2.1.3 Other ways of malaria transmission
Malaria can, however, be transmitted in other ways by design or accident, or by the inoculation of blood from an infected person to a healthy person (Abdul-Raheem and Parakoy, 2009). In this way the asexual blood forms continued to develop in their own periodicities in the peripheral blood producing attacks of fever in the recipients, but pre-erythrocytic schizonts are not formed in the liver because these forms originate only from sporozoites inoculated by mosquitoes (Arora and Arora, 2005). There are three chief means by which such transmission is effected:
(1) Therapeutic inoculation – malaria and other species have been used.
(2) Transfusion malaria– transfusion malaria is particularly common in countries where blood donation is a commercial transaction and where blood donors come from the less affluent classes who may reside in endemic malarious areas, or who may have left them (Heussier, 2006). Most acute or chronic infection occurs when the blood has been stored for less than five days and infections with blood stored for two weeks or more is exceptional (Arora and Arora, 2005; Ibeanu et al., 2012). The symptoms of accidental acute or chronic infection with P. falciparum develop within 10 days, (Arora and Arora, 2005). Syringe transmitted malaria – unintentional infection is common in drug addicts who share syringes and needles and some cases of P. falciparumd chronic infection with deaths have been recorded (Greenwood et al., 2005). Apart from transmission through inoculation, intrauterine transmission of acute infection from mother to child is well established (WHO, 2006). The placenta is normally an effective barrier but congenital infection can occur without demonstrable damage to the placenta before delivery (Arora and Arora, 2005). Tran placental infection is far commoner in non-immune mothers than among indigenous populations for the reason that passive immunity is transferred across the placenta to the infant who remain free of infection for some six months (Abdul-Raheem and Parakoy, 2009).
2.1.4 Pathogenesis of malaria
As the malaria parasites enter the blood stream they infect and destroy red blood cells (WHO, 2000). Destruction of these essential cells leads to fever and flu-like symptoms such as chills, headache, muscle aches, tiredness, nausea, vomiting and diarrhoea (WHO, 2006). The symptoms of uncomplicated malaria are non-specific and include fever. Malaria is considered uncomplicated when symptoms are present but there are no clinical or laboratory signs to indicate severity or vital organ dysfunction (Ilozumba and Uzozie, 2009). Severe malaria is caused mostly by P. falciparum and if not promptly treated can present with the following symptoms: coma, severe breathing difficulties, low blood sugar and low blood haemoglobin (severe anaemia). Children are particularly vulnerable since they have little or no immunity to the parasite (WHO, 2000).
However; children who have malaria display some early symptoms of infection such as drowsiness, irritability, loss of appetite and difficulty in sleeping. These are generally considered to be the initial warning signs that a child has malaria (Ikekpeazu et al., 2010). This is followed by chills which often develop into fever characterized by extremely fast breathing. When the fever subsides, the temperature of the body very rapidly returns to normal and the child experiences an extreme period of sweating (Cheesbrough, 2006). There has been wide variation in symptoms and presentation of cases of malaria, depending on immune status and age group (Jayant and Mani, 2010). Deaths from malaria in Africa are higher among children under the age of 5 years from the severe and complicated form of the disease (WHO, 2008).
However, children under 6 months of age are believed to be relatively immune to the disease (WHO, 2006). In malaria endemic regions of Africa, life threatening malaria due principally to P. falciparum occurs mostly during the latter part of life when the disease usually presents as severe anaemia, congenital malaria is infrequent and very young infants are reported to suffer only mild symptoms when they are infected (WHO, 2006). Clinical attacks are said to be rare in the first months of life and severe attacks are believed to more likely develop between the ages of 6 months and 2 years (Ilozumba and Uzozie, 2009). It is so in this age group because the parasite counts are generally low and high antibody titres that have crossed the placenta from the mother clear the parasites usually within one week (Ilozumba and Uzozie, 2009). Foetal haemoglobin in baby’s red blood cells and the malaria antibodies from the mother together protect the young infant from malaria during the first 6 months of life, the frequency of parasitaemia nevertheless increases with age (Ikekpeazu et al., 2010).
In the later age group various manifestations of paediatric malaria is known as prodromal symptoms. In non immune children, the primary attack can vary widely (Ikekpeazu et al., 2010). Also Jayant and Mani (2010) reported that the prodromal symptoms in Indian children includes non specific conditions like generalized weakness, headache, fatigue, abdominal discomfort and muscle ache, loss of appetite, nausea, vomiting followed by fever. Infants in endemic areas have some immunity to malaria, some symptoms of malaria are often more insidious and they include anaemia, restlessness, loss of appetite, easy fatigue, sweating and intermittent fever (Jayant and Mani, 2010). The classical presentation of malaria consists of paroxysms of chills and rigor (15 min – 1hr) followed by hot state (1 – 8hr) and then there is sweating stage (fever comes down with profuse sweating) (Jayant and Mani, 2010).
An irregular fever with respiratory or gastro intestinal symptoms may mark the presence of malaria. Rougemont et al. (2005) confirmed that during the rainy, high transmission season in Republic of Niger, there was high significant relation (p<0.0001) between the likelihood of fever and the parasite count. In Nigeria, it was reported that the diagnosis of malaria in most cases is made on clinical grounds based on the presence of fever without localizing signs which can be confirmed by finding asexual forms of the malaria parasite in the peripheral thin and thick blood films (Ikekpeazu et al., 2010). Symptoms associated with febrile paroxysm include rigor, sweating and headache as well as myalgia, backache, abdominal pain, nausea, vomiting, diarrhoea and pallor (Cheesbrough, 2006). On examination, hepatosplenomegaly was also found. However, malaria may involve every organ hence symptoms can vary accordingly (Strickland, 1988; Jayant and Mani, 2010).
2.1.5 Malaria parasitological diagnosis
The changing epidemiology of malaria and the introduction of ACTs have increased the urgency of improving the specificity of malaria diagnosis. Parasitological diagnosis has the following advantages:
_ Improve care in parasite-positive patient
_ Identification of parasite-negative patient
_ Prevention of unnecessary use of anti-malaria
_ Improve malaria case detection and reporting
_ Confirmation of treatment failures
