Officials are now using that case to demonstrate the importance of vaccinating every migrant child from the war-torn Somalia.
In June 2021, as Kenya was slowly recovering from the
Covid-19 pandemic, a 17-month-old girl and her mother crossed the border from
Somalia to visit a relative in Dagahaley camp in Garissa County. The child was
already sick. Her right arm and both legs could no longer move when she arrived in the
camp on June 21.
Now, medics have concluded this girl triggered the 2021
polio outbreak that forced Kenya to vaccinate more than three million children
across 13 counties. They concluded a detailed social and
epidemiological investigation in the Dagahaley camp.
A Community Health Promoter who saw the paralysed child the
next day after her arrival said they suspected acute flaccid paralysis, a key
symptom of polio.
Kenya reported its last case of indigenous wild poliovirus
(WPV) in 1984, but has suffered from outbreaks of circulating vaccine-derived
poliovirus type 2 (cVDPV2) since 2018. Garissa County, which borders Somalia,
has suffered several cVDPV2 outbreaks due to the influx of refugees with low
population immunity.
Health workers collected two stool samples from the girl and
sent them to the Kenya Medical Research Institute (Kemri) laboratory. The
results were clear: “Our investigation found that the unvaccinated child caused
the cVDPV2 outbreak,” Ministry of Health officials have said in a new report,
published in the Journal of Interventional Epidemiology and Public Health.
“The confirmed case
was genetically linked to an environmental sample picked from Garissa County
and had been in circulation for seven years.”
If a child has polio caused by cVDPV2, the poliovirus
multiplies in the intestines and is shed in their stool. So she can spread the
virus through her stool to others who ingest the virus accidentally through
contaminated food, water, or dirty hands.
Officials are now using that case to demonstrate the
importance of vaccinating every migrant child from the war-torn Somalia.
Freshia Waithaka of the Moh’s Disease Surveillance and
Response Unit, and her colleagues, said that a single case met the World Health
Organization definition of an outbreak.
A joint team of epidemiologists, sociologists and
surveillance officers was dispatched in November to Dadaab Sub-County. They
interviewed caregivers, reviewed health facilities, and assessed conditions in
the refugee camp and surrounding host communities.
“Polio is an oral-faecal disease; therefore, open defecation
cannot be separated from the perennial polio outbreaks,” Waithaka and her
colleagues say in the report.
It is titled, Social investigation report of cVDPV2 outbreak
in Dagahaley Refugee Camp, Dadaab Sub-County, Garissa County, Kenya, November
2021.
This girl, just like most arrivals from Somalia, had never
been vaccinated against polio. “Fifty-one under-five children had arrived from
August through October 2021, of which the majority, 49/51 (96.1 per cent) children
had not received first dose of oral polio vaccine, while none of the children
had received the inactivated poliovirus vaccine,” an injectable vaccine that
uses killed (inactivated) poliovirus strains.
“The main concern is the high numbers of vulnerable
populations who serve as a breeding ground for disease outbreaks and reservoirs
for disease vectors,” officials said in their report.
Poor sanitation in the camp added to the risks. At least
11.5 per cent of households had no sanitation facilities and practised open
defecation, creating conditions for the virus to spread through contaminated
water and food, the investigators reported,
The importation of an
unvaccinated child during this period highlighted the risks Kenya faces from
neighbouring regions with low immunisation coverage.
“The main concern is the high numbers of vulnerable
populations who serve as a breeding ground for disease outbreaks and reservoirs
for disease vectors,” the researchers said.
They urged stronger cooperation across borders and expanded
routine immunisation. “We recommended strengthening polio cross-border
surveillance systems by utilising the existing structures and ensuring high
vaccination coverage.”
They also called for
more community sensitisation and research into how to improve surveillance at
the Kenya-Somalia border.
Their report warns
that “this importation poses a significant threat to the Global Polio
Eradication Initiative’s goal two: to stop cVDPV2 transmission and prevent
outbreaks in non-endemic countries, of which Kenya is one.”
The 2021 outbreak was eventually contained through a
nationwide vaccination campaign that reached three million children.