Alarm over chikungunya outbreak

A cross-border public health approach is being considered to stem further spread of chikungunya disease in Mandera County. The outbreak has so far affected more than 500 residents.

Health Principal Secretary Nicholas Muraguri said it was prudent to involve Somalia and Ethiopia to curb further spread of the mosquito-borne disease. “Somalia recently experienced chikungunya outbreak especially in areas bordering Kenya. It is thus important to coordinate our efforts,” says Dr Muraguri, adding that prompt response is critical because Mandera is currently experiencing a twin outbreak of cholera and chikungunya.

“The proximity of mosquito breeding sites to human habitation is a significant risk factor for chikungunya, especially after heavy rains,” he says. Laboratory tests at the Kenya Medical Research Institute (Kemri) first confirmed chikungunya on May 16 after the initial 10 samples collected in Mandera County, all tested positive.

Kemri is currently undertaking a research on distribution of this infection, with preliminary results showing that chikungunya virus is circulating in low frequency along the coastline and parts of western Kenya.

Centre for Virus Research Acting Director at Kemri Rosemary Sang attributes increased cases of chikungunya outbreak in the area to the virulent nature of the virus.

It multiplies in areas with high temperatures and has a unique biting habit - mosquitoes bite mostly during daytime, with peaks of activity in the early morning and late afternoon. “It is a ferocious virus that belongs to the alphavirus genus of the family Togaviridae that replicates fast especially in warm weather, thus sustaining an outbreak,” says Dr Sang, who is also a virus specialist and chief researcher at Kemri.

The last chikungunya outbreak in Kenya was in 2004 and 2005 in Lamu, Mombasa and Kilifi, though most of the outbreaks have occurred in Africa, Asia and Europe, causing more than three million infections worldwide.

Dr Sang notes that the disease is caused by the Aedes species of the mosquito and is originally thought to have come from Tanzania in 1952.

The name chikungunya is derived from a word in the Kimakonde language of Tanzania, meaning “to become contorted”, and describes the stooped appearance of sufferers with joint pain, which is a characteristic symptom of the disease. Other symptoms include fever, severe joint pain and muscle pain, headache, nausea, fatigue and rash.

Health experts are yet to understand why the disease aggressively affects the joints, though a premise has been put forward that this way, it evades the immune system. According to the US Centre for Disease control, the chikungunya virus is rarely transmitted from a mother to her newborn around the time of birth and to date; no infants have been found to be infected with the virus through breastfeeding. Primarily, Dr Sang observes that the proximity of man to mosquitoes that prefer breeding in water containers (especially in areas with water shortage) is one of the factors that trigger the disease.

“The chikungunya virus is a ‘container-breeder’ because it thrives in areas that lack water, forcing residents to store water in their households, creating a conducive breeding ground. After the bite of an infected mosquito, onset of illness occurs usually between four and eight days, but can range from two to 12 days,” she adds. Whereas the disease shares the same signs with dengue fever, Dr Sang notes that the most characteristic symptoms in patients infected with chikungunya are severe and debilitating joint pains.

Annually, mosquito-borne related diseases are responsible for one million deaths worldwide. According to Dr Sang, supportive therapy is advised for infected persons, where treatment is given to relieve pain and fever. The patient is also advised to take enough rest and consume frequent fluids.

Kemri Head of Climate and Human Health Research Unit at Centre for Global Health Research Andrew Githeko says higher temperatures due to climate change increase the incidence of chikungunya and other diseases like cholera, malaria and dengue. “The great majority of illnesses are caused by infectious diseases, which in many cases are climate sensitive, thus increasing the risk of infectious diseases and epidemics associated with these diseases,” notes Dr Githeko.

Climate change may facilitate emergence and re-emergence of new and old infections, Dr Githeko notes, adding that the risks are higher when the transmission range expands in areas where human populations have low immunity and where the public health sector is unprepared to prevent and even treat the disease.

And as climatologists predict a 1.4°C to 5.8°C rise in mean temperatures over the next decade, Dr Githeko advises that with expertise on predictive weather patterns, being forewarned will shield Kenya from adverse effects of public health outbreaks.