Malaria

Introduction

The word malaria was coined to denote intermittent fever believed to be contracted by breathing bad air from the marshes (Latin- Mal = bad, aria = air).

Malaria is one of the oldest infestations known to mankind and has been referred to in ancient writings in Egypt, India & China. Many references to this deadly fever and herbal & magical cures for them are mentioned in the writings of Veda (1,500 - 800 B.C.) and Brahmana (800 B.C.- 100 A.D) periods. Charak and Shrushta have described tertian and quartan fever. One of the Veda postulates that malaria is carried by mosquitoes (Masaki). Though it was in 1894 that Manson in China put forward the theory that malaria is transmitted from person to person by a mosquito, Ronald Ross discovered the oocyte in the stomach wall of Anopheles mosquito in Secunderabad (in India) in 1897. Malaria is still a major health problem not only in India but also in many of the tropical countries where this disease still remains a major cause of morbidity and death, though it has been eradicated from the temperate zone. It affects over 103 endemic countries with a combined population of 2.5 billion people and causes 1-3 million deaths worldwide over every year. It threatens 2200 million people - about 40% of the world population.

India is rightly claimed to be the cradle of modern malaria. Though the earliest malarial control activity was initiated in 1901-1902 in Mianmiz, a cantonment near Lahore, the problem of malaria still persists. In 1935, Sinton and Chopra estimated that in the Indian subcontinent at least 100 million cases of malaria were occurring annually out of which nearly 1% die. In 1947, the incidence of malaria was 75 million annually with about 0.8 million deaths. Govt. of India launched National Malaria Control Programme in 1953 & achieved remarkable success and within 5 years the incidence of malaria dropped down to 2 million cases and achieved near eradication status, and by the early 1960s, these were only 1 lakh malaria cases and no death. However, there were focal outbreaks reported in many states, and the incidence of malaria started to rise again each year & a revised strategy Modified Plan Of Operation was launched in 1977. During the decade 1984-1994 malaria incidence stabilized to around 2 million cases annually. However, in 1994 with the emergence of a resistant strain of malaria, there was a sudden upsurge in malaria problems in many parts of the country including Rajasthan, Gujarat, and the North-Eastern States mainly Assam, Haryana, West-Bengal. The incidence of malaria in Mumbai has increased from 1000 to 2000 in 1980 to 25,000 to 50,000 per year between 1993-1996. Though the incidence of malaria in India has been stabilized around 2.5 million cases per year since 1990 (MHEP), the mortality rate due to the disease has steadily increased to 1,000 - 2,000 lives annually. However, the true number of both incidence and mortality may be anywhere between 5-10 times the official figures.

Presentation

There has been a wide variation in symptomatology and presentation of cases of malaria. Clinical presentation depends upon the immune state of the host and the degree of parasitemia. Children with no immunity tend to suffer serious manifestations while those with immunity have fewer symptoms in spite of heavy parasitemia. Malaria in children differs from that in adults in terms of varied manifestation and higher mortality especially under the age of 5 years. The incubation period varies from 7 days to 8 months .. Incubation period for Plasmodium vivax is 10-18 days, P.ovale and P.malariae 11-16 days, and P.falciparum 7-14 days. When malaria is induced by blood transfusion of parasitized blood, the incubation period varies from 10hours to 60 days.

Prodromal symptoms include generalized weakness, malaise, headache, body ache, loss of appetite, nausea, vomiting, and irregular fever. Fever is a cardinal symptom of malaria though it may be absent in congenital and neonatal malaria. Classically it is described as paroxysmal high fever with chills with varying intervals in between episodes. There are no typical characteristics of fever in children. P.falciparum often presents with continuous fever

Fever often has 3 stages:

• Cold stage:
  High-grade fever appearing suddenly with chills and followed by rigors lasting for 15 minutes to 1 hour. In spite of high fever, the patient feels cold and tries to cover himself with warm clothes and may be associated with headaches, dry skin, cyanosis. Convulsions may be seen particularly in children
• Hot stage:
  The patient feels hot and throws away the clothes he had put on in the previous stage, the face becomes flushed and eyes become red. This stage lasts for 1-8 hours.
• Sweating stage:
  Fever comes down on its own with profuse sweating and the patient feels better and comfortable. Other symptoms include pain in the abdomen, intense headache, nausea, vomiting, diarrhea, generalized body ache, urticaria, myalgia, and behavioral changes.

Every organ may be involved in malaria and hence symptoms are varied. Complications include Cerebral malaria associated with convulsion, altered consciousness, delirium, and deep coma and may be associated with deep jaundice, anemia, herpes labialis, uremia, etc. Respiratory symptoms like cold and cough are common and simulate viral infection. Therapeutic responses are evident in terms of control of respiratory symptoms. Other common systemic manifestations include jaundice, mimicking viral hepatitis. However, in viral hepatitis, fever rarely persists beyond few days and liver enzymes are markedly elevated whereas in malaria high fever is persistent with a mild increase in bilirubin (5-10 mg%) and SGPT (200-300 units/dl). Malaria may also present with hemolytic jaundice associated with severe anemia, increased reticulocyte count, and decreased platelet count. Other less common manifestations include renal dysfunction, diarrhea, hypoglycemia, acidosis, thrombocytopenia, and DIC. Thus malaria is a multisystemic disease with multi-organ involvement. Splenomegaly is not a pre-requisite for diagnosis as it is often absent in P.falciparum infection and also in the early stages of the disease. Firm, large spleen indicates repeated or chronic infection or tropical splenomegaly syndrome.

Neonatal malaria or congenital malaria may present with progressive pallor and hepatosplenomegaly without fever. The congenital infection manifests within 2-3 weeks after birth whereas acquired infection presents at 4-6 weeks. History of maternal infection and raised IgM antibodies favor the diagnosis of congenital infection. Acquired infections are much more common in highly endemic areas. The following table gives the difference between falciparum and non-falciparum malaria as well as various complications seen with complicated severe falciparum malaria.

Complicated/Severe Falciparum Malaria

The hallmark of Falciparum malaria is its severity and/or its complications. The various complications are:

• Cerebral malaria
• Anemia
• Hypoglycemia
• Acute renal failure
• Pulmonary edema
• Bleeding diathesis/DIC
• Hemoglobinuria
• Septicemia
• Shock
• Fluid, electrolyte and acid-base imbalance
• Hyperparasitemia
• Hyperpyrexia

Although general clinical features are the same as adult malaria, there are certain special features in children especially below the age of 5 years. In hyperendemic areas, children below the age of 2 months do not develop malaria because they have immunity transferred from the mother.

The following table gives the difference between severe malaria in children and adults.

(Ref: WHO Booklet)