Histopathological findings in mini-pigs infected with different strains of Trypanosoma brucei.

Two pigs infected with Trypanosoma brucei gambiense developed low parasitemia which became undetectable after 6 months; on autopsy 13 months after infection they showed no histopathological alterations. --Five of six pigs infected with a Trypanosoma brucei brucei strain from the Ivory Coast developed low parasitemia (up to about antilog 6.5 per ml of blood) which became progressively lower but was detectable up to one year after infection. On autopsy they showed interstitial myocarditis and meningo-encephalitis; during the course of the infection, the first became milder, the second more intense; no trypanosomes were seen in the tissues. One of these pigs developed a parasitemia of up to antilog 8 and died 172 days after infection from bacterial pneumonia, histologically it had severe myocarditis with many trypanosomes in the tissue and mild meningo-encephalitis. --Three pigs infected with a Trypanosoma brucei brucei strain from the Serengeti died 47, 68, 130 days after infection. The first dying pig had a high terminal parasitemia, in the others, the parasitemia was low until the end, being only detectable by the hematocrit centrifugation technique or by mouse passage. At autopsy, all showed massive myocarditis and interstitial nephritis with masses of extravascular trypanosomes, moderate meningo-encephalitis with very few trypanosomes, and widespread colonization of other organs and tissues by trypanosomes, still without marked cellular infiltrations.