Despite the Huruma tragedy which cost tens of human lives, we have been spared the annual ‘serikali saidia cycle’ which follows rains and raging floods in Nyando and Budalang’i, one of the things we should perhaps thank the Kibaki presidency for.
But having said that, it is prudent that we expect outbreaks of diarrhoea with predictably no drugs at the health centres. Almost one a third of rural Kenya will become ‘landlocked’ as floods render cattle tracks impassable and smash rickety bridges downstream. Lost in the minds of many, however, will be the multiplication of a small creature, only 12.5mm in length that is holding the world at ransom. The mosquito.
Mosquitoes are responsible for more human mortality around the world than any other living creature. These insects transmit a myriad of diseases – including viral infections like Dengue fever, Yellow fever and encephalitis, Zika virus (the new kid on the block), protozoans like Malaria as well as worms like filariasis and dog heartworm among others. Of these diseases, malaria is a household name. The fact that these diseases share same symptoms like fever, vomiting and joint pain means more emphasis should be put in their diagnosis to avoid misdiagnosis.
But if there is anyone is a having a ball with the arrival of the rains, it is the mosquito. The noisy little blighters will have safe havens near us, everywhere. All the mosquito requires is a stagnant pool of water for it to breed. If you thought that a stagnant pool is only a swamp, think again. Have you ever asked yourself where that polythene bag goes after you throw it away with the Sukuma wiki water? Or where that tin goes after you have applied your apricot jam on your bread? Well, they form small water collection points which the mosquitoes are now happily calling home. That is not all, the wastes that we throw away nonchalantly block the drainage and form nice little ponds of stagnant water which are a constant source of transmission of diseases.
Malaria facts from the WHO are heart wrenching. Reports show that Approximately 3.2 billion people are at risk of malaria and as at 2015, there were an estimated 214 million malaria cases and some 438 000 malaria deaths. In Kenya, 25 million people are at risk of malaria infection with the disease accounting for 30-50 per cent of all outpatient attendance and two out of every ten admissions to health facilities is from malaria. The most vulnerable are young children under five years, pregnant women and non-immune travellers from malaria-free areas. By the way, that means a tourist would rather see a Lion in South Africa than come and get infected with Malaria at a Kenyan national park.
The latest wave of global panic is from the Zika virus spread by Aedes mosquito. Zika has been around since 1947 when it was first discovered and named after the Zika forest in Uganda but shot to fame in 2015. The virus is currently circulating in 33 countries in the Americas while South Africa reported the first case from Africa, the continent where it was first described.
Although microcephaly, a congenital condition associated with incomplete brain development manifested by smallness of the head, appears to be the whole mark of the disease, Zika virus may have far reaching effects. Ultrasound images have shown abnormalities in amniotic fluid volume or blood flow in pregnant women infected with the virus and some babies are born with lesions in their retina. However, due to fewer studies that have been done in a well-controlled manner these findings are still being treated as circumstantial.
The real monster, however, remains malaria mosquitoes. Anopheles species feed on rabbits, cattle, horses and dogs and will aggressively bite humans as well. Female Anopheles mosquitoes pick up the parasite from infected people when they bite to obtain blood meal and the parasites develop and reproduce inside the mosquito. During the next meal, the parasites mix with mosquito saliva and pass into the blood of victim.
Lymphatic filariasis is transmitted by different types of mosquitoes like the Culex, Aedes and Anopheles mosquitoes. When a mosquito with infective stage larvae bites a person, the parasites are deposited on the person’s skin from where they enter the body resulting into swelling of feet commonly called elephantiasis.
The yellow fever mosquito, Aedes spp, transmits viruses that cause yellow fever, dengue fever. Dengue is caused by a complex of viruses transmitted between humans by Aedes aegypti. The disease has three forms. Dengue fever which is characterized by a high fever, severe joint pain, vomiting and a rash. Dengue hemorrhagic fever and/or dengue shock syndrome are much more serious forms of the disease that occur in people that have had dengue previously.
To mount such a scare as the mosquitoes have done requires a good strategy, like how the mosquito chooses its blood meal. It is not random that anybody gets bitten by a mosquito. The mosquito relies on its odour ques to locate its target and so woe unto you if the chemicals you apply makes you smell delicious to the mosquito in your vicinity.
The use of DDT (dichloro-diphenyl-trichloroethane) to control mosquitoes has remained controversial because of its residual effect to the environment. Although some countries allow the use DDT, recent findings that it affects semen quality and parameters in men as well urogenital malfunctions in new-born boys from South Africa and Mexico does not inspire confidence in its continued use.
—The writer is a PhD student at the Kwa-Zulu Natal Research Institute for Tuberculosis