Lymphatic Filariasis Lecture Notes PDF (BMS201)

BMS201 Lecture No: 5 Title: Lymphatic filariasis Wuchereria bancrofti and Brugia malayi Instructor Name: Prof. Khalifa E. Khalifa Medicine and Surgery Program Fall 2024 By the end of this lecture, you should be able to: 1. Categorize helminths...

BMS201 Lecture No: 5 Title: Lymphatic filariasis Wuchereria bancrofti and Brugia malayi Instructor Name: Prof. Khalifa E. Khalifa Medicine and Surgery Program Fall 2024 By the end of this lecture, you should be able to: 1. Categorize helminths and protozoa that inhabit blood, lymphatics, and macrophage phagocytic systems. 2. Describe the general character of filarial nematodes. 3. List filarial nematodes of lymphatic system. 4. Recognize adults and microfilariae of Wuchereria bancrofti and Brugia malayi from their morphological characters. 5. Describe life cycle, infective stage, mode of infection, and diagnostic stages of Wuchereria bancrofti and Brugia malayi. 6. Discuss the clinical manifestations of lymphatic filariasis with emphasis on the differences between bancroftian and Malayan filariasis. 7. Analyze and interpret the finding of case studies of lymphatic filariasis. 8. Outline the methods of diagnosis of lymphatic filariasis 9. Outline treatment and preventive measures of lymphatic filariasis. Blood, Lymphatics and Macrophage Phagocytic System Parasites Class Parasite System Helminths (Nematodes) Wuchereria bancrofti Lymphatic system Brugia malayi Protozoa (Hemoflagellates) Leishmania donovani Macrophage Phagocytic system of blood and viscera Protozoa (Hemofalgellates) Trypanosoma brucei spp. Blood outside RBCs and Lymphatics Trypanosoma cruzi Blood outside RBCs and intracellularly in tissue of mesenchymal origin) Protozoa (Apicomplexa) Plasmodium spp. Blood inside RBCs Babesia spp. Protozoa (Apicomplexa) Toxoplasma gondii Macrophage Phagocytic system and any nucleated cell Nematodes of Lymphatic System Wuchereria bancrofti Brugia malayi “Lymphatic filariasis” General Characters of Filarial Nematodes 1. They inhabit tissues (lymphatic system or subcutaneous tissue). 2. They have cylindrical esophagus. 3. They need an arthropod vector (intermediate host) for their transmission. 4. The female gives birth to elongated embryos (microfilaria). 5. The male is about 2-4 cm, and the female is double its size except female Onchocerca volvulus (25-50 cm). 6. They include nematodes of lymphatic system; Wuchereria bancrofti and Brugia malayi and nematodes of subcutaneous tissues; Loa loa and Onchocerca volvulus ( will be studied under Musculoskeletal and skin Module Wuchereria bancrofti Distribution: Tropical and subtropical areas e. g. Central and South America, coastal Asia and Africa. In Egypt It is found in the Nile Delta particularly on the eastern side of the Damietta branch, in Qalubiya, Sharkia and Dakahlia Governorates. Focal distribution is present in Giza, Cairo and Assiut. Habitat: Adults inhabit lymphatic tissues especially of lower limbs and external genitalia. Microfilariae are found in lungs by day and in blood by night. DH: Man is the only definitive host. Vector: Female Culex mosquito, rarely female Anopheles and Aedes in certain geographical areas. Morphology ▪ Male: 4 cm x 0.1 mm ▪ Female: 10 cm x 0.2 mm, ▪ Microfilariae: 280 x 8 µm, sheathed. The sheath is redundant especially at the ends; this allows the microfilaria to form graceful and smooth curves. The anterior end is rounded and blunt, the posterior end is pointed. Both ends are devoid of nuclei. Life cycle  Infective stage: Third stage filariform larva. Mode of infection: Bite of an infected female Culex. Filariform larva enter through the bite’s wound by its activity. It is not inoculated with saliva Mode of transmission: Cyclodevelopmental (2-3 weeks) one microfilaria changes into one filariform larva, i.e. change in morphology without increase in number. Diagnostic stage: Microfilaria in peripheral blood film Pathogenesis and clinical manifestations of bancroftian filariasis 1. Asymptomatic microfilaremia: Mostly found in endemic areas. This may last for months or many years during which microfilariae are discharged daily with no symptoms. Asymptomatic carriers are reservoir for ongoing infections 2. Acute inflammatory stage: This stage is due toxic products of adult worms with superimposed secondary bacterial infection. It is characterized by: i. Recurrent attacks of fever with lymphangitis and lymphadenitis (elephantoid fever). ii. Lymphangitis: affecting lymphatics of lower limbs which appear as red, swollen and tender streaks. Inflammation of the lymphatics of the male genitalia leads to funiculitis, epididymitis, orchitis iii. Lymphadenitis with enlarged tender lymph nodes of lower limbs and external genitalia. iv. By time, the attacks get milder and more spaced, but the affected part remains slightly swollen. 3. Chronic obstructive stage: i. The repeated attacks of lymphangitis leads to obstruction and and fibrosis of lymph vessels and nodes. Obstruction develops over several years. ii. Distension and varicosities of lymph vessels distal to obstruction site. iii. Rupture of distended lymphatics may occur in the scrotum (leading to hydrocele or chylocele), in the pelvis of the kidney (chyluria), in large vessels of the intestinal wall (chylous diarrhea) or vessels in the abdominal cavity (chylous ascites) iv. Elephantiasis - The lower extremities (one or both) and the external genitalia become swollen and elephantoid. Swelling is first pitting then become non-pitting due to connective tissue overgrowth stimulated by lymphatic stasis. - The skin is smooth at first, then it becomes thickened and fissured with secondary bacterial infection. Lymph may ooze from the skin. - Microfilariae are usually not present in blood Stage Clinical manifestations 1. Asymptomatic stage - Microfilaria in blood, no symptoms. 2. Acute inflammatory stage - Fever, lymphangitis, lymphadenitis. - Swollen glands, lymphatics, lower limb and genitalia. 3. Chronic obstructive stage - Elephantiasis. - Chyluria, chylocele. - Chylous diarrhoea, chylous ascites. - Microfilariae are usually absent in blood. Tropical Pulmonary Eosinophilia (TPE) Occult filariasis - It occurs in people living or visiting endemic filarious areas. - It is characterized by pulmonary symptoms (cough and asthmatic attacks), persistent hyper-eosinophilia and glandular enlargement but with no microfilariae in blood. - These symptoms are due to immune response against the microfilariae resulting in their destruction in the lungs. - The symptoms are relieved by filarial treatment using Diethylcarbamazine (DEC). - This can be used to differentiate TPE from Loeffler's syndrome in which no response to DEC is detected. Diagnosis 1. Clinical: lymphangitis and lymphadenitis, orchitis, chronic elephantiasis, chylocele or chyluria. 2. Laboratory a) Detection of microfilariae in blood specimens taken between 10 pm and 2 am by: Wet drop to detect living moving microfilaria. Thick and thin blood films stained with Giemsa. Membrane filtration technique b) Detection of circulating antigen ICT allows the detection of infection in a blood sample taken at any time of the day. c) PCR for the detection of parasite’s DNA in blood 3. Imaging techniques: US of scrotum or breast may reveal the adults inside lymphatic with their characteristic movement (Filarial dance) Treatment 1. Anti filarial drugs a) Diethylcarbamazine (DEC) Hetrazan Drug of choice. It is an effective microfilaricidal but eliminates the adult worms slowly. b) Ivermectin: It is effective against microfilaremia but does not kill the adult worm. It can be combined with albendazole for better results. c) Doxycycline: to kill the bacterial endosymbiont, Wolbachia, present in adults and microfilariae. This endosymbiont is essential for adult worms’ viability and fertility and for the development of microfilariae. 2. Antibiotic for septic complications. 3. Antihistaminics. 4. Surgical intervention in cases of elephantiasis. Prevention and Control 1. Control of mosquitoes: anti-mosquito measures by determination of mosquito vectors in the locality, destruction of breeding places and the use of insecticides and repellents. 2. Control of human sources: treatment of patients, DEC can be safely added to the table salt. Ivermectin can be given in a single dose. 3. Large scale annual treatment with single dose of Ivermectin and Albendazole has been adopted in endemic area to clear and prevent spread of infection. A case of chronic obstructive filariasis A 37-year-old male farmer from Shakya governorate presented to the hospital with swollen scrotum and right lower limb. The patient stated that the condition started five years earlier with recurrent attack of fevers rigors, severe pains in the scrotum with redness, hotness and swelling of his right lower limb that remains for few days and resolves with antibiotics and anti- inflammatory. Few months earlier he noticed that the swollen limb did not return to its normal size with some skin changes, he also noticed that the scrotum became swollen. On Examination the patient was normal except for non-pitting lymphedema of the right lower limb with thickened wrinkled skin and enlarged femoral lymph nodes. CBC revealed normal findings. US examination of the scrotum revealed fluid collection around the testis with thickened spermatic cord. Lymphangiography revealed obstructed lymphatics of the right lower limb. Lymphatic filariasis was suspected. No microfilaria was found in repeated blood samples taken between 10 pm and 2 am. Serum examination by ICT revealed the presence of filarial antigen. PCR examination of a blood sample for Wuchereria bancrofti DNA gave positive result. The patient was treated with Doxacyline and Diethylcarbamazine and advised to take care of cleanliness of his limb to avoid skin infection. Brugia malayi Distribution: India and the Far East Habitat: Adults inhabit lymphatic tissues of lower limbs limbs. DH: Man. RH: Monkey and cats (make control more difficult than W. bancrofti Vector: Mansonia spp. Morphology: Adults are similar to W. bancrofti but smaller Microfilaria is similar to W. bancrofti. The posterior end is pointed with two nuclei, the distal is big extending to tail, the proximal one is smaller. Life cycle: As W. bancrofti Malayan filariasis Infective stage: Third stage filariform larva Mode of infection: Bite of infected female Mansonia spp. Disease: Lymphangitis and elephantiasis most commonly in legs below the knees. Genitalia are less affected than in W. bancrofti. Diagnosis, treatment, prevention and control: As W. bancrofti Microfilaria of B. malayi In class assessment A) Give Reason: 1. Timing of blood sampling is important for laboratory diagnosis of bancroftian filariasis 2. Doxycycline is important adjuvant therapy for anti filarial drugs 3. Cases of Malayan filariasis are more difficult to control than bancroftian filariasis. B) Discuss the clinical manifestations of chronic obstructive filariasis BMS201 Lecture No: 6 Title: Toxoplasma gondii and toxoplasmosis Instructor Name: Prof. Khalifa E. Khalifa Medicine and Surgery Program Fall 2024 By the end of this lecture, you should be able to: 1. Describe the different morphologic forms of Toxoplasma gondii. 2. Describe life cycle, infective stages, mode of infection, and diagnostic stages of Toxoplasma gondii. 3. Discuss the clinical manifestations of toxoplasmosis in congenitally infected, immunocompetent and immunosuppressed patients. 4. Analyze and interpret the finding of case studies of toxoplasmosis. 5. Outline the diagnostic methods of toxoplasmosis. 6. Interpret the results of serological assays of toxoplasmosis. 7. Outline treatment and preventive measures of toxoplasmosis. Blood, Lymphatics and Macrophage Phagocytic system Parasites Class Parasite System Nematodes Wuchereria bancrofti Lymphatic system Brugia malayi Protozoa (Hemoflagellates) Leishmania donovani Macrophage Phagocytic system of blood and viscera Protozoa (Hemofalgellates) Trypanosoma brucei spp. Blood outside RBCs and Lymphatics Trypanosoma cruzi Blood outside RBCs and intracellularly in tissue of mesenchymal origin) Protozoa (Apicomplexa) Plasmodium spp. Blood inside RBCs Babesia spp. Protozoa (Apicomplexa) Toxoplasma gondii Macrophage Phagocytic system and any nucleated cell Toxoplasma gondii “Toxoplasmosis” Toxoplasma gondii Distribution: Worldwide DH: Cats and other felines harbor asexual and sexual stages. (asexual and sexual cycles in intestine, asexual cycle in tissues) IH: Rodents (asexual cycle in tissues) Accidental (nonspecific host): All mammals including man, domestic and farm animals, birds and reptiles (asexual cycle in tissues). Habitat: obligate intracellular parasite, it can invade any nucleated cell. Morphology 1. Trophozoites: 4-6µ x 2-3 µ, crescent or ovoid in shape with central nucleus. 2. Pseudocysts: when the trophozoites invade any cell, they multiply rapidly (tachyzoites) inside it giving a cell containing up to 100 tachyzoites know as pseudocyst. It has not a true cyst wall 3. Tissue cysts: has a true cyst wall, 10-200 µ containing up to 60000 bradyzoites, It might be present in any tissue but mostly present in muscle and nervous tissue. They are formed 1-2 weeks after infection with development of immune response and may persist for life. 4. Oocyst: 9 x12 µ, shed with the stool of cats, It is immature, non- infective when freshly passed. It needs 1-5 days for sporulation to give the infective sporulated oocyst (disporocystic-tetrazoic oocyst )  Bradyzoites tachyzoites Pseudocyst Tissue Cyst  Life Cycle Extraintestinal cycle in IH: asexual reproduction by endodyogony and Intestinal cycle in cat: pologony which Schizogony followed end in formation by gametogony and of pseudocysts formation of zygote and true cyst after and oocyst that pass development of with stool of cat immunity  Infective stage: All morphologic forms Mode and source infection: 1. Congenital: transplacental route from mother to the fetus 2. Acquired 3. Ingestion of Oocysts in food or drinks contaminated by excreta of cats. 4. Ingestion of tissue cyst in undercooked meat 5. Organ transplantation (lung, heart, bone marrow). 6. Blood transfusion (rare). Clinical manifestations of toxoplasmosis: Congenital: Infection must occur during pregnancy to be transmitted from mother to fetus. Infections occurring early during 1st or 2nd trimesters might result in abortions. Infections occurring late might (in 10-25%) results in congenital malformations as - A typical triad of hydrocephalus or microcephalus, intracranial calcifications and mental retardation + chorioretinitis (dd TORCH) - Neonatal jaundice, hepatomegaly. - Neonatal convulsions. - Chorioretinitis and blindness (early adulthood). Clinical manifestations (cont.): Acquired: Immunocompetent - Asymptomatic or Flu-like. - Maculopapular rash (typhus-like). - Lymphadenopathy (Infectious mononucleosis-like). - Fever of unknown origin. Immunosuppressed (new or reactivated). - Major opportunistic pathogens - Encephalitis, meningitis, brain abscess (50 % of AIDS), pneumonia, myocarditis. Chorioretinitis Hydrocephalus Diagnosis 1. Clinical diagnosis: depends on history and clinical manifestations. 2. Laboratory diagnosis: - Detection of different classes of anti-toxoplasma antibodies (IgG, IgM, IgA) by IHA, ELISA, IFAT, Sabin-Feldman dye test. - IgG Avidity ELISA to differentiate between acute and chronic infections in pregnant women - Isolation of the parasite from tissue or body fluids by mouse inoculation or tissue culture - Detection of antigen in tissue or body fluid. - Detection of parasites’ DNA in tissue or body fluid by PCR 3. Imaging techniques: X-Ray, US, MRI, CT to detect intracerebral calcification, brain abscess and other complications Interpretation of serological results Interpretation of serological results 1. IgG, IgM and IgA antibodies are formed soon after exposure and rise to a peak within few weeks of active infection. 2. IgG remains positive for life. IgM and IgA gradually fall with treatment or as parasites start to become encysted in the tissues. IgM may remain positive for more than one year 3. A high IgG titer does not always indicate active acute infection, but a rising titer within 2-3 weeks is diagnostic of activity. 4. Evidence of an acute infection is based on high IgM titers and/or significant increase in IgG antibody titers in addition to symptoms. So pregnant women with positive anti- toxoplasma IgG and IgM doesn’t indicate active infection, she should be followed for rising IgG antibody titer 5. Maternal IgG crosses the placenta to fetus and therefore their presence is not a marker for transmission of infection. On the other hand, specific IgM and IgA are manufactured by the fetus in response to active infection and are therefore important markers of infection in the newborn. Treatment 1. Pyrimethamine (Daraprim): 25-50mg orally/day for one month + Triple sulfa 2-6 g daily for one month + Folinic acid 2. Spiramycin (Rovamycin) antibiotics: For pregnant females during first trimester, 2-3 g tds for 3-4 weeks to be repeated every 2 weeks. 3. Corticosteroids: Are given in ocular toxoplasmosis to minimize the inflammatory reaction. Prevention and control 1. Avoiding the contamination of hands foods and water with cat feces. 2. Pregnant females should avoid cats. 3. Avoid eating improperly cooked meat. Freezing of meat for 3 weeks kill tissue cysts. 4. All newly married females should be tested for toxoplasmosis before pregnancy. A case of toxoplasma encephalitis A 24-year-old Brazilian woman was admitted to the hospital complaining of headache and vomiting for 15 days with history of loss of weight of 15 Kg over 6 months. Three days before admission, the patient developed generalized seizure followed by altered state of consciousness. The general physical examination was normal. The neurological examination revealed drowsiness but no focal deficits, cranial nerve palsies or meningism. After admission, the level of consciousness worsened. MRI examination of revealed findings suggestive of toxoplasmosis. A HIV test was done and found positive. CD4+ T lymphocyte count was 65 cells/mm3. Serum anti- toxoplasma IgG were positive. Treatment with pyrimethamine + sulphadiazine + corticosteroid + anti-retroviral therapy was started. Few days later a lumbar puncture was performed, CSF examination for bacteria, mycobacterium and fungal were negative. The CSF PCR for Toxoplasma gondii was positive. 6 weeks after therapy a follow up MRI showed significant improvement. The toxoplasmosis therapy was maintained for eight weeks followed by secondary anti-prophylaxis In class assessment A) Give Reason: 1. Pregnant women should wear gloves while cutting meat. 2. Toxoplasma gondii is an opportunistic parasite. B) Enumerate clinical manifestations of congenital toxoplasmosis References: 1. Markell and Voge's Medical Parasitology: by John , Petri (Elsevier; 10th edition). 2. Diagnostic Medical Parasitology: by Garcia (American Society for Microbiology; 6th edition, 2016). 3. Textbook of Medical Parasitology: by CK Jayaram Paniker (Jaypee; 8th edition, 2017) 4. Human Parasites: Diagnosis, treatment, prevention: By Melhorn (Springer, 2016) 5. Laboratory for Identification of Parasites of Public Health Concern, Centers for Disease Control And Prevention (http://www. cdc.gove/dpdx/ THANK YOU