Introduction
Kala-azar or visceral leishmaniasis (VL) is caused by obligate intracellular protozoan of genus Leishmania.1,2 The Indian kala-azar is caused by L donovani=1,2 L infantum causes VL in Mediterranean basin, and L chagasi in Central and South Africa.1,2
The disease is transmitted by sand fly which inoculates the flagellated promastigotes into the skin of the human host. These promastigotes are taken up by macrophages or dendrite cells and transformed into aflagellar amastigotes. The parasites are then disseminated to the reticuloendothelial system, and produce a systemic disorder with prolonged irregular pyrexia, darkening of skin, weight loss, splenomegaly and hepatomegaly, progressive anemia, pancytopenia along with hyper-gamma-globinemia. Untreated, the disease has high mortality.1,2 Malnutrition and immunocompromised state (e.g. HIV-infection) add to seriousness of the disease and death-rate.1,2 According to Alencar et al,3 VL was first described in Greece in 1835 and subsequently in India in 1882.3 Laveran and Mensil identified the parasite in 1903 in the material provided by Leishman and Donovan. In honour of Leishman the disease is called Leishmaniasis and the parasite is known as Leishman-Donovan body (LD body).4
Prevalence of VL in India
The annual incidence of VL in India is approximately 100,000 cases and our state of Bihar accounts for 90 percent of cases.2 HIV-Leishmania is an emerging disease in Bihar also.14
Kala-azar in Pregnancy
Normal pregnancy is accompanied by changes in immune response, mainly a decrease in cellular immunity and a proportional increase in humoral immunity. These physiological events result in an increase in the risk for infections caused by some parasitic agents whose immunity is based on a T-helper cell-1 response.5 On the basis of this immunological evidence, the risk of VL during pregnancy is higher.5 But Pagliano et al5 have quoted their epidemiological data to show that, at least in Italy, pregnancy per se does not increase the risk of VL. During pregnancy, the disease can produce abortions and may be life threatening for the mother and may have consequences for the fetus like in-utero death, and birth of small for date baby. Hence, VL in pregnancy warrants urgent treatment.5 However, genuine concerns can be entertained about the deleterious effects of the drugs on the fetus.
Vertical Transmission1: Transplacental or vertical transmission of leishmaniasis has been studied experimentally on mice and dogs.6,7
Transplacental transmission of LD bodies leading to congenital VL in humans has been reported from India, Kenya, Sudan, France, Germany, and England in untreated pregnant patients suffering from VL.
Clinical Features of VL
Though clinical manifestations of VL in pregnancy by and large do not differ from those of VL in non-pregnant women, many infected individuals show the inapparent or oligosymptomatic form of the disease and the number of severe cases or cases with clinical manifestations is relatively small.1 Causes of death in patients with VL generally include associated infections due to physical and immunological debilitation, and hemorrhages due to thrombocytopenia. Didactically, VL in pregnancy can be classified into several categories.45
- Inapparent: Patients with positive serology or detectable parasites in splenic or bone-marrow aspirate.
- Oligosymptomatic: Low grade fever, hepatosplenomegaly, cachexia are present but there are no hemorrhagic manifestations.
- Acute: The onset can be abrupt or insidious. In most cases fever is the first symptom, and can be high and continuous or intermittent. Hepatosplenomegaly, weight loss, anemia and hyperglobinemia are present.
- Classic: Slow onset of disease with irregular fever, asthenia, anoerexia, weight loss, cachexia, pedal edema marked hepatosplenomegaly, hair loss, generalized micro-lymphadenopathy, gingival bleeding, epistaxis, ecchymoses, petechie, purpura, and pancytopenia with lymphocytosis and hypoalbuminemia.
- Refractory: The disease does not respond to known anti-kala-azar drugs.
Laboratory Diagnosis
- Findings on peripheral blood count has already been alluded to earlier in classical VL (category D).
- Definitive diagnosis is by demonstration of parasite (LD bodies) in splenic aspirate or bone-marrow smear with Giemsa or Leishman staining. The diagnostic yield of bone marrow aspirate examination is 60–80 percent.2 The sensitively of splenic aspirate is around 95 percent2 and is the gold standard for diagnosis of VL. But if the patient has advanced pregnancy, this procedure will have to be done under ultrasound scan guidance, and only if prothrombin time1 is not more than 5 seconds above control and platelet count is not less than 40,000/ml.1 Risk of hemorrhage is deterrent to this procedure, and it requires training and expertise of the pathologist. Bone marrow aspiration is easier in pregnancy either from iliac crest or sternum. Both these procedures are examiner dependent.6LD bodies appear as round or oval bodies inside monocytes and macrophages, with pale blue cytoplasm, large red nucleus with deep red or violet rod-like body called kinetoplast set at right angle to the nucleus. Recognition of the parasite requires experience and diligent search.
- Serological tests:1 The specific diagnostic test utilizes leishmania antigen to detect antibodies. Four such tests are available.
- DAT:1,2 Direct Agglutination Test is a highly sensitive and specific technique, for diagnosis of VL. It uses trypsinized whole promastigotes as antigen. Agglutination is observed after overnight incubation of patient's serum. Only freeze dried antigen must be used. The process, however, is cumbersome and needs refrigerator. Hence, it is not an ideal method for diagnosis in remote areas.
- Antigen detection:8 A latex agglutination test (KATEX) for detecting leishmanial antigen in urine of patients with VL has 68–100 percent sensitivity and 100 percent specificity.
- Molecular diagnostic technique:1,2 The detection of DNA of LD bodies in peripheral blood has 96 percent sensitivity and 100 percent specificity. This polymerase chain reaction (PCR) test is emerging as a non-invasive tool for diagnosis of VL but technical skill, expertise and a well-equipped laboratory are required.
Older tests like Aldehyde test, Chopra Antimony test and Napier formal-gel test lack specificity and are unreliable and hence should no longer be used.
Culture of blood in Novy-McNeal-Nicolle Medium (NMN Medium) and animal inoculation in golden-hamster are methods to demonstrate parasite but are seldom used outside research laboratories.1
Skin testing:2 Leishmanian skin test (Montenegro skin test) is a test for delayed hypersensitivity specific to LD bodies but has a limited role in diagnosis.
Anti-VL Treatment
Can Anti-VL Treatment be Started on Serological Tests Alone?
Through personal communication with Prof TK Jha, Medical Director, Kala-azar Research Centre, Muzaffarpur, the author has gathered information that if demonstration of LD bodies are not possible due to lack of expertise and facility in peripheral areas, one can start treatment if strip test (rk-39) is positive.
Management of VL in Pregnancy
Correct diagnosis is a must before specific anti-VL treatment is started.
General management includes rest, nutritious food, and treatment of anemia and thrombocytopenia with blood transfusion and platelet transfusion respectively. Suitable antibacterial agents for associated bacterial infections should be used.
Specific Anti-VL Therapy
The drug of choice is Paramomycin (Aminosidin)1,2 for pregnant patients. Pivotal phase III trial2 has been completed in India (mainly Bihar and UP).8
Dose is 15 mgm/kg/day by IM route for 21 days. The drug is now licensed for VL and is available in India. Phase II and III multicenter randomized controlled trials conducted in Bihar on VL patients have shown a cure rate of more than 90–95 percent at 180 days follow-up.
It has efficacy similar to amphotericin B and miltefosin and is affordable.
The drug has been developed by the Institute for One World Health in collaboration with the Indian Council of Medical Research (ICMR). Precautions to be observed in its use are same as for any aminoglyceride viz. monitoring of renal and otic system (effects on 8th cranial nerve). It should not used in the first trimester unless the risk to mother due to VL is quite high.
Amphotericin B
Though very effective drug, it can produce hyperpyrexia which needs to be prevented by prior corticosteriod and antihistaminic (in my experience), if abortion is to be avoided. It requires hospitalization,1 and is given by IV infusion in 5 percent glucose and not in normal saline,1 in a dose of 0.75 mgm/kg to 1 mgm/kg body weight daily or on alternate days. High cure rates of 100 percent has been achieved. Pagliano et al and Figueiro-Filho et al have shown it as safe for mother and fetus. Though it crosses placenta, the concentration in fetus is too low to be harmful. As it produces azotemia, hypokalemia, renal tubular acidosis, anemia and myocarditis, close monitoring is required.2
Lipid Formulation of Amphotericin B
Lipid formulation of Amphotericin B is far better and safer (but costlier) for pregnant patients. It is taken up by macrophages in liver, spleen and bone marrow where LD Bodies are housed. This is a method of targeted drug-delivery systems. Three formulations available are: Liposomal Amphotericin B 9(AmBisome), Amphotericin B Cholesterol Dispersion (ABCD), Amphotericin B Lipid Complex (ABLC Abelcet). Although overall cure rates are similar (Amphotericin B-conventional 96%; AmBisome 96%; ABLC 92%), the safest is AmBisome.
Dose: Dose of 0.75, 1.5 and 3.0 mgm/kg body weight given on 5 consecutive days have cured 89, 93 and 97 percent patients respectively even in refractory cases. Cost, however, even of single dose therapy of 6 mgm/kg, is exorbitant and not within reach of most patients.
Pentavalent antimonials (Sodium Antimony gluconate and meglumine antimoniate) are not recommended in Indian pregnant patients. Besides being cardiotoxic (various types of cardiac arrhythmia and even fatal Torsades-de-pontis), it causes hepatotoxicity, nephrotoxicity and pancreatitis.2
Opinion is divided4 among clinicians outside India, about its mutagenic, carcinogenic and teratogenic risks. Some workers feel their usage during pregnancy may not cause important maternal-fetal injury.4 However, with the advent of Amphotericin B, Liposome of Amphotericin B and aminosidin, the author does not recommend pentavalent antimony in pregnancy.1
What About Oral Anti-VL Drugs?
- Miltefosine:2 Through this drug is highly effective against VL, it cannot be advocated for pregnant women as it has been found to be teratogenic in rats. This drug should not be used in female patients whose adequate contraception cannot be assured for the duration of pregnancy. Females treated with this drug should not become pregnant for 3 months after completion of treatment.
- Sitamaquine (WR-6026):2 This primaquine analog, developed by the Walter Reed Army Institute of Research, 10has been administered orally in doses of 1.75 mgm/kg and 2.0 mgm/kg daily with a cure rate of 89 and 100 percent respectively depending on the dose after 28-day therapy in phase II trials in India. A dose 2.0 mgm/kg/day may induce nephropathy and monitoring of renal function is mandatory. Till safety of this drug in pregnancy is established, in phase III trials, it cannot be recommended for pregnant patients at present.
Anti-VL Drugs and Breastfeeding
Amphotericin B is safe for babies on breastfeeding.4 If Antimony is used during lactation period, the newborn should be breast-fed 5–6 hours after drug administration to the mother.4
Combination Therapy9
It should not be forgotten that LD bodies may develop resistance to anti-VL drugs. This has been shown in trials conducted in India, especially Bihar in case of Pentamidine and Antimonials. Oral drug Miltefosine is also not free from this catastrophe if used indiscriminately and in suboptimal doses. However, so far the pregnant subjects of VL are concerned, the resistance of LD bodies to these drugs does not matter as they are not to be used in pregnancy anyway. But with paramomycin, which is an aminoglycoside, acquired resistance is likely to occur if used as monotherapy. As in the case of tuberculosis, leprosy and even malaria, combination of two effective anti- leishmanial agents is a desirable option in VL.9 Combination therapy is a must for treating pregnant ladies suffering from VL with HIV/AIDS. Combination of Liposomal Amphotericin B (AmBisome) with Paramomycin may be an option. Immunotherapy with exogenous Th-1 stimulating cytokines or use of anti-leishmanial vaccine in combination with a potent and safe-for-pregnancy anti-leishmanial drug is a future option, but this at present is in the domain of further research.911
Summary
VL in pregnancy is a serious illness with high mortality if untreated. Fortunately, recent epidemiological data do not suggest increased risk of developing VL in pregnancy. Demonstration of LD bodies in splenic aspirate, bone marrow and buffy coat of blood confirms diagnosis, but need expertise. Best diagnostic yield is by examination of splenic aspirate. Of the serological tests, the best is rk-39 strip test. PCR of blood may be highly diagnostic but is costly and needs advanced laboratory and expertise.
Only Liposomal or other lipid formulations of Amphotericin B and paramomycin are safe in pregnancy. Combination therapy may be needed to thwart risk of drug resistance.
Vaccine against VL has not been developed. Anti-sand fly measures are a must, but this is outside the realm of this review article.
References
- Agrawal S, Rai M, Sundar S. Management of visceral leishmaniasis: Indian perspective. J Postgrad Med 2005; 51(Suppl 1):553–7.
- Sunder S, Chakravarty J, Chauhan B. Kala-azar: Current Perspective. In: Agrawal AK, Jain DG (Eds): Clinical Medicine Update 2006, A publication of Indian Association of Clinical Medicine. Jaypee Brothers Medical Publishers (P) Ltd. New Delhi 2006;9:420–4.
- Alencar JE, Neves J, Dietze R. Leishmaniose Visceral (Calazar). In: Veronesi R, Dietze R, Foccaccia R (Eds): Tratado de Infectologia, 9th edn. Atheneu Sao Paulo: 1997.
- Figueiro-Filho EA, Duarte G, El-Beitune, Quintana SM, et al. Visceral leishmaniasis (Kala-azar) and pregnancy. Infect Dis Obstet Gynaecol 2004;12:31–40.
- Pagliano P, Carannante N, Rossi M, Gramiccia M, et al. Visceral leishmaniasis in pregnancy: A case series and a systemic review of the literature. J Anti-micro Chemo 2005;55:229–33.
- Nuwayri-Salti N, Khansa HF. Direct non-insect-vector transmission of Leishmania parasite in mice. Int J Parasitol 1985;15:497–500.
- Attar ZJ, Chance ML, el-Safi, et al. Latex agglutination test for the detection of urinary antigens in visceral leishmaniasis. Acta Trop 2001;78:11–6.
- Jha TK. Drug unresponsiveness and combination therapy for kala-azar. Indian J Med Res March 2006;123:389–98.