Introduction: malaria
Malaria is a mosquito borne human infectious disease that is caused by an eukaryotic protest of the genes plasmodium. The disease is highly wide spread I the tropical and subtropical regions of the world especially the sub-Saharan Africa, asia and the Americas.
The high prevalence in those areas is accounted for by the significance amounts of rainfall which comes accompanied by high temparectures, warm and prevalently high temparatures of humidity in addition to large and wide spread body masses of stagnant waters in which the mosquitoe lervea grow and mature thus providing them with the conducive environment that they need for breeding.
the disease is caused by plasmodium. A protozoa that was discovered in 1800 by Charles alphonse laverran while working in Constantine , Algeria. He observed the parasite in a blood smear taken from a patient who had just died of malaria. The disease occurs due to the multiplication of the malaria parasite within the red blood cells which raptures them leading to symptoms that typically consist of fever, headache and in severe cases develops in to coma and even death.
The malaria causing parasite/ plasmodia has five identified species namely, plasmodium vivax, P. falcirum, P. ovale, P. malariae, and P. knowlesi. All of which are transmitted by the female anopheles mosquitoes and has an incubation period of 48 hours after which it can lead to fatal complicatyions if noit diagonised and treated immediately.since the turn of the century, malaria has cintunued to be the number one infectious killer as well as the first priority tropical disease of the W. H. O known as millennia malaria
According to the world malaria report, malaria is prevalent in 108 countries of the tropical and semitropical world predominantly Africa the amazon, central and south America, pacific and the SE asia all which if combuned are the home to half of the world’s population. In most of the areas, malaria is aperenial problem and isreported to cause between 250- 260 million infections wlith more than a million deaths mostly among the African children.
Currently, malaria generated manace over the wolrd population is overwhelming to the WHO so the goals set by the WHO assembly and the roll back malaria partinership to reduce the number of malaria deaths and cases recorded in the year 2000 by 50% or more by the year 2015 and by 75% by the year 2035 have not been realized. Instead, over the p[ats 35 years, the disease incidence has increasesd 2- 3 fold with the surge looking to continue due to new emerging factors such as weakening of public health system especially in developing countries, continued poverty, political instability, drug resistance parasites, insedticede resistant mosquitoes, global warming and climate change, increased population movement in to malaria prone regions, changing, agricultural practices such as wide spread construction od dams and irrigation schemes which provide more breeding grounds as well as deforestation.
Notably, in most of those areas, the disease coexists with poverty and it has been established that the evarage GDP in malaria prone countries is only about a filfth compared to non malaria countries which probably erodes the population’s ability to finance conyrl and prevention measures. The disease also has a huge financial burden once it sets in and it is estimated that it costs up to $i.2billion in Africa annually. However, the global spending on it is overly meager with only $652 million being desdursed in 2007, $1.7 billion commited in 2009 in comparison to HIV/AIDS which in 2008 accounted for 33.4 million cases, 2 million deaths but got a total of $13.7billion in the continent.
Disease ecology
The disease has three ibntegral life cycles. The malaria causing parasitethough in very rare cases it can alsobe transimmited fron one person to another without passing through the parasite like mother to child in contigenital malaria or through transfusion, organ transplant or shared needles. The second aspect is anopheles mosquito which in contact with completes the invertebrate host which forms half of their life cycle. Thirdly, the presence of humans who are in contact with anopheles mosquitoes and in whom the parasite completes the vertebrate host which forms the other half of their life cycle.
In addition, climate also plays a role in determining the geographical distribution and seasinality of the diusease. For instance, rainfall leads to collection water which forms deerding grounds on which eggs develop in to larvae, pupae and adult in a 9- 12 day cycle in tropical areas. This however can be disrupted by premature drying up or absence of further rainfall while conversely, excessive rain can flush and destroy them.
On maturity, climate also determines the ambient temperature, hu,idity and rain which determinre ther survival chances of the parasite since to transimit the disease, it must survive long enough after they have been ibfected to complete their growth ncycle called extrinsic cycle which takes between 9- 12 days at 15’c, 59’F for the plasmodium vivax, 20’c, 60’F for P. falciruum which if not completed malaria cannot be transmitted.
Climate also determines human behavior which may increase contact with anopheles. For instance, hot weather enecourages people to sleep outdoor or not to use nets while during jarvest, people may sleep in the fieldswithout protection.
In relation to the anopheles mosquito, not all of themare vectors. Biologically, some species cannot transmit while others are readily infected and able to produce large numbers of parasite stage infective to humans. Different moasquitoes also heve different behavior traits which imacts on their abilirty as malaria vectors. Some feed off human and others animals. Some bite indoors and others outdoor.as such those that bite indoors have more contact with humans hence are more effective malaria vectors. Again, some rest indoor afterfeeding thus c=are likely to come in to contact with lethal sprays getting killed in the process. Additionally some mosquitoes are biologically rasistanct to insectcidesmaking prevention methods of spray ineffective.
On the other hand, humans have doth indorn qand acqueried biological characteristics and behavior that influence the idividual’s malaria risk and ecology. Characteristics of the malaria parasites also influence the occurrence of malaria and its impact on human populations. So in areas that P. falciparam occers predominantly, opeple suffer more incidences and dealth than area predominated by other speciesas they tend tocausse more severe manifestation.
On the other hand, P. vivax and P. ovale hafve stages (hypnozoites) which remains dominant in the liver cells for long priods before reactivating and invasding the blood hence a lapse can cause resumption of transmission after a seaming successful treatment or can introduce malaria in ares that are malaria free.
In addition, P. falciparum and P. vivax have developed srterains that resist antimalaria drugs while others like the P. knowlesi inhibit animal resorvior like the macaques of SE Asia hence humans living in close proximity to such animals are at a higher risk of rthis zoonotic parasite.
The clinical epidemiology of malaria in Kenya
In Kenya, the disease is traditionally regarded as unstable and limited by the low tempareactures in the countries highlands. However, brief periods of warm weather in the areas may facilitate malaria transmition thus generating epidemic conditions among those immunoilogically naïve populations. This has been established by studies spanning two decades of inpatient malaria admission data from the health facilities in the notion of a canonical unstable transmission. During the study, the adult, child ration of malaria was employed as asample tool to assess the degree of functiuonal immunity from inpatient admission data at facilities with a range of malaria endemicities in kanya. The research found the area to axhibit malarias thart can be described as seasonal or meso- endemic.
Malaria, symptomns, proximate,evolutionary causes and treatment
According to Darwin, living things mutate without reason and in some xcases random mutations helps organisms to suevive their environment , reproduce and spread their genes. In relation to humans, constantly prone to malaria, consistent exposure has overtime developed resistance through mutations, malaria infiltrates the human body and the human body naturally acquires resistance to the infiltration.
Sympotoms
Malaria is a parasitic disease whose msjor sympots include fever, chills and anaemia which are the top three major identifying symptoms. Others include nausea, vomiting, jaundice, coma,headache, muscle pain, blood stained stool and convulsions.
Proximate causes
Malaria can be spread in three stages. The first being the entry of malaria causing parasite in to a vector when a mosquito bite a human whose blood is infected witht the malaria causing parasite. The parasite enters the insects body and reproduces in its stomach before the new protozoan make their way to its saliva.
In the second stage, the plasmodia exits the vector once the mosquito bites a new host by moving from the mosquito salivqa in to the new host’s blood from where it makes its way t6o the new host’s liver and reproduces a new groupo of parasites after a few days, then bursts to release new plasmodia making the completion of stage two.
Finally, in the thoird stage, the parasite reproduces in the host.after bursting in the previous stage, each individual plasmodium invades a red blood cell and multiplies again. Eventually, the RBC raptures relasing large numbers of plasmodia which invcades additional RDCV and tge process repeats itself.
Evoluitionally ncauses
The rapture of the RDC does not do the malaria parasite any good. In fact, the reason why it devides its reproduction in to gradual stages is to keep the host alive and health long enough for it to spread to another one through a new vector. The parasite has specialized proteins on its surface for sticking to the walls of the bllod vessels to avoid being wsept in to the spleen where it woild be destroyed. This enables it to remain undetected in the host organism. In human, some people especially in Africa, have homogeneous gene that causes their RBC to change form from its original spherical shape in to sickle shape . this makes them resistamt to malaria and as a consequence suffer from sickle anaemia.
Treatment
Malaria is diagnosed by idebtifying plasmodia in a sample if the patient’s blood upo9n which most cases can be treated and cured using choroquine and primaquine. However, some varieties of plasmodia such as falciparum are resistance to this treatment in which case, quinine, mefloquine or halofautine is administered.
Malaria prevention and contro approaches
Most malaria prevention and control approaches revolves around the elimination of human contact with the potential vectors the anopheles mosquito. Such measures unclude the elimination and draining of large pools of still waters, keeping screen doors shut as well as spraying areas known to harbor mosquitoes.
However, malaria has proved to be a difficult disease to control due to the high adaptive nature of the vector and the parasite involved. Hence, to achieve an effective control of malaria, healthcare professionals need to adopt a combination of new approaches and tools and reaseerch to develop anew strategy with a keen focus on special populations
The control and prevention of the disease has long been due owing to its significant impact on the health of infants, young children and pregnant women world over. So far antimalaria drugs in combination with other mosquito control programs have been used to a very large extend in the control and prevention of the disease. In addition, new and improved diagonistic measures have proved essential as early diagonisis and treatment is vital in both control and prevention of the disease.
Other measures like use of vector management tools such as insecticides, environmental modificastion and bed nets have successfully contributed to the contro and prevention of the disease. However, for a successful control and prevention of the disease, social cultural practices and social structural organization of a population plays an important role in relation to treatment, control and prevention of malaria.
This is because, such influence the underlying recognition and treatment of fevers both at the house hold and community lavel hence determining the pathways to treatment, care seeking, and adherence to treatment regimes, malaria prevention and control within the ambit of community participation, coorparation and the machanisms underlying behavioral change.
However, keeping malaria under control has largely been elusive duet o the emergence and spread of drug resistant parasitres leading to reemergence of malaria thus roling bacxk the success of contro efforts. In addition more breeding sites are being crterated by human manipulation of the environment such as opening up new lnads for agriculkture and settlement building dams for power generastion and irrigation, house structures , rubbish disposal, complexity of the parasite plasmodia due to mutation and adaptability laedint to resistant parasite, diagnostic confusion since malaria has common symptoms as many other oilntments occasioning severe manifestation before treatment, and lastly malaria being prevalent in the developing countries, majorirty of the affected populations are either illiterate or semiilliteratethus fail to follow treatment instructions fully causind=g development of new drug resistant strains.

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