Posts or Comments 19 March 2024

Archive for "Schistosomiasis"



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.”

Schistosomiasis &water Bill Brieger | 15 Mar 2023

Effective Strategies to Eliminate Schistosomiasis in School Children in Rural Parts of Ghana

By Lauren Koranteng and originally posted in the Social and Behavioral Foundations of Primary Health Care Blog. “Overcoming poverty is not a task of charity, it is an act of justice. Like Slavery and Apartheid, poverty is not natural. It is man-made and it can be overcome and eradicated by the actions of human beings. Sometimes it falls on a generation to be great. You can be that great generation. Let your greatness blossom.” – Nelson Mandela According to the World Health Organization, Schistosomiasis is a “disease of poverty that leads to chronic ill-health “. It is caused by a parasitic worm that lives in freshwater snails. The larval forms of the parasite is released by the snails. Humans who make contact with the water during various activities like recreation, agriculture and also for livelihood get infected. The prevalence rate in Ghana is 23.3% , however there are some areas that have localized prevalence levels that are >50% ( Kulinkina et al). A vulnerable population that is often infected are school aged children who access the waters mostly for recreational reasons (Antwi et al). These are usually school aged children who live in hard to reach areas in the country with poor sanitation. It is important for the disease to be controlled because chronic ill health also impacts the cognitive abilities of the children. Praziquantel is a drug used for preventative chemotherapy against Schistosomiasis. It offers a solution to eradication of the disease and could be executed through drug administration of praziquantel through the school system. This kind of mass administration has been done before in the country, but unfortunately, the behavior of children swimming in these infected waters did not change. This behavior of continuous exposure of children to these water bodies presented a limited factor in the eradication of this disease and intervention. Using the national health insurance program in the country, praziquantel can be made available again but through school programs in these rural areas.  Additionally, the school curriculum can include health education that will encourage children to avoid fresh water bodies where possible. Sanitation improvement and reduced human and infected water contact will also be a priority health development goal. So, in working with stakeholders such as the Ghana Health Service and the Ministry of Education, a realistic plan can be developed and executed.  This can include a mass drug administration program, health education and sanitation improvement.  This may be reasonable interventions to use to support children who are in contact with fresh water bodies and at a high risk of contracting Schistosomiasis.

Schistosomiasis &water Bill Brieger | 20 Aug 2021

Schistosomiasis in Mozambique, the Importance of WASH

As part of the class blog in the Course, Social and Behavioral Foundations in Primary Health Care at the Johns Hopkins Bloomberg School of Public Health, students occasionally write about tropical diseases. Below we are re-posting one such blog by an author going by the username of “kamilinea.”

Photo by mrjn Photography on Unsplash

Schistosomiasis is a parasitic disease, estimated to affect more than 240 million people globally, in which transmission and propagation is dependent upon human exposure to contaminated freshwater. This disease, which has a prevalence of approximately 50% in Mozambique, can cause significant morbidity including blood in the urine or stool, scarring and calcification of the bladder, kidney damage, liver and spleen enlargement, scarring of the liver, genital lesions, vaginal bleeding, infertility, and eventual possible cancer of the bladder along with rare spinal cord damage. Children, who are particularly susceptible to this disease through playing in freshwater, can develop anemia, stunted growth, and intellectual delays.

Exposure typically occurs while bathing, washing clothes, swimming, fishing, or working in contaminated fresh water including lakes, streams, and rivers. Although mass drug administration (MDA) with praziquantel is a main focus of disease control, treatment does not prevent reinfection. Multiple studies have concluded that elimination is currently impossible without infrastructure changes resulting in improvements in water, sanitation, and hygiene (WASH) throughout Mozambique. Providing these changes would allow citizens to avoid exposure to schistosomiasis as well as many other infectious diseases.

Figure 2.

Distribution of Schistosomiasis haematobium in Mozambique, The American Journal of Tropical Medicine and Hygiene Am J Trop Med Hyg

A policy that implements infrastructure changes throughout Mozambique to increase WASH is necessary to improve control and progress toward elimination. More specifically, a policy that would support development of safe-water wells throughout rural regions of Mozambique would allow for sustainable access to safe water. For this policy to be effective, buy-in and support from many stakeholders is imperative including the communities themselves, the government, and the Ministry of Health and organizations such as the WHO, the Schistosomiasis Control Initiative, and the Water and Sanitation Program. The government would need to provide financial support, however funding could be obtained through the World Bank which already supports some WASH programs throughout the country.

Schistosomiasis is a disease that could be eliminated in Mozambique through various control efforts, however elimination is currently not possible without improvements in WASH. All efforts should be made to encourage the government of Mozambique to prioritize this effort and involve supporting organizations in order to eliminate schistosomiasis.

Elimination &Eradication &Health Systems &Helminths/Worms &ITNs &Journalists/Media &Leishmaniasis &NGOs &Nigeria &NTDs &Partnership &Repellent &Research &Schistosomiasis &Technical Assistance &Treatment Bill Brieger | 29 Sep 2020

Malaria News Today 2020-09-28/29: media involvement, NGOs, monitoring and research

A variety of malaria and related issues have arisen over the past two days. A media coalition for malaria elimination formed in Ghana. A Nigerian NGO stresses the importance of addressing malaria on Nigeria’s 60th Independence Day (October 1). An innovative technology foundation is supporting various malaria and NTD treatment and diagnostic research efforts. Click on links below to read the details.

Media Coalition for malaria control and elimination launched

A Media Coalition comprising of selected journalists and editors, has been launched in Ghana under the umbrella of the “Zero Malaria Starts with Me” campaign to eliminate malaria by 2030. The Coalition, which aimed to enhance the quality and quantity of malaria coverage, and support broader advocacy efforts, was launched at a workshop in Accra organized by the National Malaria Control Programme (NMCP), in collaboration with the African Media and Malaria Research Network and Speak Up Africa, an advocacy and communication Organisation based in Senegal.

The workshop brought together media personnel from across the regions, who nominated their Regional Executives, with two National Co-Chairpersons coming from Greater Accra. The Members of the Coalition, made a firm declaration of their commitment towards the elimination of malaria in Ghana by the year 2030, by championing the fight, taking responsibility for their roles through proactive, regular, accurate, and high-quality media output of news on malaria.

Chinwe Chibuike Foundation Set To Flag-off Full Scale Malaria Eradication Program On Independence Day

A Nigeria indigenous and international non-governmental organization, envisioned to create a conducive environment towards the accessibility of healthcare facilities and improved educational opportunities, has joined the fight against the bizzare challenges of Malaria. The renowned Nigeria-USA humanitarian organization, Chinwe Chibuike Foundation is collaborating with other organizations to flagoff a full scale malaria eradication exercise tagged “Nigeria at 60 Malaria Eradication Project”, on the 1st of October 2020.

According to the founder and President of Chinwe Chibuike Foundation, Ms Gloria Chibuike, during an interview session with Pulse TV few days ago, she noted the forthcoming Nigeria At 60 Malaria Eradication Program will be different and of more impact, especially with the full scale approach and introduction a new Malaria repellant Band.

While emphasizing on the extensive features of the project, Ms Gloria described Malaria as one of the biggest problems in Africa at the moment, considering the increased number of recorded deaths and infection. She narrated that the discovery of the new malaria repellent band was timely and off-course very efficient, especially with testimonies from few persons who have already tried the brand.

Drugs and Diagnostics: Malaria and NTDs

The Global Health Innovative Technology (GHIT) Fund announced today a total of 1.37 billion yen (US$13 million*) to invest in seven partnerships to develop new lifesaving drugs and diagnostics for malaria, Buruli ulcer, Chagas disease, leishmaniasis, schistosomiasis, and soil-transmitted helminths (STH). This includes three newly funded projects and four that will receive continued funding. The RBM Partnership is planning on how to monitor and provide technical support for ITN programs. Click the links within each section to read details.

As of September 29, GHIT’s portfolio includes 50 ongoing projects: 26 discovery projects, 16 preclinical projects and eight clinical trials (Appendix 3). The total amount of investments since 2013 is 22.3 billion yen (US$211 million).

Support the Improvement of Operational Efficiency of ITN Campaigns

The Alliance for Malaria Prevention (AMP) is a workstream within the RBM Partnership to End Malaria. With malaria indicators stagnating and intense pressure to improve access and use of effective ITNs, WHO has renewed focus on stratifying vector control strategies in countries. Along with the introduction of new, more expensive ITNs, countries are now challenged to determine where they should deploy different ITN types to manage insecticide resistance within limited funding envelopes, as well as to identify more efficient ways to implement mass ITN distribution.

Countries that have accessed AMP technical assistance have significantly improved their capacity to modify and update strategies and tools to increase ITN access, use and accountability. They have also continued to identify further gaps and look for effective ways to address them. Now AMP planning to support update and finalization of ITN tracking tool, aligned with priorities across major partners (GF, PMI, RBM).

 

Anemia &Dracunculiasis Guinea Worm &Elimination &Leishmaniasis &MDA &Schistosomiasis Bill Brieger | 09 Sep 2020

NTD News Today 2020-09-09 from ASTMH

The current table of contents from the American Journal of Tropical Medicine and Hygiene features several important articles on neglected tropical diseases and malaria. Below are abstracts of several with links to the journal.

Agent-Based Simulation for Seasonal Guinea Worm Disease in Chad Dogs

The campaign to eradicate dracunculiasis (Guinea worm [GW] disease) and its causative pathogen Dracunculus medinensis (GW) in Chad is challenged by infections in domestic dogs, which far outnumber the dwindling number of human infections. We present an agent-based simulation that models transmission of GW between a shared water source and a large population of dogs. The simulation incorporates various potential factors driving the infections including external factors and two currently used interventions, namely, tethering and larvicide water treatments.

By defining and estimating infectivity parameters and seasonality factors, we test the simulation model on scenarios where seasonal patterns of dog infections could be driven by the parasite’s life cycle alone or with environmental factors (e.g., temperature and rainfall) that could also affect human or dog behaviors (e.g., fishing versus farming seasons).

We show that the best-fitting model includes external factors in addition to the pathogen’s life cycle. From the simulation, we estimate that the basic reproductive number, R 0, is approximately 2.0; our results also show that an infected dog can transmit the infection to 3.6 other dogs, on average, during the month of peak infectivity (April). The simulation results shed light on the transmission dynamics of GWs to dogs and lay the groundwork for reducing the number of infections and eventually interrupting transmission of GW.

Village Response to Mass Drug Administration for Schistosomiasis in Mwanza Region, Northwestern Tanzania

Are We Missing Socioeconomic, Cultural, and Political Dimensions?

Praziquantel (PZQ)-based mass drug administration (MDA) is the main approach for controlling schistosomiasis in endemic areas. Interventions such as provision and use of clean and safe water, minimizing contacts with infested water, disposal of human waste in latrines, and snail control provide additional key interventions to break the transmission cycle and could complement and perhaps sustain the benefits of MDA. However, all interventions deployed need to be accepted by the targeted communities. A qualitative study was conducted to examine factors that might differentiate villages which did not show a substantial decrease in Schistosoma mansoni prevalence despite repeated, high treatment coverage referred to as “persistent hotspot villages” from villages which showed a substantial decrease in prevalence referred to as “responding (RES) villages.” A convenient sample of adults was drawn from eight villages. Thirty-nine key informants were interviewed and 16 focus groups were held with a total of 123 participants. Data were analyzed manually using a thematic content approach. In both hotspot and RES villages, schistosomiasis was not considered to be a priority health problem because of its chronic nature, lack of knowledge and awareness, and poverty among study communities.

Hotspot villages exhibited poor leadership style, lack of or insufficient social engagement, little or lack of genuine community participation, little motivation, and commitment to schistosomiasis control compared with RES villages where there were commitment and motivation to fight schistosomiasis. We support the view of scholars who advocate for the adoption of a biosocial approach for effective and sustainable PZQ-based MDA for schistosomiasis control.

Assessment of Incubation Period of Cutaneous Leishmaniasis due to Leishmania major in Tunisia

The period between the infective sandfly bites and appearance of cutaneous leishmaniasis (CL) lesions is still hypothetical and little studied. This work aimed at assessing the incubation time of zoonotic CL (ZCL) due to Leishmania major using a standardized methodology. The retrospective analysis used the epidemiological, clinical, and biological information available in the database recording all the CL cases diagnosed at the Parasitology Department of the Pasteur Institute of Tunis during 2015–2019. It allowed for the selection of 92 privileged observations 1) of confirmed CL cases with presentation suggestive of ZCL form 2) living in northern regions free of ZCL 3) with a single infective trip of less than a week to ZCL foci during transmission season and 4) with accurate dates of travel and onset of lesions. Incubation length computed in this population ranged from 1 to 21 weeks, with a median of 5 weeks (interquartile range: 3–8.5 weeks).

Schistosoma mansoni Vector Snails in Antigua and Montserrat

Snail-Related Considerations Pertinent to a Declaration of Elimination of Human Schistosomiasis.

Investigations leading to a WHO-validated declaration of elimination of schistosomiasis transmission are contemplated for several countries, including Caribbean island nations. With assistance from the Pan American Health Organization, we undertook freshwater snail surveys in two such nations, Antigua and Barbuda, and Montserrat in September and October 2017. Historically, the transmission of Schistosoma mansoni supported by the Neotropical vector snail Biomphalaria glabrata occurred in both countries. Transmission on the islands is thought to have been interrupted by the treatment of infected people, improved sanitation, introduction of competitor snails, and on Montserrat with the eruption of the Soufrière volcano which decimated known B. glabrata habitats. Guided by the available literature and local expertise, we found Biomphalaria snails in seven of 15 and one of 14 localities on Antigua and Montserrat, respectively, most of which were identified anatomically and molecularly as Biomphalaria kuhniana.

Two localities on Antigua harbored B. glabrata, but no schistosome infections in snails were found. For snail-related aspects of validation of elimination, there are needs to undertake basic local training in medical malacology, be guided by historical literature and recent human schistosomiasis surveys, improve and validate sampling protocols for aquatic habitats, enlist local expertise to efficiently find potential transmission sites, use both anatomical and molecular identifications of schistosomes or putative vector snail species found, if possible determine the susceptibility of recovered Biomphalaria spp. to S. mansoni, publish survey results, and provide museum vouchers of collected snails and parasites as part of the historical record.

Decreased Mortality of falciparum Malaria in Anemic Prisoners of War?

Modern clinical trials have suggested that anemia protects against malaria mortality. Military records of the Second World War in Asia were examined to see if there was support for this hypothesis. When relatively well-nourished Imperial Japanese Navy sailors captured on Nauru (n = 799) were imprisoned on the Fauro Islands, 26% died from falciparum malaria. Similarly treated but very malnourished colocated Imperial Army soldiers experienced low stable malaria mortality. One-fifth of previously healthy Australian Army soldiers (n = 252) retreating from New Britain died largely because of malaria in April 1942. Malnourished prisoners of war, who were as a group very anemic, both Australian Army soldiers in Thailand and Japanese Army soldiers in Papua New Guinea, had high malaria rates but very low (< 3%) mortality rates. Malaria immunity does not adequately explain this dichotomy, suggesting that severe nutritional deprivation may be protective against malaria mortality possibly because of iron-deficiency anemia.

Nigeria &NTDs &Schistosomiasis Bill Brieger | 04 Sep 2020

Efforts to Eliminate Schistosomiasis in Nigeria, A Multifaceted Approach

As part of the activities in the course Social and Behavioral Foundations of Primary Health Care, class members write a blog on a current health issue. Amr Marawan has shared the context of schistosomiasis control in Nigeria on the class blog. His writing is reposted below and can also be read along with those of his classmates in the SBFPHC Blog site.

Schistosomiasis was described in papyrus papers thousands of years ago by ancient Egyptians. Then it was re-described by Theodore Bilharz, a pioneer parasitologist, 150 years ago in Cairo, Egypt. Schistosomiasis is among a group of neglected tropical diseases hitting sub-Saharan Africa. There are more than 25 million individuals infected and more than 100 million at risk in Nigeria. Among the different types of schistosomiasis, Schistosoma Haematobium affects the urogenital system causing blood in the urine and other symptoms and predisposes to urinary cancer.

photo source: http://www.bio.davidson.edu/people/midorcas/GISclass/GISwebsites/grayson/Schistosomiasis.htm

Despite the global efforts over the past 50 years, we only achieved limited success in Nigeria. Most of the campaigns designed used Praziquantel for prevention and treatment, as it has shown great success in multiple countries. Unlike other previously endemic states, the use of chemotherapy was not sufficient to address this major problem in Nigeria due to several limitations. In 2012. The World Health Organization (WHO) and World Health Assembly (WHA) adopted a multifaceted plan to eradicate schistosomiasis. The plan aims at strengthening the local health systems, using chemotherapy, appropriate sanitation, and water systems, as well as promoting hygiene education and snail control. There will be multiple designs for this approach to address the different challenges in the different states.

In order to succeed in this battle, all the stakeholders should cooperate and understand their role. The Federal ministry of health in Nigeria should communicate and supervise the local communities closely to ensure that there is no waste of resources. The pharmaceutical companies play a fundamental role by supplying millions of praziquantel pills with the help of non-governmental organizations (such as the Carter Center). The schools and religious leaders should educate the citizens about this disease and the role of both chemotherapy and sanitation to lead a healthy and productive life. The local community leaders are responsible for maintaining the momentum to achieve the utmost benefit for their people in spite of the conflicting perception for this campaign.

Six years after the WHA declaration, there was a substantial success demonstrated by treating approximately 75 % of school aged children. There is a new road map issued by the WHO for the tropical diseases for 2021-2030 to address the gaps and finish the incomplete mission.

 

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.

Asymptomatic &Burden &Dengue &Diagnosis &Ebola &Elimination &Epidemiology &Health Systems &ITNs &MDA &Mosquitoes &NTDs &Schistosomiasis &Schools &Vector Control &Zoonoses Bill Brieger | 30 Jun 2019

The Weekly Tropical Health News 2019-06-29

Below we highlight some of the news we have shared on our Facebook Tropical Health Group page during the past week.

Polio Persists

If all it took to eradicate a disease was a well proven drug, vaccine or technology, we would not be still reporting on polio, measles and guinea worm, to name a few. In the past week Afghanistan reported 2 wild poliovirus type 1 (WPV1) cases, and Pakistan had 3 WPV1 cases. Circulating vaccine-derived poliovirus type 2 (cVDPV2) was reported in Nigeria (1), DRC (4) and Ethiopia (3) from healthy community contacts.

Continued Ebola Challenges

In the seven days from Saturday to Friday (June 28) there were 71 newly confirmed Ebola Cases and 56 deaths reported by the Democratic Republic of Congo’s Ministry of Health. As Ebola cases continue to pile up in the Democratic Republic of the Congo (DRC), with 12 more confirmed Thursday and 7 more Friday, a USAID official said four major donors have jump-started a new strategic plan for coordinating response efforts. To underscore the heavy toll the outbreak has caused, among its 2,284 cases, as noted on the World Health Organization Ebola dashboard today, are 125 infected healthcare workers, including 2 new ones, DRC officials said.

Pacific Standard explained the differences in Ebola outbreaks between DRC today and the West Africa outbreak of 2014-16. On the positive side are new drugs used in organized trials for the current outbreak. The most important factor is safe, effective vaccine that has been tested in 2014-16, but is now a standard intervention in the DRC. While both Liberia and Sierra Leone had health systems and political weaknesses as post-conflict countries, DRC’s North Kivu and Ituri provinces are currently a war zone, effectively so for the past generation. Ebola treatment centers and response teams are being attacked. There are even cultural complications, a refusal to believe that Ebola exists. So even with widespread availability of improved technologies, teams may not be able to reach those in need.

To further complicate matters in the DRC, Doctors Without Borders (MSF) “highlighted ‘unprecedented’ multiple crises in the outbreak region in northeastern DRC. Ebola is coursing through a region that is also seeing the forced migration of thousands of people fleeing regional violence and is dealing with another epidemic. Moussa Ousman, MSF head of mission in the DRC, said, ‘This time we are seeing not only mass displacement due to violence but also a rapidly spreading measles outbreak and an Ebola epidemic that shows no signs of slowing down, all at the same time.’”

NIPAH and Bats

Like Ebola, NIPAH is zoonotic, and also involves bats, but the viruses differ. CDC explains that, “Nipah virus (NiV) is a member of the family Paramyxoviridae, genus Henipavirus. NiV was initially isolated and identified in 1999 during an outbreak of encephalitis and respiratory illness among pig farmers and people with close contact with pigs in Malaysia and Singapore. Its name originated from Sungai Nipah, a village in the Malaysian Peninsula where pig farmers became ill with encephalitis.

A recent human outbreak in southern India has been followed up with a study of local bats. In a report shared by ProMED, out of 36 Pteropus species bats tested for Nipah, 12 (33%) were found to be positive for anti-Nipah bat IgG antibodies. Unlike Ebola there are currently no experimental drugs or vaccines.

Climate Change and Dengue

Climate change is expected to heighten the threat of many neglected tropical diseases, especially arboviral infections. For example, the New York Times reports that increases in the geographical spread of dengue fever. Annually “there are 100 million cases of dengue infections severe enough to cause symptoms, which may include fever, debilitating joint pain and internal bleeding,” and an estimated 10,000 deaths. Dengue is transmitted by Aedes mosquitoes that also spread Zika and chikungunya. A study, published Monday in the journal Nature Microbiology, found that in a warming world there is a strong likelihood for significant expansion of dengue in the southeastern United States, coastal areas of China and Japan, as well as to inland regions of Australia. “Globally, the study estimated that more than two billion additional people could be at risk for dengue in 2080 compared with 2015 under a warming scenario.”

Schistosomiasis – MDA Is Not Enough, and Neither Are Supplementary Interventions

Schistosomiasis is one of the five neglected tropical diseases (NTDs) that are being controlled and potentially eliminated through mass drug administration (MDA) of preventive chemotherapy (PCT), in this case praziquantel. In The Lancet Knopp et al. reported that biannual MDA substantially reduced Schistosomiasis haematobium prevalence and infection intensity but was insufficient to interrupt transmission in Zanzibar. In addition, neither supplementary snail control or behaviour change activities did not significantly boost the effect of MDA. Most MDA programs focus on school aged children, and so other groups in the community who have regular water contact would not be reached. Water and sanitation activities also have limitations. This raises the question about whether control is acceptable for public health, or if there needs to be a broader intervention to reach elimination?

Trachoma on the Way to Elimination

Speaking of elimination, WHO has announced major “sustained progress” on trachoma efforts. “The number of people at risk of trachoma – the world’s leading infectious cause of blindness – has fallen from 1.5 billion in 2002 to just over 142 million in 2019, a reduction of 91%.” Trachoma is another NTD that uses the MDA strategy.

The news about NTDs from Dengue to Schistosomiasis to Trachoma is complicated and demonstrates that putting diseases together in a category does not result in an easy choice of strategies. Do we control or eliminate or simply manage illness? Can our health systems handle the needs for disease elimination? Is the public ready to get on board?

Malaria Updates

And concerning being complicated, malaria this week again shows many facets of challenges ranging from how to recognize and deal with asymptomatic infection to preventing reintroduction of the disease once elimination has been achieved. Several reports this week showed the particular needs for malaria intervention ranging from high burden areas to low transmission verging on elimination to preventing re-introduction in areas declared free from the disease.

In South West, Nigeria Dokunmu et al. studied 535 individuals aged from 6 months were screened during the epidemiological survey evaluating asymptomatic transmission. Parasite prevalence was determined by histidine-rich protein II rapid detection kit (RDT) in healthy individuals. They found that, “malaria parasites were detected by RDT in 204 (38.1%) individuals. Asymptomatic infection was detected in 117 (57.3%) and symptomatic malaria confirmed in 87 individuals (42.6%).

Overall, detectable malaria by RDT was significantly higher in individuals with symptoms (87 of 197/44.2%), than asymptomatic persons (117 of 338/34.6%)., p = 0.02. In a sub-set of 75 isolates, 18(24%) and 14 (18.6%) individuals had Pfmdr1 86Y and 1246Y mutations. Presence of mutations on Pfmdr1 did not differ by group. It would be useful for future study to look at the effect of interventions such as bednet coverage. While Southwest Nigeria is a high burden area, the problem of asymptomatic malaria will become an even bigger challenge as prevalence reduces and elimination is in sight.

Sri Lanka provides a completely different challenge from high burden areas. There has been no local transmission of malaria in Sri Lanka for 6 years following elimination of the disease in 2012. Karunasena et al. report the first case of introduced vivax malaria in the country by diagnosing malaria based on microscopy and rapid diagnostic tests. “The imported vivax malaria case was detected in a foreign migrant followed by a Plasmodium vivax infection in a Sri Lankan national who visited the residence of the former. The link between the two cases was established by tracing the occurrence of events and by demonstrating genetic identity between the parasite isolates. Effective surveillance was conducted, and a prompt response was mounted by the Anti Malaria Campaign. No further transmission occurred as a result.”

Bangladesh has few but focused areas of malaria transmission and hopes to achieve elimination of local transmission by 2030. A particular group for targeting interventions is the population of slash and burn cultivators in the Rangamati District. Respondents in this area had general knowledge about malaria transmission and modes of prevention and treatment was good according to Saha and the other authors. “However, there were some gaps regarding knowledge about specific aspects of malaria transmission and in particular about the increased risk associated with their occupation. Despite a much-reduced incidence of malaria in the study area, the respondents perceived the disease as life-threatening and knew that it needs rapid attention from a health worker. Moreover, the specific services offered by the local community health workers for malaria diagnosis and treatment were highly appreciated. Finally, the use of insecticide-treated mosquito nets (ITN) was considered as important and this intervention was uniformly stated as the main malaria prevention method.”

Kenya offers some lessons about low transmission areas but also areas where transmission may increase due to climate change. A matched case–control study undertaken in the Western Kenya highlands. Essendi et al. recruited clinical malaria cases from health facilities and matched to asymptomatic individuals from the community who served as controls in order to identify epidemiological risk factors for clinical malaria infection in the highlands of Western Kenya.

“A greater percentage of people in the control group without malaria (64.6%) used insecticide-treated bed nets (ITNs) compared to the families of malaria cases (48.3%). Low income was the most important factor associated with higher malaria infections (adj. OR 4.70). Houses with open eaves was an important malaria risk factor (adj OR 1.72).” Other socio-demographic factors were examined. The authors stress the need to use local malaria epidemiology to more effectively targeted use of malaria control measures.

The key lesson arising from the forgoing studies and news is that disease control needs strong global partnerships but also local community investment and adaptation of strategies to community characteristics and culture.

Diagnosis &NTDs &Schistosomiasis Bill Brieger | 19 Nov 2016

Identifying a More Accurate Test for Schistosomiasis in The Gambia

During the recently concluded 65th Annual Meeting of the American Society of Tropical Meicine and Hygiene colleagues from The Gambian Ministry of Health and Social Welfare, the World Health Organization and the NTD Support Center presented a poster entitled, “Field Performance of a Circulating Cathodic Antigen Rapid Test at Point-Of-Care for Mapping Schistosomiasis-Endemic Districts in Gambia.” The authors included Bakary Sanneh, Kristen Renneker, Joof  Ebrima, Sanyang M. Abdoulie, Camara Yaya, Sambou M. Sana, Sey Alhagie Papa, Jagne Sherifo, Baldeh Ignacious, Louis-Albert Tchuem Tchuente, Patrick J Lammie, and Kisito Ogoussan. Their abstract appears below.

figureBackground: The traditional parasitological Kato Katz smears and urine filtration methods recommended by the World Health Organization (WHO) to implement mapping of schistosomiasis have been found to be less sensitive in the detection of light-intensity schistosomiasis infections. Field surveys in Sub-Sahara Africa have shown that the Circulating Cathodic Antigen (CCA) point-of-care (POC) test is more accurate for detecting Schistosoma mansonia than the microscopic Kato Katz technique.

Aim: To establish the field sensitivity and specificity of POC CCA as mapping tool to provide the endemicity of schistosomiasis in The Gambia.

Methods: A cross-section study …

  • Ten school per region in 4 regions with historical known risk
  • Fifty children aged 7 to 14 years: 25 boys and 25 girls (WHO Mapping sampling guide)
  • Stool, urine and finger pricks samples were examined for Schistosomiasis
  • Parasitological tests: 2 Kato-katz slides to read from each stool sample, and urine filtration technique, urine dip-stick and Circulating Cathodic Antigen (CCA) techniques,

table-1Discussion: The CCA prevalence in this study was 23.34% (95% CI, 21.51-25.26%) two times higher than the prevalence based on  egg-detection for S. haematobium and S.mansoni (10.13,95% CI 8.87-11.55; and 0.26%, (95% CI, 0.09-0.62, respectively).  Although The Gambia is thought to be endemic for only S. haematobium, yet 5 subjects were found to harbor S. mansoni. Three of the 5 individuals from the high endemic schistosomiasis regions were co-infected with S. haematobium and S. mansoni.

table-2The sensitivity of the POC-CCA proved to be relatively high (60.0%), using double Kato-Katz as a reference for S. mansoni detection, although few infections were found, 5 out 1954  tested. The specificity of the POC CCA was 76.8%, respectively.  Using urine filtration as reference standard for the detection of S. haematobium, the sensitivity of POC-CCA was 47.9% and the specificity was 79.4%.

Conclusion: The Gambia is endemic for both urinary and intestinal schistosomiasis although most of the infections are due to S. haematobium in the 4 regions investigated. The results of the study showed a low sensitivity of the POC-CCA test in detecting S. haematobium and therefore we conclude further research is needed  to develop an ideal rapid diagnosis tool for urinary schistosomiasis.

schisto-acknowledgementAcknowledgement: Thanks to the Mapping Team,  Consultants, MoHSW, WHO,  Task Force for Global Health (TFGH) for all their support. For questions please contact: Dr. Kisito Ogoussan, kogoussan@taskforce.org; or Mr. Bakary Sanneh, sheikbakary@yahoo.com