Dakar/N'djamena — A measles outbreak that is spreading across sub-Saharan Africa is showing no sign of let-up as vaccine campaigners struggle to reach all at-risk children.
Some 34,105 cases have been reported since the beginning of 2014 across Chad, Benin, Cameroon, Guinea, Nigeria, the Democratic Republic of Congo (DRC) and CAR, with 12,108 of them in DRC, 8,221 in Nigeria and 4,968 in Guinea.
Cases in Chad have risen since January 2014, with 7,105 registered as of 5th May, and nine reported deaths, according to the Ministry of Health. NGO Médecins Sans Frontières (MSF) says 70 percent of reported cases are of children under age five.
Measles is a highly contagious disease spread by human to human contact. "The biggest challenge is to stop the spread of this epidemic," said Seco Gérard with MSF in Brussels.
One of the reasons the outbreak has been so hard to stem is that Chad has weak vaccination coverage across the country, with large coverage disparities between health districts.
Health infrastructure is also weak, and children are more susceptible to falling sick due to high rates of chronic malnutrition in some parts.
Most reported cases in Chad - 3,750 by the end of April - have been in the four health districts covering N'djamena and its outskirts. Some 33 of the country's 77 health districts have reported cases thus far.
The Chadian authorities have mounted a response but have not yet declared an epidemic - only once they do so can international organizations significantly step up efforts to curb it, they say.
The government has, however, been working with international organizations such as MSF and the UN Children's Fund (UNICEF) to roll out vaccine campaigns.
A campaign targeting children aged 6-60 months was organized across 15 at-risk health districts in February, said MSF's Roger Kiamvu in N'djamena. In total some 780,709 children aged six months to nine years old, were vaccinated.
MSF has also treated thousands of cases, including across seven health centres and two hospitals in the capital between February and April.
Recently some 97,000 returnees and refugees have crossed into southern Chad from the Central African Republic, fleeing violence. Health workers fear that measles cases may escalate in the crowded camps.
Vaccination campaigns were rolled out in camps but even they did not reach all children: In Doyaba camp near Sarh, and Bitoye camp in the southwest, for instance, just two-thirds of the children aged between six and 15, had been vaccinated, according to UNICEF.
But a few weeks after the roll-out of the campaign in several districts, including the camps , "more cases are being reported," said Gérard.
This is because district by district, too many children are falling through the cracks and not being vaccinated. Logistical constraints, poor roads, remote communities cut off from health centres, and other factors play into this, as does the unreliability of census data on the number of children in each district.
In other cases health workers have "missed opportunities" to reach children when they visit health centres for other reasons, said Gerard, due to exhausted vaccine supplies, cold chain mismanagement or a lack of trained personnel.
Because population growth is not factored into census data, vaccinators "can easily believe everyone has been vaccinated when in reality, one or more groups of children have been missed," said Marie-Thérèse Guigui, focal point for measles in UNICEF's West Africa office in Dakar.
If even one cluster of children is not vaccinated, the conditions are there for the epidemic to continue, she said.
Measles vaccine coverage of under-fives was 73 percent across Africa in 2012, estimated WHO, while 95 percent coverage is necessary to stem future epidemics.
To reach every child in a district, UNICEF has to work with community volunteers, but even so, more nurses who can vaccinate children are needed, as are more transport facilities and better equipment to maintain the vaccine cold chain.
Vaccinations must be kept between 2 and 8 degrees Centigrade to maintain their potency.
Vaccination is the entry point to take charge of children's wider health problems, said Guigui. "It's through these campaigns that we can also pass on health, hygiene and nutrition messages to mothers," she said. "It's pointless to vaccinate a child against measles if the child will just develop malnutrition in the near future."
UNICEF plans to run additional measles vaccination campaigns in June and October 2014, targeting 4.3 million children between six months and nine years old, representing 37.9 percent of the Chadian population.
[This report does not necessarily reflect the views of the United Nations.]