray are intended to work best when people are indoors and sleeping. They caution that, “Mosquito bites taken outside of these times contribute to residual transmission which determines the maximum effectiveness of current malaria prevention.” Their review documented that on average 21% of mosquito bites in Africa take place outside bedtime.

A study in Tanzania by Nicodem J Govella et al. noted that the use of insecticide-treated nets for malaria control has been associated with shifts in mosquito vector feeding behaviour including earlier and outdoor biting on humans. They concluded that efforts highlighting the need for control methods that target early and outdoor biting mosquitoes are now required.

In short, various changing factors ranging from climate and mosquito genetics to even the existing interventions like bednets that we use to control the biting of malaria carrying mosquitoes, threaten our ability to eliminate malaria. New vector control measures are urgently needed as is expansion of other interventions like malaria vaccines.

Chagas Disease &Climate &Leprosy &Malaria &NTDs &Vector Control &Zika Bill Brieger | 31 Jul 2023

Fighting NTDs at Home in the United States

The United States has been assisting in the fight against malaria and tropical diseases throughout the tropics. The question now arises is it ready to tackle these diseases on the home front?

In recent months CBS News reported that “Malaria cases in Florida and Texas are first locally acquired infections in U.S. in 20 years,” according to CDC. Local transmission of these 8 cases is the key concern because there are always imported cases from travelers to malaria endemic areas throughout the year. This has led to better planning of mosquito control activities. All of the Florida cases were found in Sarasota County. Although Anopheles mosquitoes still existed in the environment, they had not been infected in recent years.

Likewise Pensacola News Journal noted that, “Rising evidence is pointing to the possibility that leprosy has become endemic in the southeastern U.S. with Florida being named among the top reported states.” The paper explains that these Leprosy cases in central Florida account for nearly 20% of the national total, and that the state is considering instituting contact tracing.

Chagas disease may affect up to 300,000 people from Florida across to California, but an Emerging Pathogens Institute report shared in the Apopka Voice, explained that most cases remain undetected. While Chagas primarily affects people who have immigrated from Latin America, researchers are discovering locally acquired cases because the vector, the kissing bug, has been found in 29 states, and thus local transmission now occurs.

An article in PLoS NTDs explains that Zika, Dengue, and Chikungunya viruses are spread in the southern and Gulf Coast states by members of the Aedes mosquito family, aided by changes in weather and climate patterns. Just as in other countries where NTDs are endemic, the US experience of these diseases also sees that, “poverty equates to substandard housing that exposes residents to insect vectors, a lack of access to sanitation and water, and degraded environments.”

Local, State and National health agencies in the US are starting to awaken to the fact that diseases which we thought were eliminated back in the mid-19th-century are making a comeback. At a minimum, funding and training are needed to equip our Health Departments with environmentally appropriate vector control measures, appropriate treatment regimens, and disease surveillance tools to tackle the same problems that are threatening the lives of people throughout low- and middle-income countries throughout the world.

Elimination &MDA &NTDs &poverty &Schistosomiasis &Trachoma &Vector Control Bill Brieger | 13 Jun 2023

Eliminating NTDs as a Public Health Problem May Not Be Enough

The concept and goal of eliminating a disease appears simple on the surface, but complications ensue when the words “as a public health problem” are added.  We know that the distinction exists between eradication and elimination with the former being globally and the latter being nationally or regionally. The sum total action of eliminating a disease from all endemic countries therefore results in total global eradication.

The challenge comes when we try to qualify the concept of elimination. The US CDC defined elimination of disease as, “Reduction to zero of the incidence of a specified disease in a defined geographical area as a result of deliberate efforts; continued intervention measures are required.” Thus, there is no more transmission.  Following from this eradication is defined as, “Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed.” Penn Medicine summarized this as, “Elimination means stopping the transmission of a disease in a specific geographic area or country, but not worldwide. Elimination is a crucial step in the path toward eradication, requiring constant monitoring and interventions to keep serious diseases at bay.”

The foregoing definitions seem straightforward, but what does elimination as a public health problem or a disease of public health concern mean? The World Health Organization recently “congratulate(d) Benin and Mali for eliminating trachoma as a public health problem. Concerning another neglected tropical disease (NTD), lymphatic filariasis (LF), global control programs are aiming “to reduce the prevalence of infection below target thresholds and to alleviate the suffering of people affected by lymphoedema and hydrocele.” Wiegand and colleagues in The Lancet Global Health note that, “For schistosomiasis, the criterion for elimination as a public health problem (EPHP) is defined as less than 1% prevalence of heavy-intensity infections (ie, ?50 Schistosoma haematobium eggs per 10 mL of urine or ?400 Schistosoma mansoni eggs per g of stool).” They take issue with the fact that such definitions mean that morbidity still exists, though at very levels, so elimination of transmission has not really occurred for any of these NTDs.

Because the social, environmental, and behavioral conditions that favor transmission may still exists, one cannot guarantee that incidence such diseases may not increase again. All three diseases, LF, Schistosomiasis, and Trachoma have been tackled primarily through preventive chemotherapy, is simply put, using mass drug administration (MDA) over a period of years until active surveillance determines that “infection (is) below target thresholds.” Trachoma does have its SAFE strategy which includes water, sanitation and hygiene interventions, but drugs can reduce the disease without long term achievements in such activities have become sustainable.

Prada et al. in the Journal of Infectious Diseases warn that there can be resurgence of a disease that was documented to be eliminated as a public health problem. They explain that the transmission assessment survey held after several MDA rounds for LF may not be enough to guarantee that low levels of transmission and eventual elimination are achieved. They conclude that, “The risk of resurgence after achieving current targets is low and is hard to predict using just current prevalence. Although resurgence is often quick (<5 years), it can still occur outside of the currently recommended post-intervention surveillance period of 4–6 years,” and recommend monitoring beyond this period.

Toor and co-researchers suggest for NTD programs that, “as case numbers drop and elimination comes into prospect, transmission reduction through other interventions, such as vector control and sanitation, becomes crucial in reducing the probability and speed of resurgence, particularly when MDA or screening programs are halted. Surveillance activities for detecting elimination and resurgence become increasingly important to ensure that successes are maintained.”

Ultimately, unless the context of NTD transmission is addressed, elimination will be an elusive goal. Therefore, as WHO advocated on the recent World NTD Day, “Everybody, including leaders and communities, to confront the inequalities that drive NTDs and to make bold, sustainable investments to free the world’s most vulnerable communities affected by NTDs from a vicious cycle of disease and poverty.”

Indoor Residual Spraying &Integrated Vector Management &ITNs &Monkeys &Mosquitoes &Nigeria &Plasmodium/Parasite &Seasonal Malaria Chemoprevention &Urban &Vector Control Bill Brieger | 21 Sep 2020

Malaria News Today 2020-09-21: Vectors, Cities and Chimpanzees

First we look at how disease can influence urban planning. We have four news stories focus on field activities for vector control from Hyderabad, India, Borno State, Nigeria, Papua New Guinea and CHAD. Finally there is an ancestry article of sorts examining plasmodia in chimpanzees and humans. Click on the links to read full details.

Can Covid-19 inspire a new way of planning African cities?

Health crises are not new in Africa. The continent has grappled with infectious diseases on all levels, from local (such as malaria) to regional (Ebola) to global (Covid-19). The region has often carried a disproportionately high burden of global infectious outbreaks.
How cities are planned is critical for managing infectious diseases. Historically, many urban planning innovations emerged in response to health crises. The global cholera epidemic in the 1800s led to improved urban sanitation systems. Respiratory infections in overcrowded slums in Europe inspired modern housing regulations during the industrial era.

Urban planning in Africa during colonisation followed a similar pattern. In Anglophone Africa, cholera and bubonic plague outbreaks in Nairobi (Kenya) and Lagos (Nigeria) led to new urban planning strategies. These included slum clearance and urban infrastructure upgrades. Urban planning in French colonial Africa similarly focused on health and hygiene issues, but also safety and security.

Unfortunately regional experiences with cholera, malaria and even Ebola in African cities provide little evidence that they have triggered a new urban planning ethic that prioritises infectious outbreaks. Our recent research paper discusses three areas that can transform urban planning in the continent to prepare for future infectious outbreaks, using lessons from Covid-19.

The Coronavirus and other viruses like Ebola have always been ‘out there’ in nature.

But it’s only when we disrupt the natural habitats of the wild animals. Deadly viruses stay beneath the surface and need just one moment of triggering to emerge in the atmosphere and take the world by storm – historian Dr Mark Honigsbaum. The point is we cannot prevent all spillover events or predict precisely when or where the next one will happen. What we can do — and should do often — is invest in local laboratories and diagnostic services so that we can spot unusual outbreaks early and close them down quickly

We should note that Plasmidium Knowlesi is an example of a form of malaria from monkeys that arose because of urban expansion on forest habitats.

Hyderabad: People sensitised on mosquito breeding

As part of a novel initiative, every Sunday 10 am, 10 minute programme, the entomology wing of Greater Hyderabad Municipal Corporation conducted awareness drive on mosquito breeding grounds at various places on Sunday. They explained the importance of cleanliness and the ways the mosquito breeding takes place in stagnated water. Speaking on the occasion, Banjara Hills Corporator Gadwal Vijayalaxmi called upon everyone not to allow accumulation of water in containers, utensils and surroundings.

Borno, WHO Administer Malaria Prevention Drug on 2.1m Children

WHO National Coordinator Malaria Emergencies in Nigeria, Dr. Iniabasi Nglas gave the figure during a four round Malaria Chemoprevention Campaigns (MPCs aka SMC) in 25 of the 27 local government areas of Borno State. During the advocacy, Nglas said the IDP camps “are given special attention for there is high threat of malaria infection due to the environment. Record has shown that the treatment has reduced malaria morbidity in the state.” She revealed that during the first cycle, 1.9 million children were targeted but due to high reception 2.1 million children were administered with the drug.

Rotary Against Malaria Distributes Nets in PNG

ROTARY Against Malaria has finally completed its distribution of bed net mosquito nets throughout the Eastern Highlands Province (EHP) after three months. Team leader of Rotary Against Malaria in the province, Helmut Magino, during a ceremony in Goroka, acknowledged his working staff, the Eastern Highlands Provincial Health Authority, district health officers, logistic company Mapai Transport, Summer Institute of Linguistics (SIL)
and the communities in Papua New Guinea.

“Without these partners, our work in distributing mosquito nets wouldn’t have been successful,” Mr Magino said. “Mapai Transport assisted with vehicles to travel to the remote parts in Okapa, Henganofi and Lufa. “SIL assisted with distribution via airplane to remote parts which are not connected by road like in Obura-Wonenara district.” The volunteer-run organisation funded by Global Fund, a US-based organisation, distributed 145,900 mosquito nets in the province. “We distributed around 45,000 nets to Okapa and Lufa, 35,000 to Obura-Wonenara and 66,900 to rural areas in Goroka district. “We will visit EHP again next year to distribute nets …”

Donating Emergency IRS Supplies to CHAD

Last week, despite the COVID-19 pandemic, a Hercules military transport aircraft took off from an Israeli military base in the south, filled to capacity with items donated by Israeli Flying Aid IFA and the American Jewish Committee (AJC) — 2,000 six-person tents, personal protection equipment (PPE) for medical teams, backpack sprayers to eradicate malaria-carrying mosquitos, and more.

Why humans can run marathons and apes cannot (implication for plasmodium species)

Chimpanzees share more than 99 percent of their genes with modern humans, but the CMAH gene is one of the areas of difference. Two to three million years ago, gorillas, chimpanzees, and other primates were dying from a type of malaria called Plasmodium reichenowi (Science, 2011;331:540-542). At that time, all primates had a surface protein called Neu5Gc on their cells that was made from Neu5Ac. Then along came a primate with a gene that had lost its ability to make Neu5Gc from Neu5Ac, so it had only Neu5Ac (Proc Natl Acad Sci USA, Sept 6, 2005;102(36):12819-12824).

That pre-human did not die from malaria like other primates, his and her children lived and proliferated, and today their descendants (all humans) have a gene that makes Neu5Ac instead of Neu5Gc. As often happens in nature, the malaria parasite then modified its genetic makeup into a variant called Plasmodium falciparum which can infect humans, but not chimpanzees, so today humans can be infected only with Plasmodium falciparum and chimpanzees can be infected only with Plasmodium reichenowi. This same genetic mutation gave homo sapiens greater endurance so they were able to run long distances while the apes could not, which gave humans an advantage in hunting for food (J Hum Evol, 2014;66:64-82).

Coordination &COVID-19 &Ebola &Microscopy &Mosquitoes &Vector Control Bill Brieger | 04 Sep 2020

Malaria News Today 2020-09-04

Today, we are sharing more updates from newsletters and journal abstracts found online. Issues include citizens in Rwanda trapping mosquitoes, the need for standardizing microscopy, more information on Uganda’s Malaria fund, the challenge of containing three epidemics at once, an increase in cases in Namibia and genetic diversity of the parasite in Comoros. Click on links to read details.

Citizen science shows great potential to reduce malaria burden

A year-long collection of mosquitoes with self-made traps and over a hundred volunteers in rural Rwanda reporting levels of mosquito nuisance revealed when and where malaria risks were the highest. In addition to their reporting, the volunteers appeared to distribute knowledge and skills on controlling malaria within communities. Studies by Wageningen University & Research and the University of Rwanda show that citizen science has great potential to reduce the disease burden across the globe.

Uganda renews fight to eliminate malaria by 2030 – more on Malaria Free Uganda Fund

Uganda says it is fast-tracking efforts to eliminate malaria, which continues to take lives and bleed the country’s economy more than any other disease. The disease is responsible for 30 to 40 percent of outpatient hospital visits, 15 to 20 percent of admissions, and 10 percent of inpatient deaths, mostly pregnant mothers and children, according to the health ministry figures. The country on September 2 launched the board of directors of the Malaria Free Uganda Fund as part of its continued investment to eliminate the disease by 2030, as per the global target.

Malaria Free Uganda Fund is a nonprofit public-private partnership established to mainstream responsibility for malaria across all sectors and help remove financial and operational bottlenecks in fighting the disease. The National Malaria Control Program currently faces a three-year 206 U.S. million dollars budget gap, or 33 percent of the total, according to the ministry of health.  External donors, according to the ministry, fund over 95 percent of the fight against the disease in the country. The country is now looking at domestic resourcing in view of the global uncertainties like the COVID-19 pandemic that is affecting foreign financing. “The talent and experience we have mobilized to this board from the private and civil society will help the government achieve a significant reduction of malaria cases and deaths in Uganda,” said Ruth Aceng, minister of health while launching the board here.

Namibia records 12,507 malaria cases, 40 deaths in 2020

Namibia’s malaria cases this year increased to 12,507 from 2,841 recorded in 2019, according to statistics from the Ministry of Health. The southern African country recorded 31,000 cases of malaria in 2018. The National Vector-borne Diseases Control Program from the Health Ministry which monitors the weekly malaria situation in the country shows that this year alone 12,507 malaria cases where recorded, while 40 deaths occurred.

The ministry said the huge difference between 2019 and this year is attributed to the fact that 2019, was a drought year and the rainfall pattern was not similar to 2020 and 2018, hence the decline in malaria cases happened in 2019. According to the ministry, currently the implementation of the program activities amid COVID-19 is on halt due to some bottlenecks.

Congo sees increase in plague, at least 10 deaths this year

DR Congo is seeing an upsurge in cases of the plague, as the vast Central African nation also battles outbreaks of COVID-19 and Ebola. Since June, Congo has recorded at least 65 cases of the plague, including at least 10 deaths, in the eastern Ituri province according to Ituri provincial chief of health Dr. Louis Tsolu. While the plague is endemic in Ituri province, the number of cases is increasing and has already surpassed the total recorded in 2019 which had 48 cases and eight deaths, according to WHO.

Towards harmonization of microscopy methods for malaria clinical research studies

Microscopy performed on stained films of peripheral blood for detection, identification and quantification of malaria parasites is an essential reference standard for clinical trials of drugs, vaccines and diagnostic tests for malaria. The value of data from such research is greatly enhanced if this reference standard is consistent across time and geography. Adherence to common standards and practices is a prerequisite to achieve this. The rationale for proposed research standards and procedures for the preparation, staining and microscopic examination of blood films for malaria parasites is presented here with the aim of improving the consistency and reliability of malaria microscopy performed in such studies.

These standards constitute the core of a quality management system for clinical research studies employing microscopy as a reference standard. They can be used as the basis for the design of training and proficiency testing programmes as well as for procedures and quality assurance of malaria microscopy in clinical research.

Genetic diversity of Plasmodium falciparum in Grande Comore Island

Despite several control interventions resulting in a considerable decrease in malaria prevalence in the Union of the Comoros, the disease remains a public health problem with high transmission in Grande Comore compared to neighbouring islands. In this country, only a few studies investigating the genetic diversity of Plasmodium falciparum have been performed so far. For this reason, this study aims to examine the genetic diversity of P. falciparum by studying samples collected in Grande Comore in 2012 and 2013, using merozoite surface protein 1 (msp1), merozoite surface protein 2 (msp2) and single nucleotide polymorphism (SNP) genetic markers.

Artesunate &Dengue &Elimination &Malaria in Pregnancy &Mosquitoes &Nigeria &Resistance &Vector Control &Zika Bill Brieger | 03 Sep 2020

Malaria News Today 2020-09-03

Various updates were found in newsletters and journal abstracts online today. These looked at mosquitoes – what attracts them to people, how ookinetes move in the midgut, and how perlite from volcanic rock may be a barrier repellent. Nigeria reports that there is no ACT resistance – so far.  And malaria partners join to coordinate actions in Uganda.  Click on links to read details.

Nigeria yet to detect resistance of malaria parasite to ACTs, says ministe

Contrary to reports that Africa has for the first time identified resistance strain of the malaria parasite to the drug of choice, Artemisinin Combination Therapy (ACT), the Minister of Health, Dr. Osagie Emmanuel Ehanire, on Monday said a study conducted in three states of the country showed there is no such phenomenon in Nigeria.  “However, we are still monitoring the situation. We insist that people should conduct a malaria test before using the drug of choice. This we hope will help prevent any kind of resistance of the malaria parasite to ACTs.”

Ministry of Health launches the Malaria Free Uganda Fund

Health Minister Dr Jane Ruth Aceng told journalists in Kampala today that the idea of having this new board was reached after realizing that different entities have been conducting the same malaria control related work. She said that the ministry resolved that mainstreaming responsibility will remove financial and operational bottlenecks that deter them from achieving set targets for elimination of the disease. The fund with a board of 11 members is chaired by Kenneth Wycliffe Mugisha of the Rotarian Malaria Partners-Uganda.

Volcanic Rock Yields a New Kind of Insecticide for Mosquitoes

Insecticide resistance to pesticides has become widespread in mosquito populations, making insecticides less effective over time. Therefore, there is an urgent need for insecticides with alternative modes of action. tested a material derived from volcanic rock, perlite, as a potential non-chemical insecticide against Anopheles gambiae, one of the primary mosquitoes that spreads malaria in Africa. In their new report published in August in the Journal of Medical Entomology, they show that perlite has encouraging potential as a mechanical insecticide. Perlite is believed to act by causing dehydration in the mosquitoes. read more…

Mosquitoes love pregnant, beer-drinking exercisers with Type O blood

Mosquitoes spread Zika, West Nile, Chikungunya, Dengue, and Malaria, resulting in 700 million illnesses a year and a million deaths. Even if you don’t get sick from a mosquito bite, the blood thinner they pump into your flesh before draining your blood causes swelling and itching. This article in Smithsonian Magazine lists the factors that make some people more tempting targets than others to mosquito bites. They include:

  • Blood type: “One study found that in a controlled setting, mosquitoes landed on people with Type O blood nearly twice as often as those with Type A.”
  • Carbon Dioxide: “people who simply exhale more of the gas over time—generally, larger people—have been shown to attract more mosquitoes than others.”
  • Exercise: “mosquitoes find victims at closer range by smelling the lactic acid, uric acid, ammonia and other substances expelled via their sweat”
  • Skin bacteria: “scientists found that having large amounts of a few types of bacteria made skin more appealing to mosquitoes”
  • Beer: “Just a single 12-ounce bottle of beer can make you more attractive to the insects”
  • Pregnancy: “pregnant people exhale about 21 percent more carbon dioxide and are on average about 1.26 degrees Fahrenheit warmer than others”
  • Clothing color: “wearing colors that stand out (black, dark blue or red) may make you easier to find”
  • Genetics: “underlying genetic factors are estimated to account for 85 percent of the variability between people in their attractiveness to mosquitoes”

Live In Vivo Imaging of Plasmodium Invasion of the Mosquito Midgut

Malaria is one of the most devastating parasitic diseases in humans and is transmitted by anopheline mosquitoes. The mosquito midgut is a critical barrier that Plasmodium parasites must overcome to complete their developmental cycle and be transmitted to a new host. Here, we developed a new strategy to visualize Plasmodium ookinetes as they traverse the mosquito midgut and to follow the response of damaged epithelial cells by imaging live mosquitoes. Understanding the spatial and temporal aspects of these interactions is critical when developing novel strategies to disrupt disease transmission.

IRS &Monkeys &Mosquitoes &Pharmacovigilence &Resistance &Vector Control Bill Brieger | 01 Sep 2020

Malaria News Today 2020-09-01

Today we feature summaries and abstracts concerning Plasmodium malariae, P. knowlesi and monkey models for vaccine testing, clothianidin insecticide resistance, the mosquito immune system and drug interactions between medicines for malaria patients.

Some mosquitoes already have resistance to the latest weapon against malaria

By Munyaradzi Makoni: An insecticide about to be widely deployed inside African homes to combat malaria-carrying mosquitoes is already losing its punch. Two years ago, the World Health Organization (WHO) gave the green light for clothianidin, long used in agriculture to kill crop pests, to be added to the current mainstays of indoor mosquito control, which are losing their effectiveness as the insects develop resistance. Since then, many African countries have been laying plans to spray the walls of homes with the pesticide—it would represent the first new class of chemicals adopted for such use in decades—and looking anxiously for evidence of pre-existing resistance.

Now, scientists at Cameroon’s Centre for Research in Infectious Diseases (CRID) have found it. They recently sampled mosquitoes from rural and urban areas around Yaoundé, the capital, including two key malaria carriers. In one standard susceptibility assay, exposure to clothianidin for 1 hour killed 100% of Anopheles coluzzii. But in some A. gambiae samples as many as 55% of the mosquitoes survived, the group reported in a preprint posted 7 August on the bioRxiv preprint server.

Atlas of Malaria Mosquitoes’ Immune System Assembled

An international team of scientists led by investigators at the Wellcome Sanger Institute and the NIH has created the first cell atlas of mosquito immune cells to understand how the insects fight malaria, as well as other mosquito-borne infections. The mosquito host is essential for the malaria parasite to complete its lifecycle, so any disruption would dramatically reduce the transmission of one of the world’s deadliest diseases.
Findings from the new study—published recently in Science through an article titled “Mosquito cellular immunity at single-cell resolution“—discussed the discovery of new types of mosquito immune cells, including a rare cell type that could be involved in limiting malaria infection. The authors also identified molecular pathways implicated in controlling the malaria parasite.

Genetic analysis of the orthologous crt and mdr1 genes in Plasmodium malariae from Thailand and Myanmar

Plasmodium malariae is a widely spread but neglected human malaria parasite, which causes chronic infections. The observed polymorphisms in pmcrt and pmmdr1 genes are unlikely to affect protein function and unlikely related to chloroquine drug pressure. Similarly, the absence of pmmdr1 copy number variation suggests limited mefloquine drug pressure on the P. malariae parasite population, despite its long time use in Thailand for the treatment of falciparum malaria.

Quantification of Plasmodium knowlesi versus Plasmodium falciparum in the rhesus liver: implications for malaria vaccine studies in rhesus models

Rhesus macaques are valuable pre-clinical models for malaria vaccine development. The Plasmodium knowlesi/rhesus and Plasmodium falciparum/rhesus models are two established platforms for malaria vaccine testing… Detection of 18S rRNA in the liver following high dose intravenous PfSPZ confirmed that rhesus are modestly susceptible to wild-type P. falciparum sporozoites. However, comparison of 18S rRNA RT-PCR biomarker signal indicates that the P. falciparum liver burden was 3–5 logs lower than in PkSPZ-infected animals. Quantification of this difference in liver stage burden will help guide and interpret data from pre-clinical studies of live-attenuated sporozoite vaccines in rhesus models.

Potential drug–drug interactions associated with adverse clinical outcomes and abnormal laboratory findings in patients with malaria

Hospitalized patients with malaria often present with comorbidities or associated complications for which a variety of drugs are prescribed. Multiple drug therapy often leads to drug–drug interactions (DDIs). The following drug pairs reported the highest frequency of adverse events associated with the interactions; calcium containing products-ceftriaxone, isoniazid–rifampin, pyrazinamide–rifampin, isoniazid–acetaminophen, and ciprofloxacin–metronidazole.

Elimination &Surveillance &Vector Control Bill Brieger | 17 Apr 2020

A look at Botswana from WHO’s E-2020 country brief

Botswana is one of a handful of countries in Southern Africa that are nearing malaria elimination targets. The information below is extracted from WHO’s Elimination 2020 program site and shared verbatim.

“Botswana has made impressive progress in reducing indigenous malaria transmission, from a reported 71 000 cases in 2000 to 533 in 2018. Despite significant variation from year to year – with a higher number of malaria cases in 2014, 2016 and 2017 – the country has continued to report an overall decline in both cases and deaths since 2000.

“Challenges faced by Botswana’s national malaria control programme include the perception, in some communities, that malaria is a low priority disease, which can lead to people not protecting themselves with insecticide-treated nets and other WHO-recommended prevention measures. Added to this, some residents do not accept vector control activities such as insecticide spraying inside homes. However, the government’s commitment to eliminate malaria remains strong.

“WHO lists the following Successes in Botswana and the accompanying graph confirms the overall drop, despite some increases:

  • 69% decrease in number of reported malaria cases following outbreaks in 2014, 2016 and 2017;
  • all districts using District Health Information Software 2 (DHIS2) for real-time malaria reporting
  • mapping of all malaria cases at household level and stratification at village level
  • adoption of the Community Acting Together to Eliminate Malaria (CATTEM) approach
    enhanced community monitoring in malarious districts by malaria surveillance agents”

Hopefully with geographical and epidemiological targeting and attention to early warnings about climate change, Botswana can be among the next group of countries achieving malaria elimination.

Agriculture &Borders &Ebola &Essential Medicines &Integrated Vector Management &ITNs &Larvicide &Mosquitoes &Schistosomiasis &Severe Malaria &Vaccine &Vector Control Bill Brieger | 15 Jul 2019

The Weekly Tropical Health News 2019-07-13

In the past week more attention was drawn to the apparently never-ending year-long Ebola outbreak in the northeast of the Democratic Republic of the Congo. Regarding other diseases, there is new information on the RTS,S malaria vaccine, river prawns have been found to play a biological control role in schistosomiasis, and an update from the World Health Organization on essential medicines and diagnostics. New malaria vector control technologies are discussed.

Second Largest Ebola Outbreak One Year On

Ronald A. Klain and Daniel Lucey in the Washington Post observed raised concern that, “the disease has since crossed one border (into Uganda) and continues to spread. In the absence of a trajectory toward extinguishing the outbreak, the opposite path — severe escalation — remains possible. The risk of the disease moving into nearby Goma, Congo — a city of 1 million residents with an international airport.”

They added their voices to a growing number of experts who are watching this second biggest Ebola outbreak in history and note that, “As the case count approaches 2,500 with no end in sight, it is time for the WHO to declare the outbreak a public health emergency of international concern — a ‘PHEIC’ — to raise the level of global alarm and signal to nations, particularly the United States, that they must ramp up their response.” They call for three actions: 1) improved security for health workers in the region, 2) stepped up community engagement and 3) extended health care beyond Ebola treatment. The inability to adequately respond to malaria, diarrheal diseases and maternal health not only threated life directly, but also threated community trust, putting health workers’ lives at risk.

Olivia Acland, a freelance journalist based in DRC, reporting for the New Humanitarian describes the insecurity and the recent “wave of militia attacks in the Democratic Republic of Congo’s northeastern Ituri province has left hundreds dead and roughly 300,000 displaced in recent weeks, triggering a new humanitarian crisis in a region.” Specifically, “Ituri, a fertile region rich in gold deposits, has been an epicentre of conflict in Congo for decades. Between 1999 and 2003, around 60,000 people were killed here, as a power struggle between rebel groups escalated into ethnic violence,” related to traditional tensions between Hema cattle herders and Lendu farmers with roots in Belgian colonization.

Updates from the DRC Ministry of Health report on average 11 new Ebola cases per day in the past week. So far over 160,000 people have been vaccinated, and yet the spread continues. The Ministry also describes new protocol contains three vaccinations strategies that can be used depending on the environment in which confirmed cases are found including:

  • Classic Ring: The classic strategy of vaccinating contacts of confirmed cases and contact contacts.
  • Enlarged ring: It is also possible to vaccinate all inhabitants of houses within 5 meters around the outbreak of a confirmed case.
  • Geographical Ring: In an area where team safety can not be guaranteed, they can vaccinate an entire village or neighborhood.

Malaria Vaccines, Essential Drugs and New Vector Control Technologies

Halidou Tinto and colleagues enrolled two age groups of children in a 3-year extension of the RTS,S/AS01 vaccine efficacy trial: 1739 older children (aged 5–7 years) and 1345 younger children (aged 3–5 years). During extension, they reported 66 severe malaria cases. Overall they found that, “severe malaria incidence was low in all groups, with no evidence of rebound in RTS,S/AS01 recipients, despite an increased incidence of clinical malaria in older children who received RTS,S/AS01 compared with the comparator group in Nanoro. No safety signal was identified,” as seen in The Lancet.

WHO has updated the global guidance on medicines and diagnostic tests to address health challenges, prioritize highly effective therapeutics, and improve affordable access. Section 6.5.3 presents antimalarial medicines including curative treatment (14 medicines) for both vivax and falciparum and including tablets and injectables. Prophylaxis includes 6 medicines including those for IPTp and SMC. The latest guidance can be downloaded at WHO.

Paul Krezanoski reports on a new technology to monitor bednet use and tried it out in Ugandan households. As a result. “Remote bednet use monitors can provide novel insights into how bednets are used in practice, helping identify both households at risk of malaria due to poor adherence and also potentially novel targets for improving malaria prevention.

In another novel technological approach to vector control, Humphrey Mazigo and co-researchers tested malaria mosquito control in rice paddy farms using biolarvicide mixed with fertilizer in Tanzanian semi-field experiments. The intervention sections (with biolarvicide) had lowest mean mosquito larvae abundance compared to control block and did not affect the rice production/harvest.

Prawns to the Rescue in Senegal Fighting Schistosomiasis and Poverty

Anne Gulland reported how Christopher M. Hoover et al. discovered how prawns could be the key to fighting poverty and schistosomiasis, a debilitating tropical disease. They found that farming the African river prawn could fight the disease and improve the lives of local people, because the African river prawn is a ‘voracious’ predator of the freshwater snail, which is a carrier of schistosomiasis.

The researchers in Senegal said that, “market analysis in Senegal had shown there was significant interest among restaurant owners and farmers in introducing prawns to the diet.” The prawn could also for the basis of aquaculture in rice paddies and remove the threat of schistosomiasis from the rice workers.

—- Thank you for reading this week’s summary. These weekly abstractings have replaced our occasional mailings on tropical health issues due to fees introduced by those maintaining the listserve website. Also continue to check the Tropical Health Twitter feed, which you can see running on this page.

Borders &Diagnosis &Elimination &Environment &Gender &Health Education &Health Workers &Indoor Residual Spraying &IRS &ITNs &Mosquitoes &Plasmodium/Parasite &Vector Control Bill Brieger | 07 Jul 2019

The Weekly Tropical Health News 2019-07-06: Eliminating Malaria in Low Transmission Settings

This week started with articles that drew attention to the challenges of malaria in low transmission areas and with low density infections. Malaria Journal has provided several insightful articles toward this end.

Being an island has certainly helped Zanzibar make progress toward malaria elimination as witness the fact that malaria prevalence has remained below 1% for the past decade. Not only does Zanzibar still face threats of infection from the mainland, it may also experience an upsurge locally if residual transmission and the role of human behavior and community actions are not well understood. April Monroe et al. conducted in-depth interviews with community members and local leaders across six sites on Unguja, Zanzibar as well as semi-structured community observations of night-time activities and special events to learn more.

While there was high reported ITN use, there were also times when people were exposed t mosquitoes while being outdoors during biting times. This could be around the house, or at special night events like such as weddings, funerals, and religious ceremonies. Men spent more time outdoors than women. Clearly appropriate interventions and needed and should be promoted in culturally appropriate ways in order to further reduce and eventually eliminate transmission.

Angela Early and colleagues presented findings on a diagnostic process of deep sequencing for understanding the dynamics and complexity of Plasmodium infections, but stress that knowing the lower limit of detection is challenging. They present “a new amplicon analysis tool, the Parallel Amplicon Sequencing Error Correction (PASEC) pipeline, is used to evaluate the performance of amplicon sequencing on low-density Plasmodium DNA samples.”

The authors learned that, “four state-of-the-art tools resolved known haplotype mixtures with similar sensitivity and precision.” They also cautioned that, “Samples with very low parasitemia and very low read count have higher false positive rates and call for read count thresholds that are higher than current default recommendations.” Better understanding of the genetic mix of plasmodium infections as countries move toward low transmission and elimination is crucial for selecting appropriate interventions and evaluating their outcomes.

Hannah Edwards and co-researchers examined conditions for malaria transmission along the Thailand-Myanmar border in areas approaching malaria elimination. While prevalence may be less than 1%, residual transmission still occurs. Transmission occurs not only around residences but in the forests where people work. The researchers therefore looked at the behavior of both humans and insects. Overall, they found that, “Community members frequently stayed overnight at subsistence farm huts or in the forest. Entomological collections showed higher biting rates of primary vectors in forested farm hut sites and in a more forested village setting compared to a village with clustered housing and better infrastructure.”

While mosquitoes preferred to bite inside huts, their threat was magnified by those who did not use long lasting insecticide-treated nets (LLINs). While out in the farms and forests, people tended to wake early and increase their likelihood of being bitten. The authors discuss the challenges of dual residences in terms of LLIN ownership and even concerning the potential access to indoor residual spraying. The definition for universal net coverage needs to expand from one net per two people to include adequate nets wherever people are located.

The Amazonian area of Brazil is another area working toward malaria elimination, in particular, Plasmodium vivax. Felipe Leão Gomes Murta et al. also looked at the human side of the equation and identified misperceptions by both community members and health workers that could inhibit elimination efforts. They found, “many myths regarding malaria transmission and treatment that may hinder the sensitization of the population of this region in relation to the use of current control tools and elimination strategies, such as mass drug administration (MDA),” and LLINs.

Problematic perceptions included mention by both groups that the use of insecticide-treated nets, may cause skin irritations and allergies. Both community members and health professionals said malaria is “an impossible disease to eliminate because it is intrinsically associated with forest landscapes.” They concluded that such perceptions can be a barrier to control and elimination.

Efforts to eliminate malaria from low transmission settings are an essential to the overall global goals. These four articles tell us that close attention to and better understanding of humans, parasites and mosquitoes is still needed to achieve these goals.

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