As the Ebola crisis in West Africa begins to ease, there is equal cause for hope and fear.
The news that infections have slowed to fewer than 100 new cases per week is cause for optimism. At last, national governments and the World Health Organization have been able to talk of bringing the epidemic to a halt, rather than simply trying to hold ground against one of the world's most deadly viruses.
But as the fight against Ebola moves into this next stage, there is still so much work to be done. The devastation wrought by the disease on the people it has touched has set back years of development efforts in West Africa, not only ruining lives but also the already fragile health systems in Sierra Leone and Liberia.
Terrible state of sanitation
It has come at a time when both of these countries had been making good progress. By 2012, nearly 75% of Liberians and 61% of Sierra Leoneans had access to clean water - dramatic improvements from a decade before.
But less than one in five people had access to a basic toilet. The terrible state of sanitation was thrown into sharp relief by the spread of Ebola in local clinics and hospitals. Without enough water for washing, cleaning and disinfection, and without functioning toilets for patients desperately ill with diarrhoea and vomiting, the virus spread quickly into a public health emergency that reached far beyond West African country borders.
Nearly 9,000 people have died in this crisis so far, most of them in Sierra Leone, Guinea and Liberia. It will be months or years before the full impact on the ground can be fully understood - lives lost, families destroyed, local economies ruined.
People gather at a health post in Vaama, Sierra Leone, in May 2013. WaterAid/Anna Kari
The rebuilding will be difficult. However with the right political will, change can happen.
Once the infection has been brought under control, it will be time to address the underlying causes - broken health systems, the need for sanitation, and the lack of a reliable water supply, which damages health, makes food more scarce and good hygiene impossible.
'Dangerously unprepared' for next outbreak
This week, World Bank President Jim Yong Kim warned the world is 'dangerously unprepared' for future, deadly pandemics like this Ebola outbreak, and called upon governments, corporations, donors and aid agencies to work together to build stronger health systems.
Water and sanitation infrastructure and hygiene promotion must be part of these efforts.
There is a danger in waiting too long to fund long-term development for West Africa to help these countries recover. Economies have slowed, crime is increasing and the toll - both emotional and economic - on families has been as great as any civil war.
This week the African Union formally launched the Kigali Action Plan, to prioritise bringing water to 5 million people and sanitation to another five million across 10 countries.
The plan reflects the key role that these services play in human development. For many African countries, achieving middle income status is within reach, if they are not there already. But it's difficult for a country to sustain a booming economy if their people do not have safe, reliable sources of water, toilets and good waste disposal systems.
Health and dignity
Children who walk for long distances for water are deprived of time at school. Girls and women who slip out into the early dawn to relieve themselves in fields or at roadsides are deprived of dignity and security, and left vulnerable to harassment or worse. Communities without clean water and sanitation are unhealthy and less productive.
Achieving lasting change and basic services for all is possible and it requires political action and leadership, as well as financing.
This year marks the countdown to the new UN Sustainable Development Goals - the map for development aid for the next 15 years and a real chance to eradicate extreme poverty. To bring this about, a dedicated goal on water and sanitation is needed, along with the inclusion of water and sanitation services in the goals on health, education and gender.
Building and improving water and sanitation infrastructure in communities and healthcare systems makes for healthier people and healthier economies - and gives a real opportunity to resist and manage the next pandemic.