OVERVIEW OF DISEASE IMPACT

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In the remote Kenyan village of Muhuru Bay a public health crisis is on the rise. Located on the edge of Lake Victoria, many of the locals rely on the water to make their living through fishing and agriculture irrigated by the lake. The lake water serves as a source for drinking water, washing clothes, and as a playground for school children. Within the lake however, infected snails harbor a parasite which causes a disease called schistosomiasis. The larvae of this parasite are released by these snails and can survive up to 48 hours in the freshwater.

Makena, 8, and her brother Kiano, 3, love to spend their weekends swimming in the lake and playing along the banks of the nearby river while their mother, Winnie, sells produce at the local market. Unknown to the residents of Muhuru Bay, merely coming into contact with the lake’s infested waters puts them at risk of becoming infected with schistosomiasis. And so, one day while swimming in the lake, Makena and Kiano were infected. There weren’t even aware that larvae had penetrated their skin.

For 2 months following infection, the larvae developed into adult worms inside Makena and Kiano’s bodies. The worms move to their internal organs and released eggs. Makena missed school for 2 weeks due to her lingering fever and cough. Prior to becoming sick, Makena was doing well in school but then she began to struggle. Winnie grew more worried when Kiano also fell ill, complaining of painful stomach aches. Winnie had to stay home from work to take care of her children. Across many homes in Muhuru Bay, a similar scene has been unfolding. Infected children stay home for weeks and months. They show signs of impaired cognitive development, stunted growth, malnutrition, and anemia. Family members are forced to stay at home to take care of the children, while others work longer hours to continue to support the family. Adults who work in and around the lake are also being infected with schistosomiasis, showing signs of abdominal pain, fever, fatigue, genital sores, and rashes, among others. It is estimated that over 45 working days are lost due to schistosomiasis infection, per person infected per year¹.

Winnie has heard from neighbors about other children with similar symptoms, and the outbreak of a “snail fever.” She rushes Makena and Kiano to the regional health clinic to have them examined. Fortunately, if schistosomiasis infection is suspected, it can be confirmed by a simple urine test. Winnie’s suspicions are confirmed, both Makena and Kiano have moderate cases of schistosomiasis.

Schistosomiasis is treatable with just 1-2 doses of the drug needed to cure the infections. Praziquantel (PZQ), the primary drug used for both prevention and treatment, has been in use since the 1980s. Makena is fortunate -- she will receive PZQ the following week during a school drug administration campaign. The medication will relieve Makena’s pain allowing her to focus on school. Drug administration programs in Kenya, such as the one in Makena’s school, are favored in areas where large number of schistosomiasis infections are suspected. Such programs have proved impactful by gaining 1 year of schooling for every $4 invested in the program².
Beyond the cost-effectiveness of the drug therapy itself, schistosomiasis therapy with PZQ also has low healthcare system costs. There are no reported cases of drug resistance to PZQ, drug administration can be ably managed by community healthcare workers without specialized medical training, and currently used PZQ tablets have an excellent storage stability profile. Therefore, as efforts to control schistosomiasis infections are being considered, access to therapy is the primary consideration.

So the little snails with their invisible parasite larvae have caused considerable impact to the small community of Muhuru Bay. But this disease affects far more than one or two villages. In 2013, it was estimated that 12 million Kenyans were at risk of being infected with schistosomiasis, half of those being children³. Out of all the people at risk, a mere 1.8 million were treated with PZQ. In sub-Saharan Africa, it has been estimated that more than 200,000 deaths per year are due to schistosomiasis⁴. On a global scale, there were an estimated 240 million people infected with schistosomiasis, with a mere 42 million people of these treated for the disease⁴. Schistosomiasis also increase the risk that Kiano and Makena will contract other infections. For instance teenage girls and women with female genital schistosomiasis are estimated to have a three times higher likelihood of contracting HIV⁵.

PZQ USE IN PEDIATRIC POPULATIONS

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PEDIATRIC PZQ FORMULATION DEVELOPMENT

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PEDIATRIC PZQ – CHALLENGES TO SUCCESSFUL ADOPTION

• The promise of PZQ therapy available to infants and toddlers is exciting, however significant challenges remain in making pediatric PZQ a reality:
  
  Tablet Stability: Commercially available PZQ tablets are highly stable, and do not need specialized storage requirements. The smaller pediatric formulation under development is designed to rapidly dissolve in the mouth, which may make it more susceptible to moisture and consequently less stable. Specialized storage requirements will not only increase the cost of making the drug available, but may also limit access to largely urban areas with adequate storage infrastructure
  
  Pricing pressure: PZQ tablets are currently available to most governmental health agencies for close to 7 cents per dose, due in part to charitable donations by the drug manufacturer. In order for pediatric PZQ to be effective, it must be delivered in a similar cost-effective manner, facilitated by either governmental purchasing programs or public-private partnership funding
  
  Ability to meet demand: A major challenge to effective control of schistosomiasis remains limited PZQ supply. In 2012, it is estimated that approximately 250 million people required preventative PZQ treatment, however PZQ supply was only sufficient to treat 45 million people. Therefore, for pediatric PZQ to be broadly effective, capital investments will need to be made to ensure its manufacture in sufficient scale to meet the outstanding global

• Photo Credit: Astellas Pharma Inc.

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