He takes it all in – the birthday streamers and unicorn backpacks, the sausages in bread and people singing about how the wipers on the bus go swish, swish, swish.

"Ba-lloon!" he cries. "Par-tee! Cheese! Yeeaahhh!"

Jacob turns 22 today. He has been coming to this attraction in Doveton from his home in Cranbourne since he was an infant. It is perhaps his favourite place in the world.

"They kind of know us here," says his mother, Helen, buying a bag of pita bread at the gate, the beginning of their Myuna Farm routine.

Before visiting the goats, camels and cows – and his favourite, the mammoth muddy pigs – she sends her severely autistic adult son to the toilet.

"Were you good?" she asks. "Did you go?"

He nods.

"Jake?" she repeats. "Are you sure?"

He nods again.

The mother smiles and so does the son, and the two of them lean in toward one another until their foreheads touch and their eyes meet. They hold head-to-head contact for a long moment.

"How clever are you?" she coos at her boy. "How clever are you?"

He flaps his arms furiously at this, as if trying but struggling to take flight, like a farm bird. People stare at the vigour and sustained force of his non-verbal tic. But he just smiles and goes on his merry way, breaking the flat bread into chunks and flinging them at the animals.

Jacob rarely watches to see where the pieces fall. He is interested but also not. His fluctuating facial expressions reflect a pragmatic personality. In an instant, wonder can turn to blankness – a full-faced smile falls away leaving a flat and unreadable visage.

Helen warns a photographer to get pictures quickly and early. You never know how Jacob will react to a place or person. Alarm can easily turn to anger. Today, he gives the photographer a hug. Twice.

He will be like this all afternoon and evening, unpredictable throughout his birthday party with pizza and cake, until he goes to sleep tonight in his own bed – assuming he can get to sleep in the room down the hall from his mother.

It is the first time in 18 months he will bunk there, since it happened, since an episode made it clear to Helen that she could no longer care for him. Since Jacob was relinquished into state care.

Helen Elzinga didn't know Jacob "was the way he was" until he was 15 months old. He was a beautiful baby, but…

"He wasn't walking, he wasn't crawling, talking, nothing," she says. "I started looking into it, this doctor, that doctor, paediatricians."

His autism became clearer as he grew, as she embarked on early intervention therapy programs. He made few gains, and his tantrums turned wilder, and she wondered what she had done to deserve this – was his condition her fault?

"You have all these dreams, that your child will play footy, go to uni, do normal stuff, get a job, have grandkids. None of that – I get none of that. It's hard. But someone said to me many years ago, 'You're given a child like this for a reason.' Don't ask me what the reason is: maybe it's because I'm strong, I can deal with it, I can cope with him? Patience maybe?"

She needs patience, or a certain stoicism at least.

Her marriage ended when Jacob was nine, around the time the family business – colour photocopying and laminating – went bust. It was the same few years in which both her mother and father died.

For more than a decade now it has been just her and her Jake, out in the world together, visiting Melbourne Zoo, the beach at Phillip Island, Gumbaya Park in Tynong.

Jacob loves trains, so a day trip could be as simple as riding the rails into Flinders Street, then a few loops on the City Circle tram.

Excursions to shopping centres were an adventure, except those times when Jacob would push or hit a smaller child, or start screaming for no reason. Or take his clothes off without warning.

He still opens the door inside moving cars, and has needed a special harness since the day he got out and sat down in the middle of the Nepean Highway.

He started going through puberty at 10, so Helen had to explain why his body was changing and why he shouldn't pull his new hairs out one by one. At 15 he began suffering from priapism, an erection that would not subside. He needed a handful of serious operations over five years, meaning long stays in hospital and longer conversations about why they needed to "fix his willy".

Helen has worked "bitsa" jobs as a receptionist and library technician. She has lived on Centrelink payments in the past, but more recently spent time working in aged care facilities. She has a job as a carer of adults, in order to pay for a carer for her child.

The help she needed most as a mother was respite – a chance for Jacob to spend a weekend away with professionals, while she recharged physically and emotionally. But access to respite is notoriously difficult to pin down, and getting worse.

Helen found she was lucky to get one weekend of freedom every three months. And when she got it, she spent the hours catching up on cleaning, or sitting at McDonalds on a Tuesday morning, sipping a coffee.

"It was nice, and I could sleep in, but I was also lost and depressed," she says. "I would get in the car, go to the shops and walk around, roaming like a little lost soul."

The Department of Human Services does not track or record the number of adults relinquished in a given year, but experts suggest there is an acute shortage of respite beds, as well as permanent accommodation for high-needs individuals.

The shortfall in both begets a nasty cycle. The lack of beds in permanent homes means more people are using respite for long-term stays. Advocates have found cases of people living in respite for years at a time, as well as respite facilities where every single bed is occupied by a disabled person who has been relinquished.

That means fewer people can access respite for its intended short-term use. This in turn strains the sanity and safety of those families, and leads to more relinquishments.

The state government claims to have invested heavily in respite, but experts suggest growth has been modest at best, and will also be nowhere near enough to accommodate an expected wave of disabled Baby Boomers currently being cared for by their elderly parents.

"The demand far outweighs the resources devoted to this problem," says Trevor Carroll of Disability Justice Advocacy. "It's obviously not seen as a priority."

Indeed, recent reports from the Office of the Public Advocate and the Victorian Equal Opportunity and Human Rights Commission make for moments of grim reading.

A father leaving his child at school, and phoning the principal to say the family simply can't cope anymore.

A mother in her eighties breaking down and leaving her middle-aged son at the Austin Hospital emergency room, with a suitcase and a note.

Colleen Pearce, head of the Office of the Public Advocate, says she now steers people away from even using the term "relinquishment", as it implies families are giving up.

"What people are asking for is help – this is a cry for help," she says. "These are people who have loved and cared for their child for a long time, but they have a complex and challenging role and are often driven to this decision out of a sense of desperation."

Australia Day weekend in 2013 was the last desperate night Jacob spent at home. He wanted to see something on the computer, but couldn't explain what.

"Wait," said Helen, "Mummy will do it for you."

Then Jacob snapped, and starting slapping at her face and body. Helen tried to wrap him in a big bear hug – the kind that settles him – but he broke free and kicked her.

"I just burst into tears," she says. "I gave him some medication. Called the neighbours, who came over to help."

Jacob could not calm down. He started ripping pictures off walls, bashing anything in his path. "He trashed the house," she says.

An ambulance was called for Helen, and the police were called for Jacob, who was driven away in tears to a respite centre.

For two months he bounced between facilities, waiting for a permanent place somewhere. Helen visited him every Thursday morning for a 30-minute session with a carer.

He eventually moved into a home in East Brighton with four men in their 30s, where he is the baby. It does not seem an ideal setting to Helen, but there is no other option.

Jacob occasionally hits out at staff. He still bites his hand until it bleeds, and he recently threw another resident out of a wheelchair.

He took off running one day and was hit by a car, taken to the Alfred Hospital with some bad cuts and grazes, and emerged with a broken foot inside a moon boot.

"I couldn't take him home," Helen said, crying. "That was really hard. He was confined to his house for six weeks, too. That did his poor little head in."

Helen is Jacob's administrator, and has regular meetings with his carers and counsellors and assessors so that she can have some input into how his life is run.

She has also been in a relationship for a year now with a man who is supportive of her and loves Jacob. One month ago they began taking him on Sunday outings.

At first the break in routine was too much. When they left, Jacob would bash his head against the walls, or throw a computer through a window.

"It's not easy. He's my life. I want to see him more," Helen says. "But you've gotta grin, you've gotta bear it, gotta take a step back sometimes."

She came up with a system of flash cards with pictures, to prepare Jacob for what will happen during each Sunday visit. She arrives at the same time, shaves his face, then they head to Elwood and look at the water. They might have Mr Whippy. And the goodbyes are short and sweet.

The trips have stretched from a 30-minute ice cream, to an hour over lunch, to three hours on the dodgem cars at 234 Fun Galore in Braybrook – and now a full afternoon and overnight stay.

She is his advocate – his fiercest ally – but in those quieter moments she does wonder if she could have him at home again, and the guilt comes flooding back.

"I absolutely hate it. I hate it. But it has to be out of my hands. I've just got to get on with my life, do the best I can, and give him every opportunity."

He is becoming more independent. He loads the dishwasher and sweeps the floor. He is talking more, and can put on a shirt without poking his head through the arm hole.

"He can make his own Milo," she says. "Those are little things – but they're big. He's getting there. It's happening. He's happy."

He certainly is now, back at Myuna Farm, as he charges with glee into the thick of someone else's outdoor birthday party, entranced by a bucket of soft drinks on ice.

Helen redirects him with ease, steering him into a quiet barn stall with two bleating lambs. Jacob sits down and strokes them softly, and Helen strokes him.

The tractor ride is the highlight of his day, bouncing down a dirt track along a winding creek, past paddocks of ponies and Clydesdales.

A bend in the river is home to honking geese and ducks, where the last of the pita bread chunks are flung up into the sunshine, and the tractor turns around.

An entire carriage of kids squeals goodbye to the ducks. Jacob yells goodbye, too. And so does Helen. They both wave, knowing they will see them again soon.

Konrad Marshall is a senior writer at The Age

konrad.marshall@fairfaxmedia.com.au

@KonradMarshall